Page-description language interpreter for a parallel-processing system

Abstract

The rasterize processing for obtaining printing picture element information from a source file described in a page-description language is distributed-processed by a plurality of information processing units (6a, 6b, 6c) loose connected via a network (7). In the information processing unit (6a) which generates a printing request, a client process (210) converts a source file (19) into an intermediate code file (10) and further divides the intermediate code file into a plurality of partial files executable in the rasterize processing, independently. A part of these plural partial files is given to a rasterizer (212) of the information processing unit (6a) which generates a printing request, so as to be rasterized into picture element information. The remaining part of the plural partial files are distributed to the other information processing units (6b, 6c) via the network. In each of these other information processing units (6b, 6c), the distributed partial file is received by a server process (211), transmitted to the rasterizer (212) to form partial picture element information. These partial picture element information formed by these other information processing units (6b, 6c) are returned to the information processing unit (6a) which generates the printing request. In this information processing unit (6a) which generates the printing request, the client process (210) combines the picture element information returned from the other information processing units (6b, 6c) with the picture element information formed by the rasterizer (212) of its own unit, to form the entire picture element information. The entire picture element information is transmitted to a printing unit (21).

Claims

I claim:

1. A page-description language interpreter for executing rasterize processing to obtain printing picture element information from a source file described in a page-description language, comprising:

a plurality of information processing units connected via a network, each of said information processing units having an independent memory which is not shared with another information processing unit of the network for independently processing an assigned task in a parallel-processing system;

means for receiving the source file and dividing a received source file or an intermediate file converted from the received source file into a plurality of partial files each of which can be rasterized independently;

means for transmitting the partial files to said plural information processing units via the network, to distributed-process the rasterize processing by the plural information processing units;

means provided for each of said plural information processing units, for obtaining partial picture element information by rasterizing the transmitted partial file; and

means for collecting the partial picture element information obtained by said plural information processing units via the network and forming entire picture element information by combining the collected partial picture element information.

2. The page-description language interpreter of claim 1, wherein said dividing means comprises:

means for detecting a mutual overlap between graphic form elements included in the source file; and

means for dividing the source file or the intermediate file into plural partial files in such a way that the detected overlapped graphic form elements are not included in different partial files.

3. The page-description language interpreter of claim 1, wherein said transmitting means comprises means for deciding information processing units which can share the rasterize processing by checking load status of said plural information processing units, respectively, and transmitting the partial files to only the decided information processing units.

4. An information processing unit connectable to at least one other information processing unit via a network, each of said information processing units having an independent memory which is not shared with another information processing unit of the network for independently processing an assigned task in a parallel-processing system, comprising:

means for receiving a source file described in a page-description language and dividing a received source file or an intermediate file converted from the received source file into a plurality of partial files each of which can be rasterized independently;

means for transmitting a part of the plural partial files to the other information processing unit via the network, to share partial rasterize processing of the plural partial files with the other information processing unit;

means for obtaining picture element information of a remaining partial file of the plural partial files, by rasterizing the remaining partial file except the partial file transmitted to the other information processing unit;

means for receiving a partial picture element information obtained by the rasterize processing in the other information processing unit from the other information processing unit via the network, and obtaining entire picture element information by combining a received partial picture element information with picture element information of the remaining partial file.

5. The information processing unit of claim 4, wherein the information processing unit is a computer.

6. The information processing unit of claim 4, wherein the information processing unit is a printing unit.

7. An information processing unit connectable to a plurality of other information processing units via a network, each of said information processing units having an independent memory which is not shared with another information processing unit of the network for independently processing an assigned task in a parallel-processing system, comprising:

means for receiving a source file described in a page-description language and dividing a received source file or an intermediate file converted from the received source file into a plurality of partial files each of which can be rasterized independently;

means for distributing the plural partial files to the plural other information processing units via the network, for rasterize processing of the plural partial files by the plural other information processing units as a distributed process; and

means for collecting partial picture element information obtained by rasterize processing in the plural other information processing units from the plural other information processing units via the network, and obtaining entire picture element information by combining the collected partial picture element information.

