System and method for distributed computation based upon the movement, execution, and interaction of processes in a network

Abstract

A distributed computing environment in which agent processes direct their own movement through a computer network. Place processes provide a computing context within which agent processes are interpreted. An agent process controls its movement from one place process to another within the network by using a ticket. An agent process which moves from one place process to another transports definitions of classes of which objects included in the agent process are members. An agent process which moves from one place process to a second place process avoids unnecessary transportation of objects included in the agent process by substituting equivalent objects which are found in the second place process. An agent process sends clones of the agent process to several place processes simultaneously. If two clones travel along paths which are coextensive for an initial portion thereof, a single clone is transported along the initial portion of the paths and other clones are formed from the single clone, thereby avoiding transferring redundant information along communications media. Two agent processes, which occupy a single place process, interact by exchanging references to one another. The single place process ensures that neither agent process receives a reference to the other agent process without simultaneously giving to the other agent process a reference to the former agent process. Unauthorized or inadvertent excessive use of network resources by an agent process, or a place process, is prevented by associating with each process a permit which defines various capabilities and resource allowances of the process.

Claims

What is claimed is:

1. A method for implementing remote programming in a computer network comprising:

defining a plurality of object-oriented classes including an agent class and a place class;

forming instructions for a computer process, said instructions including said object-oriented classes, subclasses of said object-oriented classes, and a go operation; and

interpreting said instructions on a processor in said computer network wherein, in response to said go operation, an agent process is transported to a place process and further wherein said agent process is a member of said agent class and said place process is a member of said place class.

2. The method for implementing remote programming in a computer network as in claim 1 further comprising forming said go operation within said agent process.

3. The method for implementing remote programming in a computer network as in claim 1 further comprising forming a subplace of said place process wherein said subplace is a member of said place class and said place process is a superplace of said subplace.

4. The method for implementing remote programming in a computer network as in claim 1 further comprising designating said agent process as an owner of an object.

5. The method for implementing remote programming in a computer network as in claim 4 further comprising forming within said object a digest.

6. The method for implementing remote programming in a computer network as in claim 5 further comprising interchanging for said first-mentioned object a second object at said place process wherein said second object has a second digest equivalent to said first-mentioned digest and further wherein said first object is not transported to said place process.

7. The method for implementing remote programming in a computer network as in claim 1 further comprising specifying said place process by a ticket means.

8. The method for implementing remote programming in a computer network as in claim 7 further comprising forming said ticket means within said agent process.

9. The method for implementing remote programming in a computer network as in claim 7 further comprising forming within said ticket means an address of said place process.

10. The method for implementing remote programming in a computer network as in claim 9 wherein said address is a teleaddress.

11. The method for implementing remote programming in a computer network as in claim 7 further comprising forming within said ticket means a name of said place process.

12. The method for implementing remote programming in a computer network as in claim 11 wherein said name is a telename.

13. The method for implementing remote programming in a computer network as in claim 1 further comprising:

defining a class of class objects;

forming a class object, wherein said class object (i) is a member of said class of class objects, and (ii) defines a first class which is a subclass of a selected one of said object-oriented classes; and

forming an object, said object being a member of said first class;

wherein said agent process owns said object; and transportation of said agent process to said place process comprises transporting said object and said class object to said place process.

14. A method for implementing remote programming in a computer network comprising:

defining a plurality of object-oriented classes including an agent class and a place class;

forming instructions for a computer process including said object-oriented classes, subclasses of said object-oriented classes, and a send operation; and

interpreting said instructions on a processor in said computer network wherein, in response to said send operation, a clone Of an agent process is transported to a place process and further wherein said clone and said agent process are each a member of said agent class and said place process is a member of said place class.

15. The method for implementing remote programming in a computer network as in claim 14 further comprising forming said send operation within said agent process.

16. The method for implementing remote programming in a computer network as in claim 14 further comprising forming a subplace of said place process wherein said subplace is a member of said place class and said place process is a superplace of said subplace.

17. The method for implementing remote programming in a computer network as in claim 14 further comprising designating said agent process as an owner of an object.

18. The method for implementing remote programming in a computer network as in claim 17 wherein transportation of said clone comprises transporting a copy of said object to said place process.

19. The method for implementing remote programming in a computer network as in claim 18 further comprising forming within said object a digest.

20. The method for implementing remote programming in a computer network as in claim 19 further comprising interchanging for said copy a second object, which is different from said first-mentioned object, at said place process wherein said second object has a second digest equivalent to said first-mentioned digest and further wherein said copy is not transported to said place process.

21. The method for implementing remote programming in a computer network as in claim 14 further comprising specifying said place process by a ticket means.

22. The method for implementing remote programming in a computer network as in claim 21 further comprising forming said ticket means within said agent process.

23. The method for implementing remote programming in a computer network as in claim 21 further comprising forming within said ticket means an address of said place process.

24. The method for implementing remote programming in a computer network as in claim 23 wherein said address is a teleaddress.

25. The method for implementing remote programming in a computer network as in claim 21 further comprising forming within said ticket means a name of said place process.

26. The method for implementing remote programming in a computer network as in claim 25 wherein said name is a telename.

27. The method for implementing remote programming in a computer network as in claim 14 further wherein, in response to said send operation, a second clone of said agent process is transported to a second place process wherein said second clone is a member of said agent class and is distinct from said first-mentioned clone and further wherein said second place process is a member of said place class.

28. The method for implementing remote programming in a computer network as in claim 27 further comprising:

determining that transportation of said first clone to said first place process and of said second clone to said second place process requires transportation of said first and second clones to a single computer of a plurality of computers of said computer network;

transporting said first clone to said single computer; and

forming, in said single computer, said second clone from said first clone.

29. The method for implementing remote programming in a computer network as in claim 28 further comprising:

transporting said first clone from said single computer to said first-mentioned place process; and

transporting said second clone from said single computer to said second place process.

30. A method for interprocess communication in a computer comprising:

defining a plurality of object-oriented classes including an agent class;

forming instructions for a computer process including said object-oriented classes, subclasses of said object-oriented classes, and a meet operation; and

interpreting said instructions on a processor in said computer network wherein, in response to said meet operation, a meeting place process provides a first agent process access to a second agent process and provides said second agent process access to said first agent process and further wherein said first and second agent processes are members of said agent class.

31. The method for interprocess communication in a computer as in claim 30 wherein said meeting place process is a member of a place class in said plurality of object-oriented classes and further wherein said first and second agent processes occupy said meeting place process.

32. The method for interprocess communication in a computer as in claim 31 further comprising forming a second place process wherein:

said second place process is a member of said place class;

said second place process is a subplace of said meeting place process; and

said meeting place is a superplace of said second place.

33. A method for controlling movement of processes in a computer network, said method comprising:

defining a plurality of object-oriented classes including an agent class, a place class, and a ticket class;

forming a plurality of place processes in said computer network wherein each of said plurality of place process is a member of said place class;

forming an agent process wherein said agent process is a member of said agent class and occupies a first place process in said plurality of place processes; and

forming a ticket wherein said ticket is a member of said ticket class and defines a trip involving the movement of said agent process from said first place process to a second place process in said plurality of place processes.

34. A method for limiting capabilities of processes in a computer network, said method comprising:

defining a plurality of object-oriented classes including a process class and a permit class;

forming a process wherein said process is a member of said process class; and

forming a permit wherein said permit is a member of said permit class and specifies one or more capabilities of said process.

35. The method as in claim 34 further comprising:

defining within said process class a go operation; and

specifying within said permit whether said process is capable of performing said go operation.

36. The method as in claim 34 further comprising:

defining within said process class a send operation; and

specifying within said permit whether said process is capable of performing said send operation.

37. The method as in claim 34 further comprising:

defining within said process class a charge operation; and

specifying within said permit whether said process is capable of performing said charge operation.

38. The method as in claim 34 further comprising:

defining within said process class a terminate operation; and

specifying within said permit whether said process is capable of performing said terminate operation.

39. The method as in claim 34 further comprising specifying within said permit whether said process is capable of creating a second process, different from said first-mentioned process, wherein said second process is a member of said process class.

40. The method as in claim 34 further comprising:

defining an object-oriented place class; and

specifying within said permit whether said process is capable of creating members of said place class.

41. The method as in claim 34 further comprising specifying within said permit whether said process is restarted upon failure of said process.

42. The method as in claim 34 further comprising specifying within said permit an amount of processing that is allotted to said process.

43. The method as in claim 34 further comprising specifying within said permit a time at which said process is terminated.

44. The method as in claim 34 further comprising:

defining within said process class a restrict operation;

forming instructions for a computer process, said instructions including said classes, subclasses of said classes, and said restrict operation;

interpreting said instructions on a processor in said computer network wherein, in response to said restrict operation, a second permit, which is different from said first-mentioned permit, is formed and further wherein said second permit is a member of said permit class and specifies a group of one or more capabilities of said one or more capabilities of said process; and

restricting said process to said group of one or more capabilities specified by said second permit.

45. In a computer, a method of interpreting processes of various versions of an instruction set, said method comprising:

defining a plurality of object-oriented classes including a class of classes and a class of citations;

forming one or more class objects wherein said class objects are members of said class of classes;

forming within a first of said class objects a citation wherein said citation specifies said first class object and specifies which of said class objects are backward compatible with said first class object.

46. In a computer network having a plurality of computers, a communication process comprising:

providing a plurality of place processes within said computer network wherein each place process is a locale in one of said computers for zero or more agent processes;

specifying, by a ticket means, a trip for an agent process to a destination place process in said plurality of place processes; and

transporting, in response to a send operation within said agent process, a clone of said agent process to said destination place process.

47. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising specifying, by a second ticket means, a second trip, which is different from said first-mentioned trip, for said agent process to a second destination place process in said plurality of place processes.

48. In a computer network having a plurality of computers, the communication process as in claim 47 further comprising:

determining that said first-mentioned clone, in taking said first trip, and a second clone, in taking said second trip, are both to be transported to a single computer of said computers;

moving to said single computer said first clone; and

forming within said single computer said second clone from said first clone.

49. In a computer network having a plurality of computers, the communication process as in claim 48 further comprising transporting said first clone to said first-mentioned destination place process.

50. In a computer network having a plurality of computers, the communication process as in claim 48 further comprising transporting said second clone to said second destination place process.

51. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising transporting, in response to a go operation within said agent process, said agent process to said destination place process specified by said ticket means.

52. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising specifying said destination place process by a name within said ticket means.

53. In a computer network having a plurality of computers, the communication process as in claim 52 wherein said name is a telename.

54. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising specifying said destination place process by an address within said ticket means.

55. In a computer network having a plurality of computers, the communication process as in claim 54 wherein said address is a teleaddress.

56. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising specifying, within said ticket means, said destination place process by a Citation of a class of which said destination place process is a member.

57. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising specifying, within said ticket means, said destination place process by any combination of an address of said destination place process, a name of said destination place process, and a citation of a class of which said destination place process is a member.

58. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising specifying, within said ticket means, a maximum time period for said trip.

59. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising specifying, within said ticket means, a desired time period for said trip.

60. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising specifying, within said ticket means, a transportation means wherein said transportation means specifies a type of intercomputer communications means by which said clone is transported.

61. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising controlling, with a destination permit contained in said ticket means, a deadline for said agent process at said destination place process.

62. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising controlling, with a destination permit contained in said ticket means, operations that said agent process is allowed to perform at said destination place process.

63. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising controlling, with a destination permit contained in said ticket means, resources that said agent process is allowed to consume at said destination place process.

64. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising specifying, with a destination permit contained in said ticket means, a priority for said agent process at said destination place process relative to other processes at said destination place process.

65. In a computer network having a plurality of computers, the communication process as in claim 46 further comprising controlling, via a permit means, a capability that a process is allowed to have.

66. In a computer network having a plurality of computers, the communication process as in claim 65 wherein said permit means is a native permit.

67. In a computer network having a plurality of computers, the communication process as in claim 65 wherein said permit means is a local permit.

68. In a computer network having a plurality of computers, the communication process as in claim 65 wherein said permit means is a temporary permit.

69. In a computer network having a plurality of computers, the communication process as in claim 65 wherein said capability comprises resources that said process can consume.

70. In a computer network having a plurality of computers, the communication process as in claim 65 wherein said capability comprises a deadline after which the process can not proceed.

71. In a computer network having a plurality of computers, the communication process as in claim 65 wherein said capability comprises a priority for said process relative to other processes.

72. In a computer network having a plurality of computers, the communication process as in claim 65 wherein said capability comprises permission for said process to perform selected operations.

73. In a computer network having a plurality of computers, the communication process as in claim 46 wherein said agent process owns an object.

74. In a computer network having a plurality of computers, the communication process as is claim 73 wherein said object has a digest.

75. In a computer network having a plurality of computers, the communication process as is claim 74 wherein said transporting a clone of said agent process comprises transporting a copy of said object.

76. In a computer network having a plurality of computers, the communication process as is claim 75 further comprising interchanging for said copy a second object at said destination place process wherein said second object has a digest equivalent to said first-mentioned digest and further wherein said copy is not transported to said destination place process.

77. In a computer network having a plurality of computers, the communication process as in claim 73 further comprising using an interchanged object for said object at said destination place process thereby eliminating the need to transport said object to said destination place process.

78. In a computer network having a plurality of computers, the communication process as in claim 46 wherein said transporting a clone of said agent process further comprises entering said destination place process.

79. In a computer network having a plurality of computers, the communication process as in claim 46 wherein said transporting a clone of said agent process further comprises exiting a source place process.

80. In a computer network having a plurality of computers, the communication process as in claim 46 wherein said destination place process is a meeting place process and said meeting place process arranges a meeting between a requestor agent process and a petitioned agent process.

81. In a computer, a communication process comprising:

providing a first agent process and a second agent process;

specifying a meeting between said first and second agent processes by a petition means; and

arranging said meeting between said first and second agent processes as defined by said petition means.

82. In a computer, the communication process as in claim 81 further comprising forming said petition means within said first agent process.

83. In a computer, the communication process as in claim 81 wherein said specifying a meeting comprises specifying, within said petition means, said second agent process.

84. In a computer, the communication process as in claim 83 wherein said specifying said second agent process comprises specifying, within said petition means, said second agent by a name.

85. In a computer, the communication process as in claim 84 wherein said name is a telename.

86. In a computer, the communication process as in claim 83 wherein said specifying said second agent process comprises specifying, within said petition means, a class of which said second agent process is a member.

87. In a computer, the communication process as in claim 83 wherein said specifying said second agent process comprises specifying, within said petition means, a citation of a class of which said second agent process is a member.

88. In a computer, the communication process as in claim 81 wherein said specifying a meeting comprises specifying, within said petition means, a maximum time period for arranging said meeting.

89. In a computer, the communication process as in claim 81 wherein said arranging said meeting comprises providing to said first agent process a reference to said second agent process.

90. In a computer, the communication process as in claim 89 wherein said arranging said meeting further comprises providing to said second agent process a reference to said first agent process.

91. In a computer, the communication process as in claim 81 further comprising causing, in response to an instruction within said first agent process, performance of an operation within said second agent process.

92. In a computer, the communication process as in claim 91 wherein said first agent process owns an object.

93. In a computer, the communication process as in claim 92 further comprising providing to said second agent process a reference to said object.

94. In a computer, the communication process as in claim 93 wherein said reference is a protected reference.

95. In a computer, the communication process as in claim 92 further comprising providing to said second agent process a reference to a copy of said object.

96. In a computer, the communication process as in claim 91 wherein said second agent process owns an object.

97. In a computer, the communication process as in claim 96 further comprising providing to said first agent process a reference to said object.

98. In a computer, the communication process as in claim 97 wherein said reference is a protected reference.

99. In a computer, the communication process as in claim 96 further comprising providing to said first agent process a reference to a copy of said object.

100. In a computer network having a plurality of computers, a communication system comprising:

an agent means having a ticket means and a send operation; and

a plurality of place means wherein each place means is operative in one of said plurality of computers;

wherein said agent means is at a first place means in said plurality of place means;

said ticket means specifies a trip for said agent means to a destination place means in said plurality of place means; and

said send operation transports a clone of said agent means to said destination place means.

101. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said agent means further comprises a second ticket means, different from said first-mentioned ticket means, that specifies a second trip to a second destination place means for said agent means.

102. In a computer network having a plurality of computers, the communication system as in claim 101 wherein performance of said send operation transports a second clone of said agent means to said second destination place means.

103. In a computer network having a plurality of computers, the communication system as in claim 102 wherein:

said first-mentioned trip and said second trip both include transportation to a single computer in said plurality of computers; and

further wherein, in transporting said first

mentioned clone to said first-mentioned destination place means and said second clone to said second destination place means, performance of said send operation:

(a) transports said first clone to said single computer and

(b) forms said second clone from said first clone within said single computer.

104. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said agent means further comprises a go operation wherein said go operation transports said agent means to a third destination place means specified by a third ticket means.

105. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises a name which identifies said destination place means.

106. In a computer network having a plurality of computers, the communication system as in claim 105 wherein said name is a telename.

107. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises an address for said destination place means.

108. In a computer network having a plurality of computers, the communication system as in claim 107 wherein said address is a teleaddress.

109. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises a citation means which specifies a class of which said destination place means is a member.

110. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises any combination selecting from the group consisting of an address of said destination place means, a name of said destination place means, and a citation means which specifies a class of which said destination place means is a member.

111. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises means for specifying a maximum time period for said trip.

112. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises means for specifying a desired time period for said trip.

113. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises a way means for specifying a type of intercomputer communications means by which said trip is to be accomplished.

114. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises a permit means for controlling a deadline for said agent means at said destination place means.

115. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises a permit means for controlling operations that said agent means is allowed to perform at said destination place means.

116. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises a permit means for controlling resources that said agent means is allowed to consume at said destination place means.

117. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said ticket means further comprises a permit means for specifying a priority for said agent means at said destination place means relative to other agent means at said destination place means.

118. In a computer network having a plurality of computers, the communication system as in claim 100 further comprising a permit means for controlling a capability that an agent means is allowed to have.

119. In a computer network having a plurality of computers, the communication system as in claim 118 wherein said permit means is a native permit.

120. In a computer network having a plurality of computers, the communication system as in claim 118 wherein said permit means is a local permit.

121. In a computer network having a plurality of computers, the communication system as in claim 118 wherein said permit means is a temporary permit.

122. In a computer network having a plurality of computers, the communication system as in claim 118 wherein said capability comprises resources that said agent means can consume.

123. In a computer network having a plurality of computers, the communication system as in claim 118 wherein said capability comprises a deadline after which the agent means can not proceed.

124. In a computer network having a plurality of computers, the communication system as in claim 118 further comprising other agent means wherein said capability comprises a priority for said agent means relative to said other agent means.

125. In a computer network having a plurality of computers, the communication system as in claim 118 wherein said capability comprises permission for said agent means to perform selected operations.

126. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said agent means owns an object.

127. In a computer network having a plurality of computers, the communication system as is claim 126 wherein said object has a digest.

128. In a computer network having a plurality of computers, the communication system as is claim 127 wherein a copy of said object is transported with said clone by performance of said send operation.

129. In a computer network having a plurality of computers, the communication system as is claim 128 wherein a second object at said destination place means is interchanged for said copy; and

further wherein said second object has a digest equivalent to said first-mentioned digest, thereby obviating transportation of said copy to said destination place means.

130. In a computer network having a plurality of computers, the communication system as in claim 128 wherein said send operation uses an interchanged object for said copy at said destination place means thereby eliminating the need to transport said copy of said object to said destination place means.

131. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said place means further comprises means for entering said place means.

132. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said place means further comprises means for exiting said place means.

133. In a computer network having a plurality of computers, the communication system as in claim 100 wherein said place means further comprises meeting place means wherein said meeting place means arranges a meeting between a requestor agent means and a responder agent means.

134. In a computer, a communication system comprising:

meeting place means having a meet operation wherein said meeting place means is a locale for a plurality of agent means;

a petition means;

a first agent means in said plurality of agent means; and

a second agent means in said plurality agent means wherein;

said first and second agent means can meet with any of said plurality of agent means;

said petition means specifies a meeting between said first and second agent means; and

in response to said meet operation, said meeting place means arranges said meeting.

135. In a computer, the communication system as in claim 134 wherein said first agent means contains said petition means.

