Top 37 Jbpm Interview Questions You Must Prepare 14.Jun.2024

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 be (cluster-service.xml)
  • HA-JNDI
  • HTTP session replications (tc5-cluster-service.xml)
  • Farming

Global is the keyword used in drools to define a global variable. Global variable is the one which will be visible to all the rules inside a DRL file.

Globals must be used very carefully in a DRL file, since the changes in a global variable are not notified to the working memory. For example, you are using a list variable as a global and in any rule you are adding a value in a list and in one particular rule, you are checking if list size() > 0, then in this case rule may not fire. Global variable can be used for any type of object.

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 be. However, you can use either Hibernate or JPA for persistence, and you can use Seam JavaBean components instead of session be.

The jBPM GPD is an eclipse plugin that targets usage by multiple roles. Both the business analyst and developer are able to use the same tool in different ways. The main reason why we think it is important to integrate those two in one single environment is because in many teams, these two roles are done by one person.  Then it becomes very important that the tool can support both roles and gradually shift from being a diagramming tool to an implementation tool.

  • Different components of the application are to be measured. This step is to find where the degradation is, whether it is external or internal and where is the application spending all the time. Using Joss JMX agents and monitoring the deployed components to the application server involves in the first step.
  • After finding the most of the time spent by specific components or libraries or most of the resources, one can use Jprobe a specialized tool for examining the single object or the objects loaded in the memory.

A local-tx-datasource identifies a data source that uses tractions, even distributed tr actions within the local application server, but doesn’t use distributed tractions among multiple application servers. An xa-datasource on the other hand identifies a data source that uses distributed traction among multi-ple application servers.

For Seam 1.3: Seam was developed against JBoss 4.@Seam can still be run against JBoss 4.@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.

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.

The jBPM GPD is an eclipse plugin that targets usage by multiple roles.  Both the business analyst and developer are able to use the same tool in different ways.  The main reason why we think it is important to integrate those two in one single environment is because in many teams, these two roles are done by one person.  Then it becomes very important that the tool can support both roles and gradually shift from being a diagramming tool to an implementation tool.

This business process allows you to model your business goals by describing the steps that need to be executed to achieve that goal and the order, using a flow chart. This greatly improves the visibility and agility of your business logic, results in higher-level and domain-specific representations that can be understood by business users and is easier to monitor.The core of jBPM is a light-weight, extensible workflow engine written in pure Java that allows you to execute business processes using the latest BPMN 2.0 specification. It can run in any Java environment, embedded in your application or as a service.

The source code and build script of all Seam example applications are included in the examples directory of the Seam distribution.

jBPM5 provides a different computational model for business process and rule. This model is based on a knowledge-oriented approach, where the application is not process-oriented or rules-oriented, but the end users can simply select between different paradigms to represent their business logic. All tools and interfaces the user is confronted with support this idea of a unified environment throughout the entire knowledge life cycle.

JBossCache enables easy distribution of datasets across your computing environments. It is based on JGroups and enables clustering and high availability of that data. You may choose to distribute the data with JBoss Messaging to move it where it is needed for computation or event-based programming.

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.@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.

JBoss registers in the JNDI tree a JTA UserTraction Object which can be user to manage a distributed traction.

Seam runs beautifully on other application servers – just like everything else the Hibernate team does, this is not a JBoss-only thing.

BPM stands for Business Process Management.  There are 2 different aspects of BPM: BPM as management discipline and BPM as software engineering.  The BPM vendors have long time tried to make abstraction of those 2 distinct aspects.  That path lead to more confusion then anything else.BPM as a management discipline is the responsibility of every strategic executive manager.  It’s to ensure that the organization performs well in their core business processes.  This involves understanding what values the organization delivers and how those are achieved.  This me analyzing, documenting and improving the way that people and systems work together.  As part of that work, it’s useful to work with models and diagrams.   BPMN diagrams express the execution flow of the steps to accomplish a certain goal.   Important to note that these models are used for people to people communication.  They can be underspecified, which me that they can contain valuable high level information without including unnecessary details.  Such underspecified process models are also known as abstract business processes.

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 be — you can now define back be 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 application performance, and allows us to write much simpler JSF pages.

Java Traction API (JTA) specifies standard Java interfaces between a traction manager and the parties involved in a distributed traction system: the resource manager, the application server, and the tractional applications.

The Javaâ„¢ Traction API (JTA) allows applications to perform distributed tractions, that is, tractions that access and update data on two or more networked computer resources.

The Java Traction API consists of three elements: a high-level application traction demarcation interface, a high-level traction manager interface intended for an application server, and a standard Java mapping of the X/Open XA protocol intended for a tractional resource manager.

JBossTS supports Web Services tractions, including extended traction models designed specifically for loosely-coupled, long running business processes. J2EE tractions can integrate seamlessly with Web Services tractions using our integrated, bi-directional traction bridge. Interoperability with many other vendors is provided out-of-the-box and JBoss is an active participant in these standards.

Yes, Seam provides excellent support for AJAX. First, Seam supports the ICEfaces and Ajax4JSF Ajax component libraries for JSF. If you prefer a more “old fashioned” approach, Seam provides a complete JavaScript remoting framework which lets you call Seam components and subscribe to JMS topics directly from the client. Please refer to the Seam remoting example application on how to use AJAX remoting to implement a chat room.

