Application servers

An activation group must be connected to the application server of a database manager before SQL statements can be executed.

A connection is an association between an activation group and a local or remote application server. A connection is also known as a session or an SQL session. Connections are managed by the application. The CONNECT statement can be used to establish a connection to an application server and make that application server the current server of the activation group.

An application server can be local to, or remote from, the environment where the activation group is started. (An application server is present, even when distributed relational databases are not used.) This environment includes a local directory that describes the application servers that can be identified in a CONNECT statement. For more information about the directory, see the relational database folders in iSeries(TM) Navigator or the directory commands (ADDRDBDIRE, CHGRDBDIRE, DSPRDBDIRE, RMVRDBDIRE, and WRKRDBDIRE) in the following iSeries Information Center topics:

To execute a static SQL statement that references tables or views, an application server uses the bound form of the statement. This bound statement is taken from a package that the database manager previously created through a bind operation. The appropriate package is determined by the combination of:

A DB2(R) relational database product may support a feature that is not supported by the version of the DB2 UDB product that is connecting to the application server. Some of these features are product-specific, and some are shared by more than one product.

For the most part, an application can use the statements and clauses that are supported by the database manager of the application server to which it is currently connected, even though that application is running via the application requester of a database manager that does not support some of those statements and clauses. Restrictions are listed in Appendix B. Characteristics of SQL statements.