5 minute guide to ActiveWeb

At the heart of an ActiveWeb application is a controller. A controller is a component whose role is to accept and process an HTTP request. This is similar to a Servlet, or a controller class other web frameworks.

ActiveWeb is a convention-based framework. It requires no configuration by default.

Here is an example of the simplest controller:

public class GreetingController extends AppController{
   public void index(){}
}

URL mapping convention

Controllers are automatically mapped to a URL, such that a controller name underscored or hyphened is converted to CamelCase controller class name (without the word Controller). Here is an example:

http://localhost:8080/testapp/greeting

When this URL is accessed, the GreetingController is executed. Since no further information is provided on the URL, the index() method will be processed.

Controller methods processed as a result of an HTTP request are called actions.

For more information, please see Routing

Action mapping convention

If the URL contained more information, let's say:

http://localhost:8080/testapp/greeting/hello

then the system would expect that the controller would have a hello action, as in:

public class GreetingController extends AppController{
   public void hello(){}
}

However in the previous example if the action is omitted, it causes the framework to fall back on a default action index.

View mapping convention

In this case, since the action index does not have any code, the framework will pass control to a view. This view will be looked for under:

/WEB-INF/views/greeting/index.ftl

Where /WEB-INF/views/ is a base location for all views, directory greeting is named after controller, and a view template index.ftl is called to render because action index of the controller was executed. The content of the index.ftl will be displayed in browser wrapped in a default layout.

Example passing data to view

In the graphic below, you see how ActiveWeb routes the request to GreetingController and action hello. The complete sequence of operations:

1. A URL http://localhost:8080/simple-example/greeting/hello?name=Bob is entered into the browser.
2. ActiveWeb upon receiving the request, routes it to the controller GreetingController, action "hello. The controller passes some data to view - date as internally generated data, as well as name - HTTP request parameter, accessed with param("name") method
3. The Framework then passes the data to a view template WEB-INF/views/greeting/hello.ftl for rendering

The code you see on above is all that there is. There are no XML files, no property or any other configuration files.