Object oriented representation of network requests in a client server model

Abstract

An object oriented representation for sending network protocol requests between a first and a second process in a computer network. In an object oriented implementation of a protocol stack a network definition object is used for defining an interface to a communication endpoint for a client application and a network address object for defining the communication endpoint. The protocol stack is formed by layers of instances of a protocol interface class object for defining protocol interface for a protocol layer in the protocol stack and a protocol layer class object for defining the protocol layers in the stack. The network protocol requests are sent in an instance of one of a set of network operation classes each of which correspond to a method in the protocol interface class. The client requests are wrapped in the network operation object which contains all the necessary information so the request can be presented to the appropriate protocol layer object in the protocol stack.

Claims

We claim:

1. A computer network for sending network protocol requests between a client and a server process, using a plurality of object oriented objects characterized by having a set of methods and data, the network comprising:

a network definition object for creating an interface to a communication endpoint for a client process;

a network address object for binding an address to the communication endpoint;

a protocol interface class object for creating a protocol interface for a protocol layer in a protocol stack;

a protocol layer class object for creating a protocol layer object;

a set of network operation classes each of which correspond to a respective method in the protocol interface class; and

means responsive to receipt of a network protocol request for deriving a network operation object from a selected network protocol class to send to the server process over the network.

2. A method for sending network protocol requests between a client and a server process in a computer network using a set of objects, each object having an integrated set of methods and data, the method comprising the steps of:

creating an interface to a communication endpoint for a client application;

creating a set of protocol interface objects from a protocol interface class object for protocol layers in a protocol stack;

creating a set of protocol layer objects from a protocol layer class object for the protocol layers;

selecting among a set of network operation classes each of which correspond to a method in the protocol interface class to derive a network operation object for a network protocol request; and

sending the network operation object between the first and second processes over the computer network.

3. The method as recited in claim 2 further comprising the steps of:

deriving the network operation object from the selected network operation class; and

flattening the network operation object prior to the sending step.

4. The method as recited in claim 3 further comprising the steps of:

receiving the network operation object at a server;

unflattening the network operation object at the server; and

executing a method in the network operation object which calls a method in a protocol object in a server side protocol stack.

5. The method as recited in claim 3 further comprising the step of setting a location to client for the network operation object to indicate that the network operation object was created at the client.

6. The method as recited in claim 4 further comprising the steps of:

creating an access network operation object;

creating a client side stackhead object to manage communication to the communication endpoint;

sending the access network operation object to the server; and

creating a server side stackhead object to represent the communication endpoint at the server;

wherein the stackhead objects are created at least in part by the access network operation object.

7. The method as recited in claim 6 further comprising the steps of:

creating a server side protocol stack for the communication endpoint composed of protocol layer and protocol interface layer objects; and

storing pointers to the objects in the server side protocol stack in the server side stackhead object.

8. The method as recited in claim 7 further comprising the steps of:

storing an ID for the server side stackhead object in a table at the server; and

sending the ID to the client side stackhead object.

9. A computer program product in a computer readable medium for sending network protocol requests between a client and a server process using a set of objects which have both methods and data, the product comprising:

a network definition object for creating an interface to a communication endpoint for a client application;

a network address object for binding an address to the communication endpoint;

a protocol interface class object for creating a protocol interface for a protocol layer in a protocol stack;

a protocol layer class object for creating a protocol layer object;

a set of network operation classes each of which correspond to a method in the protocol interface class for embodying a set of network protocol requests based on the methods; and

means responsive to receipt of a network protocol request for deriving a network operation object from a selected network protocol class to send to the server process over the network.

Description

DESCRIPTION

BACKGROUND OF THE INVENTION

This invention relates generally to data communication on computer networks and computer protocols which facilitate such communication. More particularly, it relates to an object oriented communication interface for network protocol access.

In the very early days of computing, computer systems were standalone processors to which peripheral devices such as displays and printers and input devices were connected. Each computer system was independent and there was little communication between computer systems. Today, it is well known to interconnect computer systems in computer networks such as local area networks or wide area networks to achieve a variety of benefits including the sharing of data, services and resources available from the various computer systems coupled to the networks.

