Stateful junction concepts
Most Web-enabled applications maintain a "state" for a sequence
of HTTP requests from a client. This state is used, for example, to:
- Track a user's progress through the fields in a data entry form generated by a CGI program
- Maintain a user's context when performing a series of database inquiries
- Maintain a list of items in an online shopping cart application where a user randomly browses and selects items to purchase
Back-end servers that run Web-enabled applications can be replicated in order to improve performance through load sharing. By default, Verify Identity Access balances back-end server load by distributing requests across all available replicated servers. Verify Identity Access uses a "least-busy" algorithm. This algorithm directs each new request to the server with the fewest connections already in progress.
However, when WebSEAL processes a request over a stateful junction, WebSEAL must ensure that all subsequent requests from that client during that session are forwarded to the same server, and not distributed among the other replicated back-end servers according to the load balancing rules.