U.S. Tech Blog ...

Lot of Application servers or containers deploy different mechanisms for runtime loading of classes and libraries...Understanding these mechanics is really important for resolving conflicts in Enterprise Applications and Runtime environments (ie:-J2EE envs , OSGi containers running on top of App servers ,etc)...Most of the modern Application containers deploy a method called "Bootstrapping" to isolate container specific and application specific runtime dependencies..What "Bootstrapping" effectively does is provide an "unpolluted" classpath for application modules so that they can work independently from container classpath , avoiding any conflicts which other wise would have occurred..(conflicts in the sense unresolved Classes, Class Cast exceptions ,unexpected initialization of code ie:- static initializers , etc )...This means that with "Bootsrapping" an application module can run a different version of a dependent library/class from a version that container depends on without affecting each other...To understand "Bootsrapping" one needs to have a good overall view on java class loading mechanisms..I came across the following article that nicely explains these concepts with several practical runtime deployment perspectives.. http://www.theserverside.com/news/1364680/Understanding-J2EE-Application-Server-ClassLoading-Architectures .. hope this would be useful for those who are interested.....