To communicate between the different computer systems along a network, many communication protocols have been developed. Some examples of well-known network protocols include the System Network Architecture (SNA), Transmission Control Protocol/Internet Protocol (TCP/IP), Network Basic Input Output System (NetBIOS), and Internet Packet Exchange/Sequence Packet Exchange (IPX/SPX). Other communication protocols are known and widely used and described in various standards of ISO, IEEE and other organizations. To facilitate an understanding of the computer network, the network functions and associated software are often described as a series of layers. Data transfer between one copy of a distributed application over the network to another copy of the distributed application is accomplished by using the services of an underlying series of communication layers. Generally, each layer in one computer system has a counterpart layer in the receiving computer system so that each layer communicates with respective peer layers.

The seven layer Open Systems Interconnect (OSI) model is one of the best known descriptions of network communications, although many communication implementations combine or omit one or more of the OSI layers. In OSI, the physical layer is the lowest layer which interacts directly with the network. It includes the actual bit stream transmission across the physical connections to the network. The second layer is the datalink layer which provides multiplexing and framing of the physical layer stream into messages. It also provides error detection, synchronization information and physical channel management. The third layer is the network layer which controls routing of information through the network. Services such as addressing, network initialization, switching, segmenting and formatting are provided in this layer. Sometimes acknowledgement of data delivery is accomplished in this layer; sometimes in the datalink layer.

The fourth layer is the transport layer which controls transparent data delivery, multiplexing and mapping. Reliable delivery as opposed to best effort in the layers below is accomplished by this layer if desired by the application. Services such as retransmission of missing data, reordering of data delivered out of order and correction of transmission errors are usually accomplished in this layer. The fifth layer is the session layer which uses the information from the transport layer to group pieces of data together as a common activity between two nodes in the network called a session. The sixth layer is the presentation layer which includes the interface between the session layer and the seventh layer the application layer. The presentation layer presents the information for use in the application layer without compromising the integrity of the session layer. The presentation layer provides data interpretation and format and code transformation while the application layer provides user application interfaces and management functions.

Another well known network standard is the IEEE Standard. The primary difference between the IEEE model and OSI, is the splitting of the second OSI layer, the datalink layer into two sublayers, the media access layer (MAC) sublayer and the logical link control (LCC) sublayer. Media access control manages the medium access attachment in its control access to the communications media. The logical link control provides state machine for supporting the protocol specified by an associated data link control.

Another well known technology is object oriented programming which encapsulates data and methods into a programming entity called an object. By protecting certain methods and data through a public interface, an object oriented program can insulate each component from changes to other components yet provide the needed functions with a minimum of reprogramming. For more background information on object oriented technologies, concepts and conventions, the reader is referred to references such as Object Oriented Design With Applications, Grady Booch (The Benjamin/Cummins Publishing Company, 1990) and Object Oriented Software Construction, by B. Meyer, (Prentice Hall, 1988).

There have been previous attempts to apply object oriented technology to the general area of communication protocol in a multiprocessor network. As will be seen below, it remains a fertile area of invention.

SUMMARY OF THE INVENTION

An object oriented representation for sending network protocol requests between a first and a second process in a computer network. In an object oriented implementation of a protocol stack a network definition object is used for defining an interface to a communication endpoint for a client application and a network address object for defining the communication endpoint. The protocol stack is formed by layers of instances of a protocol interface class object for defining protocol interface for a protocol layer in the protocol stack and a protocol layer class object for defining the protocol layers in the stack. The network protocol requests are sent in an instance of one of a set of network operation classes each of which correspond to a method in the protocol interface class. The client requests are wrapped in the network operation object which contains all the necessary information so the request can be presented to the appropriate protocol layer object in the protocol stack.

BRIEF DESCRIPTION OF THE DRAWINGS

These objects, features and advantages will be more readily understood with reference to the attached figures and following description.

