Transcript Portlet
Java Portlets (JSR-168) SSE USTC Qing Ding Agenda Java Portlet (JSR 168) WSRP Products (only a few slides) – Sun Java Enterprise Systeem Portal Server, Portlet Builder What is a Portlet? 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 <html> 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 What does JSR-168 define? Portlet API – – – – – Portlet Container – Portlet Requests Preferences User information Security Deployment packaging Extension of servlet container Contract between component and container What are out-scope of JSR 168? Aggregation Layout management Page personalization and configuration engines Portal administration and configuration Default Desktop Portal/Portlet Architecture Portal and Portlet Interaction Why Portlet? (Why can't we use Servlet?) 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 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 Portlet Architecture Portal Architecture With JSR 168 Support 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 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 Portlet vs. Servlet (Portlet is built over Servlet Architecture) 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 Deployment model Classloading Packaging and deployment Lifecycle management Session management Request dispatching 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 – Portlets have predefined states – action requests and render requests portlet modes and window states Portlets can exist many times in a portal page 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 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 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 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 Portlet and Web App. Frameworks 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 Exo Portal Build on JSF, Struts Portlet Modes & Windows State 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 – EDIT – Portlet renders markup fragment in this mode Used to change per-user settings to customize rendering HELP Used to display help information Portlet Modes (Contd.) Portals might support other custom modes – – – – – ABOUT CONFIG EDIT_DEFAULTS PREVIEW PRINT Portals might support other vendor specific modes 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 Portlet Features 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 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 Portal context Can provide information on – – Portal vendor Version Used by portlets to find out more information about additional extensions supported by Portal Security Authentication is left to the underlying servlet container Authorization – – Follows J2EE ‘roles’ model Supports programmatic role checking Session Management Facade on top of the HttpSession Two scopes: APPLICATION & PORTLET – – PORTLET is a convenience namespacing It’s 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 Portlet Request Dispatcher Portlets can include Servlets, JSPs and static content during a render request Similar to Servlet’s RequestDispatcher 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 Caching Expiration based caching Declarative caching – Specify <expiration-cache> element in deployment descriptor for the portlet Programmatic caching – Modify EXPIRATION_CACHE property of render response 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) Portlet API's Portlet Life Cycle 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 DoView() DoEdit() ProcessAction() Other Interfaces/Classes PortletConfig, PortletContext, PortalContext,PortletSession PortletPreferences interface WindowState (MINIMIZED, NORMAL & MAXIMIZED) PortletMode (VIEW, EDIT & HELP) PortletURL PortletRequestDispatcher Portlet Tag Library 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 Portlet Example – portlet class Packaging & Deployment 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\ Portlet Example – portlet.xml WeatherPortlet Sample Code WeatherPortlet WeatherPortlet (1 of 7) WeatherPortlet (2 of 7) WeatherPortlet (3 of 7) WeatherPortlet (4 of 7) WeatherPortlet (5 of 7) WeatherPortlet (6 of 7) portlet.xml WSRP (Web Services for Remote Portlet) 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) Portal Architecture With WSRP Support JSR168 and WSRP They were designed in collaboration mode Their functionality is fully aligned Portlet:Portlet.processAction() WSRP: WSRP.performBlockingInteraction() Portlet: Portlet.render() WSRP: WSRP.getMarkup() Sun Java System Portal Server Integrated Communications Desktop and Wireless Access 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 Sun Java System Portal Server and Portal standards Sun Java System Portal Server supports JSR 168 WSRP will be supported in the first Sun Java System update Sun Java System Portal Server Architecture How do JSR168 and WSRP fit in ? Sun ONE Portal Server with JSR 168 and integration to EIS Sun Java Studio Portlet Builder 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 Resources Resources JSR 168 – SunTM ONE Portal Server – http://wwws.sun.com/software/download/products/3f187b02 .html WSRP @ OASIS – http://wwws.sun.com/software/products/portal_srvr/home_p ortal.html Sun ONE Portlet Builder – http://www.jcp.org/jsr/detail/168.jsp http://www.oasis-open.org/committees/wsrp/ WSRP @ XML Cover Pages – http://xml.coverpages.org/wsrp.html