/Java-EE-Design-Patterns

Java-EE-Design-Patterns

##Todo

  • Make it a very short course
  • Look at Santosh's book further
  • Decide if creating the course makes sense. It does now!!
  • Dependency Injection

Front Controller

  • Look at all incoming requests.
  • Mapping from String to the View.
  • DataBinding
  • Spring MVC - DispatcherServlet
  • Security - Spring MVC
  • Logging

#Application Controller

  • Invoke business components.
  • Identify and redirect to the next view.

#Context Object

  • Typically Presentation Tier is tightly coupled to the Servlet API - extensively using HttpServletRequest and HttpServletResponse . Page controllers cannot be reused outside Web Application context.
  • Increase the reusability of page controllers.
  • Use a context object to encapsulate and share form data without any protocol dependency.
  • Spring MVC uses ModelMap as the Context Object. This class serves as generic model holder for both Servlet and Portlet MVC, but is not tied to either of those.
  • Easier to Test

#Composite View

  • Tiles and SiteMesh
  • Web pages have header footer navigation and content.
  • View in mobile might be different from a desktop
  • The solution to this is to use composite views that are composed of multiple atomic subviews.
  • Layout of the page may be managed independently of the content.
  • Web designers can design the layout of a site, using static content in each of the template regions.

#View Helper

  • Tag Libraries used for Date Formatting
  • Spring Tag Libraries for Form Binding

#Intercepting Filter

  • AOP
  • Logging
  • authentication filters , logging & auditing , Image conversion , data compression , encryption

#Service Locator (With Spring - these kind of things have become obselete)

  • Is a Singleton that is used to reuse code performing the JNDI lookup .
  • Abstracts complexity
  • Provides uniform service access to Clients
  • Improves performance
  • Sometimes referred to as the EJBHomeFactory ( EJB design patterns ) .

#Session Facade

  • The session bean will probably interact with two or more entity beans
  • Transaction
  • Easier to use for the Client
  • Better Performance

#Business Delegate

  • Presentation Tier need access to Distributed Business Services.
  • Code needed to access them might need understand the fact that the service is distributed, there-by, will be more complex. Example, EJB Remote Methods from time before.
  • Plain Java classes that hide EJB API complexity by encapsulating code required to discover, delegate to and recover from invocations on the session and message façade EJB layers.
  • Use on large projects where the web team is separate from the EJB team .

Service Activator

  • Some long-running use cases take long time. Instead of blocking the users, we can run these asynchronously
  • JMS Can be used

#Data Transfer Object / Value Object

  • Typically created by a Session Facade
  • Reflects the structure of the data needed by the view
  • Anaemic, without Business Logic
  • For me its an anti pattern
  • Client makes a single remote method invocation to the enterprise bean to request the Transfer Object / Value Obects instead of numerous remote method calls to get individual attribute values.
  • A value object is an object that encapsulates all the data required by a client .
  • The client can then call get methods on the value object to get all the data needed by the client .

#Data Access Object (@Repository)

  • Use a Data Access Object ( DAO ) to abstract all access to a data source.
  • The DAO will help to hide details of access to the data source from the client.
  • Promotes easier migration from one data source to another

#Value List Handler

  • Used to retrieve large amounts of data
  • Provides alternatives to EJB Finders for large queries.
  • Cache query results on server side.
  • Value List Handler sequence

#Domain Model

#Model View Controller

#Page Controller