Calling the extension

When a user opens the web page containing our blog in their browser, this request (Request) will be forwarded to the remote TYPO3 Server. Then TYPO3 starts the processing of this request straight away.

A request generally contains the identification number of the page (the so called Page-ID or PID) that should be generated (e. g. id=99). Using this PID, TYPO3 searches all relevant content elements on the specific page and converts these to HTML code one after another. While processing this page request, TYPO3 comes by the content element for our example extension, the so called plugin. This plugin should display a list of all blogs. Each with the individual title, a short description and the amount of all enclosed posts. In figure 3-4 you can see the output of the plugin in the frontend. This output is embedded within the greater overview of the page.

Figure 3-4: Output of the plugin of our example extension

The process of eradication is first forwarded to the dispatcher of Extbase by TYPO3. The dispatcher completes several preliminary tasks before it hands the further processing on to the according position within the code of our blog example:

• It interprets the incoming request and bundles all relevant information into a Request object.
• It prepares the Response object as a container for the result of the request.
• It loads the configuration of our extension from the different sources and makes it available.
• It determines whether or not the request was manipulated in an illegal manner and when this is the case deflects it (e.g. in of case maliciously added form input field).
• It sets up the persistence layer which performs the persisting of new or changed objects.
• It prepares the cache in which the content is stored for faster reuse.
• It instantiates and configures the controller of our extension which controls further processing within the extension.

When these preparations are fulfilled by the Extbase dispatcher, we are able to travel to the first stop of our destination: the controller. In our example all further processing is assigned to the :php:`BlogController`. A reference to the request and the response is handed over.

The class :php:`BlogController` can be found in the file EXT:blog_example/Classes/Controller/BlogController.php. The complete name of the controller is :php:`\MyVendor\BlogExample\Controller\BlogController`. At first this might seem long-winded but the syntax follows a very strict convention (please see box “Be careful, conventions!”).

Tip

Be careful, conventions!

The name of a class is separated into individual parts, which themselves are divided by an underscore. All parts of a class name are spelled with capital camel case, where each initial letter is capitalized. This style for notation is commonly known as UpperCamelCase because each capital letter suggests the hump of a camel. For extensions the first part always is “:php:`Tx`”. The second part is the name of the extension - in the underlying case “:php:`BlogExample`”. The last part is the name of the domain object. The center between those parts builds the path to the class file below the folder Classes. In our case the file is stored directly within the folder Controller. The name of the class file is taken from the last part of the class name appended with the suffix .php.