8. An information processing unit connectable to at least one other information processing unit via a network, each of said information processing units having an independent memory which is not shared with another information processing unit of the network for independently processing an assigned task in a parallel-processing system, comprising:

means for responsive to a message for requesting participation in page-description language translation processing, transmitted from the other information processing unit via the network, for discriminating whether the information processing unit can participate in the translation processing according to load condition, and transmitting a result of said discrimination to the other information processing unit;

means for receiving a partial file of a source file described in a page-description language or an intermediate code file converted from the source file, transmitted from the other information processing unit via the network, when the information processing unit can participate therein, and obtaining picture element information by rasterizing the partial file; and

means for transmitting the picture element information obtained by rasterizing the partial file, to the other information processing unit via the network.

9. An interpreter mounted on a first information processing unit connected to at least one other information processing unit via a network, each of said information processing units having an independent memory which is not shared with another information processing unit of the network for independently processing an assigned task in a parallel-processing system, for executing rasterize processing such that a source file described in a page-description language is converted into picture element information used in printing the source file, comprising:

client means for partially sharing rasterize processing of a first source file whose printing request is generated by the first information processing unit with the other information processing, unit; server means for partially sharing rasterize processing of a second source file whose printing request is generated by the other information processing unit; and rasterize means for executing the rasterize processing of any given file, and

wherein said client means comprises:

means for receiving the first source file and dividing the first source file, or a first intermediate code file converted from the first source file, into a plurality of partial files each of which can be rasterized independently;

means for transmitting a part of the plural partial files to the other unit via the network, to partially share the rasterize processing of the plural partial files with the other unit;

means for transmitting remaining partial files of the plural partial files except those transmitted to the other unit to said rasterize means; and

means for receiving picture element information obtained by the rasterize processing of the other unit from the other unit via the network, and obtaining entire picture element information by combining received picture element information with picture element information of a remaining portion obtained by said rasterize means, and

wherein said server means comprises:

means for receiving a partial file of the second source file or the second intermediate code file converted from the second source file from the other unit via the network, and transmitting the received partial file to said rasterize means; and

means for receiving picture element information of the partial file transmitted to said rasterize means from said rasterize means, and transmitting the received picture element information to the other information processing unit via the network.

10. An interpreting method of executing rasterize processing to obtain printing picture element information from a source file described in a page-description language, comprising the steps of:

preparing a plurality of information processing units connected via a network, each of said information processing units having an independent memory which is not shared with another information processing unit of the network for independently processing an assigned task in a parallel-processing system;

dividing the source file or an intermediate code file converted from the source file into a plurality of partial files each of which can be rasterized independently;

transmitting the partial files to the plural information processing units via the network, to distributed-process the rasterize processing by the plural information processing units;

obtaining partial picture element information by rasterizing the transmitted partial file in each of the plural processing units; and

collecting the partial picture element information obtained by the plural information processing units via the network at a place to form entire picture element information by combining the collected partial picture element information.

Description

TECHNICAL FIELD

The present invention relates to a translating processing of description language programs describing printing control for a printing unit used as one of computer peripheral units, and more specifically to an interpreter for executing the translating processing of a descriptive language (referred to as "page-description language" in general and therefore hereinafter) developed to describe printing control procedure, characters, graphic forms, image information, etc. and to generalize the conversion of these characters, graphic forms and image information into printing picture elements and the printing operation thereof, which can be applied to a system in which a plurality of information processing units are connected in a network fashion.

BACKGROUND ART

With the advance of the development of printing units suitable for high speed digital printing such as electrophotographic technique, ink jet technique, etc., there has been widely used the single page unit printing procedure control method such that images, graphic forms and characters can be handled in the same way and further characters and graphic forms can be freely enlarged, rotated or transformed, being different from the prior-art method of printing mainly characters. Since the control method as described above has been realized, it is general to develop program languages for describing control procedure, to mount a language translating processing system (so-called interpreter) on a printing unit or a computer, and to convert the language into printing picture elements through the interpreter.

In a single computer, a printing request generated by an application program calls the function of an operating system to actuate a printing unit. Under these conditions, "the page description language" is used to execute the printing procedure, without depending upon hardware such as the resolution, printing method, and the number of printing head dots of the printing unit.

An example of prior-art systems will be described hereinbelow with reference to FIGS. 1A and 1B. Source codes 19 of the page-description language generated by an application program within a computer 6d are translated by a page-description language interpreter 8 to convert the source codes into picture elements used for actual printing. This operation as to whether the page-description language interpreter 8 is executed within the computer 6d as shown in FIG. 1A or within a printing unit 21 as shown in FIG. 1B is different according to the system. In any cases, however, the page-description language interpreter is realized by a single processor in the prior-art system.

