使用stax和dom读取一个大的XML文件

I need to read several big (200Mb-500Mb) XML files, so I want to use StaX. My system has two modules - one to read the file ( with StaX ); another module ( 'parser' module ) suppose to get a single entry of that XML and parse it using DOM. My XML files don't have a certain structure - so I cannot use JaxB. How can I pass the 'parser' module a specific entry that I want it to parse? For example:I need to read several big (200Mb-500Mb) XML fi