136. In a computer, the communication system as in claim 135 wherein said petition means specifies said meeting by specifying said second agent process.

137. In a computer, the communication system as in claim 136 wherein said petition means comprises a name which specifies said second agent.

138. In a computer, the communication system as in claim 137 wherein said name is a telename.

139. In a computer, the communication system as in claim 136 wherein said petition means specifies said second agent by specifying a class of which said second agent process is a member.

140. In a computer, the communication system as in claim 136 wherein said petition means comprises a citation, said citation specifying a class of which said second agent process is a member.

141. In a computer, the communication system as in claim 134 wherein said petition means defines a maximum time period for arranging said meeting.

142. In a computer, the communication system as in claim 134 further wherein said meet operation provides to said first agent means a reference to said second agent means.

143. In a computer, the communication system as in claim 142 further wherein said meet operation provides to said second agent means a reference to said first agent means.

144. In a computer, the communication system as in claim 134 further wherein said first agent means can cause performance of an operation within said second agent means.

145. In a computer, the communication system as in claim 144 wherein said first agent means owns an object.

146. In a computer, the communication system as in claim 145 further wherein said first agent means can provide to said second agent means a reference to said object.

147. In a computer, the communication system as in claim 146 wherein said reference is a protected reference.

148. In a computer, the communication means as in claim 145 further wherein said first agent means can provide to said second agent means a reference to a copy of said object.

149. In a computer, the communication system as in claim 144 wherein said second agent means owns an object.

150. In a computer, the communication system as in claim 149 further wherein said second agent means can provide to said first agent means a reference to said object.

151. In a computer, the communication system as in claim 150 wherein said reference is a protected reference.

152. In a computer, the communication system as in claim 149 further wherein said second agent means can provide to said first agent means a reference to a copy of said object.

153. In a computer network having one or more computers, a method for transferring data from a first engine process to a second engine process, said method comprising the steps of:

(a) providing means for executing one or more agent processes wherein said executing means comprises said first and second engine processes and further wherein each said agent process comprises instructions from a computer instruction set and has an execution state;

(b) providing within said computer instruction set a go instruction wherein said go instruction is contained within a first agent process executing within said first engine process and further wherein performance of said go instruction causes:

(i) suspension of execution of said first agent process by said first engine process;

(ii) representation of said first agent process such that said execution state of said first agent process is preserved;

(iii) transfer of said representation of said first agent process from said first engine process to said second engine process; and

(iv) resumption of execution of said first agent process by said second engine process;

(c) causing execution of said agent process by said first engine process, thereby causing performance of said go instruction.

154. The method of claim 153 wherein said computer instruction set is object-oriented.

155. The method of claim 154 wherein said plurality of agent processes are objects of said object-oriented computer instruction set.

156. The method of claim 153 further comprising adding data to said first agent process prior to causing performance of said go instruction;

wherein said representation of said first agent process includes said data; and

further wherein transfer of said representation of said first agent process to said second engine process includes transfer of said data.

157. The method of claim 153 wherein said first agent process comprises data representing a message to be transported from said first engine process to said second engine process; and

further wherein transfer of said first agent process resulting from execution of said go instruction causes transfer of said data from said first engine process to said second engine process.

158. The method of claim 153 wherein said first engine process executes on a first computer and said second engine process executes on a second computer wherein said first and second computers are part of said computer network.

159. A method for transferring data from a first engine process to one or more engine processes, said method comprising:

(a) providing means for executing a plurality of agent processes which comprise instructions from a computer instruction set wherein said agent process execution means comprises said first and one or more engine processes and further wherein each said agent process has an execution state;

(b) providing within said computer instruction set a send instruction wherein said send instruction is contained within a first agent process in said plurality of agent processes and further wherein, execution of said send instruction, includes:

(i) forming one or more copies of said first agent process wherein said copies preserve and include said execution state of said first agent process;

(ii) transferring each of said copies of said first agent process from said first engine process to a respective one of said one or more engine processes; and

(iii) effectuating execution of each of said copies of said first agent process by said respective one of said one or more engine processes so as to simulate the resumed execution of said first agent process.

160. The method of claim 159 wherein, upon a condition wherein two or more of said copies of said first agent process are to be transferred from said first engine process to a single second engine process, the transfer of said two or more copies of said first agent process comprises:

transferring to said second engine process a single copy of said first agent process; and

forming within said second engine process from said single copy said two or more copies of said first agent process.

161. A method of transferring data from a first agent process which is executing within a computer system to a second agent process which is executing within said computer system wherein said first and second agent processes are occupants of a place process, said method comprising:

causing, in response to a meet instruction issued by said first agent process, execution of a procedure by said second agent process wherein said procedure is a portion of said second agent process and comprises a collection of computer instructions contained within said second agent process; and

providing to said first agent process, in response to a second instruction which is issued by said second agent process and which is part of said procedure, means for accessing said second agent process.

162. The method of claim 161 wherein said causing execution of a procedure by said second agent process comprises:

causing, in response to said meet instruction issued by said first agent process, execution of a second procedure by said place process wherein execution of said second procedure by said place process issues an instruction which causes said second agent process to execute said first-mentioned procedure.

163. The method of claim 161 wherein said means for accessing said second agent process is provided to said first agent process by said place process.

164. The method of claim 163 wherein, at approximately the time said place process provides to said first agent process said means for accessing said second agent process, said place process provides to said second agent process means for accessing said first agent process.

165. A method for transferring a first computer process from a first computer system to a second computer system, said first computer system comprising a first CPU and a first memory and said second computer system comprising a second CPU and a second memory, said method comprising:

initiating execution of said first computer process within said first CPU wherein said computer process has an execution state;

suspending execution of said first computer process within said first CPU;

representing said first computer process as data in said first memory wherein said data includes said execution state of said first computer process at the time execution of said first computer process is suspended;

transferring said data from said first memory to said second memory;

forming a second computer process on said second computer system from said data wherein said second computer process has said state of execution represented in said data; and

causing execution of said second computer process, thereby effectively simulating resumption of execution of said first computer process, within said second CPU.

Description

CROSS REFERENCE TO MICROFICHE APPENDIX

Appendix E, which is a part of this disclosure, is a microfiche appendix consisting of one (1) sheet of microfiche having a total of five (5) frames. Microfiche Appendix E describes the interchange of objects during the movement of a process through a network in one embodiment of the present invention, which is described more completely below.

Appendix F, which is a part of this disclosure, is a microfiche appendix consisting of one (1) sheet of microfiche having a total of 51 frames. Microfiche Appendix F describes the transfer of data between computer systems interconnected via a network in one embodiment of the present invention.

Appendix G, which is a part of this disclosure, is a microfiche appendix consisting of 13 sheets of microfiche having a total of 1,185 frames. Microfiche Appendix G is a list of computer programs and related data in one embodiment of the present invention, which is described more completely below.

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.

FIELD OF THE INVENTION

This invention relates to a distributed computing environment and in particular, to an improved distributed computing environment wherein processes are created in an object oriented environment and direct their own movement throughout a computer network.

BACKGROUND OF THE INVENTION

Many different computing systems are available today, but most of these systems are built around fundamental components such as those illustrated in FIG. 1. Typically, a computer system 20 includes a central processing unit 10 (CPU), which is connected through an input bus 11 to an input module 12 and through an output bus 13 to an output module 14. CPU 10 is also connected through data buses 15, 16 to a memory unit 17.

CPU 10 provides control and computing functions. Input and output modules 12, 14 are used to communicate between the computer user and CPU 10. Input module 12 supplies information to CPU 10. Typical input devices are a keyboard and a mouse. Output module 14 displays information from central processing unit 10. Typical output modules include video display monitors, printers, plotters and other visual display means. Input unit 12 and output unit 14 are frequently referred to as input/output (I/O) units.

Memory unit 17 typically contains two general types of information, instructions and data. A computer program is a sequence of instructions that are executed by the computer to perform a specific function. Data in memory unit 17 are processed by CPU 10 in response to the instructions from a computer program which is executing in CPU 10. An executing computer program is called a computer process.

Memory unit 17 typically includes mass memory 17A, sometimes called secondary memory, and main memory 17B. Main memory 17B is usually used to store at least a portion of a program currently being executed by CPU 10 and data required by the program. Mass memory 17A, e.g. magnetic disk or tape, is used to store programs, data, or portions of either programs or data which are not needed immediately by CPU 10 or which cannot be accommodated in main memory 17B because of size limitations of main memory 17B.

The operating system of a computer is a computer process which coordinates operation of CPU 10, I/O devices 12, 14 and 17A and main memory 17B and which provides an interface between user applications (defined below) and computer hardware. As is used herein, the term computer hardware refers to the physical components of the computer system. As an operating system is necessary for the orderly operation of a computer system, the operating system is loaded into main memory 17B and executed during power up of the computer system (a process called "booting") and remains in main memory 17B and in execution until the computer system is ultimately deactivated.

A user application generally refers to a computer process which executes in addition to, and is generally considered distinct from, the operating system. A user application begins at some point in time as source code, i.e., computer instructions in a form intelligible to human beings. This source code is translated or "compiled" into object code, which is a form intelligible to computer system 20, particularly CPU 10. Several object code modules may be linked to form a single executable image, which is in a form which can be processed by CPU 10 of computer system 20. The program is executed by copying the executable image into main memory 17B and instructing CPU 10 to carry out the instructions, one by one, of the executable image. As stated above, a computer program in such state of execution is called a process.

The instructions executed by a process executing within computer system 20 generally manipulate the resources of computer system 20. For example, instructions can manipulate data stored in mass memory 17A, accept data from input module 12 or display data on output module 14. Some processes, which are designed to execute on a first computer system, are configured to issue computer instructions which manipulate resources of a second computer system.

It is well-known in the art of computer communications to connect two or more computer systems such that data can be transferred between two or more computer systems. Two or more computer systems so connected are collectively called a "network". In such a network, each computer system treats each other computer system as an I/O device to which data can be sent and from which data can be received.

A first process executing on a first computer system can issue instructions to a second process executing on a second computer system. The second process then manipulates the resources of the second computer system in accordance with the instructions received from the first process. The second process is called a "server" process because the second process provides a service to the first process, which is called a "client" process. The service provided is the manipulation of resources of the second computer system.