FIG. 1 depicts a computer system configured according to e teachings of the present invention.

FIG. 2A illustrates a class hierarchy for network definition object.

FIG. 2B illustrates the class hierarchy for the network address classes.

FIG. 2C illustrates the class hierarchy for the protocol interface classes.

FIG. 2D is an illustration of the class hierarchy for the protocol layer classes invention.

FIG. 3A shows a state diagram for the connection oriented transitions.

FIG. 3B is a state diagram of the connectionless state transitions.

FIG. 4A shows the class relationships for TCP/IP embodiment of the invention.

FIG. 4B is a flow diagram of the process for setting up a network connection according to the present invention.

FIG. 5 is an architectural diagram of the various objects in their network layers in the network connection process shown in FIG. 4.

FIG. 6A is a class hierarchy for the network event objects.

FIG. 6B is a flow diagram for the process for collecting events from a single communication endpoint.

FIG. 6C is a flow diagram for the process for collecting events from multiple communication endpoints.

FIGS. 7A and 7B are architectural diagrams of a first and second embodiment for managing a pool of communication threads for handling client requests of a network protocol server.

FIGS. 8A-8D are flow diagrams of the management process for the pool of communication threads.

FIGS. 9A and 9B are class heirarchy diagrams for network operation objects.

FIG. 9C shows the class relationships between various classes for the present invention.

FIG. 9D depicts the flow of messages between various objects in the network according to the invention.

FIG. 10 is a flow diagram for passing network protocol requests in a network operation object.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention may be run on a variety of computers or collection of computers under a number of different operating systems. The computer could be, for example, a personal computer, a mini computer, mainframe computer or a computer running in a distributed network of other computers. Although the specific choice of computer is limited only by disk and disk storage requirements, computers in the IBM PC series of computers could be used in the present invention. For additional information on IBM's PC series of computers, the reader is referred to IBM PC 300/700 Series Hardware Maintenance Publication No. S83G-7789-03 and User's Handbook IBM PC Series 300 and 700 Publication No. S83G-9822-00. One operating system which an IBM personal computer may run is IBM's OS/2 Warp 3.0. For more information on the IBM OS/2 Warp 3.0 Operating System, the reader is referred to OS/2 Warp V3 Technical Library Publication No. GBOF-7116-00.

In the alternative, the computer system might be in the IBM RISC System/6000 (TM) line of computers which run on the AIX (TM) operating system. The various models of the RISC System/6000 is described in many publications of the IBM Corporation for example, RISC System/6000, 7073 and 7016 POWERstation and POWERserver Hardware Technical reference, Order No. SA23-2644-00. The AIX operating system is described in General Concepts and Procedure--AIX for RISC System/6000 Publication No. SC23-2202-02 as well as other publications of the IBM Corporation.

In FIG. 1, a computer 10, comprising a system unit 11, a keyboard 12, a mouse 13 and a display 14 are depicted in block diagram form. The system unit 11 includes a system bus or plurality of system buses 21 to which various components are coupled and by which communication between the various components is accomplished. The microprocessor 22 is connected to the system bus 21 and is supported by read only memory (ROM) 23 and random access memory (RAM) 24 also connected to system bus 21. A microprocessor in the IBM PS/2 series of computers is one of the Intel family of microprocessors including the 386 or 486 microprocessors. However, other microprocessors including, but not limited to, Motorola's family of microprocessors such as the 68000, 68020 or the 68030 microprocessors and various Reduced Instruction Set Computer (RISC) microprocessors such as the PowerPC chip manufactured by IBM, or others made by Hewlett Packard, Sun, Motorola and others may be used in the specific computer.

The ROM 23 contains among other code the Basic Input-Output system (BIOS) which controls basic hardware operations such as the interaction of the disk drives and the keyboard. The RAM 24 is the main memory into which the operating system and application programs are loaded. The memory management chip 25 is connected to the system bus 21 and controls direct memory access operations including, passing data between the RAM 24 and hard disk drive 26 of floppy disk drive 27. The CD ROM 32 also coupled to the system bus 21 is used to store a large amount of data, e.g., a multimedia program or presentation.

