Application Link Enabling (ALE) is a set of business processes and tools that allow applications on different computer systems to be linked. This can be done between different SAP systems as well as between SAP and non-SAP systems.In a single SAP system different applications are integrated via a single database (e.g. finance, sales, production, human resources). However, many companies do not have just one integrated system but a distributed environment with different applications running on different systems. To run the whole business in such an environment the distributed applications have to be linked. This can be done through Application Link Enabling (ALE). ALE provides distributed business processes that can be used to link the applications on different platforms. There are some ALE business processes delivered in the standard SAP system. Furthermore, there are tools that can be used to change the existing ALE business processes or to implement new distributed business processes.Besides the business processes there are special ALE services that are required to set up and control a distributed environment. These services include a distribution model, business object synchronization and tools for monitoring or error handling. ALE is a major part of SAP's Business Framework Architecture. Besides the basis middleware, that provides the communication between components, and the interfaces (BAPIs), ALE business processes and ALE services enable the cooperation of the single components within the framework. That makes ALE the glue of the Business Framework.