I am bit new to webAPi and I want to implement CORS (Cross Origin Resource Sharing) on Web API. I am referring to this Microsoft link. They install a Nuget package using
PM> Install-Package Microsoft.AspNet.Cors -Version 5.0.0-rc1 -Pre However, I am using .NET Framework 4.0 and it is not working. Afterwards I used this Nuget command:
Install-Package Microsoft.AspNet.WebApi -Version 4.0.20710 But it does not contain the CORS class. So, do we have any other different way to implement CORS?
I use the following and works fine for me (thought not sure about the "4.0 client profile" bit) :
public class CorsHandler : DelegatingHandler { private const string Origin = "Origin"; private const string AccessControlRequestMethod = "Access-Control-Request-Method"; private const string AccessControlRequestHeaders = "Access-Control-Request-Headers"; private const string AccessControlAllowOrigin = "Access-Control-Allow-Origin"; private const string AccessControlAllowMethods = "Access-Control-Allow-Methods"; private const string AccessControlAllowHeaders = "Access-Control-Allow-Headers"; protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { bool isCorsRequest = request.Headers.Contains(Origin); bool isPreflightRequest = request.Method == HttpMethod.Options; if (isCorsRequest) { if (isPreflightRequest) { var response = new HttpResponseMessage(HttpStatusCode.OK); response.Headers.Add(AccessControlAllowOrigin, request.Headers.GetValues(Origin).First()); string accessControlRequestMethod = request.Headers.GetValues(AccessControlRequestMethod).FirstOrDefault(); if (accessControlRequestMethod != null) { response.Headers.Add(AccessControlAllowMethods, accessControlRequestMethod); } string requestedHeaders = string.Join(", ", request.Headers.GetValues(AccessControlRequestHeaders)); if (!string.IsNullOrEmpty(requestedHeaders)) { response.Headers.Add(AccessControlAllowHeaders, requestedHeaders); } var tcs = new TaskCompletionSource<HttpResponseMessage>(); tcs.SetResult(response); return tcs.Task; } return base.SendAsync(request, cancellationToken).ContinueWith(t => { HttpResponseMessage resp = t.Result; resp.Headers.Add(AccessControlAllowOrigin, request.Headers.GetValues(Origin).First()); return resp; }); } return base.SendAsync(request, cancellationToken); } } Remember to register it in you app start (mine in global.asax)
GlobalConfiguration.Configuration.MessageHandlers.Add(new CorsHandler()); 
return base.SendAsync(...) inside if(isCorsRequest). Do you have any idea about resolving that??
The CORS package is supported in Web API 2 that needs .NET Framework 4.5 and visual studio/express 2014.
It is not available for Web API 1 (which you are using with .NET 4.0)
Refer this thread.
