Seam FrameworkCommunity Documentation

Chapter 31. Configuring Seam and packaging Seam applications

31.1. Basic Seam configuration
31.1.1. Integrating Seam with JSF and your servlet container
31.1.2. Seam Resource Servlet
31.1.3. Seam servlet filters
31.1.4. Integrating Seam with your EJB container
31.1.5. Don't forget!
31.2. Using Alternate JPA Providers
31.3. Configuring Seam in Java EE 6
31.3.1. Packaging
31.4. Configuring Seam without EJB
31.4.1. Boostrapping Hibernate in Seam
31.4.2. Boostrapping JPA in Seam
31.4.3. Packaging
31.5. Configuring Seam in Java SE
31.6. Configuring jBPM in Seam
31.6.1. Packaging
31.7. Deployment in JBoss AS 7
31.8. Configuring SFSB and Session Timeouts in JBoss AS 7
31.9. Running Seam in a Portlet
31.10. Deploying custom resources

Configuration is a very boring topic and an extremely tedious pastime. Unfortunately, several lines of XML are required to integrate Seam into your JSF implementation and servlet container. There's no need to be too put off by the following sections; you'll never need to type any of this stuff yourself, since you can just use seam-gen to start your application or you can copy and paste from the example applications!

First, let's look at the basic configuration that is needed whenever we use Seam with JSF.

Of course, you need a faces servlet!


<servlet>
    <servlet-name>Faces Servlet</servlet-name>
    <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>Faces Servlet</servlet-name>
    <url-pattern>*.seam</url-pattern>
</servlet-mapping>

(You can adjust the URL pattern to suit your taste.)

In addition, Seam requires the following entry in your web.xml file:


<listener>
    <listener-class>org.jboss.seam.servlet.SeamListener</listener-class>
</listener>

This listener is responsible for bootstrapping Seam, and for destroying session and application contexts.

There is a minor gray area in the JSF specification regarding the mutability of view state values. Since Seam uses the JSF view state to back its PAGE scope this can become an issue in some cases. If you're using server side state saving with the JSF-RI and you want a PAGE scoped bean to keep its exact value for a given view of a page you will need to specify the following context-param. Otherwise if a user uses the "back" button a PAGE scoped component will have the latest value if it has changed not the value of the "back" page. This setting is not enabled by default because of the performance hit of serializing the JSF view with every request.


<context-param>
    <param-name>com.sun.faces.serializeServerState</param-name>
    <param-value>true</param-value>
</context-param>

Seam doesn't need any servlet filters for basic operation. However, there are several features which depend upon the use of filters. To make things easier, Seam lets you add and configure servlet filters just like you would configure other built-in Seam components. To take advantage of this feature, we must first install a master filter in web.xml:


<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>/*</url-pattern>
</filter-mapping>

The Seam master filter must be the first filter specified in web.xml. This ensures it is run first.

The Seam filters share a number of common attributes, you can set these in components.xml in addition to any parameters discussed below:

Note that the patterns are matched against the URI path of the request (see HttpServletRequest.getURIPath()) and that the name of the servlet context is removed before matching.

Adding the master filter enables the following built-in filters.

In a Seam application, EJB components have a certain duality, as they are managed by both the EJB container and Seam. Actually, it's more that Seam resolves EJB component references, manages the lifetime of stateful session bean components, and also participates in each method call via interceptors. Let's start with the configuration of the Seam interceptor chain.

