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Seam Introduction


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An effective but simple introduction about JBoss Seam.

An effective but simple introduction about JBoss Seam.

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    • 1. JBoss Seam Introduction Xiaogang Cao, RedSaga 2007-4-19
    • 2. MVC
      • Pros
        • pull the page logic out of mud
        • A clean structure of request process
      • Cons
        • It’s only focus on request/response
        • Modal and View are linked static
        • Very hard to abstract ‘widgets’ in web pages
      • I dreamed : XML,DB,entity, web based data window been unified
    • 3. The Seam way
      • Consider the whole web app in a human understandable way
      • Servlet Context is not enough, people have to write codes to manage state everywhere
      • Seam unified all state management to ‘ Declared State Management’
      • The core cool feature of Seam is ‘Conversation Context’
    • 4. Conversations Samples
      • Create Order:
        • Select a customer
        • Check balance
        • Add a product to detail list
        • Add more products
        • Confirm and assign a Order Number
    • 5. Conversations Samples(cont.)
      • Online Digital Photo Print Wizard
        • Browse for photos, add them to print cart
        • Review and update print qty
        • Print them
      • User profile update wizard
        • View and begin edit of user profile
        • Add a photo
        • Edit details
        • Review changes
        • Confirm change
    • 6. Seam’s Contexts
      • Stateless context
      • Event (or request) context
      • Page context
      • Conversation context
      • Session context / Http Session
      • Business process context / JBPM
      • Application context
      • Contexts.lookupInStatefulContexts()
    • 7. Conversation context
      • Conversation spans more than one page
      • Conversation is a whole interaction of a certain task
      • Conversation may means a ‘User Story’ or a ‘Use Case’
      • Nothing magic
        • it’s implemented by url param(ServerConversationContext) or a client param(ClientConversationContext)
        • Contexts Class use ThreadLocal to store all contexts.
    • 8. Conversation Lifecycle
      • @Begin
      • @End
      • Conversation have timeout
      • Conversation doesn’t result to a transaction
      • Conversations can be nested
      • Conversation can be merged by same id
      • Conversation can be managed by ‘workspace’
    • 9. Business Process Context
      • BusinessProcessContext can span more than 1 user
      • jBPM backend
      • Sample
    • 10. The meaning of 2 additional context
      • Make program much more clear and easy to understand
      • Use conversations and Business Process (jBPM) directly in JSF
      • Eliminate the chance of silly mistakes and memory leaks
      • Reduce the debug time
      • You never want to convert back
    • 11. Events
      • Events
        • JSF events
          • <h:commandButton value=&quot;Click me!&quot; action=&quot;#{helloWorld.sayHello}&quot;/>
        • jBPM transition events
          • <start-page name=&quot;hello&quot; view-id=&quot;/hello.jsp&quot;> <transition to=&quot;hello&quot;> <action expression=&quot;#{helloWorld.sayHello}&quot;/> </transition> </start-page>
        • Seam page actions
          • <pages> <page view-id=&quot;/hello/*&quot; action=&quot;#{helloWorld.sayHello}&quot;/> </pages>
        • Seam component-driven events
          • <components> <event type=&quot;hello&quot;> <action expression=&quot;#{helloListener.sayHelloBack}&quot;/> <action expression=&quot;#{logger.logHello}&quot;/> </event> </components>
          • @Name(&quot;helloWorld&quot;) public class HelloWorld { @RaiseEvent(&quot;hello&quot;) public void sayHello() { FacesMessages.instance().add(&quot;Hello World!&quot;); } }
        • Seam contextual events
          • Lots of build-in events , such as org.jboss.seam.validationFailed
      • No Event object exists in seam. You can pass params if needed
    • 12. Seam Component
      • Seam component is a mix of jsf backingbean(managed bean),service class(normally named as ***Manager or **Service. )
      • It can maintain the states for your objects
      • It can be
        • Stateless session beans
        • Stateful session beans
        • Entity beans
        • JavaBeans
        • Message-driven beans
    • 13. Seam Component (cont.)
      • The key of lightweight container is Dependency Injection (DI).
