JSP Servlet J2EE Questions 15

71. What is Domain Naming Service(DNS)?- It is very difficult to remember a set
of numbers(IP address) to connect to the Internet. The Domain Naming Service(DNS)
is used to overcome this problem. It maps one particular IP address to a string of
characters. For example, www. mascom. com implies com is the domain name reserved
for US commercial sites, moscom is the name of the company and www is the name of
the specific computer, which is mascom’s server.

72. What is URL?- URL stands for Uniform Resource Locator and it points to
resource files on the Internet. URL has four components: http://www. address.
com:80/index.html, where http - protocol name, address - IP address or host name,
80 - port number and index.html - file path.

73. What is RMI and steps involved in developing an RMI object?- Remote Method
Invocation (RMI) allows java object that executes on one machine and to invoke the
method of a Java object to execute on another machine. The steps involved in
developing an RMI object are: a) Define the interfaces b) Implementing these
interfaces c) Compile the interfaces and their implementations with the java
compiler d) Compile the server implementation with RMI compiler e) Run the RMI
registry f) Run the application

74. What is RMI architecture?- RMI architecture consists of four layers and
each layer performs specific functions: a) Application layer - contains the actual
object definition. b) Proxy layer - consists of stub and skeleton. c) Remote
Reference layer - gets the stream of bytes from the transport layer and sends it to
the proxy layer. d) Transportation layer - responsible for handling the actual
machine-to-machine communication.

75. what is UnicastRemoteObject?- All remote objects must extend
UnicastRemoteObject, which provides functionality that is needed to make objects
available from remote machines.