Seam

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Seam
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What is Seam?

• Application Framework for JEE
• One kind of stuff
• Integrate JSF and EJB 3.0
• Declarative State management
• Bijection
• Prefer annotations to XML
• Integration Testing
• There's more to a web application than serving
  HTML pages
• Versatility

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What is Seam

• Designed for Stateful web applications
• Allows easy creation of JEE applications
• Eliminates complexity
• Easiest way to get started with EJB 3.0
• Light weight framework

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Conversation

• Why?
• Fine grained control over HTTPSession
• _at_Begin, _at_End
• Long Running vs. Temporary
• Database Transactions are tied to Conversations
• Nesting( _at_Begin(nestedtrue) )
• Foreground vs. Background
• http//solutionsfit.com/blog/2007/12/13/explaining
  -the-conversation-timeout-setting-through-example/
  
• See conversations in action

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Bijection

• Its not injection its bijection
• Seam emphasizes stateful components
• _at_In _at_Out
• Will use the name of var as default
• _at_In _at_Out private Customer customer
• _at_In(namecust) _at_Out(namecust) private
  Customer customer
• Seam manages the life cycle
• Bijection can occur with any Seam component,
  takes place every time a component is invoked
• Outject to any scope
• If not available Seam will create the component
• Careful of excessive bijection

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Entities, Entities and Entities

• Home Objects can be JPA or Hibernate
• Home objects can be defined in components.xml
• Easier but more restrictive
• ltframeworkentity-home name"personHome" entity-cl
  ass"eg.Person/gt
• Declared Home objects
• _at_Name("personHome") public class PersonHome exten
  ds EntityHomeltPersongt 
• Can override functionality or add extra
  functionality
• Can be a stateful or stateless component
• Provide default behavior persist(), remove(),
  update() and getInstance().
• First call setId() before you call the
  method

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Entities, Entities and Entities cont.

• Query Objects
• ltframeworkentity-query name"people"            
               ejbql"select p from Person p"/gt
• Can be called like any seam component
• i.e. people.resultList()
• Can support pagination
• Add to entity query max-results"20"
• Call people.firstResults, people.nextFirstResult
  or people.lastFirstResult
• Supports search criteria
•  ltframeworkrestrictionsgt     ltvaluegtlower(firstN
  ame) like lower( concat(examplePerson.firstName
  ,'') )
• lt/valuegt      ltvaluegtlower(la
  stName) like lower( concat(examplePerson.lastNam
  e,'') )
• lt/valuegt    lt/frameworkrestri
  ctionsgt

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Entities, Entities and Entities cont.

• Controller objects
• Optional
• Add convenience methods like
• createQuery, persist or addFacesMessage
• _at_Stateless
• _at_Name("register")
• public class RegisterAction extends EntityControll
  er 
• implements Register

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Observers and Events

• One of the more powerful components of Seam
• You can observe any seam event
• Raising an event is extremely easy
• _at_RaiseEvent(hello)
• Events.instance().raiseEvent("hello")
• Observe an event
• _at_Observer("hello")
• _at_Observer(org.jboss.seam.validationFailed)

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Observation and Events

• State can be passed from producer to consumer
• Events.instance().raiseEvent("hello", name)
• _at_Observer("hello")
• public void sayHelloBack(String name) 
• FacesMessages.instance().add("Hello 0!", name)
  
• However this is not necessary since state is held
  in the seam context

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POJO

• Seam Components are POJO
• Entity Manager needs to be Seam Managed
• Add lttransactionentity-transaction
  entity-manager""/gt To the components.xml
• Seam pojos can be used interchangeably instead
  of ejbs
• POJOs dont support clustering

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Pages.xml

• A very powerful way to navigate through your
  application
• Integrates with Security, JBoss Rules
• Can begin and stop a conversation
• Navigation can be evaluated from a el expression
• Navigation can occur based on an exception type
• ltexception class"org.jboss.seam.security.NotL
  oggedInException"gt
• ltredirect view-id"/login.xhtml"gt
• ltmessagegtPlease log in
  firstlt/messagegt
• lt/redirectgt
• lt/exceptiongt
• Can be driven from a return of a Seam component
  similar to a struts forward

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Seam Managed Transactions

• Transactions in Seam may not happen in a single
  method call
• Seam is a stateful framework so use of
  LazyFetching is encouraged
• Makes use of a Persisted Context at the
  Conversation level

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Seam Managed Transactions

• Seam uses JTA by default
• If you are running Seam in a non EE5 container,
  Seam will try to figure out what you are using
• Seam managed transactions can be disabled
• ltcoreinit transaction-management-enabled"false"/
  gt        lttransactionno-transaction /gt
• With EJBs you should add
• lttransactionejb-transaction /gt

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Seam Security

• Custom Authentication Method
• Roles can be any thing
• Integrates Seamlessly with JAAS
• Integrates with JBoss Rules for security checking

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Seam Security Cont

• Simple authentication
• Default
• Uses one of your seam components
• You can use your entity classes to authenticate
  with
• ltsecurityidentity authenticate-method"authenti
  cator.authenticate"/gt
• In your authenticate method add roles to the
  identity class
•  Identity.instance().addRole(ltYour Rolegt)
• If your session isnt authenticated then call add
  role before you authenticate
• Add _at_Restrict(ltRoleNamegt) to either your class or
  your method
• _at_Restrict("shasRole(ltRoleNamegt)"
• To use the default system JAAS add to
  components.xml
• ltsecurityidentity jaas-config-name"other"/gt

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Validation(DRY)

• Integrates With Hibernate Validator
• Annotate your messages or use properties file
• Use ltsvalidategt or ltsvalidateAll/gt
• lthinputText id"userName" required"true"       
         value"customer.userName"gt  ltsvalidate
   /gt
• lt/hinputTextgt
• lthmessage for"userName" styleClass"error" /gt

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Interceptors

• No Dependency on the Web.xml
• Very Easy to Use!
• Just annotate your class
• _at_Scope(ScopeType.APPLICATION)
• _at_Name("org.granite.seam.SeamMessagesFilter")
• _at_BypassInterceptors
• _at_Filter(within"org.jboss.seam.web.contextFilter")
  
• _at_Install(precedenceInstall.BUILT_IN)
• _at_Dependency()

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Seam Gen

• Creates a fully configured project including jsf
  pages
• Just type seam setup in seam root dir and then
  answer the questions

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Flexability

• Flex via Tide/GraniteDS(and BlazeDS, Flamingo)
• GWT
• Wicket
• PDF
• Web Services
• Even Spring
• Can even run in just Tomcat

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The End

• We just touched the surface
• Seam is a powerful, flexible and easy to use and
  build with framework
• For more information on seam check out
• http//www.seamframework.org
• Flex and Seam
• http//www.graniteds.org
• Email
• cameron.ingram_at_graniteds.org
• My blog
• http//www.rationaldeveloper.com
• Questions!