CODEWITHSUNDEEP
wcf
Dean Blakely
Dean Blakely

Reputation: 3585

Accessing .NET WCF services from Android

I have a .NET WCF service (not a web service) with many methods, some accepting and returning complex data types. I use these services from my Windows Phone 7 apps. It all works great and it's easy.

Now I'm evaluating the feasibility of porting some of my apps to Android, but I can't figure out how to invoke my WCF services from an Android client.

I have a working example I found in Invoke webservices from Android.

But this looks to be accessing a "Web Service", not a WCF Service.

My service is at http://www.deanblakely.com/Service2.svc, and it contains a simple method named "SimpleTest" that just returns the string "Alive".

Using the code in the linked article, I put http://www.deanblakely.com/Service2.svc in SOAP_ADDRESS and SimpleTest in OPERATION_NAME. But I have no idea what to put in SOAP_ACTION and WSDL_TARGET_NAMESPACE. I don't even know if this approach is valid.

In .NET, Visual Studio builds us a "Service Reference" and everything just works.

I also don't understand the following two lines of code...

httpTransport.call(SOAP_ACTION, envelope);
Object response = envelope.getResponse();

With WCF services, the call is async so we make the call to SimpleTestAsync and leave a callback for the async return. These two lines of code appear to be synchronous, no?

Upvotes: 1

Views: 5664

Answers (1)

Michael Edenfield
Michael Edenfield

Reputation: 28338

When communicating with WCF services from a non-Windows client, you are basically treating it as an XML Web Service. If you configure your WCF service to use a basicHttp binding, it will act just like any other web service, as far as Java is concerned.

Normally, to call a WCF service from Java, you use wsimport to create a custom set of proxy and data classes, similar to the way a service reference works. Android doesn't have all the libraries needed for those classes, but I did find this URL:
http://code.google.com/p/androidclientgenerator-wsimport/

That is a proxy class generator specifically for Android. Instead of using the code on that web page, you may want to download this proxy generator; you simply have to pass it the URL to your service's WSDL page and it will create typed Java classes for everything. If you have complex types being passed back and forth, this is probably a much better option.

However, if you want to continue with the sample code, you'll need to fill in those variables you've identified. The variables are just the typical parameters for a SOAP envelope. These are defined in the WSDL for your service, and are primarily based on the namespace that you have defined for your service. (They are largely independent of the actual URL that your service lives at, with one exception). You specify the namespace in the WCF service contract:

[ServiceContract(Namespace = "http://namespaces.deanblakely.com/wcf")]

Note that the namespace URL doesn't need to point to a real resource, though frequently they do. It doesn't even need to be a URL (I often use urns); it just needs to be a unique string of characters. For now lets assume you assigned the above namespace to your service.

The WSDL_TARGET_NAMESPACE is just the namespace, exactly as above. The OPERATION_NAME is the name of the method you want to call, for example SimpleTest. The SOAP_ACTION is the combination of namespace an operation; in your case that would be http://namespaces.deanblakely.com/wcf/SimpleTest. In your WSDL you would see this described in an operation tag:

<wsdl:operation name="SimpleTest">
    <soap:operation soapAction="http://namespaces.deanblakely.com/wcf/SimpleTest" style="document"/>

The SOAP_ADDRESS is the only one that actually points to your service file, e.g. http://www.deanblakely.com/Service2.svc.

Hopefully that will get you started calling in to your web service; if not feel free to stop back and get more assistance.

EDIT: Missed the part about async calls.

Yes, the method described on that web page is synchronous. WCF service methods are synchronous by default, with the option to include asynchronous calls when generating a service reference in Visual Studio. wsimport generates async-ready proxies, so using the Android client generate may also help you out in this area.

Upvotes: 4

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