enabling cross-origin resource sharing on IIS7

Question

I recently ran into with posting Javascript requests to another domain. By default XHR posting to other domains is not allowed. Following the instructions from http://enable-cors.org/, I enabled this on the other domain. ``` ``` Everything works fine now, however it is still return a 405 response before sending back the working 200 response. ``` Request URL:http://testapi.nottherealsite.com/api/Reporting/RunReport Request Method:OPTIONS Status Code:405 Method Not Allowed Request Headersview source Accept:*/* Accept-Charset:ISO-8859-1,utf-8;q=0.7,*;q=0.3 Accept-Encoding:gzip,deflate,sdch Accept-Language:en-GB,en-US;q=0.…

Accepted Answer

It is likely a case of IIS 7 'handling' the HTTP OPTIONS response instead of your application specifying it. To determine this, in IIS7,

Go to your site's Handler Mappings.

Scroll down to 'OPTIONSVerbHandler'.

Change the 'ProtocolSupportModule' to 'IsapiHandler'

Set the executable: %windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_isapi.dll

Now, your config entries above should kick in when an HTTP OPTIONS verb is sent.

Alternatively you can respond to the HTTP OPTIONS verb in your BeginRequest method.

```
    protected void Application_BeginRequest(object sender,EventArgs e)
    {
        HttpContext.Current.Response.AddHeader("Access-Control-Allow-Origin", "*");

if(HttpContext.Current.Request.HttpMethod == "OPTIONS")
        {
            //These headers are handling the "pre-flight" OPTIONS call sent by the browser
            HttpContext.Current.Response.AddHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE");
            HttpContext.Current.Response.AddHeader("Access-Control-Allow-Headers", "Content-Type, Accept");
            HttpContext.Current.Response.AddHeader("Access-Control-Max-Age", "1728000" );
            HttpContext.Current.Response.End();
        }

}
```

enabling cross-origin resource sharing on IIS7

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