Options for Client Server Communication in Android

Question

I'm currently in the research phase of my dissertation project.

My project is a ticket booking system for a mobile device and I have chosen to target Android.

I anticipate the need for a client/server architecture with a central server, and so am currently looking at how Android could communicate with such a server. The server would grant the client access to ticketing information, and the client would send information about ticket bookings to the server. I'm looking at Java EE for the server as Java is the language I'm most experienced with.

I'm aware that Android comes with java.nio and java.net, as well as some org.apache packages, but am also looking for libraries/technologies that would be possible to use with Android.

So far I've not found anything massively helpful on the internet, so I'm seeing what SO can suggest.

Specifically I am interested in knowing:

1. What support is there for various middleware technologies in Android? e.g.
   • RPC based middleware
   • CORBA
   • Message based middleware
   • Web services such as XML-RPC, SOAP, REST
2. How well (or not) do existing Java libraries work when used on the Android platform? (e.g. If I wanted to use a library/API designed for Java SE rather than Android what problems might I encounter?)

Ideally, as the focus of my project isn't meant to be the communication between the server and client, I could use an existing middleware to handle the communication, but I am prepared for the worst case, which is having to write my own.

Answer 1

What support is there for various middleware technologies in Android?

My personal opinion -- though I do not feel I am alone in thinking this way -- is that only protocols specifically designed to run over the Internet are remotely suitable for use with a mobile client. So, of your list, the only one that I would even entertain would be:

Web services such as XML-RPC, SOAP, REST

Some people have been maintaining an Android port of kSOAP2. However, I get the distinct impression that most Android developers working in this area have tended towards REST and REST-ish protocols. If nothing else, that's what all the fun Web sites and services are using for an API, particularly compared with XML-RPC (old) and SOAP (old and icky).

I have successfully used both the java.net.URLConnection and Apache HTTPClient libraries in Android for communicating with REST-style endpoints -- both directly and through third-party JARs -- with no real Android-specific issues.

How well (or not) do existing Java libraries work when used on the Android platform?

It is difficult to answer that in the abstract. Android implements a substantial subset of JavaSE, but not all of JavaSE, so there's a chance that any given JAR will expect something Android does not offer. Similarly, Android does not use environment variables, command-line switches, or a variety of other things that developers focused on the desktop might have introduced as semi-requirements. So, some things have worked for me with nothing more than a recompile (Beanshell), and some things have worked for me after removing redundant classs (JTwitter), and some things looked like they were going to be ghastly to get working (JavaMail).