Chapter 2: Developing an EAServer Application  Developing an EAServer application

Chapter 2: Developing an EAServer Application

Introductory concepts

An EAServer application consists of one or more packages and a client application or applet. Packages consist of components, and components are made up of one or more methods.

You can develop and distribute an EAServer application across the network. EAServer implements a three-tier or multitier distributed computing architecture. In this model, three distinct elements work together to give users access to data:

Java applets are downloaded to clients, which instantiate components on the server. Client applications are installed on client machines, from which they also instantiate components on the server.

An applet, standalone application, or Web application manages presentation and interaction with an end user. Middle-tier components, which run in EAServer, handle much of the application processing. Finally, the database stores, manages, and processes data.

If the client is an applet, users find and launch applications from traditional HTML pages. Instead of simply loading a static page, EAServer downloads an executable applet to the individual’s browser. If the client is an already-installed application, the user launches the application from his or her machine. Clients communicate directly with an application component running in the middle tier. Server components access data from one or more databases, apply business logic, and return results to the client applet for display.

When a proxy object is created on the client applet, it instantiates a corresponding component registered with EAServer. On the server side, a component is instantiated in response to a request from the proxy object running in the client environment. A method on a component is executed when it is invoked by a proxy object on the client applet.

Web applications can call EAServer components using the same proxies as used by standalone Java clients and applet clients.

Copyright © 2005. Sybase Inc. All rights reserved. Developing an EAServer application