We need to apply the SeamInterceptor to our Seam EJB components. This interceptor delegates to a set of built-in server-side interceptors that handle such concerns as bijection, conversation demarcation, and business process signals. The simplest way to do this across an entire application is to add the following interceptor configuration in ejb-jar.xml:


<interceptors>
    <interceptor>
        <interceptor-class>org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
    </interceptor>
</interceptors>
   
<assembly-descriptor>
    <interceptor-binding>
        <ejb-name>*</ejb-name>
        <interceptor-class>org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
    </interceptor-binding>
</assembly-descriptor>

Seam needs to know where to go to find session beans in JNDI. One way to do this is specify the @JndiName annotation on every session bean Seam component. However, this is quite tedious. A better approach is to specify a pattern that Seam can use to calculate the JNDI name from the EJB name. Fortunately, new portable JNDI Syntax was introduced in Java EE 6. There are three JNDI namespaces for portable JNDI lookups - java:global, java:module and java:app. More in Java EE 6 tutorial We usually specify this option in components.xml.

For JBoss AS 7, the following pattern is correct:


<core:init jndi-name="java:app/<ejb-module-name>/#{ejbName}" />

In this case, <ejb-module-name> is the name of the EJB module (by default it is filename of ejb jar) in which the bean is deployed, Seam replaces #{ejbName} with the name of the EJB.

How these JNDI names are resolved and somehow locate an EJB component might appear a bit like black magic at this point, so let's dig into the details. First, let's talk about how the EJB components get into JNDI.

EJB components would get assigned a global JNDI name automatically, using the pattern described in Java EE 6 tutorial. The EJB name is the first non-empty value from the following list:

  • The value of the <ejb-name> element in ejb-jar.xml

  • The value of the name attribute in the @Stateless or @Stateful annotation

  • The simple name of the bean class

Let's look at an example. Assume that you have the following EJB bean and interface defined.

package com.example.myapp;


import javax.ejb.Local;
@Local
public interface Authenticator
{
    boolean authenticate();
}
package com.example.myapp;
import javax.ejb.Stateless;
@Stateless
@Name("authenticator")
public class AuthenticatorBean implements Authenticator
{ 
    public boolean authenticate() { ... }
}

Assuming your EJB bean class is deployed in an EAR named myapp, the global JNDI name myapp/AuthenticatorBean/local will be assigned to it on JBoss AS. As you learned, you can reference this EJB component as a Seam component with the name authenticator and Seam will take care of finding it in JNDI according to the JNDI pattern (or @JndiName annotation).

So what about the rest of the application servers? Well, according to the Java EE spec, which most vendors try to adhere to religiously, you have to declare an EJB reference for your EJB in order for it to be assigned a JNDI name. That requires some XML. It also means that it is up to you to establish a JNDI naming convention so that you can leverage the Seam JNDI pattern. You might find the JBoss convention a good one to follow.

There are two places you have to define the EJB reference when using Seam on non-JBoss application servers. If you are going to be looking up the Seam EJB component through JSF (in a JSF view or as a JSF action listener) or a Seam JavaBean component, then you must declare the EJB reference in web.xml. Here is the EJB reference for the example component just shown:


<ejb-local-ref>
    <ejb-ref-name>myapp/AuthenticatorBean</ejb-ref-name>
    <ejb-ref-type>Session</ejb-ref-type>
    <local>org.example.vehicles.action.Authenticator</local>
</ejb-local-ref>

This reference will cover most uses of the component in a Seam application. However, if you want to be able to inject a Seam EJB component into another Seam EJB component using @In, you need to define this EJB reference in another location. This time, it must be defined in ejb-jar.xml, and it's a bit tricker.

Within the context of an EJB method call, you have to deal with a somewhat sheltered JNDI context. When Seam attempts to find another Seam EJB component to satisfy an injection point defined using @In, whether or not it finds it depends on whether an EJB reference exists in JNDI. Strictly speaking, you cannot simply resolve JNDI names as you please. You have to define the references explicitly. Fortunately, JBoss recognized how aggravating this would be for the developer and all versions of JBoss automatically register EJBs so they are always available in JNDI, both to the web container and the EJB container. So if you are using JBoss, you can skip the next few paragraphs. However, if you are deploying to GlassFish, pay close attention.

