Scalable solutions are all about architecture. You need to do the ground work right in order to get it right. It's simply naive to expect being able to realize architectural requirements at the design or coding level.
At Dijkstra ICT Consulting software architecture is core business. Our LDX+ for Java is built on a common foundation framework designed with high performance, scalability, and flexibility in mind.
LDX+ 2.0 XML Generator/Foundation Framework for Java