Many computer communication systems implement what is called "remote procedure calling". In remote procedure calling, a client process, which is executing on a first computer system and which seeks to manipulate data on a second computer system, requests action through a server process, which is executing on the second computer system and which manipulates data in response to requests from the client process. The server process performs any of an inevitably finite list of operations on behalf of the client process. Often it is the case that the precise function requested by the client process is not among the particular operations performed by the server process. To perform a function for which no server process operation is defined requires several requests to and responses from the server process that require substantial use of communications media which in turn involves considerable expense and time.

Logic flow diagram 200 (FIG. 2A) illustrates an example of remote procedure calling. Logic flow diagram 200 is described in the context of computer systems 20A and 20B (FIG. 2B), which are interconnected through network 256. Suppose a client process 252 on computer system 20A is to delete all files on computer system 20B whose names match a given pattern, e.g., file names ending in ".TMP", and which have not been modified in at least 30 days. Client process 252 sends to server process 254 which is executing on computer system 20B a request to list all files in step 21 (FIG. 2A). Arrow 260 (FIG. 2B) represents that request. Processing transfers from step 21 (FIG. 2A) to step 22 in which client process 252 (FIG. 2B) receives the list from server process 254, as shown as arrow 262. Steps 21 and 22 (FIG. 2A) involve two transfers across network communications media.

Double rectangles in FIGS. 2A and 3A indicate information transfer across network 256 (FIG. 2B). Whereas execution of an instruction within either computer 20A or computer 20B takes between several nanoseconds to several microseconds, transfer of information across network 256 generally takes seconds or minutes depending on the configuration of network 256 and on the amount of information. In some networks, transfer of a large amount of data can take an hour or more.

Processing transfers from step 22 (FIG. 2A) to for each filename step 23. For each filename step 23 and next steps 23a, 23b and 23c define a loop within which each filename of the list of filenames is processed by the client process. For each filename of the list, processing transfers from for each filename step 23 to a test step 24 in which client process 252 (FIG. 2B) compares the filename to a pattern. If the filename does not match the pattern, processing transfers from test step 24 (FIG. 2A) through next step 23a to for each filename step 23 and the next filename is processed.

Conversely, if the filename matches the pattern, processing transfers from test step 24 to step 25. In step 25, client process 252 (FIG. 2B) sends to server process 254 an instruction to provide the date that the particular file was last modified as shown by arrow 264. Processing transfers from step 25 (FIG. 2A) to step 26 in which client process 252 (FIG. 2B) receives from server process 254 the date requested as represented by arrow 266. Steps 25 and 26 (FIG. 2A) involve two more transfers across network communications media for each such matching filename.

Processing transfers from step 26 to a second test step 27 in which client process 252 (FIG. 2B) compares the date received with the current date less 30 days. If the date indicates that the file has been modified within the preceding 30 days, processing transfers from second test step 27 (FIG. 2A) through next step 23b to for each filename test step 23 in which the next filename is processed. Conversely, if the date indicates that the file has not been modified within the preceding 30 days, processing transfers from second test step 27 to step 28.

In step 28, client process 252 (FIG. 2B) sends to server process 254 an instruction directing server process 254 to delete the file from computer system 20B as represented by arrow 268. Processing transfers from step 28 to step 29 (FIG. 2A), in which client process 252 (FIG. 2B) receives from server process 254 acknowledgement of the deletion as represented by arrow 270. Thus, steps 28 and 29 (FIG. 2A) involve two further transfers across network 256 (FIG. 2B) for each file to be deleted.

Processing transfers from step 29 through next step 23C to for each filename step 23. If all filenames in the list have been processed, processing transfers from for each filename step 23 to terminal step 20b in which processing terminates. Thus, processing according to logic flow diagram 200 (FIG. 2A) requires a multitude of information transfers across network 256. Such heavy use of network communications media is both costly and time consuming.

An alternative approach to remote procedure calling is "remote programming". In remote programming, a process, which is called a "client process" and which executes on a first computer system, sends to a server process executing on the second computer system a list of instructions. The instructions are then carried out by the server process effectuating the goal of the client process. The instructions which the server process is designed to carry out must have some degree of generality; i.e., the instructions must provide some degree of decision-making capabilities.

Logic flow diagram 300 (FIG. 3A) illustrates an example of remote programming. To effectuate the example given above with respect to FIGS. 2A and 2B in a remote programming environment, client process 352 (FIG. 3B) in step 31 (FIG. 3A) builds a program whose instructions are represented by logic flow diagram 31-P. Logic flow diagram 31-P is described below.

Processing transfers from step 31 to step 32, in which the program is transferred to computer 30B (FIG. 3B) through network 356 as represented by arrow 358. Processing transfers from step 32 to step 33 (FIG. 3A) in which the program is executed within computer 30B. During execution, the program is process 352A (FIG. 3B) within computer 30B. The instructions of program 352A are executed according to logic flow diagram 300.

In step 31-B (FIG. 3A), a list of filenames is created. Processing transfers from step 31-B to for each filename step 31-C. For each filename step 31-C and next steps 31-H, 31-I, and 31-J form a loop within which each filename in the list of filenames is processed. For each filename, processing transfers from for each filename step 31-C to test step 31-D in which the filename is compared to a pattern. If the filename does not match the pattern, processing transfers from test step 31-D through next step 31-H to for each step 31-C. Conversely, if the filename matches the pattern, processing transfers from test step 31-D to step 31-E.

In step 31-E, process 352A retrieves the date of last modification of the file having the filename. Processing transfers from step 31-E to a second test step 31-F in which the date is compared to the current date less 30 days. The date of last modification of the file is retrieved from server process 354 (FIG. 3B). If the date of last modification is more recent than the date of 30 days prior, processing transfers from second test step 31-F (FIG. 3A) through next step 31-I to for each filename step 31-C. Conversely, if the date of last modification is prior to the date of 30 days prior, processing transfers from second test step 31-F to step 31-G. In step 31-G, the file is deleted by issuing an appropriate instruction to server process 354 (FIG. 3B). Processing transfers from step 31-G (FIG. 3A) through next step 31-J to for each filename step 31-C. If all filenames in the list have been processed, processing transfers from for each filename step 31-C to terminal step 31-K in which process 352A terminates. As indicated by arrows 360 (FIG. 3B), all interaction between process 352A and server process 354 transpired entirely within computer 30B without use of network 356.

After successful completion of the program, processing transfers from step 33 to step 34 (FIG. 3A) in which server process 354 (FIG. 3B) reports to client process 352 that the program completed successfully as represented by arrow 362. Note that this remote programming procedure involves only two uses of network communications media: a first to send the program or list of instructions to server process 354 as represented by arrow 358 and a second to receive from server process 354 notification of successful completion of the program as represented by arrow 362. Note also that client process 352 was able to request of server process 354 an operation not explicitly provided by, and perhaps not even anticipated by the developers of, server process 354.

However, remote programming encounters the same inefficiencies of remote procedure calling when a computer process seeks to coordinate manipulation of data on two or more computer systems. For example, a process on computer X may seek to delete all files on computer system Y or computer system Z which have the same name, date of last modification and size as any file on computer X. Since server process 354 described above with respect to FIGS. 3A and 3B is capable of directly manipulating resources on the computer system on which the server process is executing, i.e. computer system Y, the server process is unable to coordinate data management spanning more than one computer system without producing the inefficiencies discussed above in conjunction with remote process calling.

An improvement over remote programming is described by C. Daniel Wolfson, et al., "Intelligent Routers", 9th International Conference on Distributed Computing Systems at pp. 371-375 (1989). Wolfson et al. disclosed a system wherein a process could move from one computer system to another within a network. The process directed its own movement through the network by issuing an instruction whose execution caused the process to be moved. The instruction specified to which computer system the process was to be moved.

However, the solution in the form disclosed in Wolfson et al. was of limited functionality. Processes were required to be configured to comport with the specific requirements of the computer system to which the respective processes moved. Processes were not able to communicate with one another; processes instead directly stored or directly retrieved data from the mass memory of the computer system within which the respective processes were executing. One process could only interact with another process only if both processes knew the precise location within mass memory where messages were to be stored and/or retrieved.

The system disclosed by Wolfson et al. did not provide any security. Thus, to the extent that the Wolfson et al. system allowed one process to interact with another process, a malicious process could interfere with the execution of a second process. In addition, the set of instructions provided to processes of the system disclosed by Wolfson et al. was very limited; only character string data and numerical data representing real numbers were provided for.

Another system similar to that disclosed by Wolfson et al. was that described by D. Tsichritzis et al., "KNOs: KNowledge Acquisition, Dissemination, and Manipulation Objects", ACM Trans. on Office Information Systems, vol. 5, no. 1, pp. 96-112 (1987). The system described by Tsichritzis et al. added to the system described by Wolfson et al. the generality of object-oriented programming.

Object-oriented programming organizes data and instructions into "objects" in which data represent the "state" of an object and instructions are grouped into tasks or "operations" that the object can "perform". Object-oriented programming represents a very useful conceptual framework in which problems solved by a computer may be more easily reduced to a series of computer instructions.

Objects created in an object-oriented environment are grouped into classes. Objects of a class have states of the same structure and perform the same operations. The system disclosed by Tsichritzis et al. did not provide for the mobility of class definitions; therefore, objects of a given class created within the environment described by Tsichritzis et al. could only travel to those computer systems for which the given class was defined. Additionally, objects in the environment described by Tsichritzis et al. were represented in a form that required that the computer systems of the network, within which objects could travel, were homogeneous.

The system taught by Tsichritzis et al. further described an instruction by which a first process, i.e., a "head" process, could create copies of itself. The copies were called "limbs". Tsichritzis et al. taught that limbs could be sent to remote computer systems at the direction of the head process. However, the limbs were not active; the computer instructions of a limb were executed only at the direction of the head process. Directing the activity of a limb process positioned in a remote computer system required that the head process issue commands to the limbs across network communications media, involving considerable time and expense in large networks.

Further inefficiencies were found in the system taught by Tsichritzis et al. when a small computer, e.g., a personal computer, was connected to a large network through a large computer, e.g., a mainframe computer. For example, to send many limbs to various computers of the network, the small computer was required to send many identical limbs between the small computer and the large computer. As limbs, which are copies of the head process, could be quite large, inefficiencies in such a system could have been quite substantial.

