JPH0746331B2 - Data communication method between heterogeneous communication systems - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL FIELD The present invention is in a network system based on the OSI Open Systems Interconnection (O pen S ystems I nterconnection) protocol, to a data communication method between heterogeneous communication systems.

2. Description of the Related Art A conventional data communication method between heterogeneous communication systems is shown in, for example, the ISO standard (ISO 8822). FIG. 5 is an explanatory diagram of a network system to which the present invention and a conventional data communication method between heterogeneous communication systems are applied.
In FIG. 5, 20 and 20 'are application processes for realizing a communication function using the OSI protocol, 21 and 21' are communication systems in which an OSI protocol processing program is installed, and 22 physically connects the communication systems. Transmission lines 23 to 29 are OSI protocol processing programs modularized for each layer. The communication system 21 realizes the communication-related part of the application process 20 by the programs of the layers 23 to 29. The application layer 23 manages communication functions according to various business contents of the application process 20. Presentation layer
The 24 converts the data structure unique to the application process and the common data structure (transfer syntax) necessary for transfer, and even if it takes a different data structure for each application process, data is accurately transmitted and received between processes. Provide the function that can be done. The session layer 25 provides a function of transferring data while synchronizing between the communicating processes. The transport layer 26 ensures that data is reliably transferred between communicating processes. Network layer 27
Manages the relay and routing functions for establishing a communication path with the communication partner system. The data link layer 28 detects bit errors occurring on the transmission path 22 and provides recovery means to guarantee the transmission of data frames. The physical layer 29 manages the electrical, mechanical and physical conditions for using the transmission line 22 as a communication line and guarantees the transmission of bit examples.

FIG. 6 shows a conceptual diagram of a configuration of a presentation layer processing module for realizing a conventional data communication method between different types of communication systems. In FIG. 6, 1 is a processing module that realizes the services and protocols of the presentation layer, 2 is a user interface unit that interfaces with each protocol of the application layer that is a presentation user, and 3 is the execution control of the presentation protocol. A protocol control unit, 5 is an encoding unit that converts the data structure of the abstract syntax that used the protocol control unit 3 into a transfer syntax, and 6 is a conversion unit that converts the transfer syntax received from the session interface unit 7 into a data structure of the abstract syntax, Decoding unit to be passed to the protocol control unit 3, 7
Is a session interface unit that interfaces with the session layer.

In the above configuration example, the conversion from the abstract syntax to the transfer syntax is performed as follows. The data input from the presentation user via the user interface unit 2 is expressed by one or more abstract syntaxes, and the protocol control unit 3 adds header information to this input data. This header information is also described in abstract syntax.
The data described by these abstract syntaxes is encoded by the encoding unit 5.
Is converted into a transfer syntax agreed between the transmitting and receiving communication systems for each abstract syntax. At this time, only one transfer syntax name is agreed for one abstract syntax,
Since the correspondence relationship is previously notified from the protocol control unit 3 to the encoding unit 5 and the decoding unit 6, the encoding unit 5 can refer to the information and perform proper encoding. Similarly, the conversion from the transfer syntax to the abstract syntax is also performed by the decoding unit 6 with reference to the information on the corresponding relationship.

FIG. 7 is an explanatory diagram showing a method of determining the correspondence between the abstract syntax and the transfer syntax in the protocol control unit 3. Since only one transfer syntax name is determined for each abstract syntax (AS1, AS2, ..., ASk), the connection initiating communication system is supported by the local system when establishing the connection between the communication systems that want to communicate. List of transfer syntax names ((TS1-1, ..., TS1-n1), (TS2-1, ... TS2-n1)
2), ..., (TSk-1, ..., TSk-nk)) is sent to the responding communication system. The responding communication system judges whether each transfer syntax name included in the received list can be used, and marks 0 when it is available, and 1 (provider abort) is 2 (user abort) when it is not available. ) Is marked. Next, from the available transfer syntax names marked with 0, select one that is actually used (TS1-3, TS2-1, ..., TSk-2), and send the result to the initiator communication. Return to system. In this way, the transfer syntax name is negotiated, and when the transfer syntax name is agreed on a one-to-one basis for each abstract syntax, the result is determined by the presentation context identifier (1, 3, ..., 2k-1). It is managed and used when encoding and decoding presentation user data.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the conventional method of data communication between heterogeneous systems, the transfer syntax name agreed between the communicating communication systems must correspond to the abstract syntax one-to-one. For example, the receiving communication system cannot correctly decipher the transfer syntax, so when the presentation user wants to perform data communication with another kind of transfer syntax name, the presentation context change service is used, or If this service is not supported, you must disconnect the connection and specify the desired transfer syntax name to reestablish the connection. Therefore, particularly in the latter case, it is not possible to quickly deal with the case where the presentation user performs a process of switching various applications.

