Client support
Progress Dynamics supports 4GL clients, including the standard Progress run-time client and Progress WebClient™. With the WebClient, users can download a fully functional, no-cost Progress client executable over the Internet. They can run the client part of your application from anywhere in the world without the need to distribute or maintain Progress run-time installations or the application itself. Progress Dynamics also supports native Web browser-based access to the same abstract application definition.
This support allows part or all of an application to be rendered in a browser without any Progress run-time client. The application still accesses the same back-end business logic on server machines connected to the database. Most of the client part of the application is data, not procedural code. As a result, other client platforms (such as handheld display devices or platforms not yet anticipated) might be driven from the same data definition, without change to the business logic or basic application definition.
Progress Dynamics runs in a distributed environment, with the visual portion of the application running in either a 4GL client session or some other client type, without a local database connection. Business logic runs on one or more AppServer™ sessions where the Repository database and the application database are located, maximizing the efficiency of database access. Access to the AppServer is always stateless, so that a small pool of AppServer sessions can support a large number of clients.
To support this stateless AppServer access, Progress Dynamics uses manager procedures to handle various aspects of the application and its environment. Each of these procedures runs as both a client-side manager and a server-side manager. The server-side manager maintains one or more Repository database tables on the server and provides data to client sessions as needed. Data is cached on the client for maximum efficiency and, when necessary, returned to the Repository database on the server. This provides persistent storage for all data relating to the running of the application.
Figure 1–1 illustrates this architecture.
