How do I create an ISAPI filter for manipulating files between server and client?

C

CMousseau

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Joined
Mar 16, 2005
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5
Location
Calgary, AB, Canada
Ladies and Gentlemen,

I have created a VB.NET class that, when given a physical path to a .TIFF file, will output the file, edited to show a watermark.

What I would like to do is take this logic and put it in - I believe - an ISAPI filter, and configure my web server so that any time a file of extension .TIFF is fetched, it is put "through the wringer", so that the client browser gets the watermarked .TIFF

I am completely over my head at this point, so even the most simplistic of advice that gets me started is greatly appreciated.

Charles.
 
Thanks for the link! I extracted the code as suggested, yet I am still getting an error, to wit:

got the following error message:

Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: Could not load type Acme.SimpleHandler from assembly TestWM.

Source Error:
Line 3: <system.web>
Line 4: <httpHandlers>
Line 5: <add verb="*" path="test.aspx" type="Acme.SimpleHandler,TestWM"/>
Line 6: </httpHandlers>
Line 7: </system.web>


Here are the steps I went through:

First, I created a "Class Library" solution in VB, adding a class file like so:

Imports System.Web
Namespace Acme
Public Class SimpleHandler : Implements IHttpHandler
Public Sub ProcessRequest(ByVal Context As HttpContext) Implements IHttpHandler.ProcessRequest
Context.Response.Write("Hello World!")
End Sub

Public ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
Get
Return True
End Get
End Property
End Class
End Namespace


which I compiled under the name TestWM.dll; the file of which I moved from the project's bin directory to the website's bin directory. I then created a web.config file as directed:


<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.web>
<httpHandlers>
<add verb="*" path="test.aspx" type="Acme.SimpleHandler,TestWM"/>
</httpHandlers>
</system.web>
</configuration>


The website name, as registered in my IIS directory, is WatermarkTest, and so, I entered the following URL:

http://localhost/WatermarkTest/test.aspx

giving me the resultant error message.

Any ideas? My hunch is that I have a security setting botched. Changing the TestWM in the web.config gives me a different batch of error messages, on the order of "I can't find any assembly named TestWM.dll or TestWM.exe in any of these default directories", yet changing the Acme.SimpleHandler to something nonsensical gives me the same error detailed above.

Thanks for your help,

Charles.
 
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