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Example of User Request Flow in a Siebel Deployment

Figure 2 illustrates how a user request is processed within the Siebel Business Applications architecture. In the diagram, there are two types of load balancing:

• Siebel Application Interface load balancing. Web client requests can be forwarded to different instances of Siebel Application Interface.
• Siebel Server load balancing. Siebel Application Interface and Siebel Gateway work together to distribute user requests to multiple Siebel Servers.

Figure 2. Generic User Request Flow in Siebel Business Applications

A typical Siebel client request flows from the user's Siebel Web Client through the system components for Siebel Business Applications and back again, according to the following general flow:

1. A user performs an action that initiates a request. For example, the user clicks a link in the Site Map to navigate to a particular view. The request is generated by the Web browser and Siebel Web Client framework.
2. The request goes through the network, using an existing or new HTTP connection. The request might go through a network router, proxy server, cache engine, or other mechanism.
3. The Web load balancer, if present, evaluates the request, determines the best Siebel Application Interface to receive the request, and then forwards the request to the Siebel Application Interface.
4. The Siebel Application Interface receives the HTTP request and determines that it is a Siebel application request.
5. The Siebel Application Interface parses the HTTP message and generates a SISNAPI message, based on the content of the HTTP message. The Siebel Application Interface also parses the incoming cookie to obtain the user session ID. The Siebel Application Interface forwards the request to a Siebel Server on a least-loaded basis.

   NOTE:  Siebel Business Applications require session cookies and do not support cookieless mode.

6. On the Siebel Server, an Application Object Manager (AOM) receives and processes the SISNAPI message. If a database query is needed to retrieve the information, then the Application Object Manager formulates the SQL statement and sends the request to the Siebel database over a database connection.

   The database request uses a protocol format that is specific to the database connector.

7. The database executes the SQL statement and returns data back to the Application Object Manager. The Application Object Manager forwards the message to the Siebel Application Interface that originated it.
8. The Siebel Application Interface receives the SISNAPI message and translates it back to HTTP. The message is now in the form of Web page content.
9. The Siebel Application Interface forwards the Web page content through the original HTTP connection to the end user's Web browser.
10. The Web browser and the Siebel Web Client framework process the return message and display it to the end user.