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Problem with an F# HTTP Handler
f#webhttp

I wanted to try building out a simple web project to help me learn F#. Any help figuring out what the problem is would be appreciated.

SimpleHandler.fsi:

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namespace BlogEngine.Backend

open System
open System.Web
// A class type:
type SimpleHandler = class
  interface IHttpHandler
end

SimpleHandler.fs:

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// test http handler
#light

namespace BlogEngine.Backend

open System
open System.Web

type SimpleHandler = class
  interface IHttpHandler with 
    member x.ProcessRequest(context) = context.Response.Write("test")
    member x.IsReusable
        with get() = true
  end
end

I then added the following to web.config:

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<httpHandlers>
  <add verb="*" path="test.aspx" type="BlogEngine.BackEnd.SimpleHandler, blogengine.backend" />
</httpHandlers>

The solution successfully compiles, but when I try to launch the website from Visual Studio, I get an error page with the message:

Parser Error Message: Could not load type 'BlogEngine.BackEnd.SimpleHandler' from assembly 'blogengine.backend'.

Any suggestions on how to get this working would be much appreciated.

.

Hello there,

I terms of what you've written in F# and added to your web.config it seems like your very much on the right track. The problem here is that the CLR runtime can not find the dll. I think if you add a node:

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<customErrors mode="RemoteOnly" />

To your web config then you should get more details about where the runtime is looking for you're dll, although the level of details depends on the version of .NET your running, with the messages for .NET 2.0 genenerally being more useful.

The other advise I'd give is to ensure you have created an IIS application arround the directory which contains your web.config (this is different from a virtual directory, you normally need to press "create" on the first properties page of the directory in IIS - though this too varies from version to version). You also need to ensure the dll is placed in a sub directory called bin. I suppect this is the problem as C# VS web application do this by default and F# ones, for the moment, don't.

I have a demonstration of F# and ASP.NET running on my web site:
[link:www.strangelights.com]

There's also a discusion of this in my book:
[link:www.amazon.com]&

Cheers,
Rob

By on 4/19/2007 1:23 AM ()

Thanks for the suggestions. Changing CustomErrors hasn't added any new information, and the DLL is in the bin directory.

If it makes a difference, the website project (but not the handler, obviously) is C#, since I didn't know I could do the website itself in F#. I'll start working through your demo code -- thanks for the pointer.

And I'm definitely looking forward to the book. I have it pre-ordered.

By on 4/19/2007 7:15 AM ()

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