This document covers the following topics:
See also Administering the EntireX RPC Server.
This section describes the EntireX RPC examples for RPG in the library EXAMPLE of the Developer's Kit for IBM i.
An RPC client example is not currently provided in RPG.
The source file QCBLLESRC contains the server-side implementation of the procedure CALC. The associated IDL definition is the same as for the client side.
For details on the IBM i installation kit, see Step 1: Restore the EXAMPLE Library.
This section describes how to build a server application using the IBM i ILE language RPG. The server will be named CALC_RPG. Its functionality and implementation is based on the ILE COBOL server CALC as described in the section Using the COBOL Wrapper.
The function CALC_RPG is a calculator that can add, subtract, multiply
and divide two binary values PIC S9(8) BINARY and return a
result.
This section tells you how to
The PLIST in the RPG program is a good source of type information for the interface when you create the Software AG IDL file:
... D OPERATOR S 1A D OPERAND_1 S 10I 0 D OPERAND_2 S 10I 0 D FCT_RESULT S 10I 0 * C *ENTRY PLIST C PARM OPERATOR C PARM OPERAND_1 C PARM OPERAND_2 C PARM FCT_RESULT ....
The assumption is made that the program is implemented in library EXAMPLE. Convert the linkage section function above to Software AG IDL syntax as follows:
Library 'EXAMPLE' Is Program 'CALC_RPG' Is Define Data Parameter 1 Operator (A1) In 1 Operand_1 (I4) In 1 Operand_2 (I4) In 1 Function_Result (I4) Out End-Define
Note:
A 10-digit RPG integer takes 4 bytes, so it must be mapped to an
(I4) IDL field definition.
For details on how IDL field definitions are mapped to RPG elementary field items, see Using EntireX RPC for RPG under IBM i.
The server is implemented as an ILE RPG program of type *PGM.
For our IDL example CALC, the implemented server looks similar to the example below. (It is contained in the member CALC_RPG in the source file EXAMPLE/QRPGLESRC).
*-------------------------------------------------- * Member CALC_RPG * Description Calculation Engine. * * Author (c) Software AG * Platform OS/400 * * UUU YYYY-MM-DD History * HBA 2003-05-20 Created * *--------------- CALC Interface ------------------------------ D OPERATOR S 1A D OPERAND_1 S 10I 0 D OPERAND_2 S 10I 0 D FCT_RESULT S 10I 0 *------------------------------------------------------------- C *ENTRY PLIST C PARM OPERATOR C PARM OPERAND_1 C PARM OPERAND_2 C PARM FCT_RESULT C CLEAR FCT_RESULT * C SELECT C WHEN OPERATOR = '+' C EVAL FCT_RESULT = OPERAND_1 + OPERAND_2 C WHEN OPERATOR = '-' C EVAL FCT_RESULT = OPERAND_1 - OPERAND_2 C WHEN OPERATOR = '*' C EVAL FCT_RESULT = OPERAND_1 * OPERAND_2 C WHEN OPERATOR = '/' C IF OPERAND_2 <> *ZERO C EVAL FCT_RESULT = OPERAND_1 / OPERAND_2 C ENDIF C ENDSL * C PGM_EX TAG C MOVE *ON *INLR
The servers are running in a multithreaded environment. Therefore your application server programs must be thread-safe. This implies that all commands and subprograms accessed in your servers must allow multithreads.
For RPG multithreading issues in RPG, see the IBM documentation Multithreaded Applications (V4R4 in this case).
Compile the server source using the IBM i command CRTRPGMOD (create
bound RPG module) and bind it as a dynamically callable program of type *PGM
using the command CRTPGM. See the example procedure BIND_RCALC under Step 1: Restore the EXAMPLE Library.
|
Important: |
As an alternative to the commands CRTRPGMOD and CRTPGM, you can use the command CRTBNDRPG to compile and bind RPG sources in one step.
Name the resulting server program like the program name in the IDL file and put it in a library whose name corresponds to the library name in the IDL file.
If you put the server program in a library other than the IDL library,
you can reroute the call using the server parameter Library=FIX(
MyLib). In this case, the library name
sent with the client request is ignored.
If a client performs an RPC which is based on the IDL program CALC_RPG in the IDL library EXAMPLE, the remote RPC server will dynamically try to execute the ILE program CALC_RPG in the IBM i library EXAMPLE. If no corresponding program can be found, the access fails.
The principles of calling a server are described under Administering the EntireX RPC Server.
See Step 3: Verify the RPC Server using COBOL for how to start an RPC server that can execute the server program CALC_RPG.