Also connected to this system bus 21 are various I/O controllers: The keyboard controller 28, the mouse controller 29, the video controller 30, and the audio controller 31. As might be expected, the keyboard controller 28 provides the hardware interface for the keyboard 12, the mouse controller 29 provides the hardware interface for mouse 13, the video controller 30 is the hardware interface for the display 14, and the audio controller 31 is the hardware interface for the speakers 15. An I/O controller 40 such as a Token Ring Adapter enables communication over a network 46 to other similarly configured data processing systems.

One of the preferred implementations of the invention is as sets of instructions 48-52 resident in the random access memory 24 of one or more computer systems configured generally as described above. Until required by the computer system, the set of instructions may be stored in another computer memory, for example, in the hard disk drive 26, or in a removable memory such as an optical disk for eventual use in the CD-ROM 32 or in a floppy disk for eventual use in the floppy disk drive 27. One skilled in the art would appreciate that the physical storage of the sets of instructions physically changes the medium upon which it is stored electrically, magnetically, or chemically so that the medium carries computer readable information. While it is convenient to describe the invention in terms of instructions, symbols, characters, or the like, the reader should remember that all of these and similar terms should be associated with the appropriate physical elements. Further, the invention is often described in terms of comparing or validating, or other terms that could be associated with a human operator. No action by a human operator is desirable in any of the operations described herein which form part of the present invention; the operations are machine operations processing electrical signals to generate other electrical signals.

The network in which the workstation is integrated is a Local Area Network (LAN) or a Wide Area Network (WAN), the latter comprising a teleprocessing connection to other nodes or a network of systems operating under a known computer architecture. At any of the nodes, there may be one or more processing systems each of which may be a single user or a multi-user system configured more or less as described above. These processing systems operate as a client or server workstation depending upon whether it is requesting or supplying services. In one particular implementation, the invention runs on a plurality of IBM compatible workstations interconnected by a network communicating by one or more of various communication protocols. The software applications may be packaged together or sold as separate applications. A simplified description of local area networks may be found in a book by Larry E. Jordan and Bruce Churchill entitled: Communications and Networking For The IBM PC Published by: Robert J. Brady (A Prentice Hall Company 1983).

In a preferred embodiment, the invention is implemented in the C++programming language using object-oriented programming techniques. C++ is a compiled language. Programs are written in a human-readable script and this script is provided to another program called a compiler to generate a machine-readable numeric code which can be loaded into, and directly executed by a computer. The C++ language possesses certain characteristics which allow a software developer to easily use programs written by others while still providing a great deal of control over the reuse of programs to prevent their destruction or improper use. The C++ language is well-known and many articles and texts are available which describe the language in detail.

As known by those skilled in the art, object-oriented programming techniques involve the definition, creation, use and destruction of "objects". These objects are software entities comprising data elements and routines, or methods, which manipulate the data elements. The data and related methods are treated by the software as an entity and can be created, used and deleted as such. The data and functions enable objects to model real-world entity in terms of its attributes, which can be presented by the data elements, and its behavior, which can be represented by its methods.

Objects are defined by creating "classes" which are not objects themselves, but which act as templates which instruct a compiler how to construct the actual object. A class may, for example, specify the number and type of data variables and the steps involved in the functions which manipulate the data. An object is actually created in the program by means of a special function called a constructor which uses the corresponding class definition and additional information, such as arguments provided during object creation, to construct the object. Objects are destroyed by a special function called a destructor.

Many benefits arise out of three basic properties of object-oriented programming techniques: encapsulation, polymorphism and inheritance. Objects can be designed to hide, or encapsulate, all, or a portion of, the internal data structure and the internal functions. More particularly, during program design, a program developer can define objects in which all or some of the data variables and all or some of the related methods are considered "private" or for use only by the object itself. Other data or methods can be declared "public" or available for use by other programs. Access to the private variables and methods by other programs can be controlled by defining public methods which access the objects private data. The public methods form an interface between the private data and external programs. An attempt to write program code which directly accesses the private variables causes the compiler to generate an error during program compilation. This error stops the compilation process and prevents the program from being run.

