JPH02299047A - Syntax converting device - Google Patents

Abstract

PURPOSE:To simplify an interface and to reduce the load on the whole high- order layer by decomposing the output of a decoding processing means by a decomposition processing means in protocol specification units which prescribe abstract syntax and supplying them to the high-order layer. CONSTITUTION:A presentation layer 20 which receives a presentation protocol data unit PPDU1 from a session layer 10 decomposes the PPDU1 into presentation protocol control information PPCI and a presentation service data unit to extract user data. The user data is decoded according to transfer syntax indicated by the information in the PPCI. Consequently, the layer 20 passes the result to the high-order layer as user data on a presentation service parameter. An application layer 30 receives the data in the form of an encoded octet sequence of application protocol data units APDU2. Namely, the layer 30 receives the APDU2 in an encoded data sequence as the abstract syntax from the layer 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to a syntax conversion device of an ISO presentation layer. In particular, International
nalOrganization for 5tand
ardization) 3325rPresentation Service Definition", IS 08823rPresentation Protocol Specification"
I (Open Systems Interconn.
(ection) A process for decoding encoded data in a syntax conversion device that converts between the abstract syntax of the presentation layer and the transfer syntax.
l (Abstriet 5yntax Not
This relates to a method for decomposing a data string encoded using the "Basic Encoding Rules".

〔overview〕

The present invention is a syntax conversion device for an OSI presentation layer, in which encoded data strings of transfer syntax are decoded and decomposed in units of each protocol specification that defines the abstract syntax, and then provided to an upper layer. By performing the decomposition process, there is no need to determine the format of the decomposed data and exchange it in a structure, which simplifies the interface.

[Conventional technology]

FIG. 8 is an explanatory diagram of PDU decomposition processing of a conventional syntax conversion device. FIG. 9 is a diagram showing disadvantages of PDU decomposition processing of a conventional syntax conversion device.

Conventionally, when a syntax conversion device decomposes a data string encoded in the presentation layer, as shown in FIG.
A method was adopted in which all tentS octets were uniformly extracted, and all items were disassembled in the presentation layer and handed over to the upper layer.

[Problem that the invention seeks to solve]

However, with such a conventional syntax conversion device, when trying to separately decompose presentation protocol data units (hereinafter referred to as PDUs) that are separately specified in standard X and standard y, as shown in FIG. SET is represented at the beginning of the standard y 37 PDU that is to be disassembled later. 3
Because 0″H is missing, yPDU cannot be decomposed using standard y. Therefore, PDUs that are specified separately in standard (As the standards for the application layer increase, disassembling everything at the presentation layer has the disadvantage of increasing the number of abstract syntaxes (definition of PDU data structure) to manage and the number of interface items to upper layers.

The present invention solves the above-mentioned drawbacks, and aims to provide a syntax conversion device that eliminates the need to define a format for decomposed data and exchange it in a structure, and which can simplify the interface.

[Means for solving problems]

The present invention includes a decoding processing means for decoding an example of encoded data encoded based on IS 08825 "AS N,l basic encoding rules", and a decomposition processing means for decomposing the output of this decoding processing means. IS 08822 “Presentation Services Definition” and ISO 8823 with
rPresentation Protocol Specification”
In the syntax conversion device of the SI presentation layer,
The decomposition processing means is characterized in that it includes means for decomposing the output of the decoding processing means in units of each protocol specification defining its abstract syntax and providing it to an upper layer.

[Effect]

The decoding processing means performs decoding (via inversion) of encoded data encoded using the ASN, 1 basic code rule. The decomposition processing means decomposes the output of the decoding processing means into each protocol specification unit of the abstract syntax.

Due to the above operation, in the upper layer, the output of this decomposition processing means is divided into EXTERNAL type and ANY type, and the division in charge of decomposition processing is not just before the Contents octet, but just before the 1' dentifier octet, so the decomposed data is formatted as There is no need to define and exchange structures, which simplifies the interface.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram of an OSI device including a syntax conversion device according to an embodiment of the present invention. In East 1 diagram, syntax conversion device 6
0 is input from the session layer 10.
SN. Decoding processing means 2 for decoding PPDUI as an example of encoded data encoded based on ``1 Basic Encoding Rules''
3, and a decomposition processing means 22 for decomposing the output of the decoding processing means 23.

Here, the feature of the present invention is that the decomposition processing means 22
The decoding processing means 23 includes means for decomposing the output of the decoding processing means 23 in units of each protocol specification defining its abstract syntax and providing the decomposition processing to the application layer 30 as an upper layer.

The application layer 30 is an AS defined in IS 08650.
N.

According to the data structure of the 1 description, the octet string encoded with the ASN 1 basic encoding rule is decomposed, and processing as a service element is realized from the extracted values. First application service element 31 and AS specified in IS 09596
A second application service element 32 that decomposes an octet string encoded according to the ASN, 1 basic encoding rule according to the data structure of N, l description, and realizes processing as a service element from the extracted value, and the ISO 8824 standard. Shitiru EXT
According to the ERNAL type (7) f-data structure, the octet string encoded according to the ASN 1 basic encoding rule is decomposed and the contents are passed to the upper level.

EXTERNAL handler 33 and IS 08824
The octet sequence encoded using the ASN, 1 basic encoding rule is decomposed according to the data structure defined using the ASN. A
SN, 1 handler 34 (patent application 1986-23340)
including.