The present invention allows having a plurality of transfer syntax names agreed between the communication systems of the transmitting side and the receiving side, unifying the format forms of all the transfer syntaxes so as to be suitable for decoding the transfer syntaxes used, It is an object of the present invention to provide a method of data communication between heterogeneous systems, which can respond to a request of a presentation user quickly by enabling accurate transmission / reception even if a transfer syntax name is dynamically switched.

Means for Solving the Problems In a network system that realizes data communication between communication systems by the OSI protocol, each communication system converts an OSI protocol processing program modularized for each layer and conversion between abstract syntax and transfer syntax. It has a plurality of types of conversion functions to be performed and means for exchanging information related to the conversion functions between the communication systems, and at the time of negotiation of the presentation context, the communication systems of the transmission side and the reception side have transfer syntax names and conversions corresponding thereto. By exchanging information about functions with each other, the communication system on the transmitting side dynamically creates an arbitrary transfer syntax name by selecting an arbitrary transfer syntax name from a plurality of transfer syntax names agreed upon between the sender and the receiver. The first field of the transfer syntax has information about the conversion function that the receiving communication system should use for decoding, This is a data communication method between different types of communication systems in which the transfer syntax name is dynamically switched.

Action The present invention uses the above-described method to establish a connection when
Supports the presentation context change service by allowing multiple transfer syntax names to be agreed on one abstract syntax and dynamically selecting any transfer syntax name included in the set of agreed transfer syntax names. Even between communication systems that are not installed, it is possible to change the type of transfer syntax used without disconnecting the connection.

Embodiment FIG. 1 shows a conceptual diagram of a configuration of a processing module of a presentation layer to which a data communication method between heterogeneous communication systems according to an embodiment of the present invention is applied, which is the same as the conventional example of FIG. Parts are given the same numbers. First
In the figure, reference numeral 4 denotes a correspondence relationship between an abstract syntax and a transfer syntax name agreed between the communication system on the transmitting side and the receiving side, and a storage address of a processing routine (hereinafter referred to as a parser) for converting between the syntaxes. It is a context management unit that manages.

FIG. 2 is an explanatory diagram showing a method of managing transfer syntax names in the context management unit 4 of FIG. Of the transfer syntax names supported for each abstract syntax (AS1, AS2, ..., ASk) of the initiating communication system when establishing a connection between systems, select the transfer syntax name that is also supported by the responding communication system. In order to know, the connection-initiating communication system uses the list of transfer syntax names ((TS1-1, ..., TS1-n1), (TS2-1, ..., TS2) supported by the local system.
-N2), ..., (TSk-1, ..., TSk-nk)) and the address in which the parser for each transfer syntax name is stored are sent to the responding communication system. The responding communication system determines whether each transfer syntax name included in the received list can be used, and if available, marks 0 and stores the address of the parser of the initiating communication system for them. If it cannot be used, mark 1 (provider abort) or 2 (user abort). Transfer syntax names marked 0 are considered to be agreed between both communication systems, and the agreed transfer syntax names and parsers for those transfer syntax names in the responding communication system are stored. And the address are returned to the initiating communication system. As a result, both communication systems mutually know the agreed transfer syntax name and the address of the parser of the communication system on the other side corresponding to the transfer syntax name, and the information is held in the context management unit 4. 3A and 3B are flowcharts of the processes executed by the protocol control unit 3 of the communication system on the invocation side and the response side in order to obtain the information to be held by the context management unit 4 as described above. It is shown in FIG.

In the above configuration example, the conversion from the abstract syntax to the transfer syntax is performed as follows. The protocol control unit 3 shown in FIG. 1 passes the abstract syntax data to the encoding unit 5 and dynamically notifies the context management unit 4 of the transfer syntax name. The context management unit 4 passes the storage address of the encoder corresponding to the selected transfer syntax name and the address of the parser to be used by the receiving side communication system to the encoding unit 5 from the information held therein. The encoding unit 5 uses the above information to format the abstract syntax data into the transfer syntax.

