The Database Services Interface
The database services interface provides communication between the RDBMS and the other two tiers. It consists of the following components:
-
The Database Server (ladb)
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The database APIs
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The database driver
The Database Server (ladb)
The Database Server (ladb) is the main server engine. It analyzes and manages user requests, determines which database to access, and spawns database drivers. The ladb also notifies other servers of terminated database users.
Database (4GL) APIs
Presentation and application programs use Application Program Interfaces (APIs) provided by the Lawson system to communicate with the database. These APIs perform a set of functions such as finding a single record, summing each of three columns in a table, or deleting a set of records.
The Database Driver
The Database Server (ladb) communicates with the relational database management system (RDBMS) through database drivers. The driver translates Lawson 4GL Database APIs into native RDBMS SQL commands. The database driver is specific to the RDBMS you use. The following database driver is associated with the IBM DB2 server:
Database Server | Database Driver |
---|---|
IBM DB2 |
ibmdb |
The Database Utilities
Several utilities are connected with the database driver to provide additional data access and management services. They are:
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verifyibm
Compares Lawson dictionary descriptions to the expected translations in IBM DB2 to ensure the IBM DB2 database definitions match the Lawson dictionary.
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bldibmddl
Generates SQL statements for creating or deleting selected tables, indexes, and stored procedures. The utility can operate on specific tables, all tables in a system code, or all tables in a data area.
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bldibmsec
Duplicates Lawson table level security in the IBM DB2 database.
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ibmdu
Calculates the space needed for an initial number of records in the database, using information found in the Lawson dictionary and both
law_dba_table
andlaw_dba_index
.