Joomla architecture - what happened behind the scenes. Did you always wanted to know what happened behind the scenes of Joomla code? Come and find what triggered down to up with real life scenarios, like MVC architecture, Plugin design pattern, how getDBO bring me the database instance and much more.

1. Joomla Architecture
Revealed!
Ofer Cohen
@oc666
ofer.cohen@opensourcematters.org

2. About me, Joomla and Arch
● Open source volunteer since 2005.
● Joomla volunteer since 2007.
● CMS & Framework code contributor
● JBS team member
● GSoC mentor of Joomla
● Extensions Developer (TP2 at JomLand)

3. nie wystarczy?
● Joomla Hebrew translation coordinator
● Joomla Israeli community leader
● Joomla!Day Israel organiser
● OSM board member
● Daily job: R&D manager in the Start-Up
nation.

4. Joomla!
● 3.2% of all websites, worldwide
● Object Oriented since 1.5
● Components based on MVC design pattern
● What else?

5. Architecture?
● Architecture
the process and product of planning,
designing and construction...
● Software architecture
description of the system that support in the
understanding of how the system will behave
● Website architecture
approach to the design and planning of
websites...

6. Revealed?
● Who cares? It Just Works! (TM)

7. Revealed!
● Why is my Joomla! site slow? hacked?..
● Want to build a complicated website?
● What are the abilities of Joomla?
● What can't I do with Joomla?
● I just love to research and learn!

8. Object Oriented
● Data structures consisting of data fields and
methods together with their interactions
● Programming techniques include features such
as data abstraction, encapsulation, messaging,
modularity, polymorphism, and inheritance.
● This approach make your program more easy to
build and implement tricks.

9. Tricks?
The tricks are design patterns - reusable
solutions to commonly occurring problems
within a given context in software design.
(wikipedia)

10. Step back.... J! index.php
1. constants and defines declared
2. configuration loaded
3. application init triggered (lang, editor)
4. routing parsed the request (url, arguments)
5. dispatch the component
6. render the template
7. echo the response output

11. Looks simple, but what's inside?
1. Component is first dispatched and then
buffered.
2. Template render with their modules and
then set output into response (object).
3. Events trigger between each step.

12. Template Walk...
--> How is a template rendered?
1. The index.php of the template is rendered.
2. Parsing jdoc statements.
3. Each jdoc statement rendered separately,
iteratively, according to its type.
4. Component & head are parts of the
iteration, but have different rendering.

13. VMC... MCV... WTF? Prefer BMW?
● MVC - Model-View-Controller
Divide the software into 3 layers:
○ M=>Logic
○ V=>User interface
○ C=>Request handler

14. MVC - advantages
● Easier to extend.
● Less spaghetti code.
● Great approach on upgrades and new features.
● Easier collaboration between multiple
developers.

15. ● Events handling
● Simple dispatcher can be called
● It fires events to Joomla plugins on basic
triggers.
● For example, after content creation, before
user delete, etc.
Plugin=Observer

16. ● Supplier of the main entities of Joomla:
○ Session
○ User
○ Cache
○ Database
○ and more...
● Each entity is singleton
Factory

17. ● Only one instance of an object is kept.
● Saves system memory usage & cpu
Singleton

18. Adapter
● Adapter translates one interface for a
class into a compatible interface.
● For example DB adapter for DB such as
MySQL, MSSQL, Postgresql.
● Another example would be Renderer
object for rendering output of module,
component, header, etc.

19. ● Decouple an abstraction from its
implementation.
● Useful for implementation encapsulation.
● Especially when the program decides how
to implement on run time.
Bridge

20. ● J!Database instance built by its
instantiator method input.
● The method will return its nested
inheritance object
● The object type would be unknown, only
the methods we can call would be known.
Bridge - example

21. abstract class JDatabase {
public static function getInstance($options) {
$class = 'JDatabase' . ucfirst($options['driver']);
$instance = new $class($options);
self::$instances[$signature] = $instance;
return self::$instances[$signature];
}
}
Bridge - code example from J!DB

22. ● HMVC - reuse of each part of the MVC
pattern.
● Traits - the long tail story
● UCM - want to select from articles content
and virtuemart products at the same
query. ORM-Like methods (NOSQL).
Future

23. ● The only complicated thing is the problem.
● The solution must be simple.
● If you have a complicated solution, you
probably chose the wrong solution (KISS)
Conclusion

24. Ofer Cohen
Open Source Matters
ofer.cohen@opensourcematters.org
@oc666
Thank you

25. Coupon: jdpl13
Discount: 50%
TP2 - drag & drop your modules