Further, there exists a system referred to as print server as one of prior-art systems related to the present invention. In this system, another computer (not shown) is connected to the computer 6d as shown in FIG. 1A, for instance in a network fashion, and the page-description language is rasterized by another computer, instead of the computer 6d which generates a printing processing request. In this prior-art system, the interpreter is realized by a single processor of another computer.

A large capacity of memory is required for conversion of the page-description language into printing picture elements, when executed by the interpreter. Further, where the interpreter is realized by only software, there exists a serious problem in that the processing time is long. In addition, it is apparent that color page printers are expected to be used widely in the near future and high density printing will be required more and more in the case of black-and-white printing. In both the cases, a huge memory space is inevitably necessary. In the case of the color printing, since the printing control procedure is further complicated and therefore the procedure items required for the translation processing program system increase, a long processing time may be required for the execution of the color printing.

To solve the above-mentioned problems, the object of the present invention is to realize a high-speed and high-density processing, which can reduce the contents to be processed by a single processor in accordance with distributed processing such that the respective procedures of the interpreter can be executed by a plurality of processors, to provide such an effect that a huge memory space can be secured as a whole by allowing the plural processors to utilize the respective memory spaces of the respective processors.

DISCLOSURE OF THE INVENTION

The present invention provides a page-description language interpreter for executing rasterize processing such that picture element information for printing can be obtained by a source file described in a page-description language, comprising:

a plurality of information processing units loose connected via a network;

dividing means for receiving the source file and dividing the received source file or an intermediate code file converted from the source file into a plurality of partial files executable in the rasterize processing, independently;

distributing means for distributing the partial files to said plural information processing units via the network, to distributed-process the rasterize processing by the plural information processing units;

means provided for said plural information processing units respectively, for obtaining partial picture element information by rasterizing the distributed partial file; and

means for collecting the partial picture element information obtained by said plural information processing units via the network and forming entire picture element information by combining the collected partial picture element information.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are block diagrams showing prior-art PDL interpreter configurations;

FIG. 2 is a block diagram showing a first embodiment configuration of the PDL interpreter according to the present invention;

FIG. 3 is a block diagram showing a computer configuration of the embodiment shown in FIG. 2;

FIG. 4 is a block diagram showing a client process configuration of the computer shown in FIG. 3;

FIG. 5 is a block diagram showing a server process configuration of the computer shown in FIG. 3;

FIG. 6 is a flowchart showing the client process operation shown in FIG. 4;

FIG. 7 is a flowchart showing a resident program operation shown in FIG. 3;

FIG. 8 is a block diagram showing the resident program configuration;

FIG. 9 is an illustration for assistance in explaining response message specifications;

FIG. 10 is an illustration for assistance in explaining response message specifications including printer structures;

FIG. 11 is an illustration for assistance in explaining the procedure of describing a polygon;

FIG. 12 is an illustration for assistance in explaining an example of a polygon partially filled;

FIG. 13 is a flowchart showing the filling algorithm;

FIGS. 14 and 15 are illustrations for assistance in explaining the filling algorithms;

FIG. 16 is an illustration for assistance in explaining the discrimination of graphic form groups;

FIGS. 17 and 18 are illustrations for assistance in explaining the filling algorithms;

FIGS. 19 and 20 are illustrations for assistance in explaining the first method of discriminating graphic form groups;

FIG. 21 is a flowchart showing the procedure of detecting an overlap of graphic form elements of the example shown in FIGS. 19 and 20;

FIG. 22 is a flowchart showing the procedure of the discrimination and area coupling detection of graphic form group of the examples shown in FIGS. 19 and 20;

FIGS. 23 and 24 are illustrations for assistance in explaining the procedure of the area coupling detection between the graphic form groups shown in FIG. 22;

FIG. 25 is an illustration for assistance in explaining the second method of detecting a graphic form group;

FIG. 26 is an illustration for assistance in explaining the graphic form groups detected by the method shown in FIG. 25;

FIG. 27 is an illustration for assistance in explaining the third method of detecting the graphic form group;

