1. MVC pattern and implementation in java

2. Agenda Context Problem Solution What is MVC? MVC Architecture
Common MVC Implementation
MVC Interaction Order
MVC Pattern
MVC Responsibilities
Advantages of MVC
Implementation of MVC

3. CONTEXT Interactive applications with a flexible
human-computer interface

4. PROBLEM DEFINITION
User interfaces are especially prone to change requests.
Different user place conflicting requirements on the user interface.
Building a system with the required flexibility is expensive and error-prone if the user interface is tightly interwoven with the functional core.

5. PROBLEM DEFINITION The following forces influence the solution
The same information is presented differently in different windows, for example, in a bar or pie chart.
The display and behavior of the application must reflect data manipulations immediately.
Changes to the user interface should be easy, and even possible at run-time.
Support different ‘look and feel’ standards or porting the user interface should not affect code in the core of the application.

6. SOLUTION
MVC – Model View Controller

7. What is MVC?
MVC - Model-View-Controller - is a design pattern for the architecture of web applications.
It is a widely adopted pattern, across many languages and implementation frameworks, whose purpose is to achieve a clean separation between three components of most any web application.

8. MVC Architecture
The Model represents the structure of the data in the application, as well as application-specific operations on those data.
The View renders the contents of a model. It specifies exactly how the model data should be presented.
The Controller translates user actions (mouse motions, keystrokes, words spoken, etc.) and user input into application function calls on the model, and selects the appropriate View based on user preferences and Model state.

9. Cond…
The MVC architecture divides an application (code) required to manage a user interface into three parts:
Data components maintain the raw application data and application logic for the interface –model.
Presentation components provide the visual representation(s) of the data --view (usually to the screen).
Input-processing components handle input from the user by modifying the model--controller.

10. Common MVC Implementation

11. MVC Actions Model -- Notify view about data updates View
--Change rendering as needed
Controller
--Select view to be rendered based on event notifications and method invocations

12. MVC Interaction Order User performs action, controller is notified.
Controller may request changes to model.
Controller may tell view to update.
Model may notify view if it has been modified.
View may need to query model for current data.
View updates display for user. 6
View 4
Model 5 3 1
Controller 2

13. MVC Pattern – Model Contains application & its data
Provide methods to access & update data
Interface defines allowed interactions
Fixed interface enable both model & GUIs to be easily pulled out and replaced
Examples:-
Text documents
Spreadsheets
Web browser
Video games

14. MVC Pattern – View Provides visual representation of model.
Multiple views can display model at same time.
When model is updated, all its views are informed & given chance to update themselves.

15. MVC Pattern – Controller
Users interact with the controller
Interprets mouse movement, keystrokes, etc.
Communicates those activities to the model
Interaction with model indirectly causes view(s) to update

16. model responsibilities
store data in properties
implement application methods (e.g., ClockModel.setTime() or ClockModel.stop())
provide methods to register/unregister views
notify views of state changes

17. view responsibilities
create interface
update interface when model changes
forward input to controller
controller responsibilities
translate user input into changes in the model
if change is purely cosmetic, update view

18. Advantages of MVC
Separating Model from View (that is, separating data representation from presentation).
More robust
Easier to maintain
permits run-time selection of appropriate Views based on workflow, user preferences, or Model state.
Separating Controller from Model (application behavior from data representation)
allows configurable mapping of user actions on the Controller to application functions on the Model.

19. Easy to add multiple data presentations for the same data.
Multi-view applications (overview+detail, brushing,…)
Different users
Different UI platforms (mobile, client-side, server-side,…)
Alternate designs
GUI
Model
GUI
Model
GUI

20. Cond…
Facilitates adding new types of data presentation as technology develops.
Model and View components can vary independently enhancing maintainability ,extensibility, and testability.
allows user interfaces (views) to be easily added, removed, or changed
allows response to user input (controller) to be easily changed

21. COND… changes can happen dynamically at runtime
promotes code reuse (e.g., one view might be used with different models)
allows multiple developers to simultaneously update the interface, logic, or input of an application without affecting other source code.

22. Implementation of MVC

23. THANK YOU…..