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二つの基本概念が存在します。 最初のものは、イベントがJSFライクなメソッドバインディング式（method binding expression) を通じ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

>

<pages>

    <page view-id="/hello.jsp">

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

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

    </page>

</pages

>

<pages>

    <page view-id="/dashboard.xhtml">

        <action execute="#{dashboard.loadData}"

            if="#{not facesContext.renderKit.responseStateManager.isPostback(facesContext)}"/>

    </page>

</pages>

<pages>

    <page view-id="/dashboard.xhtml">

        <action execute="#{dashboard.loadData}" on-postback="false"/>

    </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" log-level="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

>