      • DI uses the lightweight framework container to inject services or other objects into a POJO.
      • The major differences between lightweight frameworks are how they wire container services together and implement Dependency Injection. The service architecture and metadata expression are the key issues here.
      • ‘ Components’ are the ‘Spring beans’ in Seam world
      • Components have the ability to be wired in Web tier
      • ---- Michael Juntao Yuan
    • 14. Seam Component (cont.2)
      • @Entity @Name(&quot;greeter&quot;) public class Greeter implements Serializable {      private long id;      private String name;      @Id(generate=AUTO)      public long getId() { return id;}      public void setId(long id) { = id; }      public String getName() { return name; }      public void setName(String name) { = name; } }
      • <h:form> Please enter your name:<br/> <h:inputText value=&quot;#{}&quot; size=&quot;15&quot;/><br/> <h:commandButton type=&quot;submit&quot; value=&quot;Say Hello&quot; action=&quot;#{manager.sayHello}&quot;/> </h:form>
    • 15. Seam Component (cont.3)
      • @Stateless @Interceptors(SeamInterceptor.class) @Name(&quot;manager&quot;) public class ManagerAction implements Manager {    @In    private Greeter greeter;    @Out    private List <Greeter> allGreeters;    @PersistenceContext    private EntityManager em;    public String sayHello () {      em.persist (greeter);      allGreeters = em.createQuery(&quot;from Greeter g&quot;).getResultList();      return null;    } }
      • <p>The following persons have said &quot;hello&quot; to JBoss Seam:</p> <h:dataTable value=&quot;#{ allGreeters }&quot; var=&quot;person&quot;>    <h:column>      <h:outputText value=&quot;#{}&quot;/>    </h:column> </h:dataTable>
      • ---------------above codes from Michael Yuan ,
    • 16. Seam bijection
      • In other containers
        • DI happens only when the POJO is created
        • Injection is the action between container and beans
        • the reference does not subsequently change for the lifetime of the component instance
        • This is good for stateless beans
      • For a stateful component, we need to change the reference within different context
      • In Seam
        • injection and outjection are the action between context and components
        • DI happens when the context switches
    • 17. Seam bijection(cont.)
      • Bijection is
        • Contextual
          • Reference can change in difference context
        • bidirectional
          • Values are ‘Injected’ from context, and also ‘Outjected’ to the context
        • dynamic
      • Bijection and contextual components are the soul of Seam!
    • 18. Other cool stuffs
      • JSF with EJB 3.0 (Ajax4jsf,icefaces,..)
      • Enhance to JSF EL
      • Validation
      • Conversation written with JPA considered
      • Build-in Testable
      • Build-in BPM
      • Build-in Security
      • Build-in mail, webmail as a option
    • 19. Develop simplified
      • Rails style seam-gen
      • Template based generation
      • EL support in HQL/EJB-QL
      • simplified annotation based configuration
    • 20. Highly integrated
      • JSF
      • EJB3/JPA
      • JAAS authentication
      • JSP
      • Unified EL
      • JavaMail
      • Portlet
      • buni-meldware mail/web mail
      • Facelets
      • jBPM
      • Hibernate
      • iText
      • Drools
      • JCaptcha
      • Ajax4JSF
      • ICEFaces
      • Spring
      • MyFaces
      • Jboss microcontainer
    • 21. EJB 3.0 or Java Beans?
      • Both EJB 3.0 session beans and entity beans are supported as a component
      • Java Beans also supported
      • EJB 3.0 have declared transactions and state replicate capability
      • Use Java Beans instead of EJB 3.0 allow you use Seam directly in Tomcat, not a EJB 3.0 container
      • Java Beans support hot deploy
    • 22. EJB 3.0 and JavaBeans(Cont.)
