Request-Handling Process Overview

When Web Server first starts up, it performs some initialization tasks and then waits for an HTTP request from a client (such as a browser). When the server receives a request, it first selects a virtual server. The obj.conf file of the selected virtual server determines how the server handles a request.

The obj.conf file contains a series of instructions known as directives that tell the server what to do at each stage in the request-handling process. These directives are grouped inside Object tags. Each directive invokes a function with one or more arguments.

Each directive applies to a specific stage in the request-handling process. For example, a directive that applies during the authorization stage in the request-handling process is an AuthTrans directive.

Stages in the Request-Handling Process

1. AuthTrans (authorization translation)

   Verify the authorization information (such as name and password) sent in the request.

2. NameTrans (name translation)

   Translate the logical URI into a local file system path.

3. PathCheck (path checking)

   Check the local file system path for validity and check if the requestor has access privileges to the requested resource on the file system.

4. ObjectType (object typing)

   Determine the Multipurpose Internet Mail Encoding (MIME) type of the requested resource (for example, text/html, image/gif, and so on), and establish other resource-specific settings.

5. Input (prepare to read input)

   Select filters that will process incoming request data read by the Service step.

6. Output (prepare to send output)

   Select filters that will process outgoing response data generated by the Service step.

7. Route (request routing)

   Select the server to service the request.

8. Service (generate the response)

   Generate and return the response to the client.

9. AddLog (adding log entries)

   Add entries to log files.

10. Error (error handling)

    Send an error message to the client and exit processing. This step is executed only if an error occurs in the previous steps.