Introduction to Frameworks

Objective

I want to be a software engineer

My first application

• I don’t know any language

• Well let’s choose a language for application programming and start learning.

… after 2 month

• I have learned programming .. I am good at it and I can build any thing ….

My first application

• As I can build anything I want to build a chess… I am a very good chess player.

• I know all the rules and I know how to program ... What else do I need…

Week 1

Week 2

Week 3

My first application

• After three weeks 600 lines of code.

• Ok it’s easy.

• After a month it’s 3500 lines of code in one file. Certainly I find scroll bar is very useful.

My first application

• But when a bug occurs … lets debug it.

• Now it seems building application is not as fun as it ought to be.

• Now after learning a good lesson … well try something different.

My first application

• Writing in one file creating problems .. :-?

3686

My first application

Ok I will write small codes in different files…

My first application

OMG now I have 100 files and to change some thing I have to change 10 files … it is worst than I imagined.

My first application

I think I have found the problem .. Thisapplication may be very big and I alone can’tcomplete it. Let’s ask a friend.

My first application

• Arrrrghhhh….

• Well we code differently so many misunderstanding… it complicates things more

My first application

• Let’s stop trying and toiling

• Think, how people writes a code which has millions of lines and thousands of developers

• How ?????

• …

My first application

• Let’s see what can be done…

• There is something wrong . What is the problem ?

Solutions

• Separability

• Independence

• Readablity

My first application

• Ok I successfully build a chess game

• Now I want to build checker or other board games.

My Next Applications

• I am so lazy, but I have to handle some things again that I have handled in chess game before. Like,

– Point Table

– Player Switching

– Board status

– Pieces

– Save, load, undo, redo etc….

DRY

• If I implement them again it will be wastage of time.

• Don't Repeat Yourself (DRY)

• Reduce repetition of code of all kinds

DRY

• I want to reuse code that I used before in chess game

DRY

• The functions need to customize as it was written in chess game i have to change it so that it also work for checker.

DRY

• Some times this changes are different because there are so many options and varieties of board games

DRY

• If I write those functionalities in a sort of generalized way such that it can be used in all board games.

• Then I can develop this games very fast without repeating myself.

DRY

• Now I can separate the similar codes that I can reuse for these board games.

• If I need to build checker then I need similar structure as chess game.

DRY

• If there is a structure that has similar features for these games then I do not need to start from the beginning.

• I can straight jump into game logic.

logic

Frameworks

• The structure that I built to use for all board games can be called framework.

• A reusable set of libraries or classes for a software system.

• Used to implement the standard structure of an application.

Few Frameworks

• For web application– Symfony

– Zend

– CodeIgniter

– CakePHP

– .NET

– Django

• For desktop application– Qt C++

– WxWidget

• Here is an idea. I am a human why should I repeat another humans work.

• I haven't coded yet but I need not to because some one has already coded it for others to reuse.

• There is no point to reinvent the wheel

MVC

Model

• "Represent knowledge"

• The data/business functionality

View

• Visual representation of the model

• The screens and widgets of app

• Gets data from model & updates model

Controller

• Link between user and system

• Responsible for intercepting user input

• Passes user input to view via messages

Questions?