FIG. 28 is an illustration for assistance in explaining the printing procedure;

FIG. 29 is a flowchart showing the printing procedure;

FIG. 30 is a flowchart showing the interpretation processing procedure;

FIG. 31 is a block diagram showing the second embodiment configuration according to the present invention;

FIGS. 32 and 33 are flowcharts showing the operation of the second embodiment;

FIG. 34 is a block diagram showing the third embodiment configuration according to the present invention;

FIG. 35 is a schematic block diagram showing the fourth embodiment configuration according to the present invention;

FIG. 36 is a schematic block diagram showing the fifth embodiment configuration according to the present invention;

FIG. 37 is a block diagram showing the sixth embodiment configuration according to the present invention; and

FIG. 38 is a block diagram showing a printer configuration of the sixth embodiment shown in FIG. 37.

PREFERRED EMBODIMENTS OF THE INVENTION

In recent computer systems, it has become usual that a plurality of personal computers and engineering work stations are connected for use into a network. The present invention can be executed under these environments, when an application program being executed by one of computers connected on the network generates a request of printing processing to the operating system. The printing request generated by any one of the computers calls the function of the operating system to actuate a printing unit. Under these conditions, "the page-description language" is used to execute the printing procedure without depending upon hardware such as the resolution, printing method, the number of printing head dots of the printing unit. In other words, since the application program does not know the hardware contents of the printing units used in the network system, a source file written in a page-description language is given to a translating program. In the present invention, the translating program divides the source file into small files that can be handled independently and converts the small files into printing picture elements by sharing the respective small file processing with other processors now usable on the network under control of the operating system.

Several preferred embodiments of the present invention will be described hereinbelow.

FIG. 2 shows a first embodiment of the page-description language parallel-processing interpreter according to the present invention. This embodiment is composed of a plurality of computers 6a to 6c and at least one printer 21. FIG. 3 shows the functions of one 6a of these computers. The other computers 6b and 6c are also provided with the same functions.

In this embodiment, the general hardware configuration for operating the page-description language parallel-processing printer of the present invention is as follows:

(a) In addition to a computer (referred to as "computer A", hereinafter) for generating a printing request, at least one information processing unit (e.g. another computer or printer) is connected to the computer A via some communicating means.

(b) The computer A and the information processing unit connected to the computer A can execute the page-description language interpreter on the basis of the distributed processing.

(c) The computer A and the information processing unit can execute at least two processes.

Here, an execution unit of a program which consumes memory and processor resources required for execution under control of the operating system, is referred to as "process". The process is controlled by the memory allocation and the process header. In this process header, a process identifier (process ID), a current program counter, a stack pointer, values held by another CPU register, and a memory status are recorded. The process that has lower priority in execution order is swappd out to an auxiliary memory (not in the main memory) by the operating system. Further, it is also possible to construct a single unit program by a plurality of processes. Further, communicating means between the computer A for generating a printing request and other information processing units, or hardware for realizing the communicating means is referred to as "network", hereinafter. The network is provided with a physical address control mechanism dependent upon the hardware, and a logical address control mechanism referred to by the upper structured programs. Although being used for packet transfer to a specific computer connected to the network, these addresses are provided with more abstract higher order processing procedure in many network protocols. In the embodiments of the present invention, the operation will be explained under the condition that a group of these higher order processing routines are supplied by the operating system. Owing to the control mechanism as described above, the assumption is made that the program can detect a computer on the basis of its name (i.e. identifier) and logical address and further can execute packet transmission/reception to/from the communicating process by use of a communication socket or a similar mechanism.

With reference to FIG. 3, the computer 6a of this embodiment will be described hereinbelow. The configuration of the other computers 6b and 6c is the same as that of the computer 6a.

This computer 6a constructs a part of the page-description language translation processing system. Here, "page-description language" implies a language used to describe the control procedure such as printed data arrangement and form, character information, etc. of printing units of dot-matrix type, electrophotography type, etc. The language grammar is generally determined by specifications peculiar to each language. However, these grammars are only a promised decision. The present invention provides a processing method of translating a document described on the basis of a specific page-description language and further converting the translated document into actually printed data. Therefore, the language specifications are not described hereinbelow. Further, "page-description language" is referred to as PDL simply, hereinafter.

