Chapter 3. Hello World

Table of Contents

Application Engine
Application Servlet
Application Specification
Home Page Specification
Home Page Template
Run the Application

In this first example, we'll create a very simple "Hello World" kind of application. It won't have any real functionality but it'll demonstrate the simplest possible variation of a number of key aspects of the framework.

We'll define our application, define the lone page of our application, configure everything and launch it.

The code for this section of the tutorial is in the Java package tutorial.hello, i.e., C:\Tapestry-x.x.x\examples\Tutorial\src\tutorial\hello.

Application Engine

As each new client connects to the application, an instance of the application engine is created for them. The application engine is used to track that client's activity within the application.

The application engine is an instance, or subclass of, the Tapestry class SimpleEngine.

In these first few examples, we have no additional behavior to add to the provided base class, so we simply use SimpleEngine directly.