In Microsoft Internet Information Services (IIS) 6.0, Active Server Pages (ASP) applications configured to run in a Web garden application pool cannot share their session state or their application state.
Note The Web gardens feature was introduced in IIS 6.0, and it is available only when IIS runs in worker process isolation mode.
ASP session data is kept in the worker process. A Web garden is an application pool that is served by more than one worker process when an application pool is configured to run with more than one worker process serving it at the same time. However, this is not the default setting. As a result, ASP session data that is stored in one process is not available to other processes in that application pool.
IIS maps incoming requests to worker processes in a Web garden application pool by using a round-robin scheme that associates a connection with a worker process and associates the next connection to the next process. If an application keeps a connection alive and uses the same source port, the requests are routed back to the same worker process. If the application does not keep a connection open or if the connection is new, the next request is routed to the next available worker process based on a round-robin scheme. The source port can be different if the client has to cross a proxy or a firewall.
For additional information about alternatives to the session object in Active Server Pages, click the following article number to view the article in the Microsoft Knowledge Base:
175167 HOWTO: Store State in Active Server Pages Applications
For additional information about Microsoft ASP.NET session modes, click the following article number to view the article in the Microsoft Knowledge Base: