Brakes India Java Questions: Networking

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  1. What is the difference between URL instance and URLConnection instance? ANSWER: A URL instance represents the location of a resource, and a URLConnection instance represents a link for accessing or communicating with the resource at the location.

  2. How do I make a connection to URL? ANSWER: You obtain a URL instance and then invoke openConnection on it. URLConnection is an abstract class, which means you can't directly create instances of it using a constructor. We have to invoke openConnection method on a URL instance, to get the right kind of connection for your URL. Eg. URL url; URLConnection connection; try { url = new URL ( “…” ); conection = url. OpenConnection (); }catch (MalFormedURLException e) { }

  3. What Is a Socket? A socket is one end-point of a two-way communication link between two programs running on the network. A socket is bound to a port number so that the TCP layer can identify the application that data is destined to be sent. Socket classes are used to represent the connection between a client program and a server program. The java. Net package provides two classes--Socket and ServerSocket--which implement the client side of the connection and the server side of the connection, respectively. What information is needed to create a TCP Socket? ANSWER: The Local System's IP Address and Port Number. And the Remote System's IPAddress and Port Number.

  4. What are the two important TCP Socket classes?

ANSWER: Socket and ServerSocket.



When MalformedURLException and UnknownHostException throws?

ANSWER: When the specified URL is not connected then the URL throw MalformedURLException and If InetAddress'methods getByName and getLocalHost are unabletoresolve the host name they throwan UnknownHostException.