This document describes the specific mapping of Software AG IDL data types, groups, arrays and structures to the Natural programming language. Please note also the remarks and hints on the IDL data types valid for all language bindings found in the IDL file. See Software AG IDL File.
This document covers the following topics:
In the table below, the following metasymbols and informal terms are used for the IDL.
The metasymbols [ and ] surround optional lexical entities.
The informal term number (or in some cases number.number ) is a sequence of numeric characters, for example 123.
| Software AG IDL | Description | Natural Data Format | Notes |
|---|---|---|---|
| Anumber | Alphanumeric | Anumber | |
| AV | Alphanumeric variable length | A DYNAMIC | |
| AVnumber | Alphanumeric variable length with maximum length | A DYNAMIC | |
| Bnumber | Binary | Bnumber | |
| BV | Binary variable length | B DYNAMIC | |
| BVnumber | Binary variable length with maximum length | B DYNAMIC | |
| D | Date | D | 3,5 |
| F4 | Floating point (small) | F4 | 2 |
| F8 | Floating point (large) | F8 | 2 |
| I1 | Integer (small) | I1 | |
| I2 | Integer (medium) | I2 | |
| I4 | Integer (large) | I4 | |
| Knumber | Kanji | Anumber | 1 |
| KV | Kanji variable length | A DYNAMIC | 1 |
| KVnumber | Kanji variable length with maximum length | A DYNAMIC | 1 |
| L | Logical | L | |
| Nnumber[.number] | Unpacked decimal | Nnumber[.number] | |
| NUnumber[.number] | Unpacked decimal unsigned | Nnumber[.number] | |
| Pnumber[.number] | Packed decimal | Pnumber[.number] | |
| PUnumber[.number] | Packed decimal unsigned | Pnumber[.number] | |
| T | Time | T | 4,5 |
| Unumber | Unicode | Unumber | |
| UV | Unicode variable length | U DYNAMIC | |
| UVnumber | Unicode variable length with maximum length | U DYNAMIC |
See also the hints and restrictions valid for all language bindings under IDL Data Types.
| 1. | Data type K is an RPC-specific data format that is not part of the Natural language. | |||||||||||||||||||||||||||
| 2. | When floating-point data types are used, rounding errors can occur, so that the values of senders and receivers might differ slightly. This is especially true if client and server use different representations for floating point data (IEEE, HFP). | |||||||||||||||||||||||||||
| 3. | Count of days AD (anno domini, after
the birth of Christ). The valid range is from 1.1.0001 up to 28.11.2737.
Mapping of the number to the date in the complete range from 1.1.0001 on,
follows the Julian and Gregorian calendar, taking into consideration the
following rules:
See the following table for the relation of the packed number to a real date:
|
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| 4. | Count of tenths of seconds AD (anno
domini, after the birth of Christ). The valid range is from 1.1.0001 00:00:00.0
up to 16.11.3168 9:46:39 plus 0.9 seconds. See the following table for the
relation of the packed number to a real time:
|
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| 5. | The relation between the packed
number of a Date and Time data type is as follows:
tenths of a second per day = 24*60*60*10 = 864000
|
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If you are using client interface objects (recommended) generated for the client side (see Using the Natural Wrapper for the Client Side), the IDL library name as specified in the IDL file (there is no 8 character limitation) is sent from a Natural client to the server. Special characters are not replaced. The IDL library alias is neither sent to the server nor used for other purposes on the Natural client side.
If you are using instead so-called stubs generated with SYSRPC (not recommended) or stubless Natural RPC (also not recommended), the IDL library name as specified in the IDL file is not supported by Natural. By default, a Natural client sends the library name SYSTEM to the server. To send a library name other than SYSTEM from a Natural client to a server, the following steps are required for the client:
Turn on the logon option.
Call application programming interface USR4008N to specify the name of the library, otherwise the name of the current library is sent. The length of the library name sent is limited to 8 characters.
A Natural RPC Server considers the library name (up to 8 characters) received from a RPC client only if the Natural Logon option is set by the sending RPC client.
If the RPC client does not set its Natural Logon option, the Library name is ignored by the Natural RPC Server and the target RPC server (Natural subprogram, extension .NSN) is searched in the startup Natural library and defined steplibs of the Natural RPC server.
If the RPC client does set its Natural Logon option, the target RPC server (Natural subprogram, extension .NSN) must reside in the Natural library, specified as IDL library name in the IDL file.
EntireX RPC client components provide a possibility to set the Natural Logon option. See Natural Logon or Changing the Library Name and the documentation of the EntireX RPC client component.