  • The perception of EJB3 as being a simple clone of Hibernate is primarily based on developer familiarity with Hibernate and a similarity of naming, as well as common purpose, and that Hibernate is morphing itself into an EJB3 implementation based on the work going into the specification, not the other way around.
  • EJBs are supposed to be components, in the sense that they’re not just one class, but a set of classes, descriptors and usage and management contracts. All of this in order to allow a container (JBoss, Weblogic, etc.) to provide services to those components, and to be able to reuse and distribute this components.
  • This services are, among others, tractions, concurrent access control, security, instance pooling, etcetera.

Hibernat is “just” an ORM (Object/Relational Mapping) tool. Quick and dirty, this me you can store an object tree belonging to an class hierarchy in a relational DB without writing a single SQL query. Quite cool, IMO. But no traction control, no instance pooling, no concurrency control, and certainly no security.

No, Seam only works on JDK 5.0 and above. It uses annotations and other JDK 5.0 features.

jBPM is a flexible Business Process Management (BPM) Suite. It makes the bridge between business analysts and developers. Traditional BPM engines have a focus that is limited to non-technical people only. JBPM has a dual focus: it offers process management features in a way that both business users and developers like it.

Seam only works on JDK 5.0 and above. It uses annotations and other JDK 5.0 features.

Drools is a Business Rules Management System (BRMS) solution. It provides a core Business Rules Engine (BRE), a web authoring and rules management application (Drools Workbench) and an Eclipse IDE plugin for core development.

Consider a scenario, where in the rules there is a requirement for database connection object. In this case, the DB Connection object can be inserted as a global variable in the working memory and the connection object will be visible to all the rules in that DRL file.

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 trport, discovery, reliability and failure detection, and cluster membership management services.

The Session interface wraps a JDBC Connection. This interface is a single threaded object which represents a single unit of work with application and persistent database. It’s retrieved by the SessionFactory’s openSession() method.

A rule engine may be viewed as a sophisticated if/then statement interpreter. The if/then statements that are interpreted are called rules.

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 test example ANT target in the Seam booking example application for more details.

Yes: that is many threads can access it cuncurrentely and request for sessions. It holds cached data that has been read in one unit of work and may be reused in a future unit of work. Good practice is to create it when the application is initialized.

  • Visual user friendly editor: Users can choose between a web based editor (Oryx) or an Eclipse based one. You can choose depending on the end user and if you are going to use the project’s BRMS (Guvnor) where you can store all your business assets such as processes, rules and documentation in a central location.
  • BPMN2 standard support: This allows you to choose a different editor to generate your business processes and run them in JBPM@There’s no 100% support for the standard yet, but progress is being made on this matter.
  • Human Task features: JBPM5 has a native notion of a Human task, an activity that needs to be completed by an actual person and has a lifecycle: it can be started, suspended, completed, etc. It is also a standard spec.
  • Process Console: You can interact with the engine through this console where you can start processes, complete human tasks, fill forms, etc. This console is GWT based.
  • JPA persistence method: it enables you to choose any database and persistence schema to store the processes variables and history log.
  • Designed for domain specific workflows: this me that you can create your own business domain specific tasks such as (Receive Claim, Approve loan , Check Blood Pressure, etc) and build a palette for end users that is very natural to their environment. This is combination with a visual modeler is a pretty explosive combination, allowing a very productive as-is process knowledge gathering and to-be process design across a whole line of business.
  • Business Activity Monitoring built in: what’s a BPM’s worth if you can’t monitor your processes? JBPM5 allows you to make reports (including tables and charts) over the process instance data and history log. This is useful for higher level users that as C-level executive who need process information to make decisions. It also enables you to use BIRT to generate your reports, so your imagination is the limit when it comes to the amount of information you can present.
  • Console Custom forms integration: By using a template framework, JBPM5 allows your users to interact with their processes using  the same console to start the process and make actions to it within a custom form for each activity. For example you can have a client’s data gathering activity in your process and a custom form can be built to fill that information into the workflow.
  • Powerful rules language: To make decisions within the process you can use Drools rule syntax to for example change a path according to a business condition, such as a credit score.

You can’t with a Servlet. A JTA traction must start and finish within a single invocation (of the service() method). You should consider using a Stateful SB. In a SFSB with a JTA traction, the association between the bean instance and the traction is retained across multiple client calls.

StringBuilder is unsynchronized whereas StringBuffer is synchronized. So when the application needs to be run only in a single thread then it is better to use StringBuilder. StringBuilder is more efficient than StringBuffer.

You could activate the “Commit Option A” that is the container caches entity bean state between tractions. This option assumes that the container has exclusive access to the persistentstore and therefore it doesn’t need to synchronize the in-memory bean state from the persistent store at the beginning of each traction.

Advantages of Rule Engines:

Greater flexibility: keeping your rules into a Knowledge base let you adapt easily your decisions when they are changing.

Easier to grasp: Rules are easier to understand than procedural code so they can be effectively used to bridge the gap between business analyst and developers.

Reduced complexity: When embedding lots of decision points to your procedural codes it can easily turn your application into a nightmare. On the other hand rules can handle much better increasing complexity because they use a consistent representation of business rules.

Reusability: By keeping rules are kept in one place leads to a greater reusability of your business rules. Also, traditional procedural code often impose unnecessary variations of base rules which are therefore more difficult to reuse in other contexts.