1. Developing Portlets With the Spring MVC Framework
Presented by: Michael Slaven
Teachers College, Columbia University
March 21st, 2011
Session ID 4271
2. Session Rules of Etiquette
• Please turn off your cell phone/pager
• If you must leave the session early, be sure not
to knock over anyone’s coffee.
• If you must yawn or snore, please do so as
discreetly as possible.
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3. Agenda
• Some examples of portlets built using the Spring
MVC framework
• Why develop portlets?
• Why use Spring MVC?
• An overview of portlets and the JSR portlet specs
—request phases
—portlet modes
—window states
—URL handling
• An overview of Spring MVC
—model, view, controller
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4. Agenda - continued
• Putting it all together
—Setting up a dev environment and directory structure
—Configuring Spring and annotations
—Creating the ViewController
—Creating the DirectoryService
—Create the JSP views “search” and “searchresults”
—Deployment
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5. About Teachers College
• The oldest and largest graduate
school of education in the U.S.
• Affiliated with Columbia
University
• Located in the northern end of
Manhattan
• ~5400 students
• ~1000 staff
• 165 full time faculty
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10. Features of the myTC Message Center
• Uses Spring 2.5
• Hibernate for data persistence
• Sends emails instantly and generates daily digest
emails for each user
• Emails use Apache Velocity templating engine
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11. The myTC Photo Directory
Our first (and smallest)
Spring MVC portlet
“More Options” allows search by
title, office, phone, email, role
(staff, student or faculty)
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13. Why develop portlets?
• Make your code portable across portal products.
— The JSR-168 portlet API is supported by all major
portal products
• Easily re-use code by having multiple instances.
• If you want to do custom development in Luminis 5,
you have to.
(Lum 5 doesn’t support channels)
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14. Why use the Spring MVC framework?
• It separates presentation from business logic.
• It uses dependency injection for simplification and to
increase testability.
• It lets you focus on functionality instead of
infrastructure.
• Spring's view resolution is very flexible.
—Out of the box, Spring enables you to use JSPs, Velocity
templates and XSLT views, among others.
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16. JSR 168 and JSR 286 Portlet Specs
• JSR 168 aka Portlet 1.0 specification
—released Oct 2003
— supported by Luminis 4.2 and Lum 5
• JSR 286 aka Portlet 2.0 specification
—released Jun 2008
—supported by Luminis 5
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17. Request Phases
• Action requests
—can be used to change system state
—executed only once
—produces no markup
• Render requests
—Cannot change system state
—executed at least once
—produces markup
• Event requests (Portlet 2.0 only)
• Resource requests (Portlet 2.0 only)
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19. Portlet Modes
• Modes specify the current function of the portlet.
• There are three standard portlet modes:
—VIEW: normal mode
—EDIT: edit mode, for portlet specific preferences
—HELP: help mode, for portlet specific help
• All 3 are not necessary. Some portlets have only a
VIEW mode.
• Portlets can have other custom-defined modes as
well.
• These can be changed by the user, usually with an
icon in the portlet’s toolbar, or they can be changed
programmatically.
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20. Window States
• Window States specify the size or amount of detail.
• There are three standard windows states:
—NORMAL: normal window state
—MAXIMIZED: largest window, usually fills the portal
window
—MINIMIZED: smallest window, usually only a toolbar
remains
• These can be changed by the user, usually with an
icon in the portlet’s toolbar, or they can be changed
programmatically.
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21. URL Handling
• There is no portlet URL you can link to, since the
portal controls the actual URL.
• Use the API for generating URLs and setting URL
parameters (PortletURL Objects).
• Use a combination of Portlet Mode, Window State,
and Request Parameters for navigation.
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23. What is Spring MVC?
• Spring is a flexible and lightweight application
framework that utilizes dependency injection.
• MVC is a common design pattern that isolates the
data (model) and domain logic (controller) from
the user interface (view).
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24. Model – The M in MVC
• The model encapsulates the data and application
state.
• It responds to requests for information about its
state (usually coming from the view).
• It responds to instructions to change state (usually
coming from the controller).
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25. Views – The V in MVC
• The view displays the user interface and renders the
model for display.
• It also sends user actions to the controller.
