Sunday, 1 February 2015

JBoss Application Server Interview Questions and Answers

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)
? HA-JNDI
? HTTP session replications (tc5-cluster-service.xml)
? Farming
? HA-JMS

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 multi-ple application servers.
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