具有相同类的自定义ServiceContract的WCF数据服务

Question

I have a problem very similar to this: Combine ADO.NET Data Service and custom ServiceContract in the same class?

(However, I can't comment on that, since i don't have 50 reputation... therefore I have to open a new question)

So, I have a WCF Data Service:

public class LearnDataService : DataService<LearnEntities>
{
    // This method is called only once to initialize service-wide policies.
    public static void InitializeService(DataServiceConfiguration config)
    {
        config.SetEntitySetAccessRule("Customers", EntitySetRights.All);
        config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V3;
    }
}

I'd like to extend it with a few custom WCF Service operations (they will be doing complex DB queries in real life, i'd be using simple calls instead just to keep the example code short). So, I created the interface:

[ServiceContract]
public interface ICustomerService
{
    [OperationContract]
    List<Customer> GetCustomers();

    [OperationContract]
    Customer GetCustomerByCustomerId(string customerID);
}

Extended the service class like this:

public class LearnDataService : DataService<LearnEntities>, ICustomerService
{
    // This method is called only once to initialize service-wide policies.
    public static void InitializeService(DataServiceConfiguration config)
    {
        config.SetEntitySetAccessRule("Customers", EntitySetRights.All);
        config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V3;


        config.SetServiceOperationAccessRule("GetCustomers", ServiceOperationRights.AllRead);
        config.SetServiceOperationAccessRule("GetCustomerByCustomerId", ServiceOperationRights.AllRead);
    }

    [WebGet]
    public List<Customer> GetCustomers()
    {
        var customers = (from c in this.CurrentDataSource.Customers
                       select c).ToList();

        return customers;
    }

    [WebGet]
    public Customer GetCustomerByCustomerId(string customerID)
    {
        var product = (from c in this.CurrentDataSource.Customers
                       where c.CustomerID == customerID
                       select c).FirstOrDefault(); ;

        return product;
    }
}

Now, when trying to use the service, I get:

LearnDataService implements multiple servicecontract types, and no endpoints are defined in the configuration file.

Ok, as said in the answer for the question I linked above, I set the config file as follows:

<services>
  <service name="LearnService.LearnDataService">
    <endpoint address="data" binding="webHttpBinding" contract="System.Data.Services.IRequestHandler" />
    <endpoint address="cust" binding="webHttpBinding" contract="LearnService.ICustomerService" />
  </service>
</services>

Now, I'm trying to add a service reference for this service in a client project. Using "Add Service Reference..." and pressing Discover button, (of course with the Service running without debugging), it discovers the ht_tp://localhost:7947/LearnDataService.svc url, and I get a 404 (no wonder, there's nothing listening there...)

Since I don' have 10 reputation, I can't post more than 2 links. This includes localhost links, so I have to mangle them this way :( sorry

Now, I modify the Address to ht_tp://localhost:7947/LearnDataService.svc/data, then it correctly discovers the LearnEntities service, and when opening it, I can see the Customers entity. So far so good, so I check the other service, ht_tp://localhost:7947/LearnDataService.svc/cust. When discovering that, I get an error:

There was an error downloading 'ht_tp://localhost:7947/LearnDataService.svc/cust/_vti_bin/ListData.svc/$metadata'. The request failed with HTTP status 404: Not Found. Metadata contains a reference that cannot be resolved: 'ht_tp://localhost:7947/LearnDataService.svc/cust'. There was no endpoint listening at http://localhost:7947/LearnDataService.svc/cust that could accept the message. This is often caused by an incorrect address or SOAP action. See InnerException, if present, for more details. The remote server returned an error: (404) Not Found. If the service is defined in the current solution, try building the solution and adding the service reference again.

When trying these URLs using a browser, the ht_tp://localhost:7947/LearnDataService.svc/data works, and shows the data in XML format, but the URL ht_tp://localhost:7947/LearnDataService.svc/cust gives a 404: (Endpoint not found.)

Do you have any idea, what is the problem with the configuration? Am I understanding the answer of the linked SO question correctly?

Answer 1

Finally, I found the solution. Apparently, there is no way to get this to work by adding standard WCF service queries to a Data Service like I tried above, but it turns out that WCF Data Services has a (somewhat limited) support for writing custom queries, which is called WCF Data Service Operations :

http://blogs.msdn.com/b/odatateam/archive/2010/05/26/service-operations-and-the-wcf-data-services-client.aspx https://msdn.microsoft.com/en-us/library/cc668788(v=vs.110).aspx

This way I could accomplish what I wanted to do in the first place. However, this solution isn't as nice as it shoud be, since there's no service contract defined for these operations, they won't show up in WSDL, no automatic client code generation for them, etc. You have to know the names and parameters of these operations when writing the client code.