Polymorphism allows objects and functions which have the same overall format, but which work with different data, to function differently to produce consistent results. For example, an addition method may be defined as variable A plus variable B, (A+B). This same format can be used whether the A and B are numbers, characters or dollars and cents. However, the actual program code which performs the addition may differ widely depending on the type of variables which comprise A and B. Thus, three separate method definitions can be written, one for each type of variable (numbers, characters and dollars). After the methods have been defined, a program can later refer to the addition method by its common format (A+B) and, during compilation, the C++ compiler will determine which of the three methods to be used by examining the variable types. The compiler will then substitute the proper function code.

A third property of object-oriented programming is inheritance which allows program developers to reuse pre-existing programs. Inheritance allows a software developer to define classes and the objects which are later created from them as related through a class hierarchy. Specifically, classes may be designated as subclasses of other base classes. A subclass "inherits" and has access to all of the public functions of its base classes as though these functions appeared in the subclass. Alternatively, a subclass can override some or all of its inherited functions or may modify some or all of its inherited functions by defining a new function with the same form.

The creation of a new subclass borrowing the functionality of another class allows software developers to easily customize existing code to meet their particular needs.

Although object-oriented programming offers significant improvements over other programming concepts, program development still requires significant outlays of time and effort, especially if no pre-existing software programs are available for modification. Consequently, a set of pre-defined, interconnected classes are sometimes provided to create a set of objects and additional miscellaneous routines which are all directed to performing commonly-encountered tasks in a particular environment. Such pre-defined classes and libraries are typically called "frameworks" and essentially provide a pre-fabricated structure for working application.

For example, a framework for a user interface might provide a set of pre-defined graphic interface objects which create windows, scroll bars, menus, etc. and provide the support and "default" behavior for these graphic interface objects. Since many frameworks are based on object-oriented techniques, the predefined classes can be used as base classes and the built-in default behavior can be inherited by developer-defined sublcasses and either modified or overridden to allow developers to extend the framework and create customized solutions in a particular area of expertise. This object-oriented approach provides a major advantage over traditional programming since the programmer is not changing the original program, but rather extending the capabilities of the original program. In addition, the framework provides architectural guidance and modeling and, at the same time, frees the developers to supply specific actions unique to the problem domain.

A networking framework is provided by the invention described below to provide network services for the applications of various computer systems in a computer network.

Protocol Interface Model

The object oriented protocol interface model and mechanism are described in this section. The generic nature of this interface enables the development of any layer of the OSI network model. As such, all the network layers will have similar syntax, the semantics of which will be defined by the particular layer specifications. In other words, objects embodying different layers in the OSI network model are similar in syntax, however, their implementation could differ depending on the particular layer responsibilities. Further, the objects embodying respective layers for a particular protocol, e.g., TCP/IP, may differ in capabilities and implementations for similar layers of a different protocol, e.g., Net BIOS, because of the differences in responsibilities of the respective layers in the two protocols. The model also provides mechanisms for defining a communication endpoint, reusing the endpoint, and monitoring network events. Being an object oriented model, it inherits all the features of object oriented implementation such as code reusability, maintainability, and ability to update the implementations without affecting the client applications.

1. Creating a communication endpoint:

The creation of a communication endpoint is facilitated through the network definition objects. Each network definition object contains the definition of a client interface. These are the abstractions for the different types of objects the client program would want to access. The communication endpoint is the TAccessDefinition object which is derived from the network definition class.

FIG. 2A gives the class hierarchy for the network definition objects. The TNetworkDefinition class 100 contains methods for instantiating the endpoint and destroying the communication endpoint, InstantiateDefinition and DeinstantiationDefinition, respectively. Methods for constructing a new instance of TNetworkDefinition or destruction of the particular class object are also provided, these methods are common to all the classes and will not be repeated below.

