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Session Manager is a layer within the Siebel Web Server Extension (SWSE) and Application Object Manager (AOM) that manages TCP/IP (SISNAPI) connections between clients to AOMs. Session Manager primarily manages Web server to Siebel Server communications. It is not a stand-alone component, and is embedded in SWSE and any other direct AOM.
NOTE: SISNAPI is a proprietary messaging format used for communication into Siebel Servers, and between multiple Siebel Servers. The acronym stands for Siebel Internet Session API (Application Program Interface).
Session Manager is primarily responsible for establishing and managing SISNAPI connections from the client to the AOM. A connection is established for each new session request, and is kept open or terminated based on SISNAPI connection multiplexing settings. Session Manager allows multiple client sessions to share the same pool of SISNAPI connections, thereby minimizing resource usage and maximizing overall performance.
When a client requests a new session, the SWSE receives the HTTP request from the Web server, translates the request into SISNAPI messaging format, and invokes Session Manager embedded in the SWSE to obtain a physical connection to the Siebel Server. Session Manager creates a new, temporary SISNAPI connection, which is load-balanced to an available Siebel Server. After this temporary connection is made to a Siebel Server, Session Manager checks to see if there are enough SISNAPI connections to the target process. If there are enough TCP connections, then the temporary connection is dropped and the existing connection is used for this new user session. If a connection is not available, then the temporary connection is retained. For further details on this process, see Siebel Performance Tuning Guide, which describes the use of the parameter Number of Sessions with respect to each SISNAPI Connection (alias SessPerSisnConn).
After Session Manager opens a connection to the Siebel Server, it closes connections based on the time the connection remains idle. The parameter SISNAPI Connection Maximum Idle Time (alias ConnIdleTime) controls this feature. After reaching the configured idle period, the connection is disconnected by the AOM process. This setting should be used when a third-party load balancer is in use for Siebel Servers configured to time out SISNAPI connections. By default, most load balancers have an idle connection timeout feature. The parameter ConnIdleTime must be set to a value slightly less than the load balancer timeout.
An additional benefit of the ConnIdleTime parameter is to manage connections that pass through a firewall placed between the Web server and the Siebel Server. As firewalls block idle connections, the ConnIdleTime parameter can be configured to disconnect idle connections before they are blocked by the firewall. This setting avoids future connection problems between the Web server and the Siebel Server.
Parameters that modify Session Manager and SISNAPI connections are available for each component at the component level. For details on these and other parameters, see Siebel Enterprise, Server, and Component Parameters.
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