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June 2015
From RAD to MVC
Arnaud Bouchez
June 2015
From RAD to MVC
RAD
MVC
MVVM
n-Tier / SOA
From RAD to MVC
June 2015
Rapid Application Development
Our beloved Delphi
WYSIWYG
Quick prototyping
Less typing
Component-based
Ownership to handle memory
Reusability
From RAD to MVC
June 2015
Rapid Application Development
Big Ball of Mud
Mixes User Interface and logic
Mixes UI, logic and database
Modules did not help
Difficult to maintain and evolve
Manual testing
Platform specific (web application?)
Fat clients (SaaS?)
From RAD to MVC
June 2015
Rapid Application Development
To be fair
Bad programmers write bad code;
Good programmers write good code.
RAD lets bad programmers write bad code faster;
RAD does NOT cause good programmers to
suddenly start writing badly.
From RAD to MVC
June 2015
Model-View-Controller (MVC)
Architecture pattern which:
Isolates “Domain Logic”
Application logic for the end-user
Business logic e.g. for data persistence
From “User Interface”
Input and presentation
Permitting independent
development, testing and maintenance of each
Separation of concerns
From RAD to MVC
June 2015
Model-View-Controller (MVC)
Model What it is
Manages the behavior of the data
View What it looks like
Renders the model for interaction
Controller What it does
Receives User inputs
Instructs the Model and View
From RAD to MVC
June 2015
Model-View-Controller (MVC)
The Model
Contains all business logic
Contains data for the application
Often linked to a database or REST
Contains state of the application
e.g. what orders a customer has
Notifies the View of state changes
If needed, e.g. not for stateless views
No knowledge of user interfaces
So it can be reused
From RAD to MVC
June 2015
Model-View-Controller (MVC)
The View
Generates the user interface
which presents data to the user
Passive (doesn’t do any processing)
Many views can use
the same model for different reasons
From RAD to MVC
June 2015
Model-View-Controller (MVC)
The Controller
Receives events from the outside world
Usually through views
Interacts with the model
Displays the appropriate view to the user
From RAD to MVC
June 2015
Model-View-Controller (MVC)
From RAD to MVC
MVC Process
Controller
Model
Use
View
Refresh
Notify updates
Command
June 2015
MVC, MVVM, MVCVM
MVVM and MVCVM
Even more uncoupled
For better testing
The ViewModel
May (or not) replace the controller
Expose data and command objects for the view
Eases two-way communication
From RAD to MVC
June 2015
MVVM, MVCVM Model
Holds the actual data (various context, store or other methods)
View Displays a certain shape of data
Has no idea where the data comes from
ViewModel Holds a certain shape of data and commands
Does not know where the data, or code, comes from or how it is displayed Is re-usable for several views
Controller Listens for, and publishes, events
Provides the logic to display the data Provides the command code to the ViewModel
From RAD to MVC
June 2015
MVVM
From RAD to MVC
MVVM Process
June 2015
MVVM in Delphi
LiveBindings
Effective since XE3
DSharp
Convention-Over-Configuration interfaces
MGM pattern used in hcOPF
Mediator component to bind the UI at design time
From RAD to MVC
June 2015
MVC and n-Tier / SOA
From RAD to MVC
Presentation Tier
Application Tier
Business Logic Tier
Data Tier
View
Controller
Model
Client 1 (Delphi) Client 2 (AJAX)
Application Server
DB Server
Presentation Tier
Application Tier
Presentation Tier
Business Logic Tier
Data Tier
June 2015
From RAD to MVC