However, since the correspondence between the abstract syntax and the transfer syntax is not uniquely determined, the transfer syntax can be correctly decoded in the communication system on the receiving side. Therefore, encoding and decoding are performed as shown in FIG. Now, there are n abstract syntaxes (AS1, A
Consider encoding of protocol data consisting of S2, ..., ASn). Each abstract syntax is converted into a transfer syntax having the basic format shown in FIG. 4A by the encoder corresponding to the selected transfer syntax name. In FIG. 4 (a), 10 is the first field of the transfer syntax, in which the address of the parser necessary for the receiving communication system to decode this transfer syntax is stored. 11 indicates the encoded data content and 12 EOC indicates the end of the data content. If encoded in such a format, the parser stored in the address written in the first field of the received transfer syntax will be used as the data after that until the EOC is detected, when decoding in the receiving communication system. The transfer syntax used can be easily decoded. Since the actual protocol data consists of n abstract syntaxes, the transfer syntax may be formed by concatenating the basic formats as shown in FIG. 4 (b). in this case,
The parser that decodes the transfer syntax starts from the one written in the first field and switches to the parser written in the next field each time EOC detects it. In FIG. 4 (b), TSk (k = 1, ...
..., n) indicates the transfer syntax name of the abstract syntax ASk. Further, as shown in FIG. 4 (c), (b) may be modified so that the leading fields of each transfer syntax are gathered at one place.

As described above, according to this embodiment, the addresses of the parser of the transfer syntax name used between the systems at the time of establishing the connection are mutually notified, so that the transfer syntax name corresponding to each abstract syntax is uniquely determined. Even if it is not necessary, by providing the address of the parser of the transfer syntax in the transfer syntax, there is an effect that it can be correctly decoded in the communication system on the receiving side.

Although the parser addresses that should be used in the respective communication systems are used for identifying the transfer syntax in this embodiment, the object identifier of the transfer syntax name exchanged at the time of negotiation of the connection may be used.

Further, in the present embodiment, the context management unit 4 is provided to hold the information regarding the correspondence between the abstract syntax and the transfer syntax, but this information may be provided inside the protocol control unit 3.

EFFECTS OF THE INVENTION As described above, according to the present invention, the correspondence between the abstract syntax and the transfer syntax need only be negotiated once when the connection is established. Since any transfer syntax name can be dynamically selected from among, it is possible to switch the transfer syntax name while maintaining the connection even in a communication system that does not support the context change service. Can be applied, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a configuration of a processing module of a presentation layer according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a presentation context management method of the embodiment, and FIG. 3 is a negotiation of a presentation context of the embodiment. 4 is an explanatory diagram of the encoding / decoding method of the same embodiment, FIG. 5 is an explanatory diagram of a network system to which the present invention and a conventional data communication method are applied, and FIG. 6 is a conventional presentation. FIG. 7 is a conceptual diagram showing the configuration of a layer processing module, and FIG. 7 is an explanatory diagram of a conventional presentation context management method. 1 ... Processing module for realizing presentation layer service and protocol, 2 ... User interface section, 3 ... Protocol control section, 4 ... Context management section, 5 ... Encoding section, 6 ... Decoding section,
7 ... session interface part, 10 ... first field of transfer syntax, 11 ... data content of transfer syntax, 12 ...
… Content end identifier, 20,20 ′ …… Applied process, 21,21 ′ …… Communication system, 22 …… Transmission path, 23 ……
Application layer, 24 ... Presentation layer, 25 ... Session layer, 26 ... Transport layer, 27 ... Network layer,
28 ... Data link layer, 29 ... Physical layer.

Claims (1)

[Claims] 1. A network system for realizing data communication between communication systems according to the OSI protocol,
Each communication system is a modular OSI
A protocol processing program, a plurality of types of conversion functions for converting between abstract syntax and transfer syntax, and means for exchanging information about the conversion functions between the communication systems,
At the time of negotiation of the presentation context, the communication system of the sending side and the communication side of the receiving side mutually exchange information on the transfer syntax name and the corresponding conversion function, and the communication system on the sending side agrees on one abstract syntax between the sending side and the receiving side. Dynamically select an arbitrary transfer syntax name from multiple transfer syntax names and use it.The first field of the created transfer syntax has information about the conversion function that the receiving communication system should use for decoding, A method of data communication between different types of communication systems that switches the transfer syntax name to.