Develop Reference

WCF services with the same object

I have two WCF services I am adding reference to in my application. Both these services have an object called X, which is the same object.
The problem is after adding the references in my application, I am getting two different objects, with the same exact structure, but with different namespace.
This prevents me from casting between them and forces me to create two different objects, one for each service.
Please notice I don’t want to use dll’s.

Please notice I don’t want to use dll’s.
You'll have to. When you generate a WCF proxy, you have the option to reuse types from referenced assemblies. This have to be assemblies containing the types also used by the service. See also How to: Configure a Service to Reuse Existing Types.
Of course as #Franck pointed out in a comment, it's possible to intervene in the serialization process. You can also use a tool like AutoMapper.
More interesting is your actual problem: why don't you want to use a DLL reference? Did you try that but do you for example wish to deploy a single-file application, then merge the assembly in your executable.

Does a webservice is a standalone or can use outside classes

Can a web service use other classes that I have in a project or should it be standalone and use only it's own methods?
Thanks !

Does a web service can use other classes that I have in the project ?
YES it can. You can also return your custom class object, after serialization. Its very unusual that you would see webservice interacting with primitive types only (internally).

You can create instances of other classes and use them to perform work.
Any class in the same project or a referenced project should be usable, subject to the usual access modifiers.
You'll either need to include a using statement. Following example assumes you want to use SomeClass which resides in MyAssembly.SomeLibrary:-
using MyAssembly.SomeLibrary;
// in code block somewhere
var thing = new SomeClass();
or fully qualify the name of the class.
var thing = new MyAssembly.SomeLibrary.SomeClass();

It sounds like you are asking in terms of best practice rather than "is this technically possible". The answer depends on the class you want to use I suppose, but in general it is acceptable to use any other classes or libraries you want in a web service as this will not affect the client being able to consume the service (i.e. using LibraryA on the service side does not mean client 1 has to also have LibraryA installed to use your service).
It is possible to reuse those classes service side (in Visual Studio this is done by ticking the "Reuse types in referenced assemblies" box when you configure a service reference and then adding a reference to the appropriate project / dll), but I would generally advise against it as it can confuse matters - not all clients will have access to those dlls when consuming your service.

WCF ServiceKnownType design issue

I'm designing a new solution that will consist of three projects:
"Server" - a WCF service
"Client" - a winforms app that will call the WCF service
"ServiceContract" - a class lib containing some base classes plus the WCF service contract (interface). This will obviously be referenced by the Server, and also by the Client (I'm using a ChannelFactory rather than have VS generate a service reference). The service contract looks something like this:-
[ServiceContract]
[ServiceKnownType("GetCommandTypes", typeof(CommandTypesProvider))]
public interface INuService
{
[OperationContract]
bool ExecuteCommand(CommandBase command);
}
It's a very basic operation - the client creates a "command" object and sends it to the server to be executed. There will be many different commands, all inheriting from CommandBase (this base class resides in the "ServiceContract" project). As I'm using the base class in the WCF operation signature, I have to specify the known types which I'm doing dynamically using the ServiceKnownType attribute. This references a helper class (CommandTypesProvider) that returns all types deriving from CommandBase.
I've created a simple proof of concept with a couple of derived command classes that reside in the "ServiceContract" project. The helper class therefore only has to reflect types in the executing assembly. This all works fine.
Now in my "real" solution these command classes will be in different projects. These projects will reference the ServiceContract project, rather than vice-versa, which makes it difficult (or impossible?) for the helper to reflect the "command" assemblies. So my question is, how can I provide the known types?
Options I've thought about:-
The "Server" and "Client" projects will reference both the "ServiceContract" project and the various "command" projects. My helper could reflect through AppDomain.CurrentDomain.GetAssemblies(), but this fails because the "command" assemblies are not all loaded (I could force this by referencing a type in each, but that doesn't feel right - I want it to be a dynamic, pluggable architecture, and not have to modify code whenever I add a new command project).
Specify the known types in config. Again it would be nice if the app was dynamic, rather than have to update the config each time I add a command class.
Is there any way to access the underlying DataContractSerializer on both the client and server, and pass it the known types? I guess I'll still have the same issue of not being able to reflect the assemblies unless they've been loaded.
Refactor things to enable the ServiceContract project to reference the various command projects. I can then reflect them using 'Assembly.GetReferencedAssemblies()'. I guess the various command classes are part of the service contract, so perhaps this is the way to go? Edit: looks like this has the same problem of only finding loaded assemblies.
Any ideas greatly appreciated! Is it something that can be achieved or do I need to rethink my architecture?!
Thanks in advance.

