Chapter 2 Developing an EAServer Application

EAServer runtime environment

A typical EAServer application has an applet or HTML page associated with it. Once you build and deploy such an application, it runs in the following fashion:

EAServer receives an HTTP request and downloads the requested HTML page or applet. Included with the applet are the Java stubs, which through a proxy, instantiate components and invoke the methods on those components.
The client establishes a session with EAServer. The session, unlike an HTTP connection, allows the client and EAServer to maintain a connection throughout the transaction.
The client creates a component instance through a client-side proxy. The proxy used depends on the type of component being instantiated. EAServer validates the user against the component's access list. If the user is validated, the dispatcher checks the location and status of the component and creates an instance.
The client invokes the component's business logic by executing its methods.
The component may interact with remote databases. If it does:
- The component obtains a connection to the database using EAServer's connection caching feature.
- EAServer checks the component's transaction property. If the component is marked as transactional, EAServer ensures that remote database commands execute as part of a larger transaction.
EAServer returns the results from the database to the client.
The client indicates that it has completed the operation. EAServer destroys the component instance or returns it to a pool for future client instantiations. The client disconnects from EAServer.