Study of the Notice Board application

The Notice Board example application: http://askvikrant.com/vaadin-7-sample-application/

Deployment

WEB-INF/Web.xml

• context-param: productionMode = true
• servlets, UI and mappings
• resource-ref:
  • res-ref-name: jdbc/nbpool
  • res-type: javax.sql.DataSource
  • res-auth: Container
  • res-sharing-scope: Shareable

META-INF/context.xml

• username, password, driver, URL, etc.

Tomcat configuration, see http://tomcat.apache.org/tomcat-7.0-doc/config/

Main UI - NoticeboardUI

class

• extends UI
• implements series of self-defined event listener interfaces

members

• transient BusinessLogic instance, instantiated
• transient Blackboard event bus, obtained
• User
• Navigator
• panels, views, windows

init

• setup panels and views
• obtain blackboard instance,
• register events - link type of listeners to type of events by calling blackboard.register()
• add listeners - add self to blackboard listener
• new navigator for content panel
• initialize guest user

my comment:

Business

DatabaseManager

• holds connection / DataSource, and a message
• on initialize - look up data source from context
• transaction management methods: begin / commit / rollback... with proper logging
• sql methods
  • checkIfExists_xxx / delete / insert_xxx / select_xxx / update_xxx
  • manual ORM

BusinessLogic

• initializing - connect to database
• get / saveNew / update / delete methods
  • calls database manager
  • manages transactions manually

Components

• extends a layout
• layouts and widgets
• fire events (e.g. when button clicked, etc.), so the button handling is really simple
• setXXX method

Comment:

• view components (e.g. NoticePanel) knows model (Notice) - this should be ok if only for data binding
• binding not used..., setXXX method is there

Events and listeners

Events all implements the blackboard event, which is only an indicator; some event has properties

Listeners (basically one event with one listener) all extends blackboard listener, a method is annotated @ListenerMethod, an empty method

Needs reading about the blackboard event system to understand this part

Model

Simply model objects

Views

These views all implements View interface, which requires implementation of enter(ViewChangeEvent) method;

enter() method simply calls load(), which obtains business logic, get the data, and adds data

initializing method sets up all the gadgets and event listeners, some logic is in there....

Comment

• still business code in view......, in buttonClick..... though minimum