Tsichritzis et al. taught a system wherein a first process communicated with a second process by giving to the second process a reference to the first process. A reference is data which identifies an object and which grants access to the object identified. As the second process contained a reference to the first process, the second process could request that the first process execute specific computer instructions which were contained within the first process. However, as the first process provided the second process with a reference to the first process without simultaneously obtaining a reference to the second process, the second process had access to the first process and the first process did not have reciprocal access to the second process. Such a system permitted a "malicious" process, i.e., a process designed by a malicious programmer or inadvertently designed to harm other processes, to gain access to a second process without granting reciprocal access.

Thus, in spite of the achievements of Wolfson et al. and Tsichristzis et al., neither discloses a system in which new classes of objects and processes can be created and can be transported to and processed by computer systems within the network which do not contain class definitions for the new classes. Neither does either Wolfson et al. or Tsichristzis et al. disclose a mechanism for implementing a complex and hierarchical security scheme. Furthermore, neither Wolfson et al. nor Tsichristzis et al. disclose computer processes which can interact with one another but which cannot gain access to other processes without granting reciprocal access.

Furthermore, neither Wolfson et al. nor Tsichristzis et al. disclose computer processes which can travel to several computer systems simultaneously by creating several autonomous clones of a process and transporting the clones to respective computer systems. The limbs taught by Tsichristzis et al. are not autonomous as the computer process controls the actions of limbs at remote computer systems. Furthermore, neither Wolfson et al. nor Tsichristzis et al. disclose efficient transportation of the clones to the respective computer systems in which transportation of redundant information across network communication media is minimized.

SUMMARY OF THE INVENTION

According to the principles of this invention, a set of interpreted, object-oriented computer instructions is used to create novel computer processes that are executed in a distributed computer system. A particular process that utilizes the set of computer instructions is activated by an engine that is executing within the distributed computer system. The engine interprets and effectuates the instructions of the particular process within the distributed computer system.

Each engine in the distributed computer system interprets the instructions that define a process uniformly. In other words, the instructions which comprise a process and which are interpreted by a first engine do not depend on the particular configuration of the computer system within which the first engine is executing. The instructions, therefore, can be moved to and interpreted by a second engine, even if the first and second engines are executing within two separate computer systems whose operating systems and hardware are otherwise generally incompatible. The interpreted instructions are implemented by using interfaces to communication, storage, computing and other subsystems of the computer system within which the engine is executing. These interfaces, which collectively form part of one embodiment of the present invention, are described in Appendix C, which is a part of this disclosure and is incorporated in its entirety herein by reference.

Two or more engines are interconnected to form a network. The network is a universe within which computer processes of this invention travel. In one embodiment, the network encompasses computer systems that would normally be considered clients of, and not part of, other networks. For example, one embodiment of the network of this invention encompasses the workstations which are connected by the network. The term "workstation" is used herein to describe a computer system which is used for purposes other than the transportation of information to other computer systems. The engines of this invention are interconnected so that engines are capable of moving computer processes among themselves.

To transport a particular computer process, the computer process is suspended and the execution state of the computer process is preserved. The instructions of the computer process, the preserved execution state, and objects owned by the computer process are packaged, or "encoded", to generate a string of data that is configured so that the string of data can be transported by all standard means of communication used to form a network. In one embodiment, the string of data is transported between engines as specified by the protocol described in Appendix D, which is a part of this disclosure and is incorporated herein in its entirety by reference.

Once transported to a destination computer system of the network, the string of data is decoded to generate a computer process within the destination computer system. The decoded computer process includes those objects encoded as described above and has the preserved execution state. The destination computer system resumes execution of the computer process. The instructions of the computer process are executed by the destination computer system to perform complex operations, including defining, creating and manipulating data objects and interacting with other computer processes executed by the destination computer system. As computer processes are uniformly interpretted throughout the network and are encoded and decoded for transport between computer systems, the computer processes of this invention provide a new level of functionality and versatility in intercomputer communication.

In one embodiment, two classes built into the set of computer instructions of this invention are an agent class and a place class. Instructions formed using the agent class are interpreted by an engine to form an "agent process", sometimes referred to herein simply as "an agent". An agent is an active object in that an engine initiates execution of an agent upon creation of the agent. The agent class provides instructions which enable an agent to (i) examine and modify itself, (ii) transport itself from a first place process, which is described more completely below, in the network to a second place process in the network, and (iii) interact with other agents found at the second place process. The first and second place processes can execute within two separate computer systems of the network. Thus, an agent can travel from a first computer system to a second computer system.

An agent can contain information which is carried with the agent from the first place process to the second place process. Additionally, the extensibility, generality and functionality of the set of computer instructions discussed more completely below provide tremendous flexibility and control in determining, according to the instructions which comprise an agent, how and to what destination the agent, and the information contained therein, travels.

The power of agents is counterbalanced by "permits". A permit limits the particular capabilities of a particular agent on particular occasions. The permit of an agent specifies which of several of the operations defined for the agent class can or cannot be performed by the agent. The permit further limits the amount of processing resources the agent can consume and the time at which the agent expires. Additionally, the permit specifies the priority of execution of the agent relative to other agents.

Instructions formed using the place class are interpreted by an engine to form a "place process", sometimes referred to herein simply as "a place". A place is also an active object, and the place class provides instructions which enable a place to examine and modify itself and to serve as a venue for agents and a context in which agents can interact. Agents each occupy a respective single place. Additionally, each place can occupy a single other place.

Places provide a degree of privacy and security for agents. For example, an agent, which is configured to avoid contact with other agents, can occupy a place which is not generally known to other agents, or which denies ingress to other agents. Conversely, an agent, which is configured to provide services publicly to a large number of agents, can occupy a place which is widely known to other agents and which grants ingress to other agents.

Agents cannot interact at a distance; i.e., no two agents can interact unless both occupy the same place. To interact with a second agent occupying a second place, a first agent, which occupies a first place, issues a command causing the first agent to be transported to the second place as discussed below with respect to the "go" operation. While both the first and second agents occupy the second place, the first agent can interact with the second agent.

Thus, the processes of this invention are a novel implementation of "remote programming," and not the more familiar "remote procedure calling" paradigm. Remote programming improves upon remote procedure calling by (i) enabling processes to interact without communicating across network communications media and (ii) improving the performance of the interactions between processes by eliminating communication across network communications media which often has high-latency.

The movement of an agent process, from a first place process in a first computer system to a second place process either in the first computer system or in a second computer system is called a trip. The agent initiates the trip by using a "go" operation, which is defined in the agent class. The agent controls the movement either through the network or within the computer system by creating and submitting, as an argument to the "go" operation, a ticket which defines the trip. In one embodiment, the ticket specifies the place to which the agent is to travel, the "way" by which the agent is to travel, the amount of time in which the trip must be completed, and an indication of the urgency of the trip, i.e., the priority of the trip relative to other trips by other agents that may be concurrently scheduled.

The ticket can identify the destination place by specifying the address, name, class or any combination of the address, name and class of a place to which the agent is to travel. The destination of the trip is any place of the specified address, name and/or class which grants the agent ingress within the time permitted by the ticket.

In the "go" operation, the agent is moved from a first place to a second place as follows: (i) the agent is suspended and the execution state of the first agent is preserved; (ii) the agent is represented in a standardized form, i.e., an octet string, which includes representation of the agent's preserved execution state; (iii) the standardized form is transported from the first place to the second place, potentially involving the transfer of the standard form from a first computer to a second computer; (iv) the agent at the second place is formed from the standardized form, including the execution state represented in the standardized form; and (v) interpretation of the agent is resumed, the agent initially having the execution state represented in the standardized form.

As mentioned above, the set of computer instructions of the present invention is object-oriented. Therefore, all objects formed according to the present invention are organized into classes. All classes in the present invention are represented by data objects which can be moved along with an agent. Thus, classes, which are not defined within a place, can nevertheless be used by an agent travelling to the place simply by the agent defining the classes and transporting the corresponding class objects to the place.

Every object in one embodiment of the present invention is owned by a process, i.e., either an agent or a place. When an agent travels from a first place to a second place, all objects owned by the agent are effectively moved to the second place along with the agent. However, as discussed below, objects which are equivalent to objects already occupying the second place are not transported in one embodiment of the present invention. In addition to the objects owned by the agent, all class objects defining classes of which those objects are members are moved along with the agent to the second place. A class object is an object constructed in accordance with the set of computer instructions described below and in Appendix A which represents a class of objects.

Thus, if an object owned by an agent travelling to a second place is a member of a class not defined in the second place, the object can still travel with the agent as the agent also carries to the second place class objects defining the classes of which the object is a member. In the prior art, a process which travelled from a first computer to a second computer could only process data objects which belonged to classes defined on the second computer. Class definitions were not typically transported with migrating processes in the prior art. As new classes can be formed within a first place and members of those new classes are free to travel to other places for which those new classes are not defined, the present invention provides agents a level of extensibility, mobility and generality not found in the prior art.

In the present invention, many classes of objects are defined at multiple places and therefore do not need to be moved to such places. Class objects and any other objects, which are likely to be found at many places are made interchangeable in one embodiment of the present invention.

Interchangeable objects each have a digest. An interchangeable object, which is owned by an agent that is travelling from a first place to a second place, does not travel with the agent. Rather, the digest of the interchangeable object is moved with the agent to the second place. When the agent arrives at the second place, interchangeable objects in the computer system which contains the second place are examined to determine whether any of the interchangeable objects has a digest equal to the digest transported with the agent. If such an interchangeable object is found in the computer system which contains the second place, the interchangeable object is substituted for the interchangeable object, which was left behind at the first place.

If, however, no such interchangeable object is found at the second place, the interchangeable object left behind at the first place is moved to the second place. In this way, the movement of objects across network communications media is avoided when equivalent objects are present at the destination place. In particular, as class objects are interchangeable, an agent travelling to a second place causes the movement to the second place of only those class objects defining classes which are not defined within the second place. Avoiding unnecessary movement of class objects through the network makes practical the movement of objects owned by an agent to places which contain no definition of one or more classes to which those objects belong.

