Question

I have a WCF service which performs CRUD operation on my data model: Add, Get, Update and Delete. And I’m using Entity Framework for my data model.
On the other side there is a client application which calls methods of the WCF service.

For example I have a Customer class:

[DataContract]
public class Customer
{
   public Guid CustomerId {get; set;}
   public string CustomerName {get; set;}
}

and WCF service defines this method:

public void AddCustomer(Customer c)
{
    MyEntities _entities = new MyEntities();
    _entities.AddToCustomers(c);
    _entities.SaveChanges();
}

and the client application passes objects to the WCF service:

var customer = new Customer(){CustomerId = Guid.NewGuid, CustomerName="SomeName"};
MyService svc = new MyService();
svc.Add(customer); // or svc.Update(customer) for example

But when I need to pass a great amount of objects to the WCF it could be a perfomance issue because of I need to create ObjectContext each time when I’m doing Add(), Update(), Get() or Delete().

What I’m thinking on is to keep ObjectContext on the client and pass ObjectContext to the wcf methods as additional parameter.

Is it possible to create and keep ObjectContext on the client and don’t recreate it for each operation? If it is not, how could speed up the passing of huge amount of data to the wcf service?

Sergey

Answer 1

No, the ObjectContext can’t be serialised over a WCF service call.

The current version of the entity framework doesn’t really have any support for n-tier apps like this.

We have an n-tier app using the entity framework and we detach our objects from the ObjectContext each time and do re-creation and re-attaching for every call and it works fine. There doesn’t seem to be any significant performance cost for doing the recreations (SQL server will be pooling the database connections anyway), so unless you are doing something requiring really heavy throughput then don’t get into premature optimisation. Just get it running, then profile it. To be honest, your biggest bottle neck is going to be the WCF service call and the data transfer over the network anyway, so if you are looking to improve performance, minimise the quantity of data you are transferring instead of worrying about your ObjectContext. Or you could create a service call that takes a list of objects and adds them all at the same time.

However, EF4 is going to do this better. Take a look at this MSDN article for some more information on n-tier support in EF4. If you work with the beta or wait a month for the release it might be worth taking a look.