      • booking example have several versions
        • /examples/booking is a EJB 3.0 version
        • /examples/hibernate is a Hibernate 3.0 version
        • /examples/icefaces is using icefaces instead of Ajax4JSF
        • /examples/glassfish is a version runs on Java EE 5 reference implementation
      • Tips: Seam has a lot of well written completed examples comparing to hibernate
    • 23. Seam and JSF
      • EJB 3 beans are JSF managed Beans
      • Actually every Component are JSF managed Beans
      • Currently JSF is the only view supported
      • Seam will be a main strength to promote JSF
      • However, JSF is not very popular in China now
    • 24. Seam and iText
      • Pros:
        • Seam use facelets document to generate PDF
      • Cons:
        • Still like a toy, comparing to Crystal Reports or JReport
        • Report is one of very important feature in real world
        • Suggest to use JasperReports as a solid report tool
      • Tips: Foxit Reader ActiveX can render PDF in lighting speed within the IE browser.
    • 25. Seam and AJAX
      • Interface.js
        • <script type=&quot;text/javascript&quot; src=&quot;seam/resource/remoting/interface.js?customerAction&accountAction&quot;></script>
      • Remote.js
        • <script type=&quot;text/javascript&quot; src=&quot;seam/resource/remoting/resource/remote.js&quot;></script>
      • Make the AJAX call
        • Seam.Component.getInstance(&quot;helloAction&quot;).sayHello(name, sayHelloCallback);
      • Return fields is been controlled at server side
        • @WebRemote(exclude = {&quot;widgetList.secret&quot;, &quot;widgetMap[value].secret&quot;})
        • public Widget getWidget();
      • Return Data is typed
        • Primitives / Basic Types ,String, Date,Number, Boolean,Enum, Bag, Map
      • Support subscribe to JMS topic
    • 26. Seam and AJAX(Cont.)
      • Pros:
        • Seam remoting allow seam been used with other client JS library
        • Currently two open source JSF-based AJAX solutions: ICEfaces and Ajax4JSF
      • Cons:
        • Actually, RichFaces also like a toy comparing to dojo or Ext
        • AJAX design pattern is still evolving. Especially in a portal page.
        • Current Seam remote.js is tied too tight with JSF.
        • It’s possible to write a customized Ext dataset to communicate with Seam Remoting, but require many codes.
        • Hope it can support JSON/Burlap in the future and support a dataSet model
    • 27. Seam PageFlow
      • Pros:jPDL visiable XML define
      • Cons: you must use jBPM
    • 28. Seam Security
      • Simple mode and Advanced mode
        • Advanced mode use Drools, provide rule based security checks
      • Authenticate
        • built upon JAAS
        • offers a much more simplified method of authentication
      • Authorization
        • Security API for securing access to components, component methods, and pages
        • Role based security check
      • Security is a major advantage comparing to other frameworks like ROR.
    • 29. Seam and persistence
      • Tight integration with EJB 3.0 entity bean ,JPA and Hibernate
      • No need to say more! 
    • 30. Conclusion
      • Seam is the most advanced J2EE stack now
        • State Management is the most important feature
        • But Seam is also heavy and complex
        • Still lack of advanced Report ability
        • AJAX support is behind era
      • You must use JSF to gain max benefit
        • But JSF is not popular enough
      • Seam can simplify your code
        • Remove glue codes between layers
      • Some of Seam function is not standard yet
        • No, but maybe that isn’t a problem, just like the success of hibernate in EJB 2.0 era.
    • 31. Conclusion(cont.)
      • Ruby improve productivity by using dynamic language and provide a ready to use Rails framework
      • ROR is lack of wide range of libraries support comparing to Java
      • Seam introduce Contextual Components , which will dramatically improve java programmer’s productivity
      • But Seam’s inner complex will cost more time for developers to go in deep
    • 32. Hope
      • resolve the problem of EJB 3 beans hot deploy, that’s really a handy feature
      • Add more views besides JSF. How about Eclipse RAP or Ext?
        • Current client conversation can be used in a full AJAX solution.
      • Exadel can improve the usability of Seam
    • 33. About redsaga
      •, an open source community only for matures
      • Open source project hosting service available for good projects
      • Contributed to Hibernate & Spring by organize the translate of reference documents and write book in Chinese
        • Hibernate Core
        • Hibernate Annotations
        • Hibernate EntityManager
        • Spring Reference
      • Seam Reference translation in progress and open for volunteers
        • Coming soon!
      • http://