Middleware Technologies Lab
Sample Viva Questions
1. What is meant by middleware?
Middleware is connectivity allows applications to transparently communicate with other programs or processes, regardless of their location.
2. What are the characteristics of Client/Server?
Relationship between two computer programs, the client makes a service request from another program, the server
3. What is Two tier / Three tier architecture
Two Tier: Refers to client/server architectures in which the user interface runs on the client and the database is stored on the server. The actual application logic can run on either the client or the server
Three Tier: three-tier architecture introduces a middle tier for the application logic
4. What are the different types of Servers?
File server, Database server, Object Server, Web server, Transaction server, Group server.
5. What is RPC
Remote Procedure Call. It enables a system to make calls to programs such as NFS across the network transparently, enabling each system to interpret the calls as if they were local
6. What is meant by peer-to-peer communication?
Peer-to-peer is a communications model in which each party has the same capabilities and either party can initiate a communication session.
7. What is Socket
A socket is one end of a two-way communications link between two programs running on the network. It uses IP address and Port number for communication
8. What are the components of EJB architecture?
EJB server, Container, EJB bean, Home interface, Remote interface, Client
9. What is meant by session bean?
An enterprise bean that is created by a client; usually exists only for the duration of a single client-server session.
10. What is meant by entity bean?
An entity bean represents a business object in a persistent storage mechanism. Some examples of business objects are customers, orders, and products.
11. What are the two different types of session bean?
Session bean objects can be either stateless (not associated with a particular client) or stateful (associated with a particular client), that is, they can maintain conversational state across methods and transactions
12. What are the two different types of entity bean?
Container managed Persistence bean, Bean Managed Persistence bean
13. What is the difference between stateful session bean and stateless session bean?
Stateful session bean maintains the configuration state, stateless is not Concurrent access is possible with stateless, only one access with stateful session bean.
14. What is the difference between CMP & BMP?
Container manages all database access aspects in CMP, where user in BMP
15. What are the roles of EJB server?
Provides low level services, like network connectivity to the EJB container.
16. What are the roles EJB containers?
Interface between EJB and outside world, Can create pool of beans, Provides services to Beans
17. What is home interface in EJB
Home interface serves as the initial point of contact for a client. When the client uses a naming service to look up an EJB bean, the naming service returns a reference to an object that implements the bean’s home interface.
18. What is remote interface in EJB
The interface with the client interacts. EJB container uses the remote interface to generate both stub and skeleton that passes client calls to EJB bean.
19. What is meant by deployment descriptor?
Deployment descriptor is a serialized instance of a java class that contains information about how to deploy the bean.
20. What is JNDI.
Java Naming Directory Interface: The client uses naming service to lookup an EJB getting a reference to an object that implements its home interface in response
21. What is passivation?
The operation of container saves the state of a given bean to persistent storage and swaps it out. Passivation is similar to the virtual-memory concept of swapping out a memory page to disk
22. What is the directory service used in RMI
RMI Registry (JNDI Naming service in EJB, COS Naming service in CORBA)
23. What is RMIC?
rmic generates stub, skeleton, and tie classes for remote objects
24. What is OLTP?
Online Transaction Processing, an OLTP system typically must handle a large volume of updates to a database.
25. What is an interface
A Method for interconnecting units or systems which may not be directly compatible
26. What is a primary key class?
Primary key is represented by a Java class that contains unique data are necessary to look up a particular entity EJB.
27. Differentiate RMI and CORBA
RMI is the Java only environment, CORBA platform and language independent environment
28. What is ORB
Object Request Broker: Facilitates communication between objects, Locates a remote object upon a reference, Marshals and un-marshals parameters.
29. What is: Naming Service.
A service that associates a symbolic name with an object
30. What is IDL
Interface Definition Language: Not an implementation language, Ensures language Independence, Provides interfaces- the implementation of interfaces can be in other languages
31. What does IIOP stand for?
Internet Inter-ORB protocol used in CORBA network model
32. What is OMG?
Object Management Group which provides standards to CORBA
33. What is a client stub, server skeleton?
To the client, the object on the server appears as if it resides in the client program. This is accomplished by using a client-side stub object. The stub object has the same interface as the server-side object it represents, but does not directly implement the object's methods. Instead, the stub object translates a method invocation into a format that is communicated over the ORB to the server. The server then finds the target servant object, which executes the actual method implementation.
A server skeleton, like a client stub, is specific to the IDL interface from which it is generated. A server skeleton is the server side analog to a client stub
34. What is an object reference?
The handle of the object in CORBA is called object reference. Handle is the address of the remote object
35. What is marshalling and un-marshaling?
o In distributed computing, the transformation of data from a local type into a type suitable for transmission over the network
o Converting the state of the objects into a series of binary bits so that it can be transmitted through network, converting back into object at the server side is called un-marshaling
36. What is meant by On-the-wire format?
Series of binary bits, the format suitable for network transmission
37. What are the duties of ORB?
Object Request Broker: Facilitates communication between objects, Locates a remote object upon a reference, Marshals and un-marshals parameters
38. What is the meaning of Oneway type in IDL?
When an object calls a method on a remote object, that calling object waits(blocking) for the method to execute and return. Oneway enables to unblock the client object.
39. What is CLR
Microsoft's new .NET Framework has two main components: the Common Language Runtime (CLR) and the .NET Framework class library. The common language runtime is the foundation of the .NET Framework. You can think of the runtime as an agent that manages code at execution time, providing core services such as memory management, thread management, and remoting.
40. What is COM
COM is a language neutral way of implementing objects which can be used in different environments
41. What is an Interface pointer?
Object reference in COM is called Interface Pointer
42. What is stub in COM? Proxy
43. What is skeleton in COM? Stub
44. ACID property of Transactions
Atomicity, Consistency, isolation, and Durability
45. Tell any four exceptions available in EJB
Create exception, Finder exception, Remote exception, Naming Exception, Remove exception.
46. What is .NET?
Ø .NET is a software framework that includes everything required for developing software for web services.
Ø It integrates
v presentation technologies,
v component technologies
v data technologies on a single platform
Ø It enables users to develop Internet applications as easily as they do on desktop systems.
47. List out the components of .NET platform.
Ø .NET infrastructure and tools
Ø .NET user experience
Ø .NET building block
Ø .NET device software
48. Write the Benefits of the .NET Approach.
Ø Simple and faster systems development
Ø Enhanced built-in functionality
Ø Easy deployment and execution
Ø Potentially better performance
Ø Interoperability with existing applications.