In one embodiment of the present invention, classes are identified by citations. In a computer network having many computer systems supplied by different vendors, various versions of the disclosed instruction set can be implemented on various computer systems to which and from which agent processes can travel. A citation is an object which is used to identify classes or objects which are forward- or backward-compatible with one another. Therefore, an instruction requiring use of an object of a first class, or the first class itself, can use an object of a second class, or the second class itself, depending on the particular requirements of the instruction, if the second class is backward-compatible with the first class.

An agent, occupying a first place, is also capable of creating one or more clones of the agent and moving each clone to a respective place. A clone is an agent process which is the result of duplicating an existing agent process. An agent initiates and controls the creation of one or more clones, and the movement of each clone to a respective place process by performance of operation "send." The agent specifies the number of clones to be created and defines the corresponding trips by creating one or more tickets which are supplied as arguments to operation "send". Each ticket defines a trip to be taken by a respective clone of the agent. The number of tickets supplied by the agent defines the number of clones created.

Once a clone of the agent is moved to a second place, the clone initially has the execution state of the agent at the time the clone was created. Thus, when the clone arrives at a second place, the clone continues to execute so as to simulate the movement of the agent to the second place as described above with respect to operation "go."

In the prior art, a first process, i.e., a head process, created limb processes which had the same interface, i.e., could generally perform the same operations, as the head process. Limb processes did not act except as directed by the head process and could move to remote computer systems only at the direction of the head process.

In the present invention, however, a clone is autonomous and is not controlled by the agent which created the clone. For example, the clone can be configured to ignore all attempts by the agent to arrange a meeting, which is discussed below, whereby the agent and the clone can interact. The agent must attempt to interact with a clone of the agent in the same way the agent attempts to interact with any other agent, as discussed below. As the clone is autonomous, the clone occupying the second place can travel to a third place by performance of operation "go" without being so instructed by the agent and even without the consent of the agent.

As limb processes of the prior art were not active and acted only at the direction of a head process, the head process and a remote limb process necessarily interacted across network communications media. The paradigm of this prior art system is therefore more closely related to remote procedure calling. In contrast, clones of agents formed in accordance with the present invention are active and autonomous and embody all of the instructions which form the agent. Therefore, no interaction is required (in fact, no interaction is allowed) across network communications media. Therefore, the paradigm of the present invention is more closely related to remote programming. The present invention therefore represents a significant increase in generality over the prior art.

Increases in efficiency in one embodiment of the present invention are realized in performance of operation "send" by deferring cloning of an agent as long as possible. For example, a first clone and a second clone are to be sent to a first place and a second place, respectively. Suppose that the agent is executing within a first computer system, that the first place is executing within a second computer system, and that the second place is executing within a third computer system. Suppose further that in travelling to the first and second places, the first and second clones must travel through an engine executing on a fourth computer system. In such a case, a single clone is formed and transported to the engine executing within the fourth computer system. Thus, only a single clone is created within the engine interpreting the original agent thereby saving space within that engine and only a single clone is transported across network communications media to the fourth computer system thereby saving time in transporting clones to the fourth computer system. The engine executing within the fourth computer system forms from the single clone the first and second clones and transports the first and second clones to the first and second places, respectively.

As an agent can own objects which account for a substantial majority of the size of the agent, e.g., a rasterized graphical image such as a facsimile transmission or digitized sound, avoiding sending several copies of such large objects, each copy owned by a respective clone, to a single engine saves substantial time and expense.

A first agent, occupying a place, can initiate a meeting between the first agent and a second agent occupying the place. During such a meeting, the first agent can transfer to and receive from the second agent data in the form of objects, and the second agent process can transfer to and receive from the first agent data in the form of objects.

The present invention represents a significant improvement over a prior art system which teaches the posting of messages on a virtual bulletin board by a first process. The messages are then "read" by the intended recipient process. In the prior art system, a first process gives to a second process a reference to the first process by posting the reference on the virtual bulletin board. However, since there is no mechanism for simultaneous exchange of references, the second process has access to the first process before giving to the first process a reference to the second process. Thus, there is no mechanism to prevent "malicious" processes from gaining access to other processes without granting to the other processes access to themselves.

The present invention represents an improved method of establishing contact between two processes such that a first process cannot obtain access to a second process without simultaneously granting to the second process access to the first process.

In one embodiment of the present invention, two agents can interact only if both agents occupy the same place and the place is a meeting place. A meeting place is a place that is a member of a class of meeting places, which is a subclass of the class of places. A first agent directs that a meeting be arranged between the first agent and a second agent by issuing an instruction directing the meeting place to arrange the meeting. The issued instruction is called operation "meet", and the first agent's issuance of the instruction is called "requesting a meeting".

The first agent supplies, as an argument to the instruction, a petition defining the meeting. The petition defines the meeting by specifying the second agent as the petitioned agent. The second agent is specified by specifying the name and/or the class of the second agent. The petition further defines the meeting by specifying the amount of time in which the meeting must be arranged or abandoned.

In arranging the meeting, the meeting place supplies to the second agent the name and class of the first agent and indicates that the first agent has issued an instruction requesting a meeting with the second agent. The second agent examines the name and class of the first agent and responds to the meeting place either accepting or rejecting the meeting with the first agent.

If the meeting is rejected, the first agent is informed that the second agent is not available. If the meeting is accepted, the meeting place gives to the second agent a reference to the first agent and gives to the first agent a reference to the second agent. With a reference to the second agent, the first agent (i) can direct the second agent to perform operations; (ii) can supply to the second agent objects as arguments; and (iii) can receive from the second agent objects as results. As the second agent has a reference to the first agent, the second agent has similar capabilities with respect to the first agent.

Either the first or the second agent can terminate the meeting between the two by issuing an appropriate command. The meeting place, in performing an operation "part" in response to the issued command, voids any references to the second agent contained within the first agent and voids any references to the first agent contained within the second agent, thereby terminating interaction between the two agents.

The present invention represents a significant improvement over the prior art as a first agent cannot gain access to a second agent unless the second agent agrees or without granting to the second agent access to the first agent. Additionally, since two agents cannot interact unless both occupy the same meeting place, intermediate levels of security are available to agents. For example, an agent can protect itself from other agents by occupying a meeting place whose location is not widely known by other agents. Inversely, an agent, which is designed to be highly visible, may occupy a well-known meeting place. No such mechanism is available in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the structure of computer systems of the prior art.

FIG. 2A is a logic flow diagram of a prior art method using remote procedure calling.

FIG. 2B shows a prior art network implementing remote procedure calling.

FIG. 3A is a logic flow diagram of a prior art method using remote programming.

FIG. 3B shows a prior art network implementing remote programming.

FIGS. 4A and 4B show the movement of an agent process through a network constructed in accordance with the present invention.

FIGS. 5A and 5B show processes, formed in accordance with the principles of the present invention, executing within a computer system.

FIG. 5C shows a portion of a class hierarchy graph in accordance with one embodiment of the present invention.

FIGS. 6A-6C show the movement of an agent process through a network formed in accordance with the present invention.

FIGS. 7A-7E show the movement of clones of an agent process through a network formed in accordance with an aspect of the present invention.

FIGS. 8A-8F illustrate interaction between two agent processes by using operation "meet".

FIGS. 9A-9E illustrate the interrelations of place processes formed in accordance with one aspect of the present invention.

FIG. 10 shows the structure of a computer network formed in accordance with the principles of the present invention.

FIGS. 11A and 11B show alternative representations of the network shown in FIG. 10.

FIG. 12 is a diagram illustrating the class relationships of an agent process in one embodiment of the present invention.

FIGS. 13A and 13B illustrate the state of an agent process formed in accordance with the present invention immediately before and after, respectively, movement of the agent process within a computer network of the present invention by performance of operation "go".

FIGS. 14A-14G are logic flow diagrams which illustrate the steps taken to move an agent process through a network in accordance with the present invention by performance of operation "go".

FIGS. 15A-15E show the structure of a network formed in accordance with the present invention and illustrate the movement of an agent process through the network.

FIG. 16 shows the structure of an agent process including a permit.

FIG. 17 shows the structure of the permit of FIG. 16.

FIG. 18A shows the structure of the ticket of FIG. 13A including a teleaddress, a citation, a telename, and a way.

FIG. 18B shows the structure of the way of FIG. 18A.

FIG. 19 shows the structure of the telename of FIG. 18A.

FIG. 20A shows a dictionary formed according to one embodiment of the present invention.

FIG. 20B shows the structure of a finder constructed according to one embodiment of the present invention.

FIG. 21 shows the structure of an encoded agent in accordance with one embodiment of the present invention.

FIGS. 22A and 22B show the state of an agent process immediately prior to and following, respectively, performance of operation "entering".

FIG. 22C is a logic flow diagram illustrating the steps taken in performance of operation "entering" in accordance with one embodiment of the present invention.

FIGS. 23A and 23B show a portion of the state of a process immediately preceding and following, respectively, performance of operation "exiting".

FIGS. 24A-24C are logic flow diagrams illustrating the steps taken in transporting an agent process through a network in accordance with an aspect of the present invention.

FIG. 24D shows the structure of a repository of interchanged objects which is used in the steps shown in FIGS. 24A-24C.

FIG. 25 shows a computer network formed in accordance with the principles of the present invention.

FIGS. 26A and 26B show a portion of the state of an agent process immediately prior to and following, respectively, performance of operation "send".

FIG. 26C shows the state of a clone of the agent process immediately following performance of operation "send".

FIGS. 27A and 27B show the state of a engine process before and after, respectively, formation of clones of an agent process in performance of operation "send".

FIG. 28 shows the computer network of FIG. 25 in which clones of the agent process have travelled to respective computer systems of the computer network in performance of operation "send".

FIGS. 29A-29E show a computer network through which clones of an agent process travel according to another aspect of the present invention referred to as "deferred cloning".

FIG. 30A shows the structure of a send frame including a nil and a list of tickets.

FIG. 30B shows the structure of an encoded clone of an agent process formed in accordance with an aspect of the present invention.

FIGS. 31A and 31B show the state of a process immediately preceding and following, respectively, performance of operation "meet".

FIG. 32 shows a logic flow diagram of the steps taken in performance of operation "meet".

FIG. 33 shows a portion of the state of an agent process including a set of contacts.

FIGS. 34A and 34B show the state of a process immediately preceding and following, respectively, performance of operation "meeting".

FIG. 35 is a logic flow diagram illustrating the steps taken in performance of operation "meeting" in accordance with one embodiment of the present invention.

