The Progress Application Server (PAS) uses several layers of container elements to direct requests from clients to Web applications and then return the responses. The containers are configured in the server.xml file.
Context: A context represents a web application and contains the path for that web application. One or more contexts are contained in a host.
Host: A host element represents a virtual host and contains one or more contexts. The host associates a network name with the server. One or more hosts are contained in an engine.
Engine: An engine handles the requests received from one or more connectors and returns the responses from the Web applications.
Service: A service contains one or more connectors linked to a single engine. Connectors facilitate communication between an engine and web server. Connectors can use HTTP and HTTPS protocols, and they can also use Apache JServ 1.3 Protocol (AJP13), which supports load balancing.
Server: A server represents a single PAS instance and contains one or more services.
The following figure shows how the containers and connectors relate to one another.
Context: A context represents a web application and contains the path for that web application. One or more contexts are contained in a host.
