Appian Corporation Most Frequently Asked Advanced Java Interview Questions Answers
What Is Orm?
ORM stands for Object/Relational mapping. It is the programmed and translucent perseverance of objects in a Java application in to the tables of a relational database using the metadata that describes the mapping between the objects and the database. It works by transforming the data from one representation to another.
What Does An Orm Solution Comprises Of?
• It should have an API for performing basic CRUD (Create, Read, Update, Delete) operations on objects of persistent classes.
• Should have a language or an API for specifying queries that refer to the classes and the properties of classes.
• An ability for specifying mapping metadata.
• It should have a technique for ORM implementation to interact with transactional objects to perform dirty checking, lazy association fetching, and other optimization functions.
What Are The Different Levels Of Orm Quality?
There are four levels defined for ORM quality.
i. Pure relational
ii. Light object mapping
iii. Medium object mapping
iv. Full object mapping.
What Is A Pure Relational Orm?
The entire application, including the user interface, is designed around the relational model and SQL-based relational operations.
What Is A Meant By Light Object Mapping?
The entities are represented as classes that are mapped manually to the relational tables. The code is hidden from the business logic using specific design patterns. This approach is successful for applications with a less number of entities, or applications with common, metadata-driven data models. This approach is most known to all.
What Is A Meant By Medium Object Mapping?
The application is designed around an object model. The SQL code is generated at build time. And the associations between objects are supported by the persistence mechanism, and queries are specified using an object-oriented expression language. This is best suited for medium-sized applications with some complex transactions. Used when the mapping exceeds 25 different database products at a time.
What Is Message Driven Beam?
An enterprise bean that is an asynchronous message consumer. A message-driven bean has no state for a specific client, but its instance variables can contain state across the handling of client messages, including an open database connection and an object reference to an EJB object. A client accesses a message-driven bean by sending messages to the destination for which the bean is a message listener.
What Is Session Bean. What Are The Various Types Of Session Bean?
SessionBeans typically are used to represent a client they are of two types
Stateful Session Beans : they maintain conversational state between subsequest calls by a client.
Stateless Session Bean : consider this as a servlet equivalent in EJB. It is just used to service clients regardless of state and does not maintain any state.
What Is The Difference Between Stateful Session Bean And Stateless Session Bean
Stateful session beans have the passivated and Active state which the Stateless bean does not have.
What Are The Call Back Methods In Session Bean?
Session bean callback methods differ whether it is Stateless or stateful Session bean they are.
Stateless Session Bean
1. setSessionContext()
2. ejbCreate()
3. ejbRemove()
Stateful Session Bean
1. setSessionContext()
2.ejbCreate()
3.ejbPassivate()
4.ejbActivate()
5.ejbRemove()
When You Will Chose Stateful Session Bean And Stateless Session Bean
stateful session bean is used when we need to maintain the client state . Where stateless session bean will not have a client state it will be in pool. Example of statefull session is Shoping cart site where we need to maintain the client state .
What Is The Relationship Between Enterprise Javabeans And Javabeans?
Enterprise JavaBeans extends the JavaBeans component model to handle the needs of transactional business applications.
JavaBeans is a component model for visual construction of reusable components for the Java platform. Enterprise JavaBeans extends JavaBeans to middle-tier/server side business applications. The extensions that Enterprise JavaBeans adds to JavaBeans include support for transactions, state management, and deployment time attributes.
Although applications deploying the Enterprise JavaBeans architecture are independent from the underlying communication protocol, the Enterprise JavaBeans architecture specifies how communication among components maps into the underlying communication protocols, such as CORBA/IIOP.
How To Implement A Bound Property In Your Bean Application?
To implement a bound property in the application, follow these steps
IBM plans to ship the JavaBeans Migration Assistant for ActiveX in Taligent's Visual Age, WebRunner Toolkit, and Visual Age for Java development tools. This will allow developers to utilize a common component model that may be leveraged by a wide range of tools, including the IBM Visual Age for Java family.