FIG. 36 shows the state of two agent processes which are interacting in accordance with an aspect of the present invention.

FIGS. 37A and 37B show a portion of the state of an agent process immediately preceding and following, respectively, performance of operation "part".

FIG. 38 shows the state of the agent processes shown in FIG. 36 immediately following performance of operation "part".

FIGS. 39A-39F show a portion of the state of a first agent process during interaction with a second agent process in accordance with the present invention.

FIG. 40 is a logic flow diagram illustrating steps taken by the second agent process during the interaction shown in FIGS. 39A-39F according to one embodiment of the present invention.

FIG. 41A shows the structure of a class definition in accordance with one aspect of the present invention.

FIG. 41B shows the structure of a class object formed in accordance with one embodiment of the present invention.

FIG. 41C shows the structure of a class object formed in accordance with a second embodiment of the present invention.

FIG. 42 shows the structure of an interface object formed in accordance with the present invention.

FIG. 43 shows the structure of a feature definition including a set, an identifier, and a boolean.

FIG. 44 shows the structure of an attribute definition including a constraint and a boolean.

FIG. 45 shows the structure of an operation definition including a constraint and a list, which in turn includes a constraint.

FIG. 46 shows the structure of a constraint.

FIG. 47 shows the structure of an implementation object which includes two lists and six lexicons.

FIG. 48 shows the structure of a method which includes a procedure and a list, which in turn includes an identifier.

FIG. 49 shows the structure of the procedure of FIG. 48.

FIG. 50 shows the structure of a citation which includes a telename, two integers, and an identifier.

FIG. 51 shows the structures of two cited objects, each of which includes a respective citation.

FIG. 52A is a logic flow diagram illustrating the steps taken in performance of operation "do".

FIG. 52B shows the structure of a predefined frame which includes an integer and a procedure.

FIG. 53 shows the execution state of a process which includes a stack, which in turn includes a user frame.

FIG. 54 shows the state of the user frame of FIG. 53.

FIGS. 55A and 55B combine as shown in FIG. 55C to form a single logic flow diagram illustrating the steps taken in performance of a user-defined operation.

FIG. 56A shows the execution state of a process which includes a stack, which in turn includes a frame.

FIG. 56B shows the execution state of the process of FIG. 56A and a second frame.

FIG. 56C shows the execution state of the process of FIGS. 56A and 56B, including the stack, which in turn includes the first-mentioned frame and the second frame.

FIG. 57 is a logic flow diagram illustrating the steps taken in selecting a feature definition and a method from the class hierarchy in accordance with the present invention.

FIG. 58A is a diagram showing the hierarchy of the classes of which a list is a member.

FIG. 58B is a diagram showing the hierarchy of the classes of which class "List" is a member.

FIG. 59 is a logic flow diagram illustrating the steps taken in the initialization of an object.

FIG. 60 is a logic flow diagram illustrating the steps taken in performance of operation "if".

FIG. 61 is a logic flow diagram illustrating the steps taken in performance of operation "either".

FIGS. 62A and 62B show a portion of the execution state of a process immediately preceding and following, respectively, performance of operation "select".

FIG. 63 is a logic flow diagram illustrating the steps taken in performance of operation "select".

FIG. 64 shows the state of a predefined frame which represents the dynamic state of a performance of operation "select".

FIG. 65 is a logic flow diagram illustrating the steps taken in performance of operation "while".

FIGS. 66A and 66B show a portion of the execution state of a process immediately prior to and immediately following, respectively, performance of operation "catch".

FIG. 67 is a logic flow diagram illustrating the steps taken in performance of operation "catch".

FIG. 68 is a logic flow diagram illustrating the steps taken in performance of operation "loop".

FIG. 69 shows the structure of a repeat frame which includes an executed object and two integers.

FIG. 70 is a logic flow diagram illustrating the steps taken in performance of operation "repeat".

FIG. 71 shows the execution state of a process which includes a stack which in turn contains, from top to bottom, a user-defined frame, a predefined frame, a repeat frame, and a second user-defined frame.

GLOSSARY OF TERMS

"Abstract Class": A class which is abstract has no instances. An abstract class can have subclasses, and an abstract class can define features, methods, and properties which are inherited by the subclasses of the abstract class.

"Agent": An agent is a process which occupies a place and which is mobile, i.e. can move from a first place to a second place.

"Arguments": An argument is an object "consumed" by performance of an operation as input data. In other words, an argument is an object transferred from the requester to the responder immediately prior to performance of the operation by the responder at the request of the requester.

"Attribute": An attribute is a feature which either retrieves or sets information regarding the internal state of an object. Usually the information pertains to the object itself, but sometimes the information pertains to the reference by which the object is identified in invoking the attribute. An attribute is a pair of operations in which one sets, and the other retrieves, information regarding the internal state of the responder.

"Authority": An authority is an entity which owns and controls various resources in the network. An example of an authority is a user of the network. Authorities are created administratively and cannot be created programmatically, i.e., cannot be created at the request of a process.

"Class": A class defines (i) zero or more properties, which define the internal states of the members of the class, (ii) zero or more methods, which define the internal behavior of the members of the class, and (iii) zero or more features, which define the external behavior of the members of the class.

"Concrete Class": A class which is concrete can have instances.

"Engine Place": Every engine contains exactly one engine place which represents the engine itself.

"Engine": An engine is a machine in a computer system which manages objects, primarily processes, and executes instructions. An engine is typically a computer process executing within a computer system in addition to an operating system and various user applications. One or more engines can be executing within each computer system of a network. Each engine processes at least one place.

"Exception": An exception is an object "thrown" by performance of a feature if the feature fails to be performed completely and successfully. An exception, as the term is used herein, is alternatively a condition which causes such an object to be thrown. The responder is said to "throw" an exception, rather than "produce" an exception, because an exception arises from the failure of an operation and is therefore distinct from a result which is produced by a successful operation. The distinction between producing a result and throwing an exception is described in more detail below and in Appendix A which is hereby incorporated herein in its entirety by reference.

"Feature": A feature is a task that an object can be directed to perform. The task is carried out by a method, which includes a set of computer instructions. Performance of a feature is accomplished by execution of the computer instructions of the feature's method. A feature is associated with a specific class of objects, and performance of a feature can vary with the specific internal state of the object performing the feature. Features are conceptually divided into the two categories: (i) attributes and (ii) operations.

"Frame": A frame is an object which records the dynamic state of a method implementing a feature during performance of the feature. A frame is used by an engine to maintain information regarding a method which the engine is executing, including information identifying the object performing the feature implemented by the method and the particular instruction that is currently executing.

"Identifier": An identifier is an object which can reference a second object. The "text" of an identifier is a string which distinguishes the identifier from other identifiers within a particular scope. The various scopes of identifiers are discussed in greater detail in Appendix A.

"Implementation": An implementation is a set of computer steps performed in performance of a particular feature. An "implementation object" is an object defining the various implementations of the various features of a class.

"Instance": An object is an instance of a class if the object is a member of that class and is not a member of any subclass of that class.

"Interface": An interface defines a particular attribute or the particular arguments consumed and the result produced by performance of a particular operation. An "interface object" is an object defining the various interfaces of the various features of a class.

"Member": An object is a member of the class of which the object is an instance and any superclasses of that class.

"Method": A method is a set of computer instructions whose execution constitutes performance of a particular feature. A "method object" is an object defining a method. A method has a dynamic state during performance of the method, i.e., execution of the instructions of the method. The dynamic state of a method is represented by a frame.

"Network": All engine places, the computer systems in which the engine places execute and communications apparatus connecting those computer systems collectively form a network.

"Object": An object is an element in a computing environment within a computer system. An object has an internal state defined by zero or more properties, an internal behavior defined by zero or more methods, and an external behavior defined by zero or more features.

"Operation": An operation is a feature for which an interface and implementation is defined.

"Place": A place is a process which is a locale for zero or more processes. A place can occupy a second place. The first-mentioned place is a subplace of the second place, and the second place is a superplace of the first place.

"Primitive": A primitive is an object that can be used in the formation of a procedure or a method, and that therefore can serve as an instruction.

"Process": A process is an object which constitutes an autonomous computation. A process is autonomous because a process performs a method without being requested to do so by another object. A process commences performance of a central method upon creation of the process, and the process is destroyed upon completion of the central method. Every object is owned by exactly one process. Every process is owned by itself. As used herein, the term "computer process" refers to a series of instructions carried out by a computer system, which is a more general and well-known definition.

"Property": A property is an object which represents a part of the internal state of a second object.

"Reference": A reference is a data structure which identifies a particular object. An object, in being directed to perform a feature, is identified by a reference to the object supplied by the requester of the feature. References are either protected or unprotected. An object cannot be altered or modified using a protected reference to identify the object.

"Region": A region is one or more engine places within a network which are controlled by a single authority. A region is generally distinguished by the close coordination and management of computer systems which support the engine places of the region. The transportation of agents within a region is therefore generally quicker and less expensive than transportation of agents between regions. A region can be, for example, a local area network which is connected to a wide area network.

"Requester": A requester is an object which directs another object, i.e. the responder, to perform a feature. The requester supplies zero or more objects as input data to the responder of the feature requested and receives zero or one object as output data from the responder of the feature. Directing an object to perform a feature is alternatively called "requesting" the object to perform the feature.

"Responder": A responder is an object performing a feature at the direction of another object, i.e. the requester. The responder receives zero or more objects as input data and supplies zero or one object as output data in performing the feature. A responder is alternatively called a "responding" object.

"Result": A result is an object "produced" by performance of an operation as output data. In other words, a result is an object transferred from the responder to the requester immediately following performance of an operation by the responder at the request of the requester.

"Subclass": A subclass inherits methods, properties, and/or feature definitions from one or more classes. A subclass can define one or more properties, methods, and/or features which are not inherited from any other class and can reimplement a feature which is inherited from another class by defining a new implementation of the feature.

"Superclass": The classes from which a subclass inherits properties, methods, and/or features are superclasses of the subclass.

"Virtual Place": Every place which is not an engine place is a virtual place.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

According to the principles of this invention, a novel set of computer processes are used to route a particular computer process to a selected computer system contained in a plurality of interconnected computer systems and to execute the particular computer process on the selected computer system. The computer processes of this invention are defined, in one embodiment, in terms of object-oriented computer processes. The computer processes of this invention include (i) an instruction set that defines the various operations in the process and (ii) an engine that interprets the instruction set and controls operation of a central processing unit (CPU) in performance of the computer processes.

