1. CSE 341, S. Tanimoto Java networking-
Motivation
Sockets
Applets
Downloading Images, MediaTracker
CSE 341, S. Tanimoto Java networking-

2. CSE 341, S. Tanimoto Java networking-
Motivation
Support distributed model of computation
Permit programs to download documents
Permit programs to run as an Applets
Anticipate bandwidth limitations
CSE 341, S. Tanimoto Java networking-

3. CSE 341, S. Tanimoto Java networking-
Sockets
Server
Client
int port=2000;
BufferedReader br;
PrintWriter pw;
ServerSocket ss;
Socket sock;
ss = new ServerSocket(port);
sock = ss.accept();
br = new BufferedReader(
new InputStreamReader(
(sock.getInputStream());
pw = new PrintWriter(
sock.getOutputStream());
System.out.println(
br.readLine());
pw.println(“HELLO”);
int port=2000;
String host=“piaget”;
BufferedReader br;
PrintWriter pw;
Socket sock;
sock = new Socket(host,port);
br = new BufferedReader(
new InputStreamReader(
(sock.getInputStream());
pw = new PrintWriter(
sock.getOutputStream());
pw.println(“ciao”);
System.out.println(
br.readLine());
CSE 341, S. Tanimoto Java networking-

4. CSE 341, S. Tanimoto Java networking-
A Tiny Server
import java.net.*; import java.io.*;
public class TestServer {
static int port=2000; static BufferedReader br;
static PrintWriter pw; static ServerSocket ss;
static Socket sock;
public static void main(String [] args) {
try {
ss = new ServerSocket(port);
sock = ss.accept();
br = new BufferedReader(new InputStreamReader(
(sock.getInputStream())));
pw = new PrintWriter(sock.getOutputStream());
System.out.println(br.readLine());
pw.println("HELLO"); }
catch (IOException e)
{System.out.println("Error connecting to port");}
} }
CSE 341, S. Tanimoto Java networking-

5. CSE 341, S. Tanimoto Java networking-
Applets
Normally applets live “in the browser”
Limited permissions (talk only to the hosting server, don’t touch local hard disk).
Use applet context as an operating env’t.
CSE 341, S. Tanimoto Java networking-

6. CSE 341, S. Tanimoto Java networking-
Downloading Images
Java anticipated the download times required to retrieve images.
provides the MediaTracker method to keep track of the status of files that are being downloaded.
Images can be retrieved with URLs that point to either JPEG or GIF images.
CSE 341, S. Tanimoto Java networking-