コンテキスト依存コンポーネントモデルを補完するものとして、Seamアプリケーションの特徴と なっている極度の疎結合を促進させる2つの基本概念が存在します。 最初のものは、イベントがJSFライクなメソッド結合式（method binding expression) を介して イベントリスナーへマップできるような強力なイベントモデルです。 二番目のものは、ビジネスロジックを実装するコンポーネントに対して横断的関心事 (cross-cutting concerns) を適用するためにアノテーションやインターセプタを広範囲に 　　使用しているということです。

<h:commandButton value="Click me!" action="#{helloWorld.sayHello}"/>

<start-page name="hello" view-id="/hello.jsp">

    <transition to="hello">

        <action expression="#{helloWorld.sayHello}"/>

    </transition>

</start-page

>

<pages>

    <page view-id="/hello.jsp" action="#{helloWorld.sayHello}"/>

</pages

>

<pages>

    <page view-id="/hello/*" action="#{helloWorld.sayHello}"/>

</pages

>

TODO: translate struts action into page action

<pages>

    <page view-id="/hello.jsp">

        <action execute="#{helloWorld.sayHello}" if="#{not validation.failed}"/>

        <action execute="#{hitCount.increment}"/>

    </page>

</pages

>

<pages>

      <page view-id="/hello.jsp" action="#{helloWorld.sayHello}">

          <param name="firstName" value="#{person.firstName}"/>

          <param name="lastName" value="#{person.lastName}"/>

      </page>

  </pages

>

<pages>

      <page view-id="/hello.jsp" action="#{helloWorld.sayHello}">

          <param name="firstName" />

          <param name="lastName" />

      </page>

  </pages

>

<page view-id="/home.xhtml">

    <rewrite pattern="/home" />

</page>

<page view-id="/home.xhtml">

    <rewrite pattern="/home/{color}" />

    <rewrite pattern="/home" />

</page>

<page view-id="/search.xhtml">

    <rewrite pattern="/search-{conversationId}" />

    <rewrite pattern="/search" />

</page>

<pages>

   <page view-id="/calculator.jsp" action="#{calculator.calculate}">

      <param name="x" value="#{calculator.lhs}"/>

      <param name="y" value="#{calculator.rhs}"/>

      <param name="op" converterId="com.my.calculator.OperatorConverter" value="#{calculator.op}"/>

   </page>

</pages

>

<pages>

   <page view-id="/calculator.jsp" action="#{calculator.calculate}">

      <param name="x" value="#{calculator.lhs}"/>

      <param name="y" value="#{calculator.rhs}"/>

      <param name="op" converter="#{operatorConverter}" value="#{calculator.op}"/>

   </page>

</pages

>

<pages>

    <page view-id="/blog.xhtml">

        <param name="date" 

               value="#{blog.date}" 

               validatorId="com.my.blog.PastDate" 

               required="true"/>

    </page>

</pages

>

<pages>

    <page view-id="/blog.xhtml">

        <param name="date" 

               value="#{blog.date}" 

               validator="#{pastDateValidator}" 

               required="true"/>

    </page>

</pages

>

<navigation-rule>

   <from-view-id

>/editDocument.xhtml</from-view-id>

    

   <navigation-case>

      <from-action

>#{documentEditor.update}</from-action>

      <from-outcome

>success</from-outcome>

      <to-view-id

>/viewDocument.xhtml</to-view-id>

      <redirect/>

   </navigation-case>

    

</navigation-rule

>

<page view-id="/editDocument.xhtml">

    

    <navigation from-action="#{documentEditor.update}">

        <rule if-outcome="success">

            <redirect view-id="/viewDocument.xhtml"/>

        </rule>

    </navigation>

    

</page

>

<page view-id="/editDocument.xhtml">

    

    <navigation from-action="#{documentEditor.update}" 

                   evaluate="#{documentEditor.errors.size}">

        <rule if-outcome="0">

            <redirect view-id="/viewDocument.xhtml"/>

        </rule>

    </navigation>

    

</page

>

<page view-id="/editDocument.xhtml">

    

    <navigation from-action="#{documentEditor.update}">

        <rule if="#{documentEditor.errors.empty}">

            <redirect view-id="/viewDocument.xhtml"/>

        </rule>

    </navigation>

    

</page

>

<page view-id="/editDocument.xhtml">

    

    <navigation from-action="#{documentEditor.update}">

        <rule if="#{documentEditor.errors.empty}">

            <end-conversation/>

            <redirect view-id="/viewDocument.xhtml"/>

        </rule>

    </navigation>

    

</page

>

<page view-id="/editDocument.xhtml">

    

    <navigation from-action="#{documentEditor.update}">

        <rule if="#{documentEditor.errors.empty}">

            <end-conversation/>

            <redirect view-id="/viewDocument.xhtml">

                <param name="documentId" value="#{documentEditor.documentId}"/>

            </redirect>

        </rule>

    </navigation>

    

</page

>

<page view-id="/editDocument.xhtml">

    

    <navigation from-action="#{documentEditor.update}">

        <rule>

            <render view-id="/viewDocument.xhtml"/>

        </rule>

    </navigation>

    

</page

>

<page view-id="/editDocument.xhtml">

    

    <navigation from-action="#{documentEditor.update}">

        <render view-id="/viewDocument.xhtml"/>

    </navigation>

    

</page

>

<page view-id="/editDocument.xhtml">



    <navigation>

        <rule if-outcome="success">

            <redirect view-id="/#{userAgent}/displayDocument.xhtml"/>

        </rule>

    </navigation>

    

