Users can therefore choose a back-end operating system and a database engine for the whole system with little or no programming. In addition users may modify existing or create new connectors through standard APIs. A failure in one request thread does not cause performance degradation or crash. In addition, the System layer also retrieves simple files and directories like major web servers do, except it uses XML and therefore information is structured natively. Each component typically uses one or more connectors and other components to perform business logic and transactions.
Business logic can extend beyond simple retrieving and saving data.
The logic can be simple or complex. Tag mapping during retrieval or field validation during saving is an example of a simple application. Users can build complex applications using the Java language and an object oriented approach. The Application layer component beans may also contain wrappers for proprietary databases, applications and systems. These prevent rewriting application code from scratch and allow seamless XML-enabled legacy systems.