FEAST was designed with a classical 3-tier architecture, using flexible communication between the layers. This makes it possible to exchange the communication protocol and thus connect nearly every application to the system.
Interoperability between different software systems from different manufacturers is a frequent requirement in heterogeneous enterprise environments.
The communication between the application and dialog layer of FEAST is therefore accomplished using Web Services standards. This includes HTTP for transport, XML and SOAP for message encoding and WSDL for interface description. Thus a FEAST service is accessible by every client that can communicate using these protocols. By inserting a proper server for scripting in the middle also a four layer thin client architecture using PHP, Javascript or ASP.NET can be implemented.
Relying on Web Services standards and supplemented by an UDDI service, FEAST can be used as a base for building applications according to the concepts of a service oriented architecture (SOA).
The Business Content Adaptor (BCA) makes up the core of the application layer. To manage the communication between the layers is only one of its tasks. The BCA also hosts the modules containing the business logic of the application. Each module operates independently of each other, thus processing the user input and updating the application data. Modules can be deployed and updated at runtime, thus maximum availability is achieved.
The data layer contains the persistent application data. The most common type of data source used here is a SQL-based relational database management system (DBMS). However, FEAST is not limited to SQL data sources. Using a sophisticated data source abstraction layer every kind of data source can be made accessible by the application programmer, e.g. SAP/R3, LDAP, local files or other processes. A common interface is used for all data sources with individually configurable commands. This way it is very easy to exchange a data source regardless of its type with a minimum coding effort or even without changing any source code at all.
Taking it all together FEAST is a good companion for keeping up with todays manifold and frequently changing system environments.