Unity, WCF and IIS

In a previous post, I showed how to integrate Unity with WCF when you are self-hosting a service. What's not clear is how to get IIS to use the Unity-enabled host when it starts hosting your service.

This is accomplished with a ServiceHostFactory. The @ServiceHost directive has an attribute named, curiously enough, Factory. This can be used to designate a class which will provide a configured ServiceHost. More on that in a moment. Let's see an example of a service that needs constructor-injection.

I've taken the default Service that Visual Studio 2008 gives you when you create a WCF Web Service, and added a SuffixProvider dependency that is satisfied in the constructor.

namespace WcfService1
{
    public class Service1 : IService1
    {
        private ISuffixProvider provider;
        public Service1(ISuffixProvider provider)
        {
            this.provider = provider;
        }

        public string GetData(int value)
        {
            return string.Format("You entered: {0}", value);
        }

        public CompositeType GetDataUsingDataContract(CompositeType composite)
        {
            if (composite.BoolValue)
            {
                composite.StringValue += provider.GetSuffix();
            }
            return composite;
        }
    }
}

namespace WcfService1
{
    public interface ISuffixProvider
    {
        string GetSuffix();
    }
}


namespace WcfService1
{
    public class MySuffixProvider : ISuffixProvider
    {
        #region ISuffixProvider Members

        public string GetSuffix()
        {
            return "estericize";
        }

        #endregion
    }
}

Using the UnityWCF project created in the previous post, I will create a factory that is derived from ServiceHostFactory, and configure a Unity container to supply a concrete implementation of ISuffixProvider. I have done this in code, most likely you will want to configure it from an XML file.

using System;
using System.ServiceModel;
using System.ServiceModel.Activation;
using Microsoft.Practices.Unity;
using UnityWCF;

namespace WcfService1
{
    public class UnityServiceHostFactory : ServiceHostFactory
    {
        protected override ServiceHost CreateServiceHost(
                                          Type serviceType, Uri[] baseAddresses)
        {
            UnityServiceHost host = new UnityServiceHost(serviceType, baseAddresses);
            UnityContainer unity = new UnityContainer();
            host.Container = unity;

            //configure container
            unity.RegisterType<ISuffixProvider,MySuffixProvider>();

            return host;
        }
    }
}

Finally, edit the Service1.svc file to reference the factory class:

<%@ ServiceHost Language="C#"
Debug="true"
Factory="WcfService1.UnityServiceHostFactory"
Service="WcfService1.Service1"
CodeBehind="Service1.svc.cs" %>