JPH0786851B2 - Syntax converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used for an ISO presentation layer syntax conversion device. In particular, ISO (International Organization fo
r Standardization) 8825 “Presentation Service Definition”, ISO8823 “Presentation Protocol Specification” OSI (Open Systems Interconnect)
processing for decoding encoded data in a syntax conversion device that performs conversion between the abstract syntax of the presentation layer and the transfer syntax, and ISO8825 “ASN.1 (Abstract Syntax)
Notation One) A basic encoding rule ”relates to a decomposition method of a data string encoded.

〔Overview〕

The present invention is a syntax conversion device for an OSI presentation layer, in which a coded data string of a transfer syntax is subjected to decoding processing, and decomposition processing is performed for each protocol specification unit that defines the abstract syntax and given to the upper layer By disassembling the data, it is not necessary to determine the format of the decomposed data and exchange it in the structure, and the interface can be simplified.

[Conventional technology]

FIG. 8 is an explanatory diagram of a PDU decomposition process of the conventional syntax conversion device. FIG. 9 is a diagram showing inconveniences of the PDU disassembly processing of the conventional syntax conversion device.

Conventionally, in a syntax conversion device, when a data string encoded in the presentation layer is decomposed, as shown in FIG. 8, a method of uniformly extracting the Contents octet defined by the ASN.1 encoding rule is adopted. , All items were disassembled in the presentation layer and delivered to the upper layer.

[Problems to be solved by the invention]

However, in such a conventional syntax conversion device, when attempting to decompose presentation protocol data units (hereinafter, referred to as PDU) separately defined by standard x and standard y as shown in FIG. The SET is indicated at the beginning of the standard yPDU that is to be disassembled later. It is not possible to disassemble the yPDU with standard y due to the missing '30'H.
Therefore, standard x and standard y are separately defined.
As the PDU also has to be decomposed collectively in the presentation layer, and as the standards of the application layer increase, in order to decompose all in the presentation layer, the abstract syntax to be managed (definition of PDU data structure) and the interface to the upper layer are managed. There was a drawback that the number of items increased.

The present invention solves the above-mentioned drawbacks, and an object of the present invention is to provide a syntax conversion device capable of simplifying the interface without the need to define the format of decomposed data and exchange it in a structure.

[Means for solving problems]

The present invention is provided with a decoding processing means for decoding an example of coded data coded based on ISO8825 “ASN.1 basic coding rules” and a decomposition processing means for decomposing the output of this decoding processing means. "Presentation service definition"
And ISO 8823 "Presentation Protocol Specification"
In the syntax conversion device for the presentation layer of OSI defined by the above, the decomposition processing means is a means for performing the decomposition processing of the output of the decoding processing means in each protocol specification unit that defines the abstract syntax, and giving it to the upper layer. It is characterized by including.

[Action]

The decoding processing means performs decoding (bit inversion) of the coded data coded according to the ASN.1 basic coding rule. The decomposition processing means decomposes the output of the decoding processing means in units of protocol specifications of the abstract syntax. As a result of the above operation, in the upper layer, the output of this decomposition processing is divided by EXTERNAL type and ANY type so that the corresponding division of the decomposition processing is divided not before the Contents octet but immediately before its Identifier octet. The interface can be simplified because there is no need to exchange in a structure.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. First
FIG. 1 is a block diagram of an OSI device including a syntax conversion device according to an embodiment of the present invention. In FIG. 1, the syntax conversion device 60
Is an example of encoded data that is encoded based on ISO8825 “ASN.1 Basic Encoding Rule” input from the session layer 10.
Decoding processing means 23 for decoding PPDU1 and this decoding processing means 2
And a decomposition processing means (22) for decomposing the output of (3).

Here, the feature of the present invention is that the decomposition processing means 22
Is to include means for decomposing the output of the decoding processing means 23 for each protocol specification unit that defines its abstract syntax and giving it to the application layer 30 as an upper layer.

The application layer 30 decomposes the octet string encoded by the ASN.1 basic encoding rule according to the data structure of ASN.1 description defined by ISO8650, and realizes the processing as a service element from the retrieved value. . First application service element 31 and ISO959
ASN.1 according to the data structure of ASN.1 described in 6.
Decompose the octet sequence encoded by the basic encoding rules,
Second application service element 32 that realizes processing as a service element from the retrieved value and EXTER specified by ISO8824
According to the NAL type data structure, the octet string encoded by the ASN.1 basic encoding rule is decomposed and the contents are passed to the upper layer.
According to the data structure defined by EXTERNAL handler 33 and ISO8824, the octet string encoded by the ASN.1 basic encoding rule is decomposed. ASN.1 Handler 34 (Japanese Patent Application Sho 63
-23340) and.

The operation of the syntax conversion device having such a configuration will be described. FIG. 2 is a flow chart showing the processing of the syntax conversion device of the present invention. FIG. 3 is a flowchart showing the processing of the application layer. FIG. 4 is a diagram showing a coded octet sequence extracted from the PPDU of the syntax conversion device of the present invention and a coded octet sequence as an output. FIG. 5 is a diagram showing a coded octet sequence to be decomposed of the first application service element of the application layer, the definition of the data structure thereof, and the decomposition result. FIG. 6 is a diagram showing the coded octet sequence to be decomposed by the EXTERNAL handler of the application layer, the definition of the EXTERNAL type, and the decomposition result. FIG. 7 is a diagram showing a coded octet string to be decomposed by the second application service element of the application layer, the definition of the data structure thereof, and the decomposition result.