The operation of the syntax conversion device having such a configuration will be explained. 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. Figure 4 shows the PPDU of the syntax conversion device of the present invention.
FIG. 3 is a diagram showing a coded octet sequence extracted from the 10-bit coded octet sequence and an output coded octet sequence. Figure 5 shows the encoded octet sequence to be decomposed of the first application service element of the application layer.
FIG. 3 is a diagram showing the definition and decomposition results of the data structure.

FIG. 6 is a diagram showing the encoded octet string 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 the encoded octet sequence to be decomposed in the second application service element of the application layer, the definition of its data structure, and the decomposition result.

1 and 2, the presentation layer 20 processes the user data shown in FIG. 4(a) extracted from the presentation protocol data unit (hereinafter referred to as PPDU) 1 according to the processing flow of the flowchart. 20 and the application layer 30 according to this embodiment will be described in detail.

First, the presentation layer 20 receives the PPDUI from the session layer 10 and converts the PPDUI into presentation protocol control information (hereinafter referred to as PPCl) and presentation service data unit (hereinafter referred to as PSDU).
That's what it means. ) and extract user data as shown in FIG. 4(a). The user data is transferred using the transfer syntax indicated by the information in the PPCl (in this example, the data string encoded according to the ASN, l basic encoding rule is bit-reversed. Note that the transfer is performed as a function of the presentation layer 20. There is a process of converting a data value in a syntactic format into a data value in an abstract syntax format.), a decoding process (bit inversion) is performed (step 511).

As a result, the presentation layer 20 passes the presentation service parameters shown in FIG. 4 as user data to the upper layer (step 512).

The application layer 30 to which this is delivered receives it as a coded octet sequence of 1 to 2 application protocol data units (hereinafter referred to as APDUs). That is, in this embodiment, the application layer 30 uses an encoded data string as shown in FIG. An APDU
2 from the presentation layer 20.

Next, in this embodiment, the first application service element 31 and the second application service element 32 of the application layer 30 process the encoded data string passed from the presentation layer 20 as needed in the process flow shown in FIG. While disassembling only the (conscious) parts and handing it over to the upper application service element (ASE),
Processing in step 3 will proceed with each service element.

First, the first application service element 31 is based on IS 0865
0 standard (Fig. 5)), the AP shown in Fig. 5(a)
When disassembling DU, in step S21, 5 octets of item 2 are extracted from C0ntentS octets. However, item ■ is of type EXTBRNAL, so Ide
from ntifier octets, '280FO606
28CA7CO20101AOO5030300422
2°H is extracted (the actual decomposition is performed by the ASN 1 handler 34).

The extracted encoded data string (Figure 6(a)) is EXTE
Since it is an R-NAL type, from step 5221, the XTERNAL handler 33 is ASN, and the l handler 34 is
is used to decompose the data according to the structure of the BXTERNAL type shown in FIG. 6, et al., and extract five octets of contents (item (C) in FIG. 6) (step 523).

Next, in step S24, the extracted encoded data string "0303004222'H is delivered to the second application service element 32 (step 525), and its processing is called (this is a recursive call, and the process returns to step S21).

The second application service element 32 decomposes the received encoding shown in FIG. 7(a) using the common management protocol shown in FIG. 7(b), and extracts "4222'H" of item ■ (step 521). Since the content is not an encoded data string, the processing of the second application service element 32 ends (step 522).
Returning to step 325 in the process of step 1, the process of the first application service element 31 also ends.

〔Effect of the invention〕

As explained above, the present invention enables the interface between implementation programs of each standard to be exchanged using encoded octet string data, eliminating the need to determine the format of decomposed data and exchange it using structures. To,
This has the excellent effect of simplifying the interface.

In addition, the presentation layer does not need to manage the data structure (ASN, 1 description) specified by each standard, and therefore the decomposition process that would be relatively borne by the implementation program of each standard can be done separately as in the example. If ASN and 1 handler are prepared as common subroutines that can be called from the program, it will not be a burden, and there is an advantage that the load on the entire upper layer of the open system will be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a 031 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 an encoded octet string extracted from a PPDU and an output encoded octet string of the syntax conversion device of the present invention. FIG. 5 is a diagram showing the encoded octet sequence to be decomposed in the first application service element of the application layer, the standard of its data structure, and the decomposition result. FIG. 6 is a diagram showing the definition of the EXTERNAL type to be decomposed by the BXTERNAL handler of the application layer and the decomposition result. FIG. 7 is a diagram showing the encoded octet sequence to be decomposed in the second application service element of the application layer, the definition of its data structure, and the decomposition result. FIG. 8 is an explanatory diagram of PDU decomposition processing of a conventional syntax conversion device. FIG. 9 is a diagram showing disadvantages of PDU decomposition processing of a 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..., EXTI3RNAL handler, 34-ASN , 1 No. 1 driver, 41... Encoded octet sequence extracted from the PPDU by the presentation layer, 42... Encoded off-kerat sequence output by the presentation, 51... Indentifier octet, 52-Length octet, 53. Co
tents octet, 61...Identifier item, 6
2... Data length of the contents of the encoded data string, 63...
The value of the content of the encoded data string.

Claims (1)

[Claims] 1. A decoding processing means for decoding an example of encoded data encoded based on ISO8825 "ASN.1 basic encoding rules"; and a decomposition processing means for decomposing the output of this decoding processing means. In the OSI presentation layer syntax conversion device defined by ISO8822 "Presentation Service Definition" and ISO8823 "Presentation Protocol Specification", the decomposition processing means converts the output of the decoding processing means into a syntax converter that specifies its abstract syntax. A syntax conversion device characterized by comprising means for performing decomposition processing in each protocol specification unit and providing it to an upper layer.