1. Repository

A Repository is the first objects a developer comes in contact to. It handles only domain objects and provide task oriented interface to retrieve them by saying findByFoo(‘Bar’). Most of the time you are done.

2. Query

The next level is the Query object. It provides methods to create an abstract query (abstract in sense of abstracted from where the objects come from). It has no clue about the underlying structure of the storage. It even does not now if it is based on a relational model or a tree model (like the content repository of [FLOW3|FLOW3 is a next generation web application framework built for the upcoming TYPO3 v5]). It also invokes the DataMapper (see below). An extension developer uses the Query object to create his own findByFoo() methods for  his Repositories.

3. QueryObjectModel

Deeper and deeper we dig … In comparison to the Query object Query Object Model knows about the underlying concepts of relations and thus Joins and Orderings. An extension developer may use this class to specify more complex and “relational model” aware queries. That makes the creation of queries (esp. Joins) al little bit laborious. But it helps to keep abstraction.

4. StorageBackend

The Storage Backend translates the Query Object Model in syntactical correct statement (SQL). It also invokes the call to the database via a handler. An extension developer normally does not have to mak his hands dirty with SQL (which is in most cases the best way to improve performance and security).

5. DatabaseHandler

The Database Handler prepares queries, fetches the result set. It can be simply the [t3lib_db|A class in TYPO3 providing methods to access a database], or [PDO|PHP Data Objects], or your preferred solution.

6. DataMapper

And finally the Data Mapper. It maps the resulting rows on the Domain Object (it creates an empty object and fills it with the converted property values). It also resolves relations according to the loading strategy (eg. Lazy Loading Proxy).

Puh! Now we are done. Hope you enjoyed the journey.

F.A.Q

Q Are you nuts! Six different layers, dozens of objects, and bunch of new things to learn! I only wanted to say “SELECT * FROM Tx_MyExt_Foo WHERE …”!
A You are right: I am nuts (at least a litte bit ;-)). But now we are fully compatible to the (Query) API of FLOW3 and reached the best level to port Extensions forward. And I really like the Idea of having totally freedom of choice.

Q And what about performance?
A That’s indeed a very important point. We will do some extensive profiling sessions, implement Lazy Loading strategies, and strive for optimized Queries.

And please keep in mind: 90% of the work is based on the concepts and code of FLOW3. Credits goes to the FLOW3 team.

The past couple of months I had numerous discussions about the new version and how to migrate from TYPO3 v4 to v5. And I had to realize that there are several reservations and concerns about all the new things to learn. All of them have to be taken into account to keep the community healthy.

The people I have talked with had different backgrounds (different knowledge about TYPO3, different involvement in the community, etc.). Most of them asked one of the following questions:

1. When will TYPO3 v5 be available?
2. How to migrate content?
3. How to migrate code (extensions)?
4. How to migrate me?

Questions 1.-3. are already covered by an article of the v5 team. The most underestimated question is, how to cope with the mental transition of the developers. Many developers pointed out that they do not have enough time to dig into the new version. Maybe that is a question of how to weight the time spent on daily business and the time spent on (self) education. This prioritization has to be done not only by the developer himself but also by the company he is working for. Therefore, many of the developers decided to wait until FLOW3/TYPO3 v5 is released at a future point in time.

To enable the developers to get in touch with the paradigms of FLOW3 as soon as possible was my personal motivation to be involved in doing a back-port of the  FLOW3 [MVC|MVC stands for Model-View-Controller, a way to separate different concerns of an application] frame-work. The result is ExtBase, a new frame-work for extensions and a successor of [pi_Base|The standard Plugin Base Class of TYPO3 v4]. It will be shipped with TYPO3 v4.3. It is planned to be released in May, 2009.

Furthermore, I am very happy about the decision at the TYPO3 snowboard tour to back-port Fluid, too. Fluid is a very sophisticated new templating engine mainly developed by Sebastian Kurfürst.

ExtBase in companion with Fluid encourages the developer of TYPO3 v4 based extensions to code the FLOW3 style right now.  There is already an example extension called BlogExample available. At time of the release of v4.3 we also plan to give a good documentation at hand.

Although we implemented already 80% of the features there is quite a lot of work to do (e.g. implementing view helper classes, doing code reviews, and integration testing, writing documentation and tutorials). Do not hesitate to send me a message, if you want to lend us a helping hand.