In FIG. 3, the translation processing system of the present invention includes two sections 1 and 2. The section 1 is a resident program and the section 2 is a PDL parallel processing interpreter for executing printing data forming processing. In this embodiment, a printing unit 21 (shown in FIG. 2) performs only the so-called bit image printing such that the printing and nonprinting of each of picture elements are determined on the basis of 0/1 of one bit included in a data string. On the other hand, the PDL parallel processing interpreter 2 inputs the page-description language source codes and outputs a data string for bit image printing and printer control codes.

The PDL parallel processing interpreter 2 of the present invention includes three processes 210, 211 and 212. The process 210 is a client process for PDL translation, which uses the rasterize process 212. The process 211 is a server process formed by the resident processing program 1. The process formation is effected by a process forming mechanism 207 of an operating system 4.

The operating system 4 allocates CPU times to a plurality of processes by a scheduler 208. Therefore, the computer 6a can realize the so-called multitask processing by which a plurality of processes can be executed simultaneously. The scheduler 208 can be realized by the priority control and the queue control processing of a kernel 206 of the operating system 4. Further, in the operating system 4, a device driver 3 such as hard disk device driver, clock driver, etc. is used. The resident program 1 and the PDL parallel processing interpreter 2 use a network device driver 213 to effect communications of data strings with the other computers 6b and 6c and the printing unit 21. Further, there is character style (font) data 205 as another source used for the printing processing. The character style data 205 is recorded in an auxiliary memory unit 204 in the form of outline font data or bit map font data.

The computer 6a can execute a plurality of application programs 5 and 18 simultaneously. The computer user operates the application programs 5 and 18 by use of an input device 23 such as mouse, keyboard, etc. A user interface process 201 detects user's operation and enqueues user's events to the user's event queue 202. In general, the application executed in the foreground is a program (e.g. application program 18) for obtaining the current event from the invent processing process 203. A printing request executed by the user to the application program 18 is detected by the event processing process 203 or a command interpreter, and then transmitted to the application program 18. As a result, in this embodiment, the application program 18 forms an output 19 described by the PDL source codes, and the PDL parallel processing interpreter 2 receives this output.

When the user requests a printing job to the application program 18 by use of the input device 23, a file 19 described in the PDL is outputted. The file 19 is stored at a specific directory, read at constant regular time intervals by a mechanism for detecting files within the directory, and then given to the process 210 of the PDL parallel processing interpreter 2, all under the file system control of the computer 6a. The printing job has been completed at this point from the user's standpoint. The user's printing request can be realized when the printer 21 outputs a printed paper 12. At this moment, in the present invention, the computer 6a which generates a printing request distributes the PDL translation processing to all the computers 6a, 6b and 6c so that the picture element formation can be executed by the parallel processing of these plural computers.

This parallel processing operation will be explained hereinbelow with reference to FIGS. 3, 4 and 5. FIG. 4 shows the function of the processes 210 and 212 within the PDL parallel processing interpreter 2; and FIG. 5 shows the function of the processes 211 and 212 within the PDL parallel-processing interpreter 2.

In FIG. 3, three computers 6a, 6b and 6c are connected to each other via a network 7. The assumption is made that the user's printing request is operated by the user through the computer 6a. Within the parallel processing interpreter 2 of the computer 6a, with reference to FIG. 4, a primary translation processing 215 forms an intermediate code type file 10 suitable for computer processing from the source file 19 described in the PDL. In some PDL specifications, any given coordinate system (referred to as user's coordinate system) is required to be designated when a graphic form is described, because the description is realized without depending upon the resolution of picture elements of the actual print engine. On the other hand, since the actual printing picture elements are handled as picture elements on a device coordinate system in accordance with the physical specifications of the print engine, it is necessary to obtain the description according to the coordinate system of the actual picture element data on the basis of the conversion of the resolution. Further, the predicate of the PDL is of a character string in general, the redundancy is high. The primary translation processing 215 converts the coordinate system and the predicate into a data format more easy to be processed.

The formed intermediate code 10 is divided into plural portions through a group detection processing 216, so as to be handled as if each divided portion is an independent intermediate code. As described later, the intermediate code 10 is divided into as many small portions as possible. This division is effected by the group detecting means 216 of the client process 210 in the computer 6a which generates a printing request. The respective portions of the divided intermediate code strings 230 are outputted to the network 7 via a group transmission socket 222, and then transferred to the respective distributed processing interpreter 2 of the other computers 6b and 6c. In practice, these data strings are received by the server process 211 shown in FIG. 5.

