Distributed Relational Database Architecture › What Is DRDA?

What Is DRDA?

DRDA is IBM's SAA architecture that provides access to data distributed across various systems and platforms. DRDA provides the user, via a high-level programming language, access to relational databases on different systems and platforms and the files that reside on the systems. DRDA is implemented using SQL/400 and the SQL CONNECT statement. Used with embedded or interactive SQL, the CONNECT statement defines the relational database (machine) to be accessed.

Note: While DRDA is implemented using SQL statements, these statements can also operate on DDS access paths, with the exception of Span access paths. To use DRDA with a DDS file only requires that the function be set to generate SQL. This permits most functions to use DDS access, while only those that require DRDA functionality will be generated as SQL COBOL or SQL RPG.

DRDA support at the Remote Unit of Work (RUOW) level is available with i OS Version 2 Release. This phase of IBM support allows for connecting an application requester (the system executing the program) to an application server (the system where data is being accessed).

As supported in CA 2E, DRDA allows the user to specify that a file is distributed and allows CA 2E functions to access the distributed data. DRDA has the constraints applied to the DRDA level of RUOW implemented under i OS Version 2 Release 1.1. The application accesses data on a single machine at a time. At present, support for DRDA is provided for DB2 and i OS platforms.

RUOW restrictions and constraints should be reduced as IBM releases the two higher levels of DRDA, Distributed Unit of Work (DUOW) (i OS Version 3 Release 1) and Distributed Request (DR).