• JSP & JSTL are the most common view
technologies, but XSLT, Velocity, PDF Docs, etc. are
all supported.
• In portlets you generally only use view technology
that produces HTML markup.
• Multiple views can exist for a single model for
different purposes.
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26. Controllers – The C in MVC
• A controller processes user input from a view and
initiates a response by making changes to the
model.
• It selects the view to use for the response.
• It often delegates to the service layer for the
business logic.
• There are often multiple controllers.
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28. Photo Directory “Lite”
• Our example is a person search that returns a
thumbnail image of a person as well as their contact
info and office hours (if applicable).
• Has 2 views:
—SEARCH: a form to enter first name, last name, etc
—SEARCHRESULTS: the results, paginated 5 at a time
• Has a single domain object:
—DirectoryEntry: setters and getters for a single entry in the
photo directory
• Has a single controller
• Has a single DB service object
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29. Notes on setting up a dev environment
• Install the JDK and set JAVA_HOME
—JRE is not enough
• Install an IDE
—Eclipse
—NetBeans
—Use Maven to simplify dependencies, building, and
deploying
• Install a portal / portlet container
—uPortal 2.5.6 is best if developing for Lum 4
—Liferay 5.2.x is best if developing for Lum 5
—Or you can use Pluto from Apache
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30. Set up the directory
structure
• /WEB-INF -- all protected resources
• Individual class files should be stored
in a directory structure within /WEB-
INF/classes that reflects the class
package.
• /WEB-INF/jsp – jsp views
• /WEB-INF/lib – referenced JAR files
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31. Include the Spring libraries
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• Use Maven to handle your dependencies.
• This is done using the “Project Object Model” pom.xml file at
the root of your project.
• Maven then downloads all necessary libraries and places them
in WEB-INF/lib.
32. Configure portlet.xml
• The Spring DispatcherPortlet dispatches requests to
your controllers.
• This will be the same for any Spring portlet.
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33. Configure web.xml
• Spring portlets are an extension of spring servlets.
• DispatcherPortlet uses ViewRendererServlet to
dispatch view rendering into a servlet context.
• Also, load the parent ApplicationContext using
ContextLoaderListener.
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34. Configure PhotoDirectory-portlet.xml
-- Annotations --
• Setup DefaultAnnotationHandlerMapping.
• Tell Spring where to scan for annotations like
@Controller, @RequestMapping, @Autowired etc.
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35. Configure PhotoDirectory-portlet.xml
-- View Resolver --
• Using JstlView we don’t have to build views ourselves.
• Refer to a view by name, and the jsp file of that name
becomes the view.
• The prefix and suffix are added, so that the view “search”
becomes /WEB-INF/jsp/search.jsp
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36. Controller & Handler Mapping
• With Spring 2.5+ we can simplify by using
annotations.
• Without annotations:
—The controller needs to extend a base controller
like AbstractController.
—Handler beans have to be defined in the application
context.
• With annotations:
—Annotate the controller class with “@Controller”.
—Annotate handlers with
“@RequestMapping([params])”.
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44. Deploy!
• Use Maven or Ant to package your portlet into a
deployable war file.
• On Lum 4
—Run cptool deploy portlet /path/to/PhotoDirectory.war
—A restart is required.
• On Lum 5 and Liferay
—Simply copy the war file to your hot deploy directory, or
upload using the Admin GUI.
• On uPortal 2.5
—Run ant deployPortletApp -DportletApp=
/path/to/PhotoDirectory.war
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45. Summary
The portlet API is defined by the JSR portlet specs:
—request phases
—portlet modes
—window states
—URL handling
• Portlets can be built once, and deployed to any compliant
portal with little or no modification.
• MVC is a design pattern that separates presentation from
business logic
• Portlets built using the Spring MVC framework can be
simple or complex. Using JSP views you could create a
portlet that doesn’t require any java coding.
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46. Summary - Continued
• To deploy a Spring MVC portlet
— setup a dev environment
— setup the directory structure
— include the spring libraries
— configure the application context (portlet, web, and
myPortlet-portlet.xml)
— use annotations to define controller and handler mappings
— create the controllers and domain objects
— create the service layer
— create the views (we used JSP views)
— deploy!
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