The Acu4GL product builds its own database queries dynamically whenever an input or output request is received. These are the steps that you take to compile your program and execute it using Acu4GL:
Compile with -Fx
1. You compile your standard COBOL application with ACUCOBOL-GT. See the section specific to your RDBMS for details to determine which version of the compiler is required. When you compile, you specify via a compile-time option that you want the compiler to generate data dictionaries, in addition to an object code file.
Dictionaries are created
2. An ACUCOBOL-GT data dictionary is created by the compiler for each indexed file in your program. These data dictionaries map COBOL records in an indexed file to rows in a database.
Set the files host
3. In your configuration file, you may specify which RDBMS or ISAM file system you are using by setting the DEFAULT-HOST variable (sets a default for all files), or the filename-HOST variable (sets a file system for individual files), or both. For example, you might say DEFAULT-HOST VISION and EMPFILE-HOST ORACLE. This would direct EMPFILE input and output functions to the Oracle RDBMS via Acu4GL, and direct I/O for all other files to the Vision system. These are runtime settings that allow you to change hosts without recompilation, and enable you to tailor your application for the specific needs of a particular end user site. The HOST variable also allows you to do load balancing and migration of your application. You can move vision files into the database in an incremental fashion allowing you to test scaling and performance of the new configuration.
Set database-specific variables
4. At this point, you set variables in the runtime configuration file which apply to the specific database system you are using. See the section specific to your RDBMS for details. They can be found in the table of contents by selecting the Contents button at the top of this screen.
I/O requests are passed to the Acu4GL product
5. You use the ACUCOBOL-GT runtime system to execute your application. Whenever the runtime system encounters an input or output instruction (such as READ or WRITE) on a file that is directed to an RDBMS, it passes the request to the Acu4GL product.
SQL statements are built automatically
6. The Acu4GL product automatically builds SQL instructions that your database management system can understand. As it builds these SQL instructions, it looks at the ACUCOBOL-GT data dictionary, which map the COBOL record and its fields to the table rows and its columns.
Database is accessed
7. The database management system uses its own dictionary as a pointer into its own data files, performs the requested I/O operation, and passes the results back to the Acu4GL product.
COBOL records are formed
8. The Acu4GL product translates the data fields into COBOL records or status codes, which are then passed back to the runtime system via the generic file handler.
All of this communication is automatic, and all database queries and translations are performed behind the scenes, so that the end user experiences no interruption in program execution.