20+ TOP JBoss Interview Questions & Answers
1. Can I unit test Seam applications without starting the Application Server?
Yes, Seam provides its own integration test framework based on TestNG. You can easily mock all Seam services using those facilities without ever loading an application server or a database. Refer to the testexample ANT target in the Seam booking example application for more details.
2. Can I use AJAX with Seam?
3. Is it true that Seam only works with JSF?
Seam only supports JSF as a view framework at this time. We plan to support other web frameworks in the future. We like JSF because it is a component-based UI framework, which fits really well with Seam’s component-based approach to business objects and persistence objects. Seam made a major improvement to JSF by eliminating almost all XML configuration for backing beans — you can now define back beans from POJOs or EJB3 components using simple annotations. We recommend you use Facelets, instead of JSP, with JSF. Facelets provide a powerful templating framework, better appplication performance, and allows us to write much simpler JSF pages. Please see the Seam booking example application for an example on how to use Facelets.
4. Where can I find Seam examples and documentation?
The source code and build script of all Seam example applications are included in the examples directory of the Seam distribution.
5. Can I run Seam with JDK 1.4 and earlier?
No, Seam only works on JDK 5.0 and above. It uses annotations and other JDK 5.0 features.
6. Can I run Seam in a J2EE environment?
Yes, as of Seam 1.1, you can use Seam in any J2EE application server, with one caveat: you will not be able to use EJB 3.0 session beans. However, you can use either Hibernate or JPA for persistence, and you can use Seam JavaBean components instead of session beans.
7. Can I run Seam outside of JBoss AS?
Yes, you can run Seam applications in plain Tomcat 5.5+ or in the Sun GlassFish application server. To run Seam application in Tomcat, you need a number of additional library files and a few configuration files to bootstrap the JBoss EJB3 inside Tomcat. Please refer to the deploy.tomcat ANT build target for the Seam booking example (in the examples/booking directory of the Seam distribution) for more on how to build a Tomcat WAR for Seam applications. Refer to this blog post on how to run Seam in Sun’s Glassfish application server.
8. What version of JBoss AS do I need to run Seam?
For Seam 1.3: Seam was developed against JBoss 4.2. Seam can still be run against JBoss 4.0. The seam documentation contains instructions for configuring JBoss 4.0.
For Seam 1.2: Since Seam requires the latest edition of EJB3, you need to install JBoss AS from the latest JEMS installer. Make sure that you select the “ejb3” or “ejb3+clustering” profile to include EJB3 support. Also, the jboss-seam.jar library file from the Seam distribution must be included in each Seam application you deploy. Refer to examples in Seam distribution (inside the examples directory) to see how to build and package Seam applications.
9. Do you know how you could add support for Web Service transactions?
JBossTS supports Web Services transactions, including extended transaction models designed specifically for loosely-coupled, long running business processes. J2EE transactions can integrate seamlessly with Web Services transactions using our integrated, bi-directional transaction bridge. Interoperability with many other vendors is provided out-of-the-box and JBoss is an active participant in these standards.
10. What is the difference between JAX–WS and JAX-RPC?
Java API for XML-Based RPC (JAX-RPC) is a Legacy Web Services Java API, it uses SOAP and HTTP to do RPCs over the network and enables building of Web services and Web applications based on the SOAP 1.1 specification, Java SE 1.4 or lower.JAX-WS 2.0 is the successor to JAX-RPC 1.1. JAX-WS still supports SOAP 1.1 over HTTP 1.1, so interoperability will not be affected. However there are lots of differences:
? JAX-WS maps to Java 5.0 and relies on many of the features new in Java 5.0 like Web Service annotations.
? JAX-RPC has its own data mapping model, JAX-WS’s data mapping model is JAXB. JAXB promises mappings for all XML schemas.
? JAX-WS introduces message-oriented functionality, dynamic asynchronous functionality which are missing in JAX-RPC.
? JAX-WS also add support, via JAXB, for MTOM, the new attachment specification.
11. What do you think about BPEL and BPM ? How do they compare?
In my opinion BPEL and BPM are quite different things so they cannot even be compared. The problems boils down to the fact that these years maybe BPEL has been marketed for something which isn’t: that is a Business Process Management framework.
BPEL is made up for service orchestration, that is publishing new services as a function of other services.
while BPM si needed for handling human task management functionalities and subprocess management.
12. How would you convince my IT department to adopt SOA?
In my opinion one of the biggest obstacle in the movement towards SOA adoption is the organization?s own IT department.Too many people in the IT organization conceive SOA as a technology concept only, and as such think of SOA as just a set of technologies and infrastructure for exposing, securing, running, and managing Services. Put it this way, SOA is nothing more than Web Services and standardized middleware. The critical flaw in thinking is confusing the technology that sits beneath the Services level of abstraction and the mechanism by which Services are accessed with the architectural approach that aims to decouple the implementation from the consumption and focus on sustainable architecture that allows for continuous change.
Successful SOA adoption requires a cultural shift in the way IT is done. The Service-oriented movement to agility and loose coupling demands a shift from traditional, waterfall styles of development (design-build-test-deploy-manage) to iterative approaches to continuous Service modeling
13. Which JDK is needed to run Seam?
Seam only works on JDK 5.0 and above. It uses annotations and other JDK 5.0 features.
14. Does Seam run on other application servers besides JBoss?
Seam runs beautifully on other application servers – just like everything else the Hibernate team does, this is not a JBoss-only thing.
15. What do you know about Seam?
Built on the standards JavaServer Faces and EJB 3.0, JBoss Seam unifies component and programming models and delivers a consistent and powerful framework for rapid creation of web applications with Java EE 5.0. Seam simplifies web application development and enables new functionality that was difficult to implement by hand before, such as stateful conversations, multi-window operation, and handling concurrent fine-grained AJAX requests. Seam also unifies and integrates popular open source technologies like Facelets, Hibernate, iText, and Lucene.
16. Is it possible to put a JBoss server instance into multiple cluster at the same time?
It is technically possible to put a JBoss server instance into multiple clusters at the same time, this practice is generally not recommended, as it increases the management complexity.
17. Which component handles cluster communication in JBoss?
The JGroups framework provides services to enable peer-to-peer communications between nodes in a cluster. It is built on top a stack of network communication protocols that provide transport, discovery, reliability and failure detection, and cluster membership management services.
18. What optimization could I use if the EJB container is the only point of write access to the database?
You could activate the “Commit Option A” that is the container caches entity bean state between transactions. This option assumesthat the container has exclusive access to the persistentstore and therefore it doesn?t need to synchronizethe in-memory bean state from the persistent store at the beginning of each transaction.
19. What do you need to set-up a cluster with JBoss?
Basically starting JBoss with the ?all? configuration contains everything needed for clustering:
It has all the libraries for clustering:
? JGroups.jar, jboss-cache.jar
? Clustered beans (cluster-service.xml)
? HTTP session replications (tc5-cluster-service.xml)
20. What is the diffrence between a local-tx-datasource and a xa-datasource? can you use transactions in both?
A local-tx-datasource identifies a data source that uses transactions, even distributed trans actions within the local application server, but doesn?t use distributed transactions among multiple application servers. An xa-datasource on the other hand identifies a data source that uses distributed transaction among multiple pplication servers.