One thing to consider is using the DataContractResolver.
Few resources:
WCF Extensibility – Data Contract Resolver by Carlos
Building Extensible WCF Service Interfaces With DataContractResolver by Kelly
Configuring Known Types Dynamically - Introducing the DataContractResolver by Youssef

Thanks for the replies regarding the Data Contract Resolver guys. I probably would have gone down this route normally but as I was using Windsor I was able to come up with a solution using this instead.
For anyone interested, I added a Windsor installer (IWindsorInstaller) to each of my "command" projects, which are run using Windsor's container.Install(FromAssembly.InDirectory.... These installs are responsible for registering any dependencies needed within that project, plus they also register all the command classes which my known types helper can resolve from the container.

Type Redefinition With WSE Web Service Import

Consider the following Visual Studio project structure
ProjectA.csproj
AClass.cs
ProjectB.csproj
References
ProjectA
Web References
AWebService
AWebService.csproj
References
ProjectA
ReturnAClassViaWebService.asmx
The issue occurs when ProjectB adds the web reference to AWebService and automatically generates all the proxy code for accessing AWebService including a new implementation of AClass. Since all of our other code needs to use the AClass defined in ProjectA, we're forced to convert the AWebService.AClass returned from the service into something we can use.
We're currently considering two solutions, neither of which are ideal.
Manually editing the generated Reference.cs to remove new definitions of AClass
Serializing AWebService.AClass to a stream then deserializing to ProjectA.AClass
Does anyone have any better solutions? This seems like something common enough for other developers to have experienced it.
Ideally we would like to have the proxy code generated in ProjectB to reference ProjectA.AClass rather than generating a whole new implementation.
Our environment is VS 2008 using .NET 2.0.

I have had the same problem that you are describing and I have tried both of the options you specify without being entirely happy about either of them.
The reason we both have this issue is at least partly because the shared-library-between-consumer-and-provider-of-a-web-service-solution is in violation of accepted patterns and practices for web service design. On the consumer side, it should be sufficient to know the interface published in the WSDL.
Still, if you are prepared to accept a tight coupling between your web service provider and web service consumer and you know for certain that your current client will never be replaced by a different client (which might not be capable of referencing the shared library), then I understand why the proposed solution seems like a neat way to structure your app. IMPORTANT NOTE: Can we really honestly answer yes to both of these questions? Probably not.
To recap:
The issue appears when you have classes (e.g. a strongly typed dataset) defined in some sort of shared library (used on both client and server).
Some of your shared classes are used in the interface defined by your web service.
When the web reference is added there are proxy classes defined (for your shared classes) within the web reference namespace.
Due to the different namespaces the proxy class and its actual counterpart in the shared library are incompatible.
Here are four solutions that can be tried if you want to go ahead with the shared library setup:
Don't. Use the proxy class on the client side. This is how it is intendend to be done. It works fine unless you simultaneously want to leverage aspects of the shared library that are not exposed by the web service WSDL.
Implement or use a provided copy/duplication feature of the class (e.g. you could try to Merge() one strongly typed dataset into another). A Cast is obviosuly not possible, and the copy option is usually not a very good solution either since it tends to have undesirable side-effects. E.g. When you Merge a dataset into another, all the rows in the target dataset will be labeled as 'changed'. This could be resurrected with AcceptChanges(), but what if a couple of the received rows were actually changed.
Serialize everything - except for elementary data types - into strings (and back again on the consumer side). Loss of type safety is one important weakness of this approach.
Remove the explicit declaration of the shared class in Reference.cs and strip the namespace from the shared class wherever it is mentioned within Reference.cs. This is probably the best option. You get what you really wanted. The shared class is returned by the web service. The only irritating drawback with this solution is that your modifications to the reference.cs file is lost whenever you update your web reference. Trust me: It can be seriously annoying.
Here is a link to a similar discussion:

