2 Marks IP 

51. Write a note on Connect Exception.

This exception is raised when a connection is refused at the remote host. (ie, no process is

listening on that port).

52. What is a multicast socket?

Multicasting sends data from one host to many different hosts, which are in the multicast

group.

53. What is multicast address and the range of address?

A multicast address is the address of a group of hosts called a multicast group. Multicast

addresses are IP addresses in the range 224.0.0.0 to 239.255.255.255

54. What are the different types of IP addresses?

Unicast address: It is used for transmitting a message to single destination node

Multicast address: It delivers a message to a group of destination nodes, which are

necessarily in the same sub network.

Broadcast address: It transmits a message to all nodes in a sub network.

55. What is meant by protocol handler?

Protocol handlers are used to retrieve the web objects using application specific protocols.

The protocols are specified in the URL referencing the object.

56. How are the protocol handlers implemented?

Four different classes in the java.net package implement the protocol handlers:

1. URL

2. URLStreamHandler

3. URLConnection

4. URLStreamHandlerFactory

57. What are the methods for parsing URLs?

1. parseURL(URL u, String spec, int start, int limit)- splits the URL into parts

2. setURL(URL u, Sring protocol, String host, int port, String file, String ref) -assigns

values to the URL's fields.

58. What is content handler?

Content handlers are used to retrieve objects via an URLConnection object.

59. What is Remote Method Invocation?

The Remote Method Invocation is application-programming interface that allows java

objects on different hosts communicate with each other.

60. What do you mean by remote object?

Objects that have methods that can be called across virtual machines are remote objects.

61. Define serialization.

It is the process of converting a set of object instances that contain references to each other

into a linear stream of bytes, which can then be through a socket. It is the mechanism used by

RMI to pass objects between Java Virtual Machines.

62. What are the responsibilities of stub?

A stub for a remote object is the client side proxy for the remote object. A client side stub

is responsible for:

1.Initiating a call to the remote object

2.Marshaling arguments to a marshal stream

3.Informing the remote reference layer that the call should be invoked

4.Unmarshaling the return value or exception from a marshal stream

63. What is the role of skeleton in RMI?

A skeleton for a remote object is a server side entity that contains a method which

dispatches calls to the actual remote object implementation. The skeleton is responsible for

1.Unmarshaling arguments from the marshal stream.

2.Making the up-call to the actual remote object.

3.Marshalling the return value of the call to an exception onto the Marshall stream

64. List down the layers of RMI architecture.

1.Stubs/Skeletons

2.Remote reference layer

3.Transport layer

65. Define Object Activation.

Object Activation is mechanism, which allows a java object to be bound and then

activated at some later data simply by referencing the object through the Registry.