Java Portlets (JSR-168)

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Java Portlets(JSR-168)

• SSE USTC
• Qing Ding

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Agenda

• Java Portlet (JSR 168)
• WSRP
• Products (only a few slides)
• Sun Java Enterprise Systeem Portal Server,
  Portlet Builder

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• What is a Portlet?

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What is a Portlet?

• Java technology based web component
• Managed by a portal container
• Generates a piece of markup called fragment
• Adheres to certain rules such as no lthtmlgt tags,
  for instance
• Fragment generated by a Portlet aggregates with
  that from other Portlets to form a portal page
• Fragment generated by a Portlet may vary from one
  user to another depending on the user
  configuration

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What does JSR-168 define?

• Portlet API
• Portlet Requests
• Preferences
• User information
• Security
• Deployment packaging
• Portlet Container
• Extension of servlet container
• Contract between component and container

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What are out-scope of JSR 168?

• Aggregation
• Layout management
• Page personalization and configuration engines
• Portal administration and configuration

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Default Desktop
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Portal/Portlet Architecture
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Portal and Portlet Interaction
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• Why Portlet?
• (Why can't we use Servlet?)

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Why Portlets?

• Servlet architecture does not define the Desktop
  metaphor where markup aggregation can occur
• Servlet architecture does not define the possible
  states and transitions of an included Servlet or
  JSP
• Servlet architecture does not define how the
  state of one Servlet or JSP affects the display
  of the other included Servlets or JSPs

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Why Portlets?

• Servlet architecture does not define a
  personalization interface nor the idea of
  persisting the personalization information
• Servlet architecture does not define URLrewriting
  functions to allow the creation of links and
  actions targeted to a specific form within the
  fragment of a page (Portlet markup fragment)
• Servlet architecture does not support caching
  scheme of fragments

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• Portlet Architecture

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Portal ArchitectureWith JSR 168 Support
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Portal

• A specialized web application that provides
  value-added services such as
• Personalization
• Single Sign-On
• Content aggregation from various sources
• Secure search facilities
• Localization of content
• A Portal page represents a complete markup
  document consisting of several Portlet components

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Portlet Container

• Portlets are deployed in a Portlet container such
  that container can
• Provides runtime environment for Portlets
• Manage life cycle of Portlets
• Provide persistent storage for storing Portlet
  preferences
• Cache the portlets
• Receive requests from the portal to execute
  requests on the portlet
• Not responsible for contents aggregation

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• Portlet vs. Servlet
• (Portlet is built over
• Servlet Architecture)

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Similarity with Servlet

• Both are Java technology based web components
• Life-cycle is managed by a specialized container
• Servlet by servlet container
• Portlet by portlet container
• Both generate dynamic content
• Both interact with web client via a
  request/response paradigm

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• Deployment model
• Classloading
• Packaging and deployment
• Lifecycle management
• Session management
• Request dispatching

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Differences from Servlet

• Portlets only generate markup fragments, not
  complete documents
• Portlets are not directly bound to a URL
• Web clients interact with portlets through a
  portal system
• Portlets have a more refined request handling
• action requests and render requests
• Portlets have predefined states
• portlet modes and window states
• Portlets can exist many times in a portal page

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Extra Features of Portlets

• Portlets have means for accessing and storing
  persistent configuration and customization data
• Portlets have access to user profile information
• Portlets have URL rewriting functions for
  creating hyperlinks within their content
• allow portal server agnostic creation of links
  and actions in page fragments
• Portlets can store transient data in the portlet
  session in two different scopes
• application-wide scope
• the portlet private scope

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Servlet Features Forbidden to Portlets

• Setting the character set encoding of the
  response
• Setting HTTP headers on the response
• The URL of the client request to the portal

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Servlet Features that are leveraged by Portlets

• Portlets can leverage servlets, JSPs and JSP
  tag-libraries for generating content
• Content should be markup fragment
• A portlet can call servlets and JSPs using a
  request dispatcher

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Integration between the two

• Attributes set in the portlet request are
  available in the included servlet request
• Attributes set in the portlet session are
  accessible from the servlet session and vice
  versa
• Portlet and the included servlet or JSP share the
  same output stream

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• Portlet and
• Web App. Frameworks

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• Struts/JSF are built over Servlets
• Struts/JSF can be built over Portlets
• APIs exposed to Struts/JSF developers should
  remain the same
• Struts/JSF developers must be aware of the markup
  fragment he has to produce
• The markup fragment must follow the rules
• Generate Portlet URL

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Exo Portal Build on JSF, Struts
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• Portlet Modes
• Windows State

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Portlet Modes

• Indicates function that a portlet performs
• Execute different tasks and generate different
  content based on the function they perform
• Portals must support three modes
• VIEW
• Portlet renders markup fragment in this mode
• EDIT
• Used to change per-user settings to customize
  rendering
• HELP
• Used to display help information

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Portlet Modes (Contd.)