As explained more completely below, the particular computer process directs its own movement, i.e., transportation, through the computer network by executing an instruction which identifies a destination computer system within the network and directs that the particular computer process be transported there. While executing within the destination computer system, the particular computer process may have access to information which is not available elsewhere in the network. The particular computer process can access that information and use that information to determine to which other computer systems to travel. As explained more completely below, the present invention provides computer processes with a level of mobility, extensibility and generality not found in the prior art.

In remote programming paradigms typically found in the prior art, a computer process does not direct its own movement, but is sent from a source computer system to execute within a destination computer system. If the computer process cannot direct its own movement throughout the network, the computer process cannot select further destination computer systems to which to travel on the basis of information obtained by the computer process at the destination computer system. Thus, such a computer process must return to the source computer system with the information obtained before being sent to a second destination computer system. As computer processes of the present invention can direct their own movement through the network, computer processes of the present invention represent a substantial extension of the traditional remote programming paradigm.

Existing remote programming systems, which provide processes which direct their own movement through a computer network, lack generality and extensibility. Such systems lack generality in that such systems (i) are limited to homogeneous computer networks or (ii) require that a travelling process in a heterogeneous network contain instructions which conform specifically to whichever computer system is executing the process, i.e. computer systems to which the travelling process travels. In the present invention, a process travels within a heterogeneous computer network and the execution of the instructions of the process is independent of which particular computer system within which the process executes, i.e., to which the process travels. As discussed below in greater detail, the computer instructions disclosed below are implemented uniformly by each of the computer systems of a heterogeneous network. Thus, a process formed in accordance with the present invention can travel to any computer system within a heterogeneous computer network and execute there without any specific information regarding the nature of the computer system.

Remote programming systems of the prior art typically lack extensibility in that a process cannot create a class of data objects and utilize data objects of that class within computer systems to which the process subsequently travels. Many computer processes formed today are "object-oriented". As defined above in the Glossary of Terms, an object has (i) an internal state defined by a number of properties, (ii) an internal behavior defined by a number of methods, and (iii) an external behavior defined by a number of features. The properties, methods, and features of a group of objects with like properties, methods, and features are defined by a class. In prior art systems, a process which defines a class cannot use objects of the class while executing in computer systems to which the process subsequently travels. Transportation of class definitions with travelling processes is not feasible or practical in prior art systems because class definitions are not standardized; class definitions are generally very large and complex; and a single process generally uses objects of many classes.

Class definitions are not "standardized" in that prior art systems are typically based on existing programming languages which are not designed with mobile processes in mind. Therefore, class definitions in a process formed using one of these existing programming languages typically rely on information specific to the computer system within which the process is created, such as the specific memory addresses of portions of the class definitions. Reliance on such information, which is specific to a particular computer system, makes class definitions of prior art systems very difficult to transport to remote computer systems.

In the present invention, classes are represented by class objects which are part of the disclosed computer instruction set. A process formed in accordance with the present invention includes class objects when travelling from one computer system to another. Thus, a process can define a class of object in a first computer system, travel to a second computer system, and utilize objects of the class within the second computer system. Unnecessary delay and expense in transporting all classes utilized by a travelling process are eliminated by transporting only those classes which are not defined within the computer system to which the process travels.

Additionally, the present invention provides efficiencies not found in the prior art in transporting several clones of a process to several destination computer systems simultaneously. As discussed more completely below, substantial efficiencies are realized by deferring creation of one or more clones of the process so long as the travel path of one clone coincides with the travel path of another clone. Clones, and this aspect of the present invention, are discussed further below.

In remote programming systems, two processes share information by a first process giving a second process access to the first process. The first process gives the second process access to the first process without simultaneously obtaining access to the second process. In such a situation, the second process is free to interfere with the execution of the first process without compromising the security of the second process. In the present invention, a first process obtains access to a second process and simultaneously gives to the second process access to the first process through the cooperation and coordination of a third process. Further security is provided as the second process either accepts or rejects such an exchange with the first process according to the configuration of the second process. The third process ensures that (i) the second process agrees to such an exchange and that (ii) each process gains access to the other process simultaneously such that neither process can interfere with the execution of the other process without affording a similar opportunity to the other process.

A novel computer process of this invention is an agent process. An agent process is a computer process formed of the computer instructions disclosed below in Appendix A, which is a part of this disclosure and which is incorporated herein by reference in its entirety. Agent processes are each interpreted by another novel computer process of this invention, i.e., an engine, and thereby effectuates the computer instructions disclosed below and in Appendix A. The term "interpreted" is used herein as it is understood in the art; a computer instruction in a series of computer instructions is read and executed by an engine before the next computer instruction in the series is read.

Interpreting, rather than compiling, instructions of the disclosed instruction set provides greater generality. A first agent can travel from a first computer system to a second computer system and meet with a second agent there which gives to the first agent a procedure. The first agent can then perform the procedure which the first agent was not originally designed to perform.

Yet another novel computer process of this invention is a place process. Place processes are dispersed throughout a computer network. Each agent process "occupies" a respective place process; i.e., a place process is part of the internal state of an agent process and therefore provides a context within which the agent process executes. Each agent process can initiate and control the agent process's transportation from a first place process to a second place process. "Agent" and "place" as used herein are shorthand terms for "agent process" and "place process", respectively.

FIG. 4A shows computer network 100 which includes computer systems 120A and 120B which are connected by communications link 102AB. Computer system 120A is executing place 220A and agent 150A. Agent 150A occupies place 220A as shown in FIG. 4A. Computer system 120B is executing place 220B. Hereinafter, the statement that an agent or place occupies a particular place should be interpreted as including a statement that the agent or place is executing within the computer system which contains the particular place.

Agent 150A issues an instruction to computer system 120A. In response to the instruction, agent 150A is transported to a place, e.g. place 220B, specified in the instruction. The instruction is called operation "go", and the issuance of the instruction by agent 150A is called herein performance of operation "go" by agent 150A.

Upon performance of operation "go" by agent 150A, (i) execution of agent 150A is suspended; (ii) agent 150A is encoded into a standardized form which preserves the execution state of agent 150A; (iii) the standardized form of agent 150A is transported to computer system 120B; (iv) agent 150A, including the preserved execution state, is decoded from the standardized form; and (v) execution of agent 150A is resumed within computer system 120B. After performance of operation "go" by agent 150A, agent 150A no longer occupies place 220A and is no longer executing within computer system 120A; instead, agent 150A occupies place 220B and is executing within computer system 120B (FIG. 4B). By enabling an agent to travel to a remote computer system in the midst of the agent's execution, the agent is free to travel to data which the agent is configured to access.

A standardized form is a form to which agents are encoded for the transportation of the agent from one computer system to another. The standardized form preserves the execution state of the encoded agent such that the agent can be decoded at the destination computer system and execution of the agent can resume by executing the instruction of the agent which sequentially follows operation "go". Each computer system of the network of the present invention can maintain an agent in whatever form is convenient for carrying out the computer instructions included in the agent. However, in transporting an agent from one computer system to another, each computer system of the network must use the standardized form of an agent during transportation much the same way that two people must agree to the vocabulary and syntax of a single language to communicate. The nature of the standardized form is discussed in greater detail in Appendices B, C, D, E and F, which are part of this disclosure and which are incorporated in their entirety herein by reference.

As an agent can direct its own movement, i.e., transportation, through the network, means must be provided for specifying a number of parameters of a trip from a first computer system to a second computer system. A first parameter of a trip is the place to which the agent is transported, i.e., the destination of the trip. In one embodiment, a trip destination can be specified by name, by class, or by address. An address can be, for example, a location within a local area network.

Frequently, two or more pathways exist between a first computer system and a second computer system. One pathway may be quick but expensive and another may be time consuming but inexpensive. In such a case, no single pathway is always preferred in the transportation of an agent. Therefore, a second parameter of a trip is the "way" and the "means" for travel of an agent.

In addition, errors in configuring an agent for a trip to a nearby computer system can cause the agent to be inadvertently transported to distant computer systems at considerable expense to the creator of the agent. Therefore, an important parameter of a trip is the amount of time or resources that can be expended in transporting the agent before the trip is aborted.

Yet another important consideration in controlling the transportation of agents throughout a network is security. For example, if all agents travelling to a particular computer system are granted ingress, the particular computer system may become overburdened with many processes requiring substantial processing, and throughput of the particular computer system can suffer. Therefore, another parameter of a trip is the amount of resources the agent requires at the destination place. Thus, the agent can be denied ingress to the place if the resources required by the agent are more than the place is able or willing to provide.

In one embodiment, a ticket 1306 (FIG. 4A) controls the transportation of agent 150A and specifies place 220B as the destination place. As shown in FIG. 4A, agent 150A contains ticket 1306. Ticket 1306 defines the trip taken by agent 150A from place 220A to place 220B. In one embodiment, ticket 1306 specifies (i) the destination place of the trip, (ii) the "way" or pathway and "means" agent 150A is to take to the destination place, (iii) the maximum amount of time within which the trip must be completed before the trip is aborted and (iv) the amount of resources agent 150A asks to use at the destination place. By specifying the amount of resources agent 150A is permitted to use at place 220B, place 220B can determine whether agent 150A requires more resources than place 220B is configured to provide. In such a situation, place 220B can deny ingress to agent 150A. Thus, using a ticket as described more completely below, an agent can completely define a pending trip between a first place and a second place.

As discussed above, the prior art process known to the inventors cannot manipulate objects of a class defined only in a previously occupied computer system. In other words, if a prior art process defines a class of objects and thereafter travels to a destination computer system, the process cannot manipulate objects of the class unless the destination computer system contains a definition of the identical class or the process defines the same class again within the destination computer system. As described in greater detail below, agents of the present invention, which travel from one place to another, transport definitions of classes which are not defined within the destination place. Thus, agents of the present invention can define a class within a first computer system, travel to a second computer system and manipulate objects of the class while executing within the second computer system. Agents of the present invention therefore represent a significant improvement over the known prior art processes.

What is also generally lacking in the prior art is a means to implement a complex, multi-level