As long as businesses only have one enterprise application or back-end application system, there is no need to share data with any other system in the company. All data that has to be managed is contained within one back-end application system. However, as businesses grow, more back-end application systems find their way into their information technology infrastructure, managing different business data. These back-end application systems are not independent of each other; in general they contain similar business data or are part of the same business processes. This requires their integration for exchanging data between them. The technology that allows this is called enterprise application integration (EAI) technology. EAI technology is able to connect to back-end application systems in order to retrieve and to insert data. Once connected, EAI technology supports the definition of how extracted data is propagated to back-end application systems, solving the integration problem.