For application servers that stubbornly adhere to the EJB specification, EJB references must always be defined explicitly. But unlike with the web context, where a single resource reference covers all uses of the EJB from the web environment, you cannot declare EJB references globally in the EJB container. Instead, you have to specify the JNDI resources for a given EJB component one-by-one.

Let's assume that we have an EJB named RegisterAction (the name is resolved using the three steps mentioned previously). That EJB has the following Seam injection:

@In(create = true)

Authenticator authenticator;

In order for this injection to work, the link must be established in the ejb-jar.xml file as follows:


<ejb-jar>
    <enterprise-beans>
        <session>
            <ejb-name>RegisterAction</ejb-name>
            <ejb-local-ref>
                <ejb-ref-name>myapp/AuthenticatorAction/local</ejb-ref-name>
                <ejb-ref-type>Session</ejb-ref-type>
                <local>com.example.myapp.Authenticator</local>
            </ejb-local-ref>
        </session>
    </enterprise-beans>

    ...
    
</ejb-jar>

Notice that the contents of the <ejb-local-ref> are identical to what we defined in web.xml. What we are doing is bringing the reference into the EJB context where it can be used by the RegisterAction bean. You will need to add one of these references for any injection of a Seam EJB component into another Seam EJB component using @In. (You can see an example of this setup in the jee5/booking example).

But what about @EJB? It's true that you can inject one EJB into another using @EJB. However, by doing so, you are injecting the actual EJB reference rather than the Seam EJB component instance. In this case, some Seam features will work, while others won't. That's because Seam's interceptor is invoked on any method call to an EJB component. But that only invokes Seam's server-side interceptor chain. What you lose is Seam's state management and Seam's client-side interceptor chain. Client-side interceptors handle concerns such as security and concurrency. Also, when injecting a SFSB, there is no guarantee that you will get the SFSB bound to the active session or conversation, whatever the case may be. Thus, you definitely want to inject the Seam EJB component using @In.

Finally, let's talk about transactions. In an EJB environment, we recommend the use of a special built-in component for transaction management, that is fully aware of container transactions, and can correctly process transaction success events registered with the Events component. If you don't add this line to your components.xml file, Seam won't know when container-managed transactions end:


<transaction:ejb-transaction/>

Seam comes packaged and configured with Hibernate as the default JPA provider. If you require using a different JPA provider you must tell seam about it.

Telling seam about a different JPA provider can be done in one of two ways:

Update your application's components.xml so that the generic PersistenceProvider takes precedence over the hibernate version. Simply add the following to the file:


<component name="org.jboss.seam.persistence.persistenceProvider" 
           class="org.jboss.seam.persistence.PersistenceProvider"
           scope="stateless">
</component>

If you want to take advantage of your JPA provider's non-standard features you will need to write you own implementation of the PersistenceProvider. Use HibernatePersistenceProvider as a starting point (don't forget to give back to the community :). Then you will need to tell seam to use it as before.


<component name="org.jboss.seam.persistence.persistenceProvider" 
           class="org.your.package.YourPersistenceProvider">
</component>

All that is left is updating the persistence.xml file with the correct provider class, and what ever properties your provider needs. Don't forget to package your new provider's jar files in the application if they are needed.

If you're running in a Java EE environment, this is all the configuration required to start using Seam!

Once you've packaged all this stuff together into an EAR, the archive structure will look something like this:

my-application.ear/
    jboss-seam.jar
    lib/
        jboss-el.jar
    META-INF/
        MANIFEST.MF
        application.xml
        jboss-deployment-structure.xml
    my-application.war/
        META-INF/
            MANIFEST.MF
        WEB-INF/
            web.xml
            components.xml
            faces-config.xml
            lib/
                jboss-seam-ui.jar
        login.jsp
        register.jsp
        ...
    my-application.jar/
        META-INF/
            MANIFEST.MF
            persistence.xml
        seam.properties
        org/
            jboss/
                myapplication/
                    User.class
                    Login.class
                    LoginBean.class
                    Register.class
                    RegisterBean.class
                    ...

