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The process used by the Internet Transaction Server (ITS) to drive applications guarantees high throughput and fast response times:

The graphic below shows this process in more detail through a single request/response cycle from the Web browser client to the R/3 application server.

This graphic is explained in the accompanying text

When an Internet user starts an application in a Web browser by clicking on a hyperlink or URL, or entering data in an HTML form for processing, this starts an ITS service.

The ITS processes the request as follows:

  1. The Web browser passes the request as a set of name/value pairs known as the request context to the Web server via HTTP.
  1. The Web server passes the request to WGate (the Web gateway).
  1. WGate passes the request to AGate (the application gateway) via TCP/IP.
  1. AGate loads the relevant service file, which contains parameters required to run the application.

The information stored in these parameters includes such details as the business application area, logon information and timeout details, as well as the transaction that drives the service.

There is also a global service file that contains system-wide settings. Some of the required parameters are taken from there and merged with those in the specific service file. However, the settings in the specific service file always override those in the global service file.

The AGate itself does not execute any business logic - this is done in the R/3 System.

  1. AGate establishes a connection with the R/3 System and forwards the prepared request.

If this is a subsequent request from the same user, the ITS identifies the SAP GUI connection previously established and sends information to R/3 down the same channel as before. The user session is identified by a session ID, which is either returned from the Web browser to the Web server in the URL, or stored in a cookie.
  1. R/3 starts the transaction, calls the function module, executes the report for the service requested and sends the result back to AGate.
  1. AGate merges the data into the response context and passes this to an HTML template, which is the HTML page that displays the result of the request in the user’s Web browser.

At the same time, AGate loads the flow files that define the dialog flow in applications based on ITS Flow Logic and language resource files (if used).

  1. AGate forwards the formatted HTML page to WGate
  1. WGate loads any MIME files used in the application and forwards the formatted HTML page to the Web server
  2. WGate passes the formatted page to the Web server
  1. The Web server passes the formatted HTML page to the Web browser, where it can be viewed by the user

The ITS bundles the information handled by each request/response cycle into user sessions.

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