Application programs like Net.Data must connect to DB2 for OS/390 to access DB2-managed data or to execute DB2 stored procedures. When using ICAPI, GWAPI or Net.Data Servlets, Net.Data accomplishes this objective by using the Resource Recovery Services Attachment Facility (RRSAF), which is provided as part of the DB2 product. Because establishing a connection to a DB2 subsystem involves significant overhead, the reuse of existing connections is an attractive alternative to recreating a new connection for each user request.
Net.Data supports the reuse of connections that are used by the SQL and ODBC language environments when Net.Data is configured for use with ICAPI, GWAPI, or Net.Data servlets. When a Web server thread processes a Net.Data user request that requires access to DB2, Net.Data connects to DB2 and creates a DB2 thread. The DB2 thread remains as long as the Web server is running. When the Web server assigns subsequent requests to this Web server thread, and access to DB2 is needed, Net.Data reuses the existing DB2 thread. Net.Data modifies the DB2 plan name and user ID, and switches to a new subsystem ID as needed to match the requirements of the request. The number of DB2 threads created increases until the number of DB2 threads matches the number of Web server threads. At this point, the steady state operation of the server is reached. Net.Data reuses the existing DB2 threads, and no new DB2 threads are created.
No configuration of Net.Data is required for the use of connection management facilities. However, if you want to use Work Load Manager (WLM) to manage the Web server address spaces that process Net.Data requests, some additional WLM configuration is needed.