To verify the server program CALC_RPG, Software AG recommends that you use a client Java program from the EntireX Workbench. See EntireX Workbench.
To start the Java Client
Confirm that an EntireX Broker and an EntireX RPC server are available in your network.
Start/submit an RPC server on your IBM i machine as described under Starting the RPC Server under IBM i.
Open the EntireX Workbench and find the sample IDL file example.idl delivered with the Windows installation kit.
Copy the IDL program CALC to CALC_RPG.
From the menu bar choose and . After compilation, a pop-up menu will offer you the option of running the Java client program. Select the server program CALC_RPG.
On the Java calculation menu, specify the numbers you want to compute and choose CALL. The RPC request will be sent to the RPC Server on your IBM i, which will run the ILE server program CALC_RPG in library EXAMPLE. If the Broker connection fails, you will receive an appropriate error message.
This section describes the specific mapping of Software AG IDL data types, groups, arrays and structures to the RPG programming language. See also the remarks and hints on the Software AG IDL data types valid for all language bindings found in Software AG IDL File.
The following topics are covered here:
In the table below, the following metasymbols and informal terms are used for the Software AG IDL.
The metasymbols [ and ] enclose 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 | RPG Data Type | See Notes |
|---|---|---|---|
| A number | Alphanumeric | numberA | |
| AV | Alphanumeric variable length | not supported | |
| AV[number] | Alphanumeric variable length with maximum length |
numberA | 2 |
| Bnumber | Binary | numberB | |
| BV | Binary variable length | not supported | |
| BV[number] | Binary variable length with maximum length |
numberB | |
| D | Date | 8U | 1 |
| 8P | 10 | ||
| 21U | 11 | ||
| F4 | Floating point (small) | 4F | 5, 6 |
| F8 | Floating point (large) | 8F | 5, 6 |
| I1 | Integer (small) | 3I 0 | |
| I2 | Integer (medium) | 5I 0 | 7 |
| I4 | Integer (large) | 10I 0 | 7 |
| Knumber | Kanji | numberA | |
| KV | Kanji variable length | not supported | |
| KV[number] | Kanji variable length with maximum length |
numberA | 2 |
| L | Logical | not supported | |
| Nnumber1 [.number2] | Unpacked decimal | number1S number2 | 3, 8 |
| NUnumber1 [.number2] | Unpacked decimal unsigned | number1U number2 | 3 |
| Pnumber1 [.number2] | Packed decimal | number1P number2 | 3, 9 |
| PUnumber1 [.number2] | Packed decimal unsigned | number1P number2 | 3 |
| T | Time | 15U | 4 |
| 15P | 12 | ||
| 21U | 13 |
See also the hints and restrictions under IDL Data Types valid for all language bindings.
Notes:
Do not use the special characters '#', '$', '&', '+', '-', '.', '/' and '@' within names of programs and libraries in the IDL file. These characters are not allowed within names of server programs and libraries created on IBM i.
Fixed arrays within the Software AG IDL file are mapped to fixed RPG
tables. See the array-definition under Software AG IDL Grammar in the IDL Editor documentation
for the syntax on how to describe fixed arrays within the Software AG IDL file and
refer to fixed-bound-array-index.
Unbounded arrays without a maximum are not supported.
Groups within the Software AG IDL file are mapped to RPG tables.
See the group-parameter-definition under Software AG IDL Grammar
for the syntax on how to describe groups within the Software AG IDL file.
Example
The following IDL definition shows a simple group structure:
Library 'EXAMPLE' Is
Program 'GROUP' Is
Define Data Parameter
1 MYGROUP
2 PART1 (A10) In Out
2 PART2 (A10) In Out
End-Define
The following source file excerpt from a sample RPG program named GROUP shows the corresponding field definitions and the entry parameter list:
CL0N01Factor1+++++++Opcode&ExtFactor2+++++++Result++++++++Len++D+ * D MYGROUP DS D PART1 10 D PART2 10 * ************************************************ * C *ENTRY PLIST C PARM MYGROUP *
Structures within the Software AG IDL file are mapped to RPG tables like groups. See the structure definition for the syntax on how to describe structures within the Software AG 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 in the stubless call of the RPC Server as follows:
Direction attributes do not change the call interface because parameters are alway treated as "called by reference".
Usage of direction attributes may be useful to reduce data traffic between RPC client and RPC server.
Parameters with the IN attribute are sent from the RPC client to the RPC server.
Parameters with the OUT attribute are sent from the RPC server to the RPC client.
Parameters with the IN and OUT attribute are sent from the RPC client to the RPC server and then back to the RPC client.
Note that 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 Software AG IDL file and refer
to direction-attribute.