With reference to FIG. 5, each server process 211 of the other computer 6b or 6c receives the intermediate code data strings via a group reception socket 225, extracts the data portion by a group reception processing 227, and transfers them to a rasterizer 212. The rasterizer 212 is a process of forming actual picture elements, at which a dot string is generated on the basis of the description of a curve or a straight line, so that data corresponding to actual printing data are generated on the memory. These data are compressed by a picture element transfer processing 228 and then outputted to the network 7 through the picture element data transmission socket 226.

With reference to FIG. 4 again, on the other hand, the client process 210 of the computer 6a receives picture element data from the respective server processes 211 of the other computers 6b and 6c via the picture element data reception socket 223, and stores these data in an image memory area 229. Further, the parts of the divided intermediate code strings 230 are directly transferred to a direct rasterizer 212 and converted into picture element data. These picture element data are synthesized (or combined) by a picture element synthesize processing 220 to complete printing processing data.

After a series of the above-mentioned processing have been completed, the client process 210 executes a printer control code addition processing 221 for the picture element data in accordance with the physical specifications of the printer 21 and transmits these data from the printing data transmission socket 224 to the printer 21 via the network 7.

With reference to FIG. 2, a network device driver 303 of the printer 21 transmits the data strings received via the network 7 to an engine controller 302. The engine controller 302 rearranges the bit arrangement of picture element data in accordance with the physical specifications of the print engine 301, and outputs the rearranged printing picture element data to the print engine 301, so that a printing output 12 can be obtained.

To realize the above-mentioned processing procedure, the PDL parallel processing interpreter according to the present invention is provided with two advantageous portions, which are described with reference to the flowcharts shown in FIGS. 3, 6 and 7.

When a printing request generated by the application program 18 is transmitted to the parallel processing interpreter 2 via the operating system 4, the parallel processing interpreter 2 executes the printing procedure by use of as many processors as possible. The usable processors are provided within the other computers 6b and 6c, and additionally a processor within the printing unit 21 may be usable. The decision as to whether the distributed processing interpreter 2 can use other processors provided for the other information processing units or not can be determined according to whether the other information processing units respond to a specific format message transferred to the other information processing units.

In more detail, the client process 210 within the parallel processing interpreter 2 of the computer 6a which generates a printing request reads addresses of the computers 6b and 6c connected to the network from the address control table 214 and calls for computers participatable to the distributed processing (in steps 13 to 16). In this case, the client process 210 transmits a message to request participation to the distributed processing to the other computers 6b and 6c via the network. In response to the message to request the participation to the distributed processing, the resident program is actuated to check the current processor load of the computer 6a or 6b, and transmits an answer indicative of the participatability to the distributed processing, as far as necessary memory areas can be secured and the process formation is not obstructed (in steps 25 to 29).

In response to this answer, the computer 6a which generates a printing request operates in such a way that the succeeding procedure can be executed by use of only the information processing units (only the computers in this embodiment; however, a printer can be used in another embodiment) participatable to the distributed processing on the network. Here, the addresses on the network of the information processing units usable for the distributed processing are registered in a server machine control table 219 shown in FIG. 4.

In the above-mentioned processing by use of a network, there exists a possibility that a printing request or another request is generated simultaneously from a plurality of information processing units. Under these request concurrence conditions, all the information processing units provided with the distributed processing interpreter according to the present invention cannot respond to the request immediately. FIG. 8 is a block diagram of the resident processing program 1. The processor load can be discriminated by detecting the length of the request queue 209 to the scheduler 208 of the operating system 4. The load detecting mechanism 324 of the resident program 1 determines the degree of the processor load by checking the length of the queue 209 on the basis of interprocess communications, and responds to the request from the client process 210.

The above-mentioned response operation will be described hereinbelow with reference to the flowcharts shown in FIGS. 6 and 7 and the block diagram shown in FIG. 8.

As already described, the information processing units connected on the network can be discriminated by unit identifiers independently given to the respective information processing units on the network. The respective computers can know the respective unit identifiers by use of the broadcast function prepared for the network protocol, and stores the identifiers in a network control table 214 (shown in FIG. 4). Therefore, the computer which generates a printing request transmits a message to inquire the possibility of starting of the server process 211 to any one of the information processing units on the network, as shown by step 13 in FIG. 6.

