I am design the architecture of my android app now. At this stage, I am considering the interface between my app and the server. I am thinking to use the XML SOAP protocol. This is because the XML is very heavy weighted. There are Extra text in xml , such as "". So, I choose to JSON. Because that used less text. Moreover, I think JSON is good to de-serialize in Java. But GlasshFish does not come with JSON webservice by default. I have to use some extra package. I need to learn in Java!