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To understand the design of the interfaces described in detail in ICF Interfaces, it is first necessary to be familiar with the interaction model between the client (usually a Web browser), the Internet Communication Framework (ICF), the HTTP request handler, and the application.

The Internet Communication Framework (ICF) serves as the bridge between the C kernel in the SAP System and the application program (in ABAP).

The following paragraphs deal only with the server role. The client role is dealt with separately in HTTP Communication Using the SAP System as a Client.

When the ICM receives a HTTP request that is to be processed in a work process, the task handler takes over (see graphic). This starts the ICF controller. From this point on, we are only concerned with ABAP and the Internet Communication Framework. The Internet Communication Framework consists of ABAP classes and interfaces.

This graphic is explained in the accompanying text

The following steps are involved in the interaction process (also refer to the graphic and the additional notes below):

  1. The function module HTTP_DISPATCH_REQUEST is called.
  2. An object of the class CL_HTTP_SERVER is created (see IF_HTTP_SERVER). The object is flagged as a server control block.
  3. The HTTP request is read.
  4. The server control clock is filled with data from the HTTP request.
  5. The desired HTTP request handler is selected using the URL (the URL is mapped to the HTTP request handler in transaction SICF).
  6. The client logs in.
  7. The HTTP request handler is called (the handler can then process the request data, call applications that need to access the response object, and so on).
  8. The ICF controller resumes control at this point. The ICF controller may transfer control to further handlers (depending on the settings in SICF).
  9. Another HTTP stream is created (serialization of the response).
  10. The result is written to memory pipes, and is sent back to the client via the ICM (see Structure linkSAP Web Application Server Components).

In the graphic, the red arrows represent the control flow, and the blue arrows represent the data flow.

These steps are described in detail in the following sections:

 

 

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