You should declare jboss-seam.jar as an ejb module in META-INF/application.xml; jboss-el.jar should be placed in the EAR's lib directory (putting it in the EAR classpath.

If you want to use jBPM or Drools, you must include the needed jars in the EAR's lib directory.

If you want to use the Seam tag library (most Seam applications do), you must include jboss-seam-ui.jar in the WEB-INF/lib directory of the WAR. If you want to use the PDF or email tag libraries, you need to put jboss-seam-pdf.jar or jboss-seam-mail.jar in WEB-INF/lib.

If you want to use the Seam debug page (only works for applications using facelets), you must include jboss-seam-debug.jar in the WEB-INF/lib directory of the WAR.

Seam ships with several example applications that are deployable in any Java EE container that supports EJB 3.1.

faces-config.xml is not required in JSF 2, but if you want to set up something non-default you need to place it in WAR/WEB-INF.

I really wish that was all there was to say on the topic of configuration but unfortunately we're only about a third of the way there. If you're too overwhelmed by all this tedious configuration stuff, feel free to skip over the rest of this section and come back to it later.

Seam is useful even if you're not yet ready to take the plunge into EJB 3.1. In this case you would use Hibernate 4 instead of EJB 3.1 persistence, and plain JavaBeans instead of session beans. You'll miss out on some of the nice features of session beans but it will be very easy to migrate to EJB 3.1 when you're ready and, in the meantime, you'll be able to take advantage of Seam's unique declarative state management architecture.

Seam JavaBean components do not provide declarative transaction demarcation like session beans do. You could manage your transactions manually using the JTA UserTransaction or declaratively using Seam's @Transactional annotation. But most applications will just use Seam managed transactions when using Hibernate with JavaBeans.

The Seam distribution includes a version of the booking example application that uses Hibernate and JavaBeans instead of EJB, and another version that uses JPA and JavaBeans. These example applications are ready to deploy into any Java EE application server.

It is possible to use Seam completely outside of an EE environment. In this case, you need to tell Seam how to manage transactions, since there will be no JTA available. If you're using JPA, you can tell Seam to use JPA resource-local transactions, ie. EntityTransaction, like so:


<transaction:entity-transaction entity-manager="#{entityManager}"/>

If you're using Hibernate, you can tell Seam to use the Hibernate transaction API like this:


<transaction:hibernate-transaction session="#{session}"/>

Of course, you'll also need to define a datasource.

Seam's jBPM integration is not installed by default, so you'll need to enable jBPM by installing a built-in component. You'll also need to explicitly list your process and pageflow definitions. In components.xml:


<bpm:jbpm>
    <bpm:pageflow-definitions>
        <value>createDocument.jpdl.xml</value>
        <value>editDocument.jpdl.xml</value>
        <value>approveDocument.jpdl.xml</value>
    </bpm:pageflow-definitions>
    <bpm:process-definitions>
        <value>documentLifecycle.jpdl.xml</value>
    </bpm:process-definitions>
</bpm:jbpm>

No further special configuration is needed if you only have pageflows. If you do have business process definitions, you need to provide a jBPM configuration, and a Hibernate configuration for jBPM. The Seam DVD Store demo includes example jbpm.cfg.xml and hibernate.cfg.xml files that will work with Seam:


<jbpm-configuration>

  <jbpm-context>
    <service name="persistence">
       <factory>
          <bean class="org.jbpm.persistence.db.DbPersistenceServiceFactory">
             <field name="isTransactionEnabled"><false/></field>
          </bean>
       </factory>
    </service>
    <service name="tx" factory="org.jbpm.tx.TxServiceFactory" />
    <service name="message" factory="org.jbpm.msg.db.DbMessageServiceFactory" />
    <service name="scheduler" factory="org.jbpm.scheduler.db.DbSchedulerServiceFactory" />
    <service name="logging" factory="org.jbpm.logging.db.DbLoggingServiceFactory" />
    <service name="authentication" 
             factory="org.jbpm.security.authentication.DefaultAuthenticationServiceFactory" />
  </jbpm-context>

</jbpm-configuration>

The most important thing to notice here is that jBPM transaction control is disabled. Seam or EJB3 should control the JTA transactions.