• Portals might support other custom modes
• ABOUT
• CONFIG
• EDIT_DEFAULTS
• PREVIEW
• PRINT
• Portals might support other vendor specific modes

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Windows State

• Is an indicator of the amount of portal page
  space that will be assigned to the content
  generated by a portlet
• Provided by portlet container
• Three states
• NORMAL
• MAXIMIZED
• MINIMIZED
• Custom states are possible

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• Portlet Features

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Portlet Persistence

• Portlets can store persistent data for a given
  user in a PortletPreferences object
• Preferences are read-write in the action phase
  (processAction()) and read-only in render phase
• Usually user preferences are modified in EDIT
  mode

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User Profile Attributes

• Can store information about user that can be used
  to personalize content for that user
• User profile information is represented as a
  USER_INFO structure which is then mapped to the
  real information in datastore
• Portlet defines the attributes it wants to access
  in the deployment descriptor

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Portal context

• Can provide information on
• Portal vendor
• Version
• Used by portlets to find out more information
  about additional extensions supported by Portal

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Security

• Authentication is left to the underlying servlet
  container
• Authorization
• Follows J2EE roles model
• Supports programmatic role checking

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Session Management

• Facade on top of the HttpSession
• Two scopes APPLICATION PORTLET
• PORTLET is a convenience namespacing
• Its common for portlets to appear more than once
  in a page (i.e. EU-News, US-News)
• Servlets, JSPs and Portlets within a Portlet
  Application share the same session
• Session creation event notification is supported

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Portlet Request Dispatcher

• Portlets can include Servlets, JSPs and static
  content during a render request
• Similar to Servlets RequestDispatcher

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Localization

• Portlets can be localized by using resource
  bundles
• Resource bundles are specified in deployment
  descriptor
• Portlet can access resource bundle via
  PortletContext.getResourceBundle() API

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Caching

• Expiration based caching
• Declarative caching
• Specify ltexpiration-cachegt element in deployment
  descriptor for the portlet
• Programmatic caching
• Modify EXPIRATION_CACHE property of render
  response

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Portlet URL

• Portlets are always accessed through a Portal
• Portlets do not have a direct URL mapping
• Portlet URLs allow Portlets to create URLs that
  target to themselves (through the Portal
  end-point)

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• Portlet API's

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Portlet Life Cycle
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GenericPortlet class

• Implements Portlet interface
• Render()--like service() in servlets, calls
  specified render methods based on Portlet mode
• doView() for View mode
• doEdit() for Edit mode
• doHelp() for Help mode
• Is extended by portlet developers
• Override render methods as necessary

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DoView()
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DoEdit()
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ProcessAction()
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Other Interfaces/Classes

• PortletConfig, PortletContext,
• PortalContext,PortletSession
• PortletPreferences interface
• WindowState (MINIMIZED,
• NORMAL MAXIMIZED)
• PortletMode (VIEW, EDIT HELP)
• PortletURL
• PortletRequestDispatcher
• Portlet Tag Library

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PortletPreferences

• Persistent read/write Portlet configuration
• getValues(), setValues() to access
  PortletPreferences
• May modify attributes and store() in persistence
  during processAction()
• Normally, portlet preferences are per portlet/per
  user
• Persistency is managed by the portletcontainer
• Default values are defined in the portlet.xml
  deployment descriptor

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Portlet Example portlet class
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• Packaging
• Deployment

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Portlet Web Application

• All resources, portlets, deployment descriptors
  are packaged in one web application archive (WAR
  file)
• PortletApp\
• jsp
• htmls
• WEB-INF\
• web.xml
• portlet.xml
• sun-portlet.xml
• classes\
• Lib\

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Portlet Example portlet.xml
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• WeatherPortlet
• Sample Code

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WeatherPortlet
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WeatherPortlet (1 of 7)
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WeatherPortlet (2 of 7)
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WeatherPortlet (3 of 7)
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WeatherPortlet (4 of 7)
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WeatherPortlet (5 of 7)
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WeatherPortlet (6 of 7)
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portlet.xml
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• WSRP
• (Web Services for
• Remote Portlet)

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WSRP Value Proposition

• Provides protocols and metadata for
• Presentation-oriented Web services
• Meant for aggregation and syndication with no
  programming on the consumer side
• Roles
• WSRP Producers (Web service provider)
• WSRP Consumers (Web service consumer)

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Portal ArchitectureWith WSRP Support
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JSR168 and WSRP

• They were designed in collaboration mode
• Their functionality is fully aligned
• PortletPortlet.processAction()
• WSRP WSRP.performBlockingInteraction()
• Portlet Portlet.render()
• WSRP WSRP.getMarkup()

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• Sun Java SystemPortal Server

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Integrated CommunicationsDesktop and Wireless
Access
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Personalization

• Modify any aspect of the desktop (as allowed by
  the Administrator)
• Add or delete portlets
• Customize the desktop layout
• Use or create personalized themes
• Modify or create multiple tabs
• Update user profile information
• Modify portlets settings and properties

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Sun Java System Portal Server andPortal standards

• Sun Java System Portal Server supports JSR 168
• WSRP will be supported in the first Sun Java
  System update

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Sun Java SystemPortal Server Architecture

• How do JSR168 and WSRP fit in ?

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Sun ONE Portal Server withJSR 168 and
integration to EIS
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• Sun Java Studio
• Portlet Builder

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Portlet Builder

• Portlet development plug-in for Sun JavaTM Studio
• Easy development
• It has wizards
• It creates and updates the portlet.xml
• Supports portlets execution, debugging and
  deployment within the Studio IDE
• Runs in Sun JavaTM Studio 4.x and 5.x

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• Resources

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Resources

• JSR 168
• http//www.jcp.org/jsr/detail/168.jsp
• SunTM ONE Portal Server
• http//wwws.sun.com/software/products/portal_srvr/
  home_portal.html
• Sun ONE Portlet Builder
• http//wwws.sun.com/software/download/products/3f1
  87b02.html
• WSRP _at_ OASIS
• http//www.oasis-open.org/committees/wsrp/
• WSRP _at_ XML Cover Pages
• http//xml.coverpages.org/wsrp.html