Why Would A Developer Need The Javabeans Migration Assistant For Activex?
Many of the capabilities that are so exciting to JavaBeans developers are not available on ActiveX, or are incomplete. There is, therefore, a need for a set of conversion conventions and tools designed to convert desktop ActiveX components into JavaBeans components. The resulting Beans will be usable in both in new network savvy e-business applications as well as traditional desktop applications, includingActiveX containers. Developers and customers benefit from the advantages offered by JavaBeans by simply leveraging their current investments in ActiveX.
Can Javabeans Use Dcom As Its Network Model?
JavaBeans works with any network model (i.e., to communicate between components across the network), including CORBA, DCOM, etc. JavaBeans integrates well with CORBA IDL, which is an excellent solution for customers in a heterogeneous distributed computing environment with platform independent components. However, we recommend RMI for Java to Java inter-object communication.
Can Both Java Applets And Javabeans Components Use The Infobus?
Yes.
Javabeans Has Mechanisms Like Bound Properties For Data Transfer Between Components. Why Is The Infobus Necessary?
JavaBeans mechanisms, such as bound properties, are very useful in cases where the type of data to be communicated can be hard-coded into the source and target components. The InfoBus adds additional features required for more dynamic data interchange. These can be cases where communication is driven by the content of the data and where the nature of the data to be exchanged is determined at runtime.
Is Infobus Easy To Use?
Using InfoBus aware components, such as the ESuite components from Lotus, users can easily construct powerful data driven applications. No programming or scripting is required: simple parameters are used to establish connections to databases and to select data for processing. For developers creating InfoBus components, InfoBus offers a straightforward API compatible in style with other features of JavaBeans.
Does The Infobus Compete With Javabeans?
On the contrary, InfoBus extends the power of JavaBeans to a new range of more dynamic applications. InfoBus is fully compatible with JavaBeans, and Lotus enthusiastically supports JavaBeans as the component standard for Java. Wherever possible, InfoBus uses the existing mechanisms of JavaBeans.
What Is The Infobus?
The InfoBus is a compact Java API which allows cooperating applets or Beans, on a Web page or in any other Java application, to communicate data to one another. The InfoBus architecture enables Beans to be categorized as "data providers" and "data consumers". Data providers are Beans whose primary function is to access data from their native store, such as a DBMS, spreadsheet, flat file, Lotus Notes database etc., and to offer data onto the InfoBus.
Data consumers retrieve data from the bus, for analysis or visual display. This segregation of provider from consumer is extremely powerful in that it enables applications to be independent of their data; for example, a charting Bean need not understand SQL or JDBC in order to access DBMS data.
Of course, a Bean can be both a consumer and provider: for example a spreadsheet may accept data from a DBMS and provide data to a chart Bean.
What Are/is Enterprise Javabeans?
Enterprise JavaBeans (EJB) is an API specification for building scalable, distributed, component-based, multi-tier applications. It leverages and extends the JavaBeans component model to provide a rich object-oriented transactional environment for developers building enterprise applications.
Enterprise JavaBeans (EJB) technology is the basis of Java 2 Platform, Enterprise Edition (J2EE). EJB technology provides the scalable architecture for executing business logic in a distributed computing environment. J2EE makes the life of an enterprise developer easier by combining the EJB component architecture with other enterprise technologies to solutions on the Java platform for seamless development and deployment of server side applications.
Who Is Developing The Javabeans Migration Assistant To Activex?
IBM and Taligent, its object oriented technology subsidiary, with support from JavaSoft, are developing a set of conversion conventions, a porting guide and tool that will allow developers to easily convert their Windows ActiveX components into JavaBeans.
What Is Orm?
ORM stands for Object/Relational mapping. It is the programmed and translucent perseverance of objects in a Java application in to the tables of a relational database using the metadata that describes the mapping between the objects and the database. It works by transforming the data from one representation to another.
