What is the correct way to solve the ambiguous reference issue in WCF services? - silverlight

Question

Project Structure
I have a silverlight project SLProj, that references a silverlight class library project called ServiceClients. ServiceClients has two wcf service references, Svc1.svc and Svc2.svc. Both Svc1.svc and Svc2.svc are in two different WCF projects which use the same set of DataContracts which are again in a different class library project called MyDataContracts.dll.
Problem description
Now in my ServiceClients project I get an ambiguous reference issue when I need to use a datacontract class which is present in both the service references. If this were a winforms or webforms project, I could reference the MyDataContracts.dll and reuse the common types. But since, this MyDataContracts.dll was built using a non silverlight class library, it can't be referenced in the silverlight project
Workaround...
I am not sure if this below is the best method to go about taking care of this issue. Can anybody let me know if there is a cleaner way to solve this problem, or is this the best way we have so far?
create a single service reference.
click the 'show all files' button in the solution explorer
drill into the service reference and find Reference.svcmap and open it
find the MetadataSources section
add a second line to include the address to your second service. for example:
MetadataSource Address="http://address1.svc" Protocol="http" SourceId="1"
MetadataSource Address="http://address2.svc" Protocol="http" SourceId="2"
save, close, and update service reference.

Answer 1

Use Automapper
Map the DataContracts with AutoMapper.
You will have to invest some time in understanding AutoMapper and reworking your application. Also AutoMapper adds overhead because all data objects will be mapped. But first you will have a clean solution without hacks and second you gain a decoupled and simple data object layer just for your client. Once done you can forget the mapping but you stay flexible for future changes.
If you never have worked with Automapper it's important to play around with it before starting. Automapper is special and needs some time to familiarise with it.
So there. These are the rough steps:
1. Create a subdirectory and sub-namespace Data and copy the DataContracts. Remove the attributes and properties your client doesn't need because these mapped classes live only in your client. You can also change some types or flatten some complex properties.
2. Create an AutoMapperInit.cs like described at Automapper (read the Getting Started Guide). Use the conflicting references like this:
using ref1 = YourProjectServiceReference1;
using ref2 = YourProjectServiceReference2;
3. Wrap the service client like this:
Example GetExample() {
return AutoMapper.Map<ref1.Example, Example>(ref1.YourService.GetExample());
}
The wrapper also needs the same using directives as in step 2.
4. In this wrapper add a static initializer like this (assuming your wrapper class is called Wrapper):
static Wrapper() {
AutoMapperInit.CreateMaps();
}
5. Omit service references in the client and use using YourClient.Data;, the namespace you created in step 1.
Your client is now decoupled from the service and you don't have conflicts anymore.
Disclaimer: I am not affiliated with AutoMapper. I just used it in a project with a similar problem and am happy with it and wanted to share my experience.

Answer 2

Your workaround is actually quite OK. We've used it in several projects like this with 3 service references. It is actually a workaround for the IDE which for some reason only allows to select one service to create a service reference at a time.
Another thing you could try-out is to multi-target your shared contract to .NET and Silverlight, using the same codebase. Details on how to do such thing is described in http://10rem.net/blog/2009/07/13/sharing-entities-between-wcf-and-silverlight. Might be more work but feel less hacky.