JBoss AS 7 is default deployment target for all examples in Seam 2.3 distribution.

Seam 2.3 requires to have setup special deployment metada file jboss-deployment-structure.xml for correct initialization. Minimal content for EAR is:


Deployment of multiple modules in one EAR

There is a significant enhancement for speed up the application deployment in AS 7. This unfortunatelly can cause some issues while you have multiple war/ejb modules in your application.

This situation requires to use and set up new Java EE 6 configuration parameter - Module initialization order - in application.xml - initialize-in-order to true. This causes that initialization will happen in defined order like it is in application.xml. Example of application.xml:

<?xml version="1.0" encoding="UTF-8"?>
<application xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  version="6" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/application_6.xsd">
  <application-name>test-app</application-name>
  <initialize-in-order>true</initialize-in-order>
  <module>
    <ejb>jboss-seam.jar</ejb>
  </module>
  <module>
    <web>
      <web-uri>test-web1.war</web-uri>
      <context-root>test</context-root>
    </web>
    <web>
      <web-uri>test-web2.war</web-uri>
      <context-root>test</context-root>
    </web>
  </module>
</application>

If you are using maven-ear-plugin for generation of your application, you can use this plugin configuration:

<plugin>
    <artifactId>maven-ear-plugin</artifactId>
    <!-- from version 2.6 the plugin supports Java EE 6 descriptor -->
    <version>2.7</version>
    <configuration> 
        <version>6</version>
        <generateApplicationXml>true</generateApplicationXml> 
        <defaultLibBundleDir>lib</defaultLibBundleDir>                
        <initializeInOrder>true</initializeInOrder>
        <modules> 
            <jarModule> 
                <groupId>org.jboss.el</groupId> 
                <artifactId>jboss-el</artifactId> 
                <includeInApplicationXml>false</includeInApplicationXml> 
                <bundleDir>lib</bundleDir> 
            </jarModule> 
            <ejbModule> 
                <groupId>org.jboss.seam</groupId> 
                <artifactId>jboss-seam</artifactId> 
                <bundleFileName>jboss-seam.jar</bundleFileName>                         
            </ejbModule> 
            <ejbModule> 
                <groupId>some.user.module</groupId> 
                <artifactId>hello-ejbs</artifactId> 
                <bundleFileName>hello-ejbs.jar</bundleFileName>                         
            </ejbModule> 
            <webModule> 
                <groupId>some.user.module</groupId> 
                <artifactId>hello-web1</artifactId> 
                <contextRoot>/hello1</contextRoot> 
                <bundleFileName>hello-web1.war</bundleFileName> 
            </webModule> 
            <webModule> 
                <groupId>some.user.module</groupId> 
                <artifactId>hello-web2</artifactId> 
                <contextRoot>/hello2</contextRoot> 
                <bundleFileName>hello-web2.war</bundleFileName> 
            </webModule>                                         
        </modules> 
    </configuration> 
</plugin>

It is very important that the timeout for Stateful Session Beans is set higher than the timeout for HTTP Sessions, otherwise SFSB's may time out before the user's HTTP session has ended. JBoss Application Server has a default session bean timeout of 30 minutes, which is configured in standalone/configuration/standalone.xml (replace standalone.xml with your standalone-full.xml if you use full profile).

