Creating Web Service for Android Application

Use SQL Server to manage the data on your desktop and create a web-service in .NET on Visual Studio.

Then connect to the web-service in your application and set/get data from the DB, using web-services. You can use either XML or JSON to transfer your data between the phone and the server.

There is no need for the use of Java Socket API for this.

Links which might be useful :

How to make a web-service in .NET (does not include the implementation in Android) : http://srikanthtechnologies.com/blog/dotnet/wsdaljava.aspx

How to connect your service with Android :

http://seesharpgears.blogspot.in/2010/11/basic-ksoap-android-tutorial.html

http://www.codeproject.com/Articles/304302/Calling-Asp-Net-Webservice-ASMX-From-an-Android-Ap

http://adrianandroid.blogspot.in/2012/05/access-c-net-web-service-in.html

Note: I have never worked on RESTful services. My work has always been on SOAP and hence it remains my preference.

Your final choice of how, exactly, to architect your app, is going to be based on all sorts of things that you haven't included in your questions: your experience, the experience of the other developers in the project, so on and so on.

I will say this, however. REST is deep in the heart of Android. If you decide to go with REST and, possibly, JSON instead of XML (there is, almost certainly, no reason to use byte arrays), you will find that Android's architecture supports you. SOAP and such and you are on your own.