Design Patterns
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During the development of pLog, we've put special attention in its design. 
As a result, several design patterns are used in many places thoughout
the code of the application. This file is a simple catalog of which 
patterns are used, where and a reference (if available) to some information
about them.

The Patterns
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* 1. MVC
The Model-View-Controller is used to separate content/presentation layer
from the application layer. The base classes Controller, Action and
View represent each one of the layers in an MVC application.

http://www.phppatterns.com/index.php/article/articleview/11/1/1/
http://java.sun.com/blueprints/patterns/MVC-detailed.html (Java)

* 2. Front Controller
The Front Controller pattern is the class through which all the incoming
requests are handled. It takes care of mapping user parameters to Action
classes. The Controller class implements a Front Controller patttern.

http://www.phppatterns.com/index.php/article/articleview/81/1/1/
http://java.sun.com/blueprints/corej2eepatterns/Patterns/FrontController.html

* 3. Strategy
The Strategy pattern allows us to encapsulate an algorithm in its own class,
making it easier to change the algorithm in the future since client classes
are only dependant on the interface and not on the implementation.

The Strategy pattern is used in the Validator classes, where every class that
implements the Validator superclass offers mechanisms to validate each type of
data. In this way, if we add an additional requirement in the future for one
of our types of data, simply modifying the correct Validator will
automatically provide all the client classes with the new feature.

http://www.vico.org/pages/PatronsDisseny/Pattern Strategy/

* 4. DAO (Data Access Object)
This pattern is also refered as Data Mapper in the book
"Patterns of Enterprise Application Architecture" by Martin Fowler. Such
pattern moves data between objects while keeping them independent of each
other and the mapper itself. In other words, it separates the domain of our
data from the data source. 

The DAO pattern is implemented by many of the classes in the classes/dao/
folder.

http://www.phppatterns.com/index.php/article/articleview/25/1/1/

* 5. Singleton
The Singleton pattern ensures that a class has only one instance, providing a
global access point to it.

The Singleton pattern is used in the Config and DB classes. It helps there to
make sure that there is only one instance of the class, providing also caching
mechanisms.

http://www.vico.org/pages/PatronsDisseny/Pattern Singleton/

* 6. Pipeline
The Pipeline pattern is used in the security framework that is going to be
implemented in pLog 0.3. Allows complex tasks to be broken up in smaller
sub-tasks that can be carried independently.

Have a look at the class/security folder.

http://www.cise.ufl.edu/research/ParallelPatterns/PatternLanguage/AlgorithmStructure/Pipeline.htm