The TAccessDefinition object 101 contains the protocol interface objects that define the particular protocol type and its layers. The TAccessDefinition object 101 serves as the handle for the communication endpoint. In addition, to the methods inherited from its parent, TNetworkDefinition, the TAccessDefinition object 101 also include methods that add an interface layer to the access definition on top of the ones already added, Add to top to add an interface layer to the AccesssDefinition to the ones already added at the bottom, add to bottom, and methods to get the highest protocol layer interface, GetTopOfStack. The TEventDefinition, class 103 is used to monitor the network events. The TEventDefinition class 103 will be described in greater detail below in the NetworkEvent section.

2. Network Address Classes

The TNetworkAddress class 111 is the base class used to define all the protocol address classes and the hardware address classes. FIG. 2B illustrates the class hierarchy of the protocol address classes. The TNetworkAddress class 111 contains methods for testing a type of address, IsOf AddressType, testing for a group address IsGroup, testing for a broadcast address, IsBroadCast, testing for a multicast address, IsMulticast and testing for a null address, IsNullAddress. This class also contains methods for getting the wire length of an address, GetWireLength, formatting the address into a header, AddressToWire, and getting the address from a header, WireToAddress. There are operators to determine whether a stream is coming into the endpoint which or the stream is originating from the endpoint are also part of the class. A method for getting a pointer is unique for each class, GetClassIdentifier, is provided by the class.

An instance of the TProtocol Address class object serves as a communication endpoint so that the protocol address can be passed. The TProtocolAddress object 113 adds methods for getting a broadcast address, BroadCastAddress, and for getting a null address, NullAddress. Instances of the THardwareAddress object 115 pass hardware addresses to an application if needed. The THardwareAddress object 115 similarly adds methods for getting a broadcast address, BroadCastAddress and getting a null address, NullAddress. It also adds a method for testing for a functional address, IsFunctional. The TIEEE8023 Address class changed the hardware class address according to the IEEEE802.3 addressing conventions. In addition, it adds methods for testing for group address, IsGroup, setting to the group address, SetGroup, reset the group address, ClearGroup. Other methods include BroadCastAddress which gets a BroadCastAddress, IsMulticast which tests for a multicast address, null address which gets a NullAddress and CanonicalAddress which gets an address from canonical input.

The TTCPAddr 117 and TNBAddr 119 are the examples of some concrete address classes that represent the TCP/IP and NetBIOS addressing specifics, respectively. Similarly, the TIEEE8023Addr 121 and TIEEE8025Addr 123 represent the concrete hardware addresses for IEEE802.3 and IEEE802.5 addressing.

3. Protocol Interface Classes

The invention supports both the connection oriented and connectionless transactions. It also describes the state machines that a protocol independent application would follow. The object hierarchy for the protocol interface classes is illustrated in FIG. 2C. The protocol interface classes are derived from a base class called MProtocolServe 133 which contains methods for all the common functions that a protocol must have. The TProtocolInterface class 135 contains additional methods for the network functions. These methods are detailed below in Table 1 and Table 2. A network protocol such as TCP/IP will derive its TCPIPInterface class from the TProtocolInterface to override the default implementations and add its own specific features such as a check for valid flags on a send or receive request. Separate classes which derive from the TProtocolInterface class are provided for the session layer, TSessionInterface 137, for the transport layer TTransportInterface 138, for the network layer TNetworkInterface 141, for the family layer TFamilyInterface 143, and for the data link layer TDLCInterface 145. In the object hierarchy is illustrated in this embodiment, the OSI network layer is split into a Network Layer and a lower layer called a protocol Family Layer. The family layer contains the non-replicated portion of the OSI Network Layer such as routing information. The Network Layer contains information relative to a particular endpoint such as the peer address and local SAP. This is done to ensure that only one object such as a FamilyLayer object stays resident in the system keeping all the global information relative to the protocol. As each endpoint is created and destroyed by the client applications, the other protocol layer objects such as the sessions layer and the transport layer objects and network layer object are created and destroyed while the family layer object and the datalink layer object stay resident.

