Tuesday, 23 July 2013

Unit of work pattern in WCF

See here for an example of how to implement a unit of work pattern in WCF (using Unity).

http://blogs.5dlabs.it/post/2012/05/23/Implementing-Repository-and-UnitOfWork-patterns-in-a-WCF-service-using-Unity.aspx

public class CustomServiceHostFactory : ServiceHostFactory
{
protected override ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)
  {
return new CustomServiceHost(serviceType, baseAddresses);
  }
}

public class CustomServiceHost : ServiceHost
{
static IUnityContainer _container;
static CustomServiceHost()
  {
    _container = new UnityContainer();
    _container.RegisterType<ICompanyRepository, CompanyRepository>();
    _container.RegisterType<IUnitOfWork, DbUnitOfWork>();
    _container.RegisterType<SVCContext>(new ServiceInstanceLifeTimeManager());
  }
public CustomServiceHost(Type serviceType, params Uri[] : base(serviceType, baseAddresses)
  {
  }
protected override void ApplyConfiguration()
  {
base.ApplyConfiguration();
    Description.Behaviors.Add(_container.Resolve<UnityServiceBehavior>());
  }
}

public class UnityServiceBehavior : BehaviorExtensionElement , IServiceBehavior
{
IUnityContainer _container;
public UnityServiceBehavior(IUnityContainer container) : base()
  {
    _container = container;
  }
public void AddBindingParameters(ServiceDescription serviceDescription,
ServiceHostBase serviceHostBase,
Collection<ServiceEndpoint> endpoints,
BindingParameterCollection bindingParameters)
  {
  }
public void ApplyDispatchBehavior(ServiceDescription serviceDescription,
ServiceHostBase serviceHostBase)
  {
Type serviceType = serviceDescription.ServiceType;
IInstanceProvider instanceProvider = new UnityInstanceProvider(_container, serviceType);
foreach (ChannelDispatcher dispatcher in serviceHostBase.ChannelDispatchers)
    {
foreach (EndpointDispatcher endpointDispatcher in dispatcher.Endpoints)
      {
        endpointDispatcher.DispatchRuntime.InstanceProvider = instanceProvider;
        endpointDispatcher.DispatchRuntime.MessageInspectors.Add(
new UnitOfWorkMessageInspector(_container)
        );
      }
    }
  }
public void Validate(ServiceDescription serviceDescription,
ServiceHostBase serviceHostBase)
  {
  }
public override Type BehaviorType
  {
get { return this.GetType(); }
  }
protected override object CreateBehavior()
  {
return this;
  }
}

public class UnityInstanceProvider : IInstanceProvider
{
IUnityContainer _container;
Type _serviceType;
public UnityInstanceProvider(IUnityContainer container, Type serviceType)
  {
    _container = container;
    _serviceType = serviceType;
  }
public object GetInstance(InstanceContext instanceContext, Message message)
  {
return _container.Resolve(_serviceType);
  }
public object GetInstance(InstanceContext instanceContext)
  {
return this.GetInstance(instanceContext, null);
  }
public void ReleaseInstance(InstanceContext instanceContext, object instance)
  {
  }
}

 

 

public interface IUnitOfWork
{
void Commit();
}

public class DbUnitOfWork : IUnitOfWork
{
SVCContext _context;
public DbUnitOfWork(SVCContext context)
  {
    _context = context;
  }
public void Commit()
  {
    _context.SaveChanges();
  }
}

 

public class UnitOfWorkMessageInspector : IDispatchMessageInspector
{
IUnityContainer _container;
public UnitOfWorkMessageInspector(IUnityContainer container)
  {
    _container = container;
  }
public object AfterReceiveRequest(ref Message request, IClientChannel channel,
InstanceContext instanceContext)
  {
return _container.Resolve<IUnitOfWork>();
  }
public void BeforeSendReply(ref Message reply, object correlationState)
  {
    ((IUnitOfWork)correlationState).Commit();
  }
}

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