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Q191038: INFO: WebClass Initialize, BeginRequest, Terminate Events

Article: Q191038
Product(s): Microsoft Visual Basic for Windows
Version(s): 6.0
Operating System(s): 
Keyword(s): kbInternet kbVBp kbVBp600 kbWebClasses kbGrpDSASP kbDSupport
Last Modified: 25-APR-2001

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The information in this article applies to:

- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
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SUMMARY
=======

The WebClass Initialize, BeginRequest, EndRequest, and Terminate events may fire
more than once when starting and stopping a WebClass application. You need to
take this into consideration when putting code inside these events.

MORE INFORMATION
================

WebClass Object
---------------

The WebClass run-time is not loaded when the Initialize event is fired so you
cannot access any part of the WebClass object in that event. The WebClass
run-time has already been terminated when the Terminate event is fired so you
cannot access any part of the WebClass object in that event.

Events Firing
-------------

The initialize event occurs when an end user accesses the .asp (Active Server
Pages) file that acts as the host for your IIS application. In the Initialize
event, the WebClass is created as an object. This is always the first event in
the WebClass's lifetime. The WebClass run-time is not loaded when the Initialize
event is fired so you cannot access any part of the WebClass object in that
event.

NOTE: If the StateManagement property for the WebClass is set to wcNoState, the
WebClass fires the Initialize event each time it receives an HTTP request. See
"State Management in IIS Applications" for more information about setting the
StateManagement property.

The BeginRequest event is the next event called after the Initialize event when
the user starts the application, and is also fired each time the WebClass
receives a subsequent request from the browser. This event marks the beginning
of processing for an HTTP request. You might use this event to perform
processing required for every request the WebClass will perform. For example,
you could use BeginRequest to retrieve state information from a database or to
verify user information before processing a request.

NOTE: The WebClass fires the BeginRequest event each time it receives an HTTP
request.

The Start event generally occurs the first time BeginRequest is fired in the
application. It is not fired on subsequent requests. This event is generally
used to send an initial response to the browser, launching the Respond event for
the specified webitem.

NOTE: If the end user specifies a webitem and event in the initial URL they use
to launch the application, the WebClass does not fire the Start event. In this
case, the specified event would be the first event fired. See "Setting the Start
Event" for more information.

The EndRequest event occurs when the WebClass has finished processing an HTTP
request and has returned a response to the client. The processing of an event
might require the WebClass to process several templates or webitems and their
associated event procedures before a response is returned to the client.

NOTE: The WebClass fires the EndRequest event each time it receives an HTTP
request.

The Terminate event tells the run-time DLL to destroy the instance of the
WebClass. The WebClass run-time has already been terminated when this event is
fired so you cannot access any part of the WebClass object in that event.

NOTE: If the StateManagement property for the WebClass is set to wcNoState, the
WebClass fires the Terminate event each time it sends a HTTP response to the
browser. If the StateManagement property for the WebClass is set to
wcRetainInstance, the WebClass fires the Terminate event only after their is a
call the to ReleaseInstance method.

Example
-------

For this sample, there are three HTTP requests going from the browser to the
server to show the page:

- If StateManagement=wcRetainInstance the BeginRequest, EndRequest will be
  fired three times and the initialize event will be fired once with NO
  Terminate event because the ReleaseInstance method was not called.

- If StateManagement=wcNoState the BeginRequest, Initialize, EndRequest,
  Terminate will all be fired three times.

REFERENCES
==========

Please see the following Microsoft Knowledge Base article for more information
on WebClasses:

  Q189539 INFO: VB 6.0 Readme Part 8: WebClass Designer Issues

Additional query words:

======================================================================
Keywords          : kbInternet kbVBp kbVBp600 kbWebClasses kbGrpDSASP kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB600Search kbVBA600 kbVB600
Version           : :6.0
Issue type        : kbinfo

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