Socket & Server Socket
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This document provides an overview of socket programming in Java, including types of sockets (TCP and UDP) and the necessary classes and methods in the java.net package. It outlines the differences between connection-oriented and connection-less sockets, as well as the steps involved in creating client-server applications using both TCP and UDP protocols. Additionally, the document includes sample code examples demonstrating basic socket functionality and data transmission.
![InputStream Basics
// reads some number of bytes and
// puts in buffer array b
int read(byte[] b);
// reads up to len bytes
int read(byte[] b, int off, int len);
Both methods can throw IOException.
Both return –1 on EOF.](https://image.slidesharecdn.com/adjava-130410107010-180720193113/85/Socket-Server-Socket-12-320.jpg)
![// writes b.length bytes
void write(byte[] b);
// writes len bytes starting
// at offset off
void write(byte[] b, int off, int len);
Both methods can throw IOException.
OutputStream Basics](https://image.slidesharecdn.com/adjava-130410107010-180720193113/85/Socket-Server-Socket-13-320.jpg)
![DatagramPacketConstructors
For receiving:
DatagramPacket( byte[] buf, int len);
For sending:
DatagramPacket( byte[] buf, int len
InetAddress a, int port);](https://image.slidesharecdn.com/adjava-130410107010-180720193113/85/Socket-Server-Socket-21-320.jpg)
![DatagramPacket methods
byte[] getData();
void setData(byte[] buf);
void setAddress(InetAddress a);
void setPort(int port);
InetAddress getAddress();
int getPort();](https://image.slidesharecdn.com/adjava-130410107010-180720193113/85/Socket-Server-Socket-22-320.jpg)
Socket & Server Socket
- 1. ACTIVE LEARNING ASSIGNMENT FOR THE SUBJECT “ADVANCE JAVA” SOCKET, SERVER SOCKET, DATAGRAM SOCKET AND DATAGRAM PACKET Guided By : - Ronak Roy (Assistance prof.) Prepared By :- Hemant H. Chetwani (130410107010 TY CE-II)
- 2. What is Socket ? • A natural or artificial hollow into which something fits or in which something revolves. • An electrical device receiving a plug or light bulb to make a connection. • Means, basically it is used to form a connection or communication between two or more end-points (ports).
- 3. Technically . . . • A Socket is an endpoint of a two-way communication link between two programs running on the network. • Basically there are two types of Sockets : 1) Connection-oriented Sockets. (Based onTCP) 2) Connection-less Sockets. (Based on UDP) • Java provides a set of classes, defined in a package called java.net, to enable the development of network applications. • Key classes in java.net package, simplifying the complexity involved in creating client and server programs are :
- 5. InetAddress class • Static methods you can use to create new InetAddress objects. getByName(String host) getAllByName(String host) getLocalHost() InetAddress x = InetAddress.getByName(“gtu.ac.in”); Throws UnknownHostException
- 6. try { InetAddress a = InetAddress.getByName(hostname); System.out.println(hostname + ":" + a.getHostAddress()); } catch (UnknownHostException e) { System.out.println("No address found for " + hostname); }
- 7. Sample Code: Lookup.java • Uses InetAddress class to lookup hostnames found on command line. java Lookup www.yahoo.com www.yahoo.com:209.131.36.158
- 8. SocketClass • Corresponds to activeTCP sockets only! • client sockets • socket returned by accept(); • Passive sockets are supported by a different class: • ServerSocket
- 9. SocketConstructors • Constructor creates aTCP connection to a namedTCP server. • There are a number of constructors: Socket(InetAddress server, int port); Socket(InetAddress server, int port,InetAddress local, int localport); Socket(String hostname, int port);
- 10. Socket Methods void close(); InetAddress getInetAddress(); InetAddress getLocalAddress(); InputStream getInputStream(); OutputStream getOutputStream(); • Lots more (setting/getting socket options, partial close, etc.)
- 11. Socket I/O • Socket I/O is based on the Java I/O support • in the package java.io • InputStream and OutputStream are abstract classes • common operations defined for all kinds of InputStreams, OutputStreams.
- 12. InputStream Basics // reads some number of bytes and // puts in buffer array b int read(byte[] b); // reads up to len bytes int read(byte[] b, int off, int len); Both methods can throw IOException. Both return –1 on EOF.
- 13. // writes b.length bytes void write(byte[] b); // writes len bytes starting // at offset off void write(byte[] b, int off, int len); Both methods can throw IOException. OutputStream Basics
- 14. ServerSocketConstructor ServerSocket(int port); ServerSocket(int port, int backlog); ServerSocket(int port, int backlog,InetAddress bindAddr);
- 15. Socket accept(); void close(); InetAddress getInetAddress(); int getLocalPort(); throw IOException, SecurityException ServerSocket Methods
- 16. Example client-server app: • Client reads line from standard input, sends to server via socket. • server reads line from socket • server converts line to uppercase, sends back to client • client reads, prints modified line from socket. outToServer to network from network inFromServer inFromUser keyboard monitor Process clientSocket input stream input stream output stream TCP socket Input stream: sequence of bytes into processoutput stream: sequence of bytes out of process Client process client TCP socket Socket programming with TCP
- 17. Client/server socket interaction: TCP wait for incoming connection request connectionSocket = welcomeSocket.accept() create socket, port=x, for incoming request: welcomeSocket = ServerSocket() create socket, connect to hostid, port=x clientSocket = Socket() close connectionSocket read reply from clientSocket close clientSocket Server (running on hostid) Client send request using clientSocketread request from connectionSocket write reply to connectionSocket TCP connection setup
- 18. Socket Programming with UDP • UDP • Connectionless and unreliable service. • There isn’t an initial handshaking phase. • Doesn’t have a pipe. • transmitted data may be received out of order, or lost • Socket Programming with UDP • No need for a welcoming socket. • No streams are attached to the sockets. • the sending hosts creates “packets” by attaching the IP destination address and port number to each batch of bytes. • The receiving process must unravel to received packet to obtain the packet’s information bytes.
- 19. DatagramSocketConstructors DatagramSocket(); DatagramSocket(int port); DatagramSocket(int port, InetAddress a); All can throw SocketException or SecurityException
- 20. Datagram Methods void connect(InetAddress, int port); void close(); void receive(DatagramPacket p); void send(DatagramPacket p); Lots more!
- 21. DatagramPacketConstructors For receiving: DatagramPacket( byte[] buf, int len); For sending: DatagramPacket( byte[] buf, int len InetAddress a, int port);
- 22. DatagramPacket methods byte[] getData(); void setData(byte[] buf); void setAddress(InetAddress a); void setPort(int port); InetAddress getAddress(); int getPort();
- 23. Example: Java client (UDP) sendPacketto network from network receivePacket inFromUser keyboard monitor Process clientSocket UDP packet input stream UDP packet UDP socket Output: sends packet (TCP sent “byte stream”) Input: receives packet (TCP received “byte stream”) Client process client UDP socket
- 24. Client/server socket interaction: UDP close clientSocket Server (running on hostid) read reply from clientSocket create socket, clientSocket = DatagramSocket() Client Create, address (hostid, port=x, send datagram request using clientSocket create socket, port=x, for incoming request: serverSocket = DatagramSocket() read request from serverSocket write reply to serverSocket specifying client host address, port umber