If you are using client interface objects (recommended) generated with the Natural Wrapper for the client side (see Using the Natural Wrapper for the Client Side), the IDL program name as specified in the IDL file (there is no 8-character limitation) is sent from a Natural client to the server. Special characters are not replaced. The IDL program alias is not sent to the server, but it is used to derive the suggestion for the source file names of the client interface objects (NSN, PDA, PGM) instead using the IDL program names. See Step 2: Customize Natural Client Names.
If you are using instead so-called stubs generated with SYSRPC (not recommended) or stubless Natural RPC (also not recommended) the IDL program name as specified in the IDL must match the name in your CALLNAT statement. In this case the IDL program is limited to 8 characters. Example:
CALLNAT 'MYSRV' P1 P2 P3
If you are using a so-called client-side server mapping file (see CVM File) the target RPC server (Natural subprogram, extension .NSN) is located with the help of this file. This has the following advantages:
IDL program names do not have to match the target RPC server (Natural subprogram, extension .NSN) names.
Target RPC server names (Natural subprogram, extension .NSN) can be customized during wrapping (see Step 2: Customize Natural Server Names) or during extraction (see Step 6: Redesign the Interface for Natural Subprograms (Optional) under Extracting Software AG IDL File from a New Natural RPC Environment in the IDL Extractor for Natural documentation).
IDL program names are not limited to 8 characters.
The CVM file is generated either during wrapping (see Using the Natural Wrapper for the Server Side) or during extraction (see IDL Extractor for Natural). It is wrapped into the RPC client components and the relevant information is sent from a client to the server. Therefore it is important to generate or extract the target Natural RPC (Natural subprogram, extension .NSN) server first, before creating any RPC client component.
If you are not using a CVM file, the target RPC server (Natural subprogram, extension .NSN) must match the IDL program name. In this case the length of the IDL program name is limited to 8 characters.
The parameter names as given in the IDL file are replaced by artificial
names in the generated Natural interface object (stub subprogram).
See parameter-data-definition under Software AG IDL Grammar.
Fixed arrays within the IDL file are mapped to fixed Natural arrays. The lower bound is set to 1 and the upper bound is set to the upper bound given in the IDL file.
See array-definition under Software AG IDL Grammar for the syntax on how to
describe fixed arrays within the IDL file and refer to
fixed-bound-array-index.
Unbounded arrays within the IDL file are mapped to Natural X-arrays. The lower bound is always fixed and set to 1.
See array-definition for the syntax of unbounded
arrays within the IDL file and refer to unbounded-array-index.
Groups within the IDL file are mapped to Natural groups. See the
group-parameter-definition under Software AG IDL Grammar for the syntax on how to
describe groups within the IDL file.
Structures within the IDL file are mapped to Natural groups. See structure-definition under Software AG IDL Grammar for the syntax on how to describe
structures within the IDL file.
The IDL syntax allows you to define parameters as IN parameters, OUT parameters, or IN OUT parameters (which is the default if nothing is specified). This direction specification is reflected by Natural as follows:
Parameters with the OUT attribute are
sent from the RPC client to the RPC server. They are always provided with the
call by reference method.
Parameters with the IN attribute are
sent from the RPC server to the RPC client. They are always provided with the
call by reference method.
Parameters with the IN OUT attribute are
sent from the RPC client to the RPC server and then back to the RPC client.
Only the direction information of the top-level fields (level 1) is relevant. Group fields always inherit the specification from their parent. A different specification is ignored.
See the attribute-list under Software AG IDL Grammar for the syntax on how to
describe attributes within the IDL file and refer to direction
attribute.
Note:
If you define an interface object layout in the Natural application
SYSRPC, the meaning of the direction attributes IN and OUT are reversed
compared to the IDL:
IN in SYSRPC is OUT in IDL
OUT in SYSRPC is IN in IDL
The ALIGNED attribute is not relevant for
the programming language Natural. However, a Natural client can send the
ALIGNED attribute to an RPC server where it
might be needed. To do this you need a Natural interface object (stub
subprogram) that has been generated from an IDL file.
See the attribute-list under Software AG IDL Grammar for the syntax of
attributes in the IDL file and refer to the aligned attribute.
The IDL syntax allows definitions of procedures only. It does not have the concept of a function. A function is a procedure which, in addition to the parameters, returns a value. Procedures and functions are transparent between clients and server. This means a client using a function can call a server implemented as a procedure, and vice versa.
The Natural RPC does not support functions.
