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SAP Sybase SQL Anywhere 16.0 » SQL Anywhere Server - Programming » HTTP web services » SQL Anywhere as an HTTP web server » How to develop web service applications in an HTTP web server » HTTP session management on an HTTP server


HTTP session administration

A session created by an HTTP request is immediately instantiated so that any subsequent HTTP requests requiring that session context is queued by the session.

In this example, a local host client can access the session with the specified session ID, session_63315422814117, running within the database, dbname, running the service session_service with the following URL once the session is created on the server with the sa_set_http_option procedure.


A web application can require a means to track active session usage within the HTTP web server. Session data can be found using the NEXT_CONNECTION function call to iterate through the active database connections and checking for session related properties such as SessionID.

The following SQL statements illustrate how to track an active session:

        IF conn_id IS NULL THEN
            LEAVE conn_loop;
        END IF;
        SELECT CONNECTION_PROPERTY( 'SessionID', conn_id ) 
            INTO the_sessionID;
        IF the_sessionID != '' THEN
            PRINT 'conn_id = %1!, SessionID = %2!', conn_id, the_sessionID;
            PRINT 'conn_id = %1!', conn_id;
        END IF;
        SELECT NEXT_CONNECTION( conn_id, NULL ) INTO conn_id;
    END LOOP conn_loop;
    PRINT '\n';

If you examine the database server messages window, you see data that is similar to the following output:

conn_id = 30
conn_id = 29, SessionID = session_63315442223323
conn_id = 28, SessionID = session_63315442220088
conn_id = 25, SessionID = session_63315441867629

Explicitly dropping a connection that belongs to a session causes the connection to be closed and the session to be deleted. If the connection being dropped is currently active in servicing an HTTP request, the request is marked for deletion and the connection is sent a cancel signal to terminate the request. When the request terminates, the session is deleted and the connection closed. Deleting the session causes any pending requests on that session's queue to be re-queued.

In the event the connection is currently inactive, the session is marked for deletion and re-queued to the beginning of the session timeout queue. The session and the connection are deleted in the next timeout cycle (normally within 5 seconds). Any session marked for deletion cannot be used by a new HTTP request.

All sessions are lost when the database is stopped.

 See also