What Does An Orm Solution Comprises Of?
• It should have an API for performing basic CRUD (Create, Read, Update, Delete) operations on objects of persistent classes.
• Should have a language or an API for specifying queries that refer to the classes and the properties of classes.
• An ability for specifying mapping metadata.
• It should have a technique for ORM implementation to interact with transactional objects to perform dirty checking, lazy association fetching, and other optimization functions.
What Are The Different Levels Of Orm Quality?
There are four levels defined for ORM quality.
i. Pure relational
ii. Light object mapping
iii. Medium object mapping
iv. Full object mapping.
What Is A Pure Relational Orm?
The entire application, including the user interface, is designed around the relational model and SQL-based relational operations.
What Is A Meant By Light Object Mapping?
The entities are represented as classes that are mapped manually to the relational tables. The code is hidden from the business logic using specific design patterns. This approach is successful for applications with a less number of entities, or applications with common, metadata-driven data models. This approach is most known to all.
What Is A Meant By Medium Object Mapping?
The application is designed around an object model. The SQL code is generated at build time. And the associations between objects are supported by the persistence mechanism, and queries are specified using an object-oriented expression language. This is best suited for medium-sized applications with some complex transactions. Used when the mapping exceeds 25 different database products at a time.
What Is Message Driven Beam?
An enterprise bean that is an asynchronous message consumer. A message-driven bean has no state for a specific client, but its instance variables can contain state across the handling of client messages, including an open database connection and an object reference to an EJB object. A client accesses a message-driven bean by sending messages to the destination for which the bean is a message listener.
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| Appian Corporation Most Frequently Asked Advanced Java Interview Questions Answers |
What Is Session Bean. What Are The Various Types Of Session Bean?
SessionBeans typically are used to represent a client they are of two types
Stateful Session Beans : they maintain conversational state between subsequest calls by a client.
Stateless Session Bean : consider this as a servlet equivalent in EJB. It is just used to service clients regardless of state and does not maintain any state.
What Is The Difference Between Stateful Session Bean And Stateless Session Bean
Stateful session beans have the passivated and Active state which the Stateless bean does not have.
What Are The Call Back Methods In Session Bean?
Session bean callback methods differ whether it is Stateless or stateful Session bean they are.
Stateless Session Bean
1. setSessionContext()
2. ejbCreate()
3. ejbRemove()
Stateful Session Bean
1. setSessionContext()
2.ejbCreate()
3.ejbPassivate()
4.ejbActivate()
5.ejbRemove()
When You Will Chose Stateful Session Bean And Stateless Session Bean
stateful session bean is used when we need to maintain the client state . Where stateless session bean will not have a client state it will be in pool. Example of statefull session is Shoping cart site where we need to maintain the client state .
What Is The Relationship Between Enterprise Javabeans And Javabeans?
Enterprise JavaBeans extends the JavaBeans component model to handle the needs of transactional business applications.
JavaBeans is a component model for visual construction of reusable components for the Java platform. Enterprise JavaBeans extends JavaBeans to middle-tier/server side business applications. The extensions that Enterprise JavaBeans adds to JavaBeans include support for transactions, state management, and deployment time attributes.
Although applications deploying the Enterprise JavaBeans architecture are independent from the underlying communication protocol, the Enterprise JavaBeans architecture specifies how communication among components maps into the underlying communication protocols, such as CORBA/IIOP.
How To Implement A Bound Property In Your Bean Application?
To implement a bound property in the application, follow these steps
- Import the java.beans package. This gives you access to the PropertyChangeSupport class.
- Instantiate a PropertyChangeSupport object. This object maintains the property change listener list and fires property change events. You can also make your class a PropertyChangeSupport subclass.
- Implement methods to maintain the property change listener list. Since a PropertyChangeSupport subclass implements these methods, you merely wrap calls to the property-change support object's methods.
- Modify a property's set method to fire a property change event when the property is changed.