As shown in FIG. 8, within the information processing unit, the message received via the network device driver 213 is given to a request message analysis processing 322 via a device driver interface 321. The information resident processing program 1 which receives this message operates in accordance with the flowchart as shown in FIG. 7. That is, control first checks whether the message requests a status confirmation and an answer in step 25. If YES, control checks the amount of the request for the processor in step 26, and further determines that no problem arises even if a new process is formed under the current load in step 27. If no problem arises, control proceeds to step 28 to check the status of use of the memory, and confirms that a new process can be formed in step 29. If no problem arises in all the cases, a normal end code is returned. If some problems arise in step 27 or 29, control returns an error code.

When a normal end code is returned, the computer which generates a printing request regards it as the return of an acceptance message. Further, no acceptance message is returned from the information processing units provided with no parallel processing interpreter of the present invention. This determination is executed in step 14 shown in FIG. 6. When an acceptance message is returned, a message is transmitted again to the responded information processing unit as shown in step 15 so that the process is started to activate the distributed processing interpreter. In response to this message, the information processing unit discriminates whether the received message is a process formation request message in step 30 in FIG. 7. If YES, a new process 211 is formed in step 31. In the configuration shown in FIG. 8, a starting processing 323 is executed, and a server process 211 is formed by a forming mechanism 207 of the operating system 4.

The client process 210 of the computer which generates a printing request checks whether the possibility of starting the server process has been inquired to all the information processing units on the network on the basis of the network control table 214 in step 16. If NO, the processing of steps 13, 14 and 15 is repeated to the information processing units to which the possibility is not yet inquired. When it has been inquired to all the units, the PDL translation processing to be executed by itself starts in step 17. As already described, the client process 210 executes this translation process by use of the rasterizer 212.

The software operation required when the PDL distributed processing interpreter of the present embodiment is executed will be described hereinbelow in detail. The description thereof is roughly composed of the following four points:

(A) The computer which generates a printing request must know that any kinds of fonts are stored in the auxiliary memory unit of the respective computers which execute the translation distributed processing on the network.

(B) The physical conditions such as the resolution, paper size, etc. of the printing unit now being operated must be indicated in common to all the computers for executing the translation distributed processing of a PDL source file in response to "printing request" now being executed on the network.

(C) The graphic form group must be detected from the source file and divided for each group, so that a printing image quite the same as that obtained when all the portions are replaced with sequential picture elements can be obtained, even if the PDL source file is divided; the respective divided portions are translated into picture elements, independently; and the translated picture elements are overlapped with each other in the other procedure, later.

(D) The information processing units on the network which share the translation processing of the respective divided file portions must be recorded, and the respective execution status must be grasped.

With reference to FIG. 2, information related to character style, size and ornament is added to the transferred character codes, in addition to the actual character string, when the process is executed such that the computer 6a which generates a printing request transfers character codes to a plurality of other computers 6b and 6c on the network and further receives bit maps obtained by the translation processings from these computers 6b and 6c. For instance, information to be transferred to convert a character string of "weather of Kanto districts" into printing data may be {FONT=lightfaced}+{number of points=12}+{character ornament=Skew}+"Weather"+{FONT=lightfaced}+{number of points=12}+"of Kanto districts". Even if the character information of such a layout as described above is transferred to the computer 6c, when there exist no character style data to form the printing character data of lightfaced print style in the computer 6c, it is impossible to form a bit map. Here, "character style data" implies a so-called "outline font" such that picture elements actually used for printing are formed on the basis of original data for determining the outer forms and the curve types representative of the outer forms, or a so-called "bit map font" such that 0/1 data of picture elements given to represent each character of a predetermined size are gathered into a group. However, the computer 6a must request the conversion processing 6c of the above-mentioned character string into printing data to the computer 6c, at least after the computer 6a knows that the computer 6c is provided with means for processing the characters such as {character style=lightfaced print style}, {number of points=12}, etc.

