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 are able to 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 content element of the extension (plugin) on the page. It does not call the extension directly, but hands over the control to the Extbase Dispatcher (1).

The Dispatcher bundles all information of the request in a Request and sends it to the appropriate part of the extension, which takes over the flow control — the so called Controller (2).

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 — the View — and advises it to render the content in the requested output format (5).

The View returns the rendered content encapsulated in a Response back to the Dispatcher, which in turn returns the HTML code to the calling TYPO3 process (6).