IBM plans to ship the JavaBeans Migration Assistant for ActiveX in Taligent's Visual Age, WebRunner Toolkit, and Visual Age for Java development tools. This will allow developers to utilize a common component model that may be leveraged by a wide range of tools, including the IBM Visual Age for Java family.
Why Would A Developer Need The Javabeans Migration Assistant For Activex?
Many of the capabilities that are so exciting to JavaBeans developers are not available on ActiveX, or are incomplete. There is, therefore, a need for a set of conversion conventions and tools designed to convert desktop ActiveX components into JavaBeans components. The resulting Beans will be usable in both in new network savvy e-business applications as well as traditional desktop applications, includingActiveX containers. Developers and customers benefit from the advantages offered by JavaBeans by simply leveraging their current investments in ActiveX.
Can Javabeans Use Dcom As Its Network Model?
JavaBeans works with any network model (i.e., to communicate between components across the network), including CORBA, DCOM, etc. JavaBeans integrates well with CORBA IDL, which is an excellent solution for customers in a heterogeneous distributed computing environment with platform independent components. However, we recommend RMI for Java to Java inter-object communication.
Can Both Java Applets And Javabeans Components Use The Infobus?
Yes.
Javabeans Has Mechanisms Like Bound Properties For Data Transfer Between Components. Why Is The Infobus Necessary?
JavaBeans mechanisms, such as bound properties, are very useful in cases where the type of data to be communicated can be hard-coded into the source and target components. The InfoBus adds additional features required for more dynamic data interchange. These can be cases where communication is driven by the content of the data and where the nature of the data to be exchanged is determined at runtime.
Is Infobus Easy To Use?
Using InfoBus aware components, such as the ESuite components from Lotus, users can easily construct powerful data driven applications. No programming or scripting is required: simple parameters are used to establish connections to databases and to select data for processing. For developers creating InfoBus components, InfoBus offers a straightforward API compatible in style with other features of JavaBeans.
Does The Infobus Compete With Javabeans?
On the contrary, InfoBus extends the power of JavaBeans to a new range of more dynamic applications. InfoBus is fully compatible with JavaBeans, and Lotus enthusiastically supports JavaBeans as the component standard for Java. Wherever possible, InfoBus uses the existing mechanisms of JavaBeans.
What Is The Infobus?
The InfoBus is a compact Java API which allows cooperating applets or Beans, on a Web page or in any other Java application, to communicate data to one another. The InfoBus architecture enables Beans to be categorized as "data providers" and "data consumers". Data providers are Beans whose primary function is to access data from their native store, such as a DBMS, spreadsheet, flat file, Lotus Notes database etc., and to offer data onto the InfoBus.
Data consumers retrieve data from the bus, for analysis or visual display. This segregation of provider from consumer is extremely powerful in that it enables applications to be independent of their data; for example, a charting Bean need not understand SQL or JDBC in order to access DBMS data.
Of course, a Bean can be both a consumer and provider: for example a spreadsheet may accept data from a DBMS and provide data to a chart Bean.
What Are/is Enterprise Javabeans?
Enterprise JavaBeans (EJB) is an API specification for building scalable, distributed, component-based, multi-tier applications. It leverages and extends the JavaBeans component model to provide a rich object-oriented transactional environment for developers building enterprise applications.
Enterprise JavaBeans (EJB) technology is the basis of Java 2 Platform, Enterprise Edition (J2EE). EJB technology provides the scalable architecture for executing business logic in a distributed computing environment. J2EE makes the life of an enterprise developer easier by combining the EJB component architecture with other enterprise technologies to solutions on the Java platform for seamless development and deployment of server side applications.
Who Is Developing The Javabeans Migration Assistant To Activex?
IBM and Taligent, its object oriented technology subsidiary, with support from JavaSoft, are developing a set of conversion conventions, a porting guide and tool that will allow developers to easily convert their Windows ActiveX components into JavaBeans.
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