The concrete classes are derived from the individual interface classes. For example, as is discussed below concrete classes are provided for transport, network, and family interface classes for a particular protocol, e.g., TCP/IP, to build the protocol stack.

                  TABLE 1
    ______________________________________
    As mentioned above, the MProtocolService object
    serves as the base class for the protocol layer
    definitions. Following are the list of methods that are
    provided in the MProtocolService object. Most of these
    methods are pure virtual functions.
    Bind-           Initialize and bind a local
                    address
    Unbind-         Unbind a local address
    SendRelease-    Orderly release initiation
    ReceiveRelease- Acknowledge receipt of orderly
                    release initiation.
    GetLocalAddress-
                    Get the local address
    SetLocalAddress-
                    Set the local address
    GetPeerAddress- Get the peer address
    SetPeerAddress- Set the peer address
    GetProtocollnfo-
                    Get the protocol info
    SetProtocollnfo-
                    Set the protocol info
    GetProtocolOptions-
                    Set the protocol options
    GetRequestMode- Get the request mode
    SetRequestMode- Set the request mode
    GetRetry-       Get the protocol layer retry
                    parameter
    SetRetry-       Set the protocol layer retry
                    parameter
    GetTimeout-     Get the protocol layer timeout
                    Parameter
    SetTimeout-     Set the protocol layer timeout
                    parameter
    GetStatistics-  Get the protocol layer statistics
    SetStatistics-  Set the protocol layer statistics
    IsSession-      Return TRUE if protocol layer is a
                    session layer
    IsTransport-    Return TRUE if protocol layer is a
                    transport layer
    IsNetwork-      Return TRUE if protocol layer is a
                    network layer
    IsFamily-       Return TRUE if protocol layer is a
                    family layer
    Operator<<=-    Operator for receiving the object
                    into a data stream
    Operator<<=-    Operator for sending the object
                    into a data stream
    ______________________________________


              TABLE 2
    ______________________________________
    The following are the list of functions that are provided
    in TProtocolInterface class.
    ______________________________________
    GetLayerIndex- Get the index of the protocol layer
    Cancel Requests-
                   Cancel all the current outstanding
                   requests
    ReceiveEvent-  Receive events on this stack
    GetConnectionInfo-
                   Obtain connection info & memory
                   constraints
    BorrowMemory-  Borrow system memory for network
                   data
    ReturnMemory-  Return system memory for network
                   data
    GetAccessDefinition-
                   Get the pointer to the
                   TAccessDefinition
    GetLocalAddress-
                   Get the local address for a layer
    SetLocalAddress-
                   Get the local address for a layer
    GetPeerAddress-
                   Get the peer address for a layer
    SetPeerAddress-
                   Get the peer address for a layer
    GetProtocolInfo-
                   Get the protocol info for a layer
    SetProtocol Info-
                   Set the protocol info for a layer
    GetProtocolOptions-
                   Get the protocol options for a
                   layer
    SetProtocolOptions-
                   Set the protocol options for a
                   layer
    GetRequestMode-
                   Get the request mode for a layer
    SetRequestMode-
                   Set the request mode for a layer
    GetRetry-      Get the protocol layer retry
                   parameter
    SetRetry-      Set the protocol layer retry
                   parameter
    GetStatistics- Get the protocol layer statistics
    GetTimeout-    Get the protocol layer timeout
                   parameter
    SetTimeout-    Set the protocol layer timeout
                   parameter
    Bind-          Bind a protocol stack
    Unbind-        Unbind a protocol stack
    Receive-       Receive network data
    Send-          Send network data
    Connect-       Initiate an attempt to establish a
                   connection
    ReceiveConnection-
                   Wait for an attempt to establish
                   connection
    Disconnect-    Terminate a connection
    ReceiveDisconnect-
                   Wait for a disconnection
    AcceptConnection-
                   Accept an attempt to establish a
                   connection
    RejectConnection-
                   Reject an attempt to establish a
                   connection
    Listen-        Listen for attempts to establish
                   connections
    ListenForConnection-
                   Listen for an attempt to establish
                   a connection
    SendRelease-   Orderly release initiation => no
                   more data to send
    ReceiveRelease-
                   Acknowledge receipt of orderly
                   release indication
    Operator<<=-   Operator to stream-in the object to
                   a data stream
    Operator>>=-   Operator to stream-out the object
                   to a data stream
    ______________________________________

