QuoteOriginally posted by: traderjoe1976I have seen ONE of these implementations in Java.Everything must be in core Java.No frameworks like Spring, Hibernate, Struts are used.They implement Lists, Maps, Sets collection objects using Arrays.Heavy use multi-threading.Heavy use of web services, SOAP, WSDL, UDDI.It looks quite different from a normal Java application, but is ideal for someone who is very strong in Core Java.Any idea why they used WebServices instead of custom building that layer. If they bothered to build even Lists from Arrays and avoided frameworks I suppose they were after performance. How did Web Services fit in then? There is lot of heavy weight junk in there unless you wanted to communicate across diverse environments like .NEt and Java. A thin network layer based on TCP/IP or Servlets( for web fetishist) is what I generally use.