Modernizing IBM eServer iSeries Application Data Access - A Roadmap Cornerstone

Chapter 7. Embedded SQL 79

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7.2 Creating a SQLRPG - Program/service program/module

Creating Integrated Language Environment (ILE) objects is always a two-step process:

1. The language compiler converts the source code and creates module objects.

RPG modules are created by the CL command CRTRPGMOD.

A module is sometimes called a compilation unit since it comes from the compilation of

one source member. Modules are not executable. They must be built to either program or

service program objects.

2. The binding process creates programs or service programs by binding the module

objects.

A program is created by the CL command CRTPGM, while to create a service program

the CL command CRTSRVPGM must be used. In this way it is possible to combine

modules that are written in different programming languages into a single program or

service program.

Modules can be bound by copy or by reference to the program objects. Bind by copy

means that the module is physically copied into the program object. Every time a module

is changed all programs that contain this module must be rebound. When using bind by

reference, a module is bound into a service program and only the service program’s

signature is bound to the program object.

After a module is bound to a program or service program, the module object is no longer

needed and can be deleted.

When using CRTBNDRPG, a module is generated in the QTEMP library and then bound

to a program with the same name. If the compilation succeeds, the module will be deleted.

To compile an ILE Object with embedded SQL, an additional preceding step, the

precompilation, is necessary.

The SQL precompile creates an output source file member. By default, the precompile

process creates a temporary source file QSQLTxxxxx in QTEMP, or you can specify the

output source file as a permanent file name on the precompile command. If the precompile

process uses the QTEMP library, the system automatically deletes the file when the job

completes. A member with the same name as the program name is added to the output

source file.

This member contains the following items:

򐂰 The embedded SQL statements are commented out and replaced by calls to the SQL

run-time support.

򐂰 Parsed and syntax-checked SQL statement.

򐂰 SQL Communications Area (SQLCA) is added in the Definition specifications; if not, SET

OPTION SQLCA = *NO is specified.

By default, the precompiler calls the host language compiler. When creating a program

CRTBNDRPG is used, while for modules and service programs CRTRPGMOD is used.