The default SFSB timeout can be adjusted by modifying the value of default-access-timeout in the EJB subsystem subsystem xmlns="urn:jboss:domain:ejb3:1.2":


<subsystem xmlns="urn:jboss:domain:ejb3:1.2">
            <session-bean>
                <stateless>
                    <bean-instance-pool-ref pool-name="slsb-strict-max-pool"/>
                </stateless>
                <stateful default-access-timeout="5000" cache-ref="simple"/>
                <singleton default-access-timeout="5000"/>
            </session-bean>
            ...
</subsystem>

The default HTTP session timeout can't be modified in JBoss AS 7.

To override default value for your own application, simply include session-timeout entry in your application's own web.xml:

        <session-config>
            <session-timeout>30</session-timeout>
        </session-config>

If you want to run your Seam application in a portlet, take a look at the JBoss Portlet Bridge, an implementation of JSR-301 that supports JSF within a portlet, with extensions for Seam and RichFaces. See http://labs.jboss.com/portletbridge for more.

Seam scans all jars containing /seam.properties, /META-INF/components.xml or /META-INF/seam.properties on startup for resources. For example, all classes annotated with @Name are registered with Seam as Seam components.

You may also want Seam to handle custom resources. A common use case is to handle a specific annotation and Seam provides specific support for this. First, tell Seam which annotations to handle in /META-INF/seam-deployment.properties:

# A colon-separated list of annotation types to handle
org.jboss.seam.deployment.annotationTypes=com.acme.Foo:com.acme.Bar

Then, during application startup you can get hold of all classes annotated with @Foo:

@Name("fooStartup")

@Scope(APPLICATION)
@Startup
public class FooStartup {
   @In("#{deploymentStrategy.annotatedClasses['com.acme.Foo']}")
   private Set<Class<Object>> fooClasses;
   
   @In("#{hotDeploymentStrategy.annotatedClasses['com.acme.Foo']}")
   private Set<Class<Object>> hotFooClasses;
   @Create
   public void create() {
      for (Class clazz: fooClasses) {
         handleClass(clazz);
      }
      for (Class clazz: hotFooClasses) {
         handleClass(clazz);
      }
   }
   
   public void handleClass(Class clazz) {
       // ...
   }
}

You can also handle any resource. For example, you process any files with the extension .foo.xml. To do this, we need to write a custom deployment handler:

public class FooDeploymentHandler implements DeploymentHandler {

    private static DeploymentMetadata FOO_METADATA = new DeploymentMetadata()
    {
        public String getFileNameSuffix() {
            return ".foo.xml";
        }
    };
    
   public String getName() {
      return "fooDeploymentHandler";
   }
    public DeploymentMetadata getMetadata() {
        return FOO_METADATA;
    }
}

Here we are just building a list of any files with the suffix .foo.xml.

Then, we need to register the deployment handler with Seam in /META-INF/seam-deployment.properties. You can register multiple deployment handler using a comma separated list.

# For standard deployment
org.jboss.seam.deployment.deploymentHandlers=com.acme.FooDeploymentHandler
# For hot deployment
org.jboss.seam.deployment.hotDeploymentHandlers=com.acme.FooDeploymentHandler

Seam uses deployment handlers internally to install components and namespaces. You can easily access the deployment handler during an APPLICATION scoped component's startup:

@Name("fooStartup")

@Scope(APPLICATION)
@Startup
public class FooStartup {
   @In("#{deploymentStrategy.deploymentHandlers['fooDeploymentHandler']}")
   private FooDeploymentHandler myDeploymentHandler;
   
   @In("#{hotDeploymentStrategy.deploymentHandlers['fooDeploymentHandler']}")
   private FooDeploymentHandler myHotDeploymentHandler;
   @Create
   public void create() {
      for (FileDescriptor fd: myDeploymentHandler.getResources()) {
           handleFooXml(fd);
      }
      
      for (FileDescriptor f: myHotDeploymentHandler.getResources()) {
           handleFooXml(fd);
      }
   }
   public void handleFooXml(FileDescriptor fd) {
       // ...
   }
}