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Introduction
Chapter 6 Managing Process Execution 159
An ACTIVE or SUSPENDED session can be terminated by an application or user,
or by a system manager. A RECONNECTION_IN_PROGRESS session can be
suspended or terminated by a system manager. A session that has been terminated
is deleted from the engine and the engine’s current state database table.
Disrupted Sessions
A session is a two-way communication between client application and engine. Both
the client application and the engine maintain an object representing the session.
The state of the engine object determines the state of the session. The client
application’s session object uses code in the client API to restore the connection
when a temporary disruption occurs. (A temporary disruption can be due to
network interruptions or engine failure.)
The client session object tests the connection to the engine at regular intervals (refer
to the iIS online help for the WFSession.SetPingInterval). When the client session
object detects a disruption in the connection between the client application and the
engine, it automatically attempts to restore the connection. If the client session
object is unsuccessful in restoring the connection within a specified auto reconnect
timeout period, it notifies the client application that the connection has been
permanently lost. The auto reconnect timeout period is configured in a client
application using the WFSession methods SetRetry and SetPingInterval.
Network failure The engine does not know about a network interruption until it
touches an engine session object, for example, to post an event or assign an activity.
If the engine finds the session disrupted, the engine suspends or terminates the
session, depending on the value of the session’s disconnect action property (set
using the control parameter to WFEngine.OpenSession or WFSession.SetControl).
Engine failure When a primary engine unit fails, all active sessions are
automatically set to RECONNECTION_IN_PROGRESS. During recovery, sessions
remain in this state for a specified timeout period (set in the engine’s configuration),
waiting for the client sessions to reconnect. During this period, a system
administrator can suspend or terminate these sessions.
RECONNECTION_IN_PROGRESS During engine recovery, a previously active
session that is waiting to be restored to active
during the engine recovery.
Session state Description