Handling Invalid URI passed to a WCF service

Question

I have WebGet, and WebInvoke attributes describing my contract, but what is the best method of handling invalid URI's? Right now, if a user passes an URI that does not match my current operations, they get an "Endpoint not found." message. I want to pass back a more descriptive message.

For example, my URI template looks like:

/Stuff/{ID}/subStuff

but say they type

/Stuff/{ID}/OtherStuff

There is no such thing as OtherStuff, and I do not have a template for that.

Is there a way to cover all non mapped URI's with a single contract?

Thanks!

score 1 · Answer 1 · edited May 23 '17 at 12:04

1

If you want to catch all the unhandled requests at a global level in WCF REST then you have to create a custom WebHttpBehavior and custom IOperationInvoker as described in this post.

If you want to return a custom error text with custom status code(404) you can also look into the WebOperationContext.OutgoingResponse property as described here.

edited May 23 '17 at 12:04

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answered Jun 25 '12 at 17:39

VJAI

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Ok, so I have tried both techniques. both do not work, because I am relying on IIS to provide the endpoint. at the time the service is being created, the endpoint does not exist, So I can't bind a behavior. – Nathan Tregillus Jul 19 '12 at 19:59

score 1 · Accepted Answer · answered Jul 19 '12 at 22:21

While I did follow the links mark provided, and they did give a hint of what I needed. The answers that were linked did not actually answer my original question.

I was able to follow the steps, and I wanted to list my steps to solve this problem on this question as well.

To create my own response to any URI that was not mapped to a method in my contract I created the following:

A custom ServiceHostFactory
Behavior that I mapped to my end points within the custom ServiceHostFactory
a dispatcher that would handle all unmapped uri's that were provided to the service.

Below are the full definitions of the object's I created:

using System.ServiceModel;
using System.ServiceModel.Activation;

namespace your.namespace.here
{
    public class CustomServiceHostFactory : WebServiceHostFactory
    {
        protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)
        {
            ServiceHost host = base.CreateServiceHost(serviceType, baseAddresses);
            //note: these endpoints will not exist yet, if you are relying on the svc system to generate your endpoints for you
            // calling host.AddDefaultEndpoints provides you the endpoints you need to add the behavior we need.
            var endpoints = host.AddDefaultEndpoints();
            foreach (var endpoint in endpoints)
            {
                endpoint.Behaviors.Add(new WcfUnkownUriBehavior());
            }

            return host;
        }
    }
}

As you can see above, we are adding a new behavior: WcfUnknownUriBehavior. This new custom behavior's soul duty is to replace the UnknownDispatcher. below is that implementation:

using System.ServiceModel.Dispatcher;
using System.ServiceModel.Channels;
using System.ServiceModel.Web;
namespace your.namespace.here
{
    public class UnknownUriDispatcher : IOperationInvoker
    {
        public object[] AllocateInputs()
        {
            //no inputs are really going to come in,
            //but we want to provide an array anyways
            return new object[1]; 
        }

        public object Invoke(object instance, object[] inputs, out object[] outputs)
        {
            var responeObject = new YourResponseObject()
            {
                Message = "Invalid Uri",
                Code = "Error",
            };
            Message result = Message.CreateMessage(MessageVersion.None, null, responeObject);
            WebOperationContext.Current.OutgoingResponse.ContentType = "text/html";
            outputs = new object[1]{responeObject};
            return result;
        }

        public System.IAsyncResult InvokeBegin(object instance, object[] inputs, System.AsyncCallback callback, object state)
        {
            throw new System.NotImplementedException();
        }

        public object InvokeEnd(object instance, out object[] outputs, System.IAsyncResult result)
        {
            throw new System.NotImplementedException();
        }

        public bool IsSynchronous
        {
            get { return true; }
        }
    }
}

Once you have these objects specified, you can now use the new factory within your svc's "markup":

<%@ ServiceHost Language="C#" Debug="true" Service="your.service.namespace.here" CodeBehind="myservice.svc.cs"
                Factory="your.namespace.here.CustomServiceHostFactory" %>

And that should be it. as long as your object "YourResponseObject" can be serialized, it's serialized representation will be sent back to the client.

where is the definition for WcfUnknownUriBehavior please? – user1108069 Jun 18 '19 at 06:05 — user1108069, Jun 18 '19 at 06:05
its the custom class i wrote in the question above – Nathan Tregillus Jun 19 '19 at 15:02 — Nathan Tregillus, Jun 19 '19 at 15:02

Handling Invalid URI passed to a WCF service

2 Answers2

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