Since a plurality of character styles are used for a single document, it is not known that all the character styles can be available by all the computers just prior to the printing processing, because the computer user can always erase data of unnecessary character styles. To prevent the disadvantages as described above, in the present invention, the messages are received and transmitted in accordance with the processing as follows:

The information processing units on the network which can execute the distributed processing in response to a printing request now being generated are the ones which have already executed normally all the processings from the steps 25 to 31 in the flowchart shown in FIG. 7. The network addresses of these units have already been stored in the server machine control table 219 shown in FIG. 4. The processing down to the step 31 in FIG. 7 is executed by the resident processing program 1 shown in FIG. 3 in the server side information processing unit (e.g. computer 6c). Thereafter, the server process 211 formed in step 31 in FIG. 7 controls the rasterizer process 212 of the PDL parallel processing interpreter 2 to form the actual printing data, in accordance with the message transferred from the network. The server process structure members as listed in Table 1 below in this embodiment.

                  TABLE 1
    ______________________________________
    Structure   Variable
    Member      Type      Meaning of Variables
    ______________________________________
    FontName    string    Name of font
    BOSelection integer   Bit map font if 0
    Size        integer   Size (See Spec)
    FDPtr       longint   Address at which font data are
                          stored
    CurvAlgo    word      Trap word of interpolation
                          curve processing
    FixAlgo     word      Trap word of end processing
    FillAlgo    word      Trap word of filling processing
    ProcPtr     longint   Address at which additional
                          processing procedure starts
    ______________________________________

                  TABLE 2
    ______________________________________
    Structure   Variable
    Member      Type      Meaning of Variables
    ______________________________________
    ClippingLTH integer   Clipping value on left top end
                          (horizontal direction)
    ClippingLTV integer   Clipping value on left top end
                          (vertical direction)
    ClippingRBH integer   Clipping value on right bottom
                          end (horizontal direction)
    ClippingRBV integer   Clipping value of right bottom
                          end (vertical direction)
    ResolutionH integer   Resolution in horizontal
                          direction
    ResolutionV integer   Resolution in vertical
                          direction
    RGB         integer   Color designation
    ProcPtr     longint   Address at which additional
                          processing procedure starts
    ______________________________________

    ______________________________________
    Polygon A =     ( 6,
                    (0, 87), (22, 93), (92, 51),
                    (92, 82), (20, 27), (0, 33) )
    Polygon B =     ( 4,
                    (34, 58), (55, 58), (55, 34),
                    (34, 34) )
    Polygon C =     ( 4,
                    (17, 51), (78, 51), (78, 0),
                    (17, 0) )
    FillPolygon (.uparw. Polygon A)
    FillPolygon (.uparw. Polygon B)
    InvertPolygon (.uparw. Polygon C)
    ______________________________________

    ______________________________________
    Polygon A =      ( 6,
                     (0, 87), (22, 93), (92, 51),
                     (92, 82), (20, 27), (0, 33) )
    Polygon B =      ( 4,
                     (34, 58), (55, 58), (55, 34),
                     (34, 34) )
    FillPolygon (.uparw. Polygon A)
    FillPolygon (.uparw. Polygon B)
    and further the distributed processing interpreter 2 of
    the computer 6b executes simultaneously
    Polygon C =      ( 4,
                     (17, 51), (78, 51), (78, 0),
                     (17, 0) )
    InvertPolygon (.uparw. Polygon C)
    ______________________________________

                  TABLE 3
    ______________________________________
    Graphic Graphic form    Processing
    form group
            group area      status    Destination
    ______________________________________
    1       GLTH[1], GLTV[1],
                            -1, -1    6a
            GRBH[1], GRBV[1]
    2       GLTH[2], GLTV[2],
                            100, 140  6b
            GRBH[2], GRBV[2]
    3                       0, 0      6b
    N       GLTH[N], GLTV[N],
                            -1, -1    6a
            GRBH[N], GRBV[N]
    ______________________________________

• Inventors
  Nagasaka, Fumio;
• Assignee
  Seiko Epson Corporation (Tokyo, JP)
• Published
  Jul-26-1994
• Current US Classes:
  345/502
  345/619
  715/515
• Application #
  777386
• International Classes
  G06F 015/62
• Field of Search
  395/162-166 395/161 395/155 395/153 395/144-149 395/133-139
• Examiner
  Herndon; Heather R.
• Agent
  Ladas & Parry
• US Patent References:
  4945500
  4951280