I\'ve started my degree project, a mobile application suitable for iPhone, Android and (in the near future) Symbian. The server architecture is the following:
SOAP with Fast Infoset is suited for small devices:
JAX-WS 2.0 and its reference implementation support both Fast Infoset and MTOM/XOP. This article includes information about Web Service Performance for Fast Infoset vs. MTOM/XOP:
http://www.devx.com/xml/Article/35385/1954
Fast Infoset is optimized for small devices that have bandwidth constraints, and is supported by many vendors such as Microsoft .NET and .NET CF, Sun GlassFish, BEA WebLogic, IBM SDK for Java 6.0 and others.
http://en.wikipedia.org/wiki/Fast_Infoset