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Saturday, January 23, 2010

JTS For students

1. What is JTS?
A. JTS (JAVA TRANSACTION SERVICE) is the java implementation of CORBA’s
2. What is JTA?
A. JTA (JAVA TRANSACTION API) is the API released by java soft under J2EE.
It was released after the release of JTS.
3. what are the advantages of JTA over JTS?
A. JTA (JAVA TRANSACTION API) is more flexible and simple to use by the
Programmer .The JTA API is divided into two parts
a)high-level X/Open Call Level Interface(CLI)
b)low-level XA Call Level Interface(CLI)

As a programmer using JTA he has to concentrate on high-level x/open interface .The low-level XA operations are taken care by the server, which is giving the implementation to JTA API.The, user will never perform XA operations directly. This makes the user simpler to manipulate with transactions.
4. How JTA or JTS is used by client?
A. Client uses User Transaction interface in both the cases(JTA/JTS).

A message-driven bean is an asynchronous message consumer. The container as a result of the arrival of a JMS message invokes a message-driven bean. A message-driven bean has neither a home nor a remote interface. A message-driven bean instance is an instance of a message-driven bean class. To a client, a message-driven bean is a JMS message consumer that implements some business logic running on the server. A client accesses a message-driven bean through JMS by sending messages to the JMS Destination (Queue or Topic) for which the message-driven bean class is the Message Listener. Message-driven bean instances have no conversational state. This means that all bean instances are equivalent when they are not involved in servicing a client message. Message-driven beans are anonymous. They have no client-visible identity.A message-driven bean instance is created by the container to handle the processing of the messages for which the message-driven bean is the consumer. Its lifetime is controlled by the container. A message-driven bean instance has no state for a specific client. However, the instance variables of the message-driven bean instance can contain state across the handling of client messages. Examples of such state include an open database connection and an object reference to an EJB object.

Goals The goal of the message-driven bean model is to make developing an enterprise bean that is asynchro-nously invoked to handle the processing of incoming JMS messages as simple as developing the same functionality in any other JMS MessageListener.A further goal of the message-driven bean model is to allow for the concurrent processing of a stream of messages by means of container-provided pooling of message-driven bean instances.
While the EJB 2.0 specification requires support for only JMS-based messaging, a future goal
of the message-driven bean model is to provide support for other types of messaging in addi-tion
to JMS, and to allow for message-driven beans that are written to their APIs.

1.what does Activation Instantinator mean?
A. It is a responsible for creating instances of “activatable” objects.
2.what are the activation group works?
A. It is responsible for informing its activation monitor, when either its objects become active or inactive.
3.what is the responsibility of Activator?
A. It is responsible for monitoring and detecting when Activation groups fail.
4.what is the job of Activation monitor?
A. It receives information about active and inactive Objects.
5.what is DGC?
A. Distributed Garbage Collection is server side algorithm. It contains two methods those are dirty () and clean ().
6.what is the handle?
A. It represents the Remote for a remote object
7.what is the Remote Stub?
A. Remote stub uses a remote references to carry out a remote method invocation to a Remote Object.
8.What is the Remote Server?
A. The function needs to create and export remote objects (to make them remotely available)
9.what is the RMI / IIOP?
A. This is the Naming service (tnameserv).
10.what is the rmi port no?
11.what is meant by portable component?
A. Writing and keep somewhere, and using from there without changing code.
12.what is the heap Stored?
13.what is the proxy pattern?
A. The copy of the Remote object in our Local Machine (it works like mediating to client & Server)
14.why the interface is required to rmi?
15.which type of objects reference will be given to client?
A. Implement type class type of object references
16.what does bootstrapping mean?
A.  When the server startup time it will send some information
to client, that is requirement to client .
java -D java.rmi.server.codebase=”http”//servername:8080”

17.why the constructor required in implemented class?
A. The super class is having one public constructor. many requests having ServerSockets ?
A.its minimum of 50.
19.what is the activation process?
A. When the clients request comes to the registry then only objects will be bound dynamically.
20.what is meant by jrmp?
A. This is standard rmi communication messaging protocol
A. Tests to see whether a remote virtual is still alive.
22.narrow :-
Checks to ensure that an object of a remote or abstract interface type can be cast to a desired type.
23.Remote Reference  Layer ?
A. Checks for Rmi symantics and to identify remote system in the network
transferable stream. This stream is then passed to transport layer
24.  How many requests can server fetch at a time?
A. only one.
25.what is the JNDI  [java Naming and Directory Interface] ? what its provides?
A. It provides standard java interface-to-naming events
26. what is the use of Object-Factories?
A.Colon-separated  Object list of ContextFactory to use during invocation of naming and directory service operation
27.what is the use of State-Factories?
A.Colon separated list of state factory used to get an object’s state   given  a reference to the object
28.what is the use of colon_pkg_prefixes?
A.  prefix to use when loading context factory.

A.   URL defining the DNS host to use for Addresses associated        with JNDI urls
A. Value of true indicates that service access offers the most
authoritative source
A. Specifies batch size of data returned from service protocol

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