The IDE enables you to create Java web applications that run on multiple platforms. Most web applications have three tiers.
- Tier 1 is the client. The client is a user running a web browser displaying
HTML pages on a local intranet or the Internet.
- Tier 2 is the web server. The web server runs the web application. The web
server and web application communicate with the client using standard
HTTP protocols. The web server for a Java web application is a
Java 2 Platform, Enterprise Edition web servlet container such as the Sun JavaTM System Application Server Platform Edition 8.2.
- Tier 3 is the database server or web service. The database server or web service
contains information the web application needs to access and, perhaps, change.
The following diagram shows this simple, high-level view:
Inside the Web Server
Java web applications are typically composed of two main parts that run inside the web servlet container on a web server:
- Java ServletTM. The servlet
extends the HTTP servlet class and processes the business logic.
The servlet processes user requests, interacts with
databases, and sends responses back to the user.
The servlet interacts with JavaServer Pages (JSP) technology to interpret requests coming from the user and to send web pages back to the user. The IDE generates much of the servlet code for you and makes it easy for you to customize this Java class with your business logic.
The servlet can make use of Java frameworks like JavaServer Faces technology to simplify the coding of user interface components and handle more of the details of maintaining sessions with the client. The IDE provides a full set of JavaServer Faces components and visual tools for adding them to pages.
In addition, the servlet can call web services to perform a task, such as requesting a stock quote from a quote server on the Internet. The IDE sets up the required stubs and classes for you to easily identify and call the methods of web services that you want to use.
- JSP pages. JavaServer Pages technology dynamically builds the HTML
pages sent to the user. JSP pages separate the presentation
part of the web application from the Java code that implements the business
logic of the application.
The IDE provides a graphical designer for creating JSP pages visually by dragging and editing components onto the Visual Designer. You can also edit the JSP code itself, and you can switch back and forth to create your JSP pages.
The following diagram shows how these elements of a Java web application interact.
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