This document introduces portlets and discusses their key characteristics. Portlets are self-contained components that can be placed on web pages and portals to provide modular functionality like weather, feeds, etc. They run in a portlet container on top of the servlet API and provide modes and states. The standard portlet API lacks MVC and data binding capabilities, which frameworks like Spring Portlet address. Best practices include treating portlets as view-only technologies and separating business logic into services.

1. Portlets:
An Introduction
Part 1 of 2
Monday, March 16, 2009

2. Why Portlets?
• Java standard
• Highly pluggable
• Portlet modes
• Self-contained/decoupled
Monday, March 16, 2009

3. What is a Portlet?
• Self contained component on Page/Portal
• Introduced to offer user oriented components
• Email
• Weather
• Feeds
• and more!
Monday, March 16, 2009

4. Portlet Specifics
• Servlet runs in a ServletContainer(tomcat/
jboss/websphere...)
• Portlet runs in a PortletContainer(eXo,
Pluto, Liferay...)
• Portlet api build on top of the Servlet API
• doGet, doPost are mapped to HTTP GET/
POST
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5. Portlet/Servlet
differences
• Servlet -> Page, Portlet -> HTML Fragment
• Portlets are not URL addressable
• web.xml describes webapplication
• portlet.xml describes the portlets
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6. Portlet Functionality
• Portlet Modes Portlet States
•
• Edit Normal
•
• View Maximised
•
• Help Minimised
•
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7. Traditional portlet
pattern
• User oriented
• Behave like mini windows within a portal/
web page
• Can be created/positioned/destroyed by
the front-end user
• Think iGoogle
Monday, March 16, 2009

8. Unify portlet pattern
• Developer oriented
• Used to deploy functionality
• No concept of windows
• Usually consist of the following modes
• edit (configuration)
• view (display)
• xml (view data source)
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9. The standard portlet
api lacks
• Clear MVC framework
• Data binding
• Hence Spring portlets
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10. MVC
(Model View Controller)
• Architectural pattern Controller
•
• Separate concerns
Respond to user events
•
• Model represents
domain Delegates to business tier
•
• View renders the Passes model to the view
•
view, with help of
ViewHelpers
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11. Spring
es
ic
rv
se
eb
W
• Application Framework
• Pojo Based with xml configuration Hibe
rna
• Promotes decoupling of components te
• Reduces the amount of code to write
ts
• ru
Offers plenty of 3rd party integration
t
S
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12. Spring Portlet MVC
• Basically Spring MVC
• Data Binding
• Validation
• Lots of plumbing/boilerplate code
• JSF Portlets, Struts Portlets also offer MVC
ontop of Portlet API
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13. Best Practices
• Portlets are a VIEW ONLY
TECHNOLOGY
• Only user interaction/rendering logic
• Decouple business logic and business
services
• Program to interfaces
• Use spring dependency injection
Monday, March 16, 2009

14. Architecting Portlets
• N-Tiered approach
• Presentation tier(Portlet)
• Business tier (Services/Domain model)
• Integration tier (hibernate/jdbc , SOAP/
rest)
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15. Deployment
• Portlets are packaged in a Web application
• Deploying to Tomcat
• Copy to $vyre_home/webapps
• Create context in $tomcat/conf/catalina/
localhost
• web.xml needs webapprootkey
Monday, March 16, 2009