Singleton DBContext for a Per-Call WCF Service using castle

Question

I am trying find a proper way of injecting an EF6 DbContext into my WCF service but I kind of struggle to find a proper working example. Does anyone know of a good demonstration of a per-call WCF service and Entity framework? I use Castle for the injection however any other IOC container is welcomed. If you are against using Singleton dbcontext [Massive DB] please show me a working example with the least performance hit.

See [this answer](http://stackoverflow.com/questions/10585478/one-dbcontext-per-web-request-why/10588594#10588594) for the reasons why a singleton `DbContext` is such a bad idea. — qujck, Feb 24 '14 at 17:35

score 0 · Answer 1 · answered Mar 09 '14 at 13:31

This worked for me: Create a concrete context interface:

public class CustomersContext :DbContext, ICustomerContext

Then register in the container as singleton

container.Register(Component.For<ICustomerContext>().ImplementedBy<CustomersContext>());

Then you should register it as a WCF service and provide your own Instance Provider like this:

First add some attributes to your interface:

[InstanceProviderBehavior(typeof (ICustomerContext))]
[DataContract]
public class CustomersContext :DbContext, ICustomerContext

Then, write the InstanceProviderBehavior attribute:

 public class InstanceProviderBehaviorAttribute : Attribute, IServiceBehavior
{
    private readonly Type _type;

    public InstanceProviderBehaviorAttribute(Type type)
    {
        _type = type;
    }

    public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {

    }

    public void AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, Collection<ServiceEndpoint> endpoints, BindingParameterCollection bindingParameters)
    {

    }

    public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {
        foreach (ChannelDispatcher cd in serviceHostBase.ChannelDispatchers)
        {
            foreach (EndpointDispatcher ed in cd.Endpoints)
            {
                if (!ed.IsSystemEndpoint)
                {
                    ed.DispatchRuntime.InstanceProvider = new WindsorServiceInstanceProvider(_type);
                }
            }
        }
    }
}

Note that you tell the WCF to use the WindsorServiceInstanceProvider.

Here it is:

    public class WindsorServiceInstanceProvider : IInstanceProvider
{
    public static IWindsorContainer Container;

    private readonly Type _type;

    public WindsorServiceInstanceProvider(Type type)
    {
        _type = type;
    }

    public object GetInstance(InstanceContext instanceContext, Message message)
    {
        return Container.Resolve(_type);
    }

    public object GetInstance(InstanceContext instanceContext)
    {
        return this.GetInstance(instanceContext, null);
    }

    public void ReleaseInstance(InstanceContext instanceContext, object instance)
    {
        Container.Release(instance);
    }
}

Please note the static object named Container, this is pretty ugly, but I didnt find any other way to pass my container instance into the InstanceProvider

Thats it. now, when some client will ask for ICustomerContext from your WCF service, it will resolve it from your container.

More about WCF Instance Provider here

Singleton DBContext for a Per-Call WCF Service using castle

1 Answers1