You can reuse existing referenced types between the client and service by clicking on the 'Advanced' button on the 'Add Service Reference' form. Make sure the 'Reuse types in referenced assemblies' checkbox is checked and when the service client is generated it should reuse all types from project A.
In past versions this has not always worked correctly and I've had to explicitly select the shared type assemblies by selecting the 'Reuse types in specified referenced assemblies' option and then checking the appropriate assemblies in the list box. However, I just tested this with VS 2008 SP1 and it appears to work as expected. Obviously, you need to make sure that the types that are being used by the service and client projects are both from project A.
Hope that this helps.

We encountered a similar problem with one of our projects. Because we had several dependencies, we ended up creating a circular reference because project 1 required objects from project 2, but project 2 could not be build before project 3, which relied on project 1 to be build.
To solve this problem, we extracted all the public standalone classes from both projects and placed them inside a single librarie. In the end we created something like this:
Framework.Objects
Framework.Interface
Framework.Implementation
WebService
The WebService would be linked to all projects in our case, whereas external parties would only be linking to the objects and interface classes to work with. The actuall implementation was coupled at runtime through reflection.
Hope this helps

Using a webservice type directly through the DLL

I have a webservice with a function that returns a type (foo). If I consume this webservice in .NET through the 2.0 generated proxies, it creates a class called foo in the generated proxy. If I have the DLL that contains that class (foo) that is the DLL being used by the webservice, is there any way to have it use that class instead of creating a custom proxy class? I'm looking for something similar to what remoting does... but not remoting.

I've seen 3 ways of doing this:
Let Visual Studio generate the proxy and then change the classes in the proxy to the full class names of the dll, by hand. Works, but you would have to do this again everytime you update your proxy. Plus it's really dirty, isn't it?
Use a generic class/method that
creates deep copies of your proxy
objects into the "real" objects by
reflection. Works, but of course
with a little performance offtrade
Use WCF, where you can reference the
dll with the data contracts (your
data classes) and use them instead
of creating any proxy by code
generation.

I think the key issue here is in generating the proxies. I've generally used two different approaches to web services:
1) Traditional services, where you expose methods and a client generates the proxy in Visual Studio to consume the methods.
2) Request/Response services, where the exposed "service" is more of a pass-through and the "actions" being performed are encapsulated in the objects being sent to and received from the service. These actions would be in that shared library that both the server and the client have.
In the former I often run into this same problem and I don't really think there's a solution, at least not one that Visual Studio is going to like at all. You could perhaps manually modify the generated proxies to use the other classes, but then you'll have to repeat that step any time you re-generate. Conversely, you can generate outside of Visual Studio in something like CodeSmith (the older version is free, but depends on .NET 1.1), which will require some work to create a template for the proxies and to step outside the IDE to re-generate any time you need to update them.
I can recommend a good tool for the latter, however, and that would be the Agatha project. It takes the approach of separating the "service" from the "actions" that are being performed, and makes the approach of the shared library very easy. Such a re-architecture may very well be out of the question for the project you're working on depending on your schedule, but it's definitely something to explore for future projects.

You could write your own proxy class, or you could implement a constructor on your Foo class that takes an instance of the generated Foo class and copies over the data as appropriate.