SQL Reference

Remote Unit of Work Connection Management

This section outlines the connection states that an application process may enter.

Connection States:

An application process is in one of four states at any time:
Connectable and connected
Unconnectable and connected
Connectable and unconnected
Implicitly connectable (if implicit connect is available).

If implicit connect is available (see Figure 4), the application process is initially in the implicitly connectable state. If implicit connect is not available (see Figure 5), the application process is initially in the connectable and unconnected state.

Availability of implicit connect is determined by installation options, environment variables, and authentication settings. See the Quick Beginnings for information on setting implicit connect on installation and the Administration Guide for information on environment variables and authentication settings.

The implicitly connectable state:

If implicit connect is available, this is the initial state of an application process. The CONNECT RESET statement causes a transition to this state. Issuing a COMMIT or ROLLBACK statement in the unconnectable and connected state followed by a DISCONNECT statement in the connectable and connected state also results in this state.

The connectable and connected state:

An application process is connected to an application server and CONNECT statements can be executed.

If implicit connect is available:

Whether or not implicit connect is available, this state is entered when:

The unconnectable and connected state:

An application process is connected to an application server, but a CONNECT TO statement cannot be successfully executed to change application servers. The process enters this state from the connectable and connected state when it executes any SQL statement other than the following statements: CONNECT TO, CONNECT with no operand, CONNECT RESET, DISCONNECT, SET CONNECTION, RELEASE, COMMIT or ROLLBACK.

The connectable and unconnected state:

An application process is not connected to an application server. The only SQL statement that can be executed is CONNECT TO, otherwise an error (SQLSTATE 08003) is raised.

Whether or not implicit connect is available:

If implicit connect is not available:

State Transitions are shown in the following diagrams.

Figure 4. Connection State Transitions If Implicit Connect Is Available


REQTEXT

Figure 5. Connection State Transitions If Implicit Connect Is Not Available


REQTEXT

Additional Rules:


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