                  TABLE 3
    ______________________________________
    The following are the main functions of the
    TProtocolLayer class.
    ______________________________________
    Dispatch-       Dispatch an inbound packet to a
                    higher layer
    Transmit-       Transmit an outbound packet to a
                    lower layer
    DispatchEvent-  Dispatch an event to a higher
                    layer
    TransmitEvent-  Transmit an event to a lower layer
    ReceiveEvent-   Enable reporting of events
    CancelReceiveEvent-
                    Cancel reporting of events
    InstantiateInterface-
                    Create an interface object from a
                    layer object
    GetUpperProtocol-
                    Get the pointer to the next higher
                    layer
    GetLowerProtocol-
                    Get the pointer to the next lower
                    layer
    Bind-           Bind a protocol stack
    Unbind-         Unbind a protocol stack
    Connect-        Initiate an attempt to establish a
                    connection
    ReceiveConnection-
                    Wait for an attempt to establish
                    connection
    Disconnect-     Terminate a connection
    GetPacketQueue- Return the pointer to the packet
                    queue from
                    which to obtain inbound data
                    packets
    ReceiveDisconnect-
                    Wait for a disconnection
    AcceptConnection-
                    Accept an connection initiation
    RejectConnection-
                    Reject an attempt to establish a
                    connection
    Listen-         Listen for attempts to establish
                    connections
    ListenForConnection-
                    Listen for an attempt to establish
                    a connection
    SendRelease-    orderly release initiation => no
                    more data to send.
    ReceiveRelease- acknowledge receipt of orderly
                    release indication.
    operator<<=-    Operator to marshal the
                    TProtocolLayer object to a data
                    stream
    operator>>=-    Operator to unmarshal the
                    Tprotocollayer object to a
                    datastream
    ______________________________________

    ______________________________________
    GetPSDUSize     Get the protocol service Data
    Unit            maximum size SetPSDUSize
                    Get the Protocol Service Data
                    Unit maximum size
    GetEPSDUSize    Get the Expedited Protocol
                    Service Data Unit maximum size
    PSDUSize        Set the Expedited Protocol
                    Service Data Unit maximum size
    GetConnectionDataSize
                    Get the Connect Data maximum
    size
    SetConnectDataSize
                    Set the Connect Data maximum
    size
    GetDisconnectDataSize
                    Get the Disconnect Data maximum
                    size
    SetDisconnectDataSize
                    Set the Connect Data maximum
    size
    GetDisconnectDataSize
                    Get the Disconnect Data maximum
                    size
    Set DisconnectDataSize
                    Set the Disconnect Data maximum
                    size
    GetServiceType  Get the service type such as
                    connection/connectionless
    SetServiceType  Set the Service Type
    SetServiceType  Set the Service Type
    SetServiceFlags Set the Service Flags
    ______________________________________

• Inventors
  Heimsoth, Daniel Dean; Horn, Gary Randall; Sharma, Mohan; Turner, Laurie Beth; Yeung, Leo Yue Tak;
• Assignee
  International Business Machines Corporation (Armonk, NY)
• Published
  Aug-17-1999
• Current US Classes:
  709/230
  719/316
• Application #
  612741
• International Classes
  G06F 009/40
• Field of Search
  395/200.6 395/200.58 395/680 395/614 395/683 395/684
• Examiner
  Oberley; Alvin E.
• Agent
  LaBaw; Jeffrey S.
• US Patent References:
  5136716
  5280610
  5307490
  5414812
  5509123
  5515508
  5548723
  5613100
  5764915