</page

>

<page action="#{calculator.calculate}">

    <param name="x" value="#{calculator.lhs}"/>

    <param name="y" value="#{calculator.rhs}"/>

    <param name="op" converter="#{operatorConverter}" value="#{calculator.op}"/>

</page

>

<components>

    <event type="hello">

        <action execute="#{helloListener.sayHelloBack}"/>

        <action execute="#{logger.logHello}"/>

    </event>

</components

>

@Name("helloWorld")

public class HelloWorld {

    public void sayHello() {

        FacesMessages.instance().add("Hello World!");

        Events.instance().raiseEvent("hello");

    }

}

@Name("helloWorld")

public class HelloWorld {

    @RaiseEvent("hello")

    public void sayHello() {

        FacesMessages.instance().add("Hello World!");

    }

}

@Name("helloListener")

public class HelloListener {

    public void sayHelloBack() {

        FacesMessages.instance().add("Hello to you too!");

    }

}

@Name("helloListener")

public class HelloListener {

    @Observer("hello")

    public void sayHelloBack() {

        FacesMessages.instance().add("Hello to you too!");

    }

}

@Name("helloWorld")

public class HelloWorld {

    private String name;

    public void sayHello() {

        FacesMessages.instance().add("Hello World, my name is #0.", name);

        Events.instance().raiseEvent("hello", name);

    }

}

@Name("helloListener")

public class HelloListener {

    @Observer("hello")

    public void sayHelloBack(String name) {

        FacesMessages.instance().add("Hello #0!", name);

    }

}

public class LoggedInInterceptor {


   @AroundInvoke

   public Object checkLoggedIn(InvocationContext invocation) throws Exception {

   

      boolean isLoggedIn = Contexts.getSessionContext().get("loggedIn")!=null;

      if (isLoggedIn) {

         //the user is already logged in

         return invocation.proceed();

      }

      else {

         //the user is not logged in, fwd to login page

         return "login";

      }

   }


}

@Target(TYPE)

@Retention(RUNTIME)

@Interceptors(LoggedInInterceptor.class)

public @interface LoggedIn {}

@Stateless

@Name("changePasswordAction")

@LoggedIn

@Interceptors(SeamInterceptor.class)

public class ChangePasswordAction implements ChangePassword { 

    

    ...

    

    public String changePassword() { ... }

    

}

@Interceptor(around={BijectionInterceptor.class,

                     ValidationInterceptor.class,

                     ConversationInterceptor.class},

             within=RemoveInterceptor.class)

public class LoggedInInterceptor

{

    ...

}

@Interceptor(type=CLIENT)

public class LoggedInInterceptor

{

    ...

}

<filter>

    <filter-name

>Seam Filter</filter-name>

    <filter-class

>org.jboss.seam.servlet.SeamFilter</filter-class>

</filter>



<filter-mapping>

    <filter-name

>Seam Filter</filter-name>

    <url-pattern

>*.seam</url-pattern>

</filter-mapping

>

@HttpError(errorCode=404)

public class ApplicationException extends Exception { ... }

@Redirect(viewId="/failure.xhtml", end=true)

@ApplicationException(rollback=true)

public class UnrecoverableApplicationException extends RuntimeException { ... }

@Redirect(viewId="/error.xhtml", message="Unexpected error")

public class SystemException extends RuntimeException { ... }

<pages>

   

   <exception class="javax.persistence.EntityNotFoundException">

      <http-error error-code="404"/>

   </exception>

   

   <exception class="javax.persistence.PersistenceException">

      <end-conversation/>

      <redirect view-id="/error.xhtml">

          <message

>Database access failed</message>

      </redirect>

   </exception>

   

   <exception>

      <end-conversation/>

      <redirect view-id="/error.xhtml">

          <message

>Unexpected failure</message>

      </redirect>

   </exception>

   

</pages

>

...

throw new AuthorizationException("You are not allowed to do this!");



<pages>



    <exception class="org.jboss.seam.security.AuthorizationException">

        <end-conversation/>

        <redirect view-id="/error.xhtml">

            <message severity="WARN"

>#{org.jboss.seam.handledException.message}</message>

        </redirect>

    </exception>



</pages

>

    <exception class="org.jboss.seam.security.NotLoggedInException" log="false">

        <redirect view-id="/register.xhtml">

            <message severity="warn"

>You must be a member to use this feature</message>

        </redirect>

    </exception

>

    <exception class="org.jboss.seam.security.NotLoggedInException" logLevel="info">

        <redirect view-id="/register.xhtml">

            <message severity="warn"

>You must be a member to use this feature</message>

        </redirect>

    </exception

>

<exception class="javax.persistence.EntityNotFoundException">

   <redirect view-id="/error.xhtml">

      <message

>Not found</message>

   </redirect>

</exception>



<exception class="javax.persistence.OptimisticLockException">

   <end-conversation/>

   <redirect view-id="/error.xhtml">

      <message

>Another user changed the same data, please try again</message>

   </redirect>

</exception

>

<exception class="org.jboss.seam.framework.EntityNotFoundException">

   <redirect view-id="/error.xhtml">

      <message

>Not found</message>

   </redirect>

</exception

>

<exception class="org.jboss.seam.security.AuthorizationException">

   <redirect>

      <message

>You don't have permission to do this</message>

   </redirect>

</exception>

    

<exception class="org.jboss.seam.security.NotLoggedInException">

   <redirect view-id="/login.xhtml">

      <message

>Please log in first</message>

   </redirect>

</exception

>

<exception class="javax.faces.application.ViewExpiredException">

   <redirect view-id="/error.xhtml">

      <message

>Your session has timed out, please try again</message>

   </redirect>

</exception

>