Business Server Pages
How it works (simplified):
§Client submits request via Sap system running in SAP WEB AS
Internet Communication Manager (ICM)
§BSPs as ABAP requests routing through the ICM
§When user enters a URL, the browser opens a TCP/IP connection to the WEB AS, The ICM will accept the incoming TCP/IP connection and then will wait until the complete HTTP request has been received from the browser before dispatching it to the next layer for processing.
§After processing within the ABAP stack , an HTTP response is available for transmission to the browser.
Accessing ICM in SAP
§T-Code SMICM
§Shows state of ICMan threads
§Defines ports for HTTP, HTTPS and SMTP
§Sets Trace Level
§Shows Trace File
§Stop/Start of ICMan
Internet Communication Framework (ICF)
§Handles access control , authentication, and dispatching of incoming HTTP request.
§Maintains a tree of URL segments, which looks very similar to a directory structure on disk.
§Each requested URL are split into segments and each segment is then matched against a node in the tree.
§After a valid path has been through , an authentication step is performed
§Authentication information can be read from URL parameter or can be configured.
§MPI (Memory Pipes) are a medium for communication and data transport between the work processes and the ICM
§Dispatcher generates work processes, manages the following services: Dialog Service, Spool Service, Batch Service, Enqueue Service, Update Service and Gateway Service. Dispatcher manages system’s memory resources and conducts communication between processes
§Dispatcher queue collects requests for work processes
§SAP Web AS can function in stateful mode and stateless mode
§Stateful – web application comparable to a normal SAP transaction, application context is retained for each request/response cycle
§Stateless – application context is lost after each request/response cycle
Internet Communication Framework (ICF) –Process Flow
§The ICF handles the HTTP request/response in the SAP work process
§The ICF provides the developer an object-oriented framework for dealing with HTTP (SMTP, …) requests/responses in the ABAP personality
§Client sends request to SAP WEB Application Server (WEB AS) via HTTP/HTTPS/WML protocol
§Request includes specific server, port and target page
§Internet Communication Manager (ICM) receives client request, determines that a BSP page has been requested and selects appropriate handler
§ICM stores the received data in a memory pipe (MPI) in shared memory and notifies the Dispatcher
§Dispatcher puts request in Dispatcher Queue, creates a new context (assuming one doesn’t exist and stateful condition in use), and selects a work process to edit
§Work process Taskhandler reads data from MPI, edits request, writes response back to MPI. ICM is then notified that task is complete
§ICM returns response data to client
ICF – How response is send
§Low Level HTTP Communication
§ABAP Objects classes, which implement IF_HTTP_EXTENSION interface
§Objects SERVER, REQUEST and RESPONSE directly available
§assigning URL to HTTP-extension in TA SICF
§HTTP server and client functionality
ICF – Accessing in SAP
§T-Code SICF
§services defines URL for HTTP handlers
§Default user settings for public sites
§Default client, language
§definition of Aliases
§Individual ICF Services for BSP Applications
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