3.1.2 Backend Server Scalability The scalability issues related to the potentially huge number of different BES, such as relational, object-relational, or XML-based database management systems, are critical to our application middleware. The point to note here is that the application server provides the right place to encapsulate different kinds of BES and to give them an uniformly accessible and manageable interface. Thus, our middleware solves the application-related scalability issues at a higher level of abstraction: Each BES is encapsulated within general application objects which hide the different kinds of BES and their implementations respectively. For each application object, a pool can be configured which is managed by the general application server. A pool basically synchronizes the access to and manages the pooling of application objects, i.e. connection pooling for fast and efficient handling of database connections. Various configuration policies can be applied even at run-time to each pool of application objects in an uniform manner since the architecture strictly separates between the management of application objects and their implementations, as discussed in [14]. Our naming scheme enables a scalable approach to reuse existing application objects in different application contexts by providing different symbolic names to the application objects. In general, solving scalability issues at a higher level of abstraction leads to an exhaustive reuse of the provided middleware services and speeds up the overall integration process tremendously.