In FIG. 1 and FIG. 2, the presentation layer 20 has a presentation protocol data unit (hereinafter referred to as PPDU) 1 according to the process flow of the flowchart.
Details of the disassembly processing of the present embodiment for the user data shown in FIG. 4 (a) taken out from the presentation layer 20 and the application layer 30 will be described.

First, the presentation layer 20 that has received the PPDU1 from the session layer 10 decomposes the PPDU1 into presentation protocol control information (hereinafter referred to as PPCI) and presentation service data units (hereinafter referred to as PSDU),
User data as shown in FIG. 4 (a) is taken out. The transfer syntax indicated by the information in the PPCI for the user data (in this example, the data string encoded by the ASN.1 basic encoding rule is bit-inverted. A decoding process (bit inversion) is performed according to the process of converting a syntax-format data value into an abstract syntax-format data value (step S11).

As a result, the presentation layer 20 delivers it as a user data of the presentation service parameter of FIG. 4 (b) to the upper layer (step S12).

The delivered application layer 30 receives it as a coded octet string of application protocol data unit (hereinafter referred to as APDU) 2. That is, in the present embodiment, the application layer 30 uses an encoded data string as shown in FIG. 5A as an abstract syntax (a data format in which a data value in the transfer syntax format is converted so that it can be handled by a self-open system). An APDU2 will be received from the presentation layer 20.

Next, in this embodiment, the first application service element 31 of the application layer 30
And the second application service element 32 decomposes only the necessary (conscious) portion of the encoded data string passed from the presentation layer 20 in the process flow shown in FIG. ), The processing in each service element will proceed.

First, the first application service element 31 is the ISO8650 standard (the fifth
When disassembling the APDU shown in Fig. 5 (a) according to Fig. 5 (b)), the 5 octets of the item are set to Content in step S21.
Remove from s octet. However, the items are EXTERNAL
Since it is a type, from the Identifier octet, '280F060628
Take out CA7C020101A0050303004222'H (The actual disassembly is
ASN.1 handler 34).

The extracted encoded data string (Fig. 6 (a)) is EXTERNAL
Since it is a type, in step S22, EXTERNAL handler 3
3 uses the ASN.1 handler 34 and uses EXTERN of FIG. 6 (b).
Decomposes according to the AL type structure and contains 5 octets of content (6th
Figure (c) item) is taken out (step S23).

Then, in step S24, the extracted encoded data string '0
303004222'H is passed to the second application service element 32 (step S25), and the process is called (recursive call,
Again to step S21).

In the second application service element 32, the received encoding shown in FIG. 7 (a) is decomposed by the common management protocol shown in FIG. 7 (b) and the item '4222'H is taken out (step S2
1). Since the content is not the encoded data string, the process of the second application service element 32 ends (step S22).
Here, the process returns to step S25 in the processing of the first application service element 31, and the processing of the first application service element 31 is also ended.

〔The invention's effect〕

As described above, according to the present invention, it is possible to exchange the interface between the standard implementation programs with the data of the encoded octet string, and it is not necessary to determine the format of the decomposed data and exchange it with the structure. Therefore, there is an excellent effect that the interface can be simplified.

In addition, the presentation layer does not need to manage the data concept (ASN.1 description) defined by each standard, so that the disassembly processing that is relatively borne by each standard's implementation program is different from that of each embodiment. If an ASN.1 handler is prepared as a common subroutine that can be called from a program, it will not be a burden and has the advantage of reducing the load on the entire upper layer of an open system.

[Brief description of drawings]

FIG. 1 is a block diagram of an OSI device including a syntax conversion device according to an embodiment of the present invention. FIG. 2 is a flowchart showing the processing of the syntax conversion device of the present invention. FIG. 3 is a flowchart showing the processing of the application layer. FIG. 4 is a diagram showing a coded octet sequence extracted from a PPDU of the syntax conversion device of the present invention and a coded octet sequence as an output. FIG. 5 is a diagram showing a coded octet string to be decomposed of the first application service element of the application layer, the standard of its data structure, and the decomposition result. Figure 6 shows the EXTERN to be decomposed by the EXTERNAL handler in the application layer.
The figure which shows the definition and decomposition result of AL type. FIG. 7 is a diagram showing a coded octet string to be decomposed of the second application service element of the application layer, the definition of the data structure thereof, and the decomposition result. FIG. 8 is an explanatory diagram of a PDU decomposition process of the conventional syntax conversion device. FIG. 9 is a diagram showing inconveniences of the PDU disassembly processing of the conventional syntax conversion device. 1 ... PPDU (presentation protocol data unit), 2 ... APDU (application service data unit), 10 ... session layer, 20 ... presentation layer, 21 ... syntax conversion device, 22 ... decomposition processing means, 23 ... decoding processing means, 30 ... Application layer, 31 ... First application service element, 32 ... Second application service element, 33 ... EXTERNAL handler, 34 ... ASN.1 handler, 41
... The encoded octet sequence extracted from the PPDU by the presentation layer, 42 ... The encoded octet sequence output by the presentation, 51 ... Indentfier octet, 52 ... Length octet, 53 ... Contents octet, 61 ... Identifier item, 62 ... Encoded data Data length of the contents of the column, 63 ... Value of the contents of the encoded data string.

Claims (1)

[Claims] 1. Decoding processing means for decoding an example of coded data coded based on ISO8825 "ASN.1 basic coding rule", and decomposition processing means for decomposing the output of the decoding processing means. ISO8822 "Presentation Service Definition" and ISO
In the OSI presentation layer syntax conversion device defined in 8823 “Presentation protocol specifications”, the decomposition processing means decomposes the output of the decoding processing means into each protocol specification unit that defines the abstract syntax. A syntax conversion device comprising means for giving to an upper layer.