The stations of the journey

Now that you have had a look at your journey destination and hopefully don’t feel disoriented when we stop at the several steps, you can start. Figure 3-3 gives you an overview of the stations on the journey, which you will get to know in more detail during the upcoming sections.

Figure 3-3: The several stations of the journey

When an extension like the blog example is called, the following happens behind the scenes:

TYPO3 digs into the page content and discovers the extension’s content elements (plugins) on the page. It does not call the extension directly, but hands over the control to the Extbase Dispatcher (1).

TYPO3 calls Extbase’s Bootstrap, which then uses a RequestBuilder to create an Extbase Request. Then Extbase tries to find a suitable RequestHandler which then uses a class called Dispatcher.

The Dispatcher handles all bundled information in the request object and hands it over to the extension. Depending on the action parameter of the url, it sends the request to the appropriate part of the extension. This is the so-called Controller (2) , which takes over the flow control and processes the request. The Dispatcher calls the __construct and the appropriate action method of the controller.

Within the controller, the appropriate storage facility which is in charge of the blogs — the repository — is instructed to return all the stored blog posts using the method findAll() (3).

The repository returns a collection of the already present Blog objects with all of their posts, comments and tags (4).

The Controller sends these blogs to the part of the extension responsible for the output generation — the View — and advises it to render the content in the requested output format (5).

The View returns the rendered content in HTML format back to the “Controller”. This returns the output result encapsulated in a Response object to the Dispatcher, which in turn returns it to the calling TYPO3 process (6).