CORS on Self Hosted WCF Service - wcf

Question

I'm trying to implement CORS suppor into my WCF service.
I got some codes from
https://enable-cors.org/server_wcf.html
public class CustomHeaderMessageInspector : IDispatchMessageInspector
{
Dictionary<string, string> requiredHeaders;
public CustomHeaderMessageInspector (Dictionary<string, string> headers)
{
requiredHeaders = headers ?? new Dictionary<string, string>();
}
public object AfterReceiveRequest(ref System.ServiceModel.Channels.Message request, System.ServiceModel.IClientChannel channel, System.ServiceModel.InstanceContext instanceContext)
{
return null;
}
public void BeforeSendReply(ref System.ServiceModel.Channels.Message reply, object correlationState)
{
var httpHeader = reply.Properties["httpResponse"] as HttpResponseMessageProperty;
foreach (var item in requiredHeaders)
{
httpHeader.Headers.Add(item.Key, item.Value);
}
}
}
But I'm getting error message on this line
public class CustomHeaderMessageInspector : IDispatchMessageInspector
ERROR: Classes can inherit only from other classes
How can i inherit IDispatchMessageInspector
Thanks

Answer 1

I have made a demo, wish it is useful to you.
Reference.
using System;
using System.Collections.Generic;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Configuration;
using System.ServiceModel.Description;
using System.ServiceModel.Dispatcher;
using System.ServiceModel.Web;
Server.
class Program
{
static void Main(string[] args)
{
using (ServiceHost sh = new ServiceHost(typeof(MyService)))
{
sh.Open();
Console.WriteLine("service is ready...");
Console.ReadLine();
sh.Close();
}
}
}
[ServiceContract(Namespace = "mydomain")]
public interface IService
{
[OperationContract]
[WebGet(ResponseFormat =WebMessageFormat.Json)]
string SayHello();
}
public class MyService : IService
{
public string SayHello()
{
return $"Hello, busy World,{DateTime.Now.ToShortTimeString()}";
}
}
public class CustomHeaderMessageInspector : IDispatchMessageInspector
{
Dictionary<string, string> requiredHeaders;
public CustomHeaderMessageInspector(Dictionary<string, string> headers)
{
requiredHeaders = headers ?? new Dictionary<string, string>();
}
public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
{
string displayText = $"Server has received the following message:\n{request}\n";
Console.WriteLine(displayText);
return null;
}
public void BeforeSendReply(ref Message reply, object correlationState)
{
var httpHeader = reply.Properties["httpResponse"] as HttpResponseMessageProperty;
foreach (var item in requiredHeaders)
{
httpHeader.Headers.Add(item.Key, item.Value);
}
string displayText = $"Server has replied the following message:\n{reply}\n";
Console.WriteLine(displayText);
}
}
public class CustomContractBehaviorAttribute : BehaviorExtensionElement, IEndpointBehavior
{
public override Type BehaviorType => typeof(CustomContractBehaviorAttribute);
public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
{
}
public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
{
}
public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
{
var requiredHeaders = new Dictionary<string, string>();
requiredHeaders.Add("Access-Control-Allow-Origin", "*");
requiredHeaders.Add("Access-Control-Request-Method", "POST,GET,PUT,DELETE,OPTIONS");
requiredHeaders.Add("Access-Control-Allow-Headers", "X-Requested-With,Content-Type");
endpointDispatcher.DispatchRuntime.MessageInspectors.Add(new CustomHeaderMessageInspector(requiredHeaders));
}
public void Validate(ServiceEndpoint endpoint)
{
}
protected override object CreateBehavior()
{
return new CustomContractBehaviorAttribute();
}
}
App.config
<system.serviceModel>
<services>
<service name="Server3.MyService" behaviorConfiguration="mybahavior">
<endpoint address="" binding="webHttpBinding" contract="Server3.IService" behaviorConfiguration="rest"></endpoint>
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"></endpoint>
<host>
<baseAddresses>
<add baseAddress="http://localhost:5638"/>
</baseAddresses>
</host>
</service>
</services>
<behaviors>
<serviceBehaviors>
<behavior name="mybahavior">
<serviceMetadata httpGetEnabled="true" httpsGetEnabled="true"/>
<serviceDebug includeExceptionDetailInFaults="true"/>
</behavior>
</serviceBehaviors>
<endpointBehaviors>
<behavior name="rest">
<webHttp />
<CorsBehavior />
</behavior>
</endpointBehaviors>
</behaviors>
<extensions>
<behaviorExtensions>
<add name="CorsBehavior" type="Server3.CustomContractBehaviorAttribute, Server3" />
</behaviorExtensions>
</extensions>
</system.serviceModel>
Client.
<script>
$(function(){
$.ajax({
method:"Get",
url: "http://10.157.13.69:5638/sayhello",
dataType:"json",
success: function(data){
$("#main").html(data);
}
})
})
</script>
Result
Feel free to let me know if there is anything I can help with.

Answer 2

You should add
Dim method = httpRequest.Method
If method.ToLower() = "options" Then httpResponse.StatusCode = System.Net.HttpStatusCode.NoContent
to your example at the end of BeforeSendReply, otherwise at least POST requests won't work.