Server Role 

The following illustration shows the entire process, from the sending of a HTTP request from a Web client, to receipt of the response by the client.

The ICM receives the HTTP request, as the URL contains the combination of server name and port to which the ICM responds.

The ICM decides on the basis of the URL whether local handlers need to be called, and if so, which ones. The procedures for the handlers - redirect handler, file access handler, server cache handler, logging handler and J2EE handler -  are described in section Processing HTTP Requests. If the default handler, the ABAP handler, is used, the following occurs:

·         The ICM stores the data it receives in a memory pipe (located in shared memory) and informs the dispatcher.

·         The dispatcher enters the ICM request in the dispatcher queue, creates a new context (unless the system is in stateful mode and a context already exists), and chooses a work process.

·         The work process (task handler) reads the data from the memory pipe, processes the request (via ICF and the HTTP request handler), and writes the response back into the MPI. Then, the work process signals to the ICM that it has finished processing the request.

·         The ICM sends the response data back to the client.

For a detailed description of the ICF procedure, see Internet Communication Framework.

The section Client Role describes in detail the client role of SAP Web Application Server.