Jboss Seam interview questions

Seam Interview Questions

Q: What is Jboss Seam?
Ans:

Seam is an Enterprise Java application framework.

• Seam works in your application server that supports EJB 3.0.
• Seam framework can be used in you application using JSF, Hibernate/JPA/JDBC etc, JavaBeans (Business Logic)
• Seam can be stateful, with state associated with the conversation context, long-running context, business process context, persistent , which maintain state across multiple web requests in a user conversations.

Q: Why Seam?
Ans:

• Keeping AJAX in mind, Seam's completely unique concurrency model and state-management system were developed and designed.
• Seam integrates jBPM deeply and makes using jBPM for task management or pageflow incredibly easy, and is a perfect way to get started with BPM technology
• This is the best way to develop application using JSF.
• Seam has been developed for use with EJB 3.0 and can be used everywhere with the latest module framework.
• Seam's conversation model resolves a number of programming problems related to persistence caused by conventional stateless architecture for web applications. Seam allows using extended persistence contexts in a simple way, and lets you avoid unnecessary replication of the state when using an extended context of persistence in a clustered environment.
• When it is a matter of creating easy data-driven applications, seam is as efficient as every other crop of CRUD frames.
• Seam presents a new automated integration testing approach, which allows you to simulate the entire request or conversation process.
• The Seam project is completely committed to the idea of open source new ideas and developments in the Java platform.
• Seam is the first programming model which can be used from the persistence layer up to the UI using Java 5 annotations end to end.

Q: Does Seam support internationalization?
Ans:

Seam includes multiple JSF extensions, which make internationalized user interfaces super-easy and super-elegant.

Q: What does it mean by conversation model
Ans:

• During the application request values, process validations, updating model values, invoking application and rendering response phases of the JSF request lifecycle, a conversation context is always active.
• Seam attempts to restore a long-running conversation context after the restoration process of the JSF request life cycle. If there is none, Seam will create a new temporary context for conversation.
• The temporary conversation context is transferred to a long-running conversation when a @Begin method is encountered.
• Any long-running conversation context is demoted into a temporary conversation when a @End method is encountered.
• Seam stores the contents of a long-running conversation context or removes the contents of a temporary conversation context at the end of the JSF request lifecycle's render response phase.
• Any request for faces (JSF postback) will distribute the conversation context.By default, requests for non-faces (e.g. GET requests) do not distribute conversation context.
• If a redirect foreshort the lifecycle of the JSF query, Seam can transparently store and restore the current conversation context unless the conversation has already been completed via@End(beforeRedirect = true).

Seam propagates the conversation context through JSF postbacks and redirects in a transparent manner (by considering temporary conversation context). If you do nothing different, a non-face request (for example, a GET request) will not spread the context of the conversation and will be handled in a new temporary conversation. This is typically the desired behavior, however not always

Q: How to configure Seam Listener?
Ans:

To manage Seam context, add Seam servlet listener in your web.xml.

<faces-config>
. . .
 <lifecycle>
  <phase-listener>org.jboss.seam.jsf.SeamPhaseListener</phase-listener>
 </lifecycle>
. . .
</faces-config>

Q: How to configure JSF Phase Listener?
Ans:

Seam Phase Listener handles the Seam contexts associated with a JSF request throughout the application's lifecycle. Add below entry in faces-config.xml.

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

Q: How to configure EJB Seam Interceptor?
Ans:

Declare EJB SeamInterceptor in ejb-jar.xml file.

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

Q: Where to define Seam's core initialization component?
Ans:

For Seam to use the EJB container, a Seam core initialization module entry must be included in Seam's components.xml.

<?xml version="1.0" encoding="UTF-8"?>
<components xmlns="http://jboss.com/products/seam/components"
            xmlns:core="http://jboss.com/products/seam/core"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation=
                "http://jboss.com/products/seam/core http://jboss.com/products/seam/core-2.0.xsd
                 http://jboss.com/products/seam/components http://jboss.com/products/seam/components-2.0.xsd">

    <core:init jndi-pattern="@jndiPattern@"/>

</components>

Q: How can I access Session or Seam Request?
Ans:

• Using ServletContexts.instance().getRequest() in your backing bean.
• Inject the HttpServletRequest or HttpSession directly from your Seam component by declaring factory component descriptor.

<factory name="httpRequest"
  value="{facesContext.externalContext.request}"
  auto-create="true"/>
<factory name="httpSession"
  value="{facesContext.externalContext.request.session}"
  auto-create="true"/>

Q: How to use conversation in application?
Ans:

If you wantur to propagate a Seam conversation across a non-faces request, you need to explicitly code the Seam conversation id as a request parameter: Or, the more JSF-ish: If you use the Seam tag library, this is equivalent: If you wish to disable propagation of the conversation context for a postback, a similar trick is used: If you use the Seam tag library, this is equivalent: Note that disabling conversation context propagation is absolutely not the same thing as ending the conversation. The conversationPropagation request parameter, or the <s:conversationPropagation> tag may even be used to begin and end conversation, or begin a nested conversation.

Q: What is workspace management?
Ans:

The user is able to switch between many conversations within the same browser window. This feature is called workspace management.

Q: What is nested conversation?
Ans:

A nested conversation is created by invoking a method marked @Begin(nested=true) inside the scope of an existing conversation. A nested conversation has its own conversation context, but can read values from the outer conversation's context.