The AppServer is the core of OpenEdge® support for application services in an n-tier environment, and provides an overview of its central concepts. It is the mechanism that allows you to distribute an OpenEdge application across multiple machines in a network and to provide OpenEdge application services to both ABL (Advanced Business Language) and non-ABL clients (Open Clients and Web service clients). It does this by supporting separate sessions that communicate by having one session (the client session) establish a connection (or binding) with an AppServer. The connected AppServer then provides a separate session to execute ABL procedures and to return any results to the client. The AppServer supports connections for several different operating modes, each of which provides a different mix of resource consumption and performance characteristics.
This chapter describes the basic concepts and architecture required to begin developing AppServer application services and their clients, and where to go for more information.
