Summary of Last Lecture

1
Summary of Last Lecture

• Stream Service
• Datagram Service
• Internet Addressing
• 4-byte address
• Ports
• 2-byte port number

2
Summary of Last Lecture

• Sockets
• Stream sockets
• Byte-stream
• Datagram sockets
• Datagram packets
• Socket-programming using TCP
• Socket-programming using UDP

3
Summary of last lectureSocket programming with
TCP

• Client must contact server
• server process must first be running
• server must have created socket (door) that
  welcomes clients contact
• Client contacts server by
• creating client-local TCP socket
• specifying IP address, port number of server
  process
• When client creates socket client TCP
  establishes connection to server TCP

• When contacted by client, server TCP creates new
  socket for server process to communicate with
  client
• allows server to talk with multiple clients
• source port numbers used to distinguish clients

4
Summary of Last Lecture Socket programming with
UDP

• UDP no connection between client and server
• no handshaking
• sender explicitly attaches IP address and port of
  destination to each packet
• server must extract IP address, port of sender
  from received packet
• UDP transmitted data may be received out of
  order, or lost

5
Summary of Last Lecture

• Threads in Java
• Concurrency
• Multi-threaded server
• Synchronized methods

6
Summary of Last Lecture

• Transport layer services and protocols
• Logical communication
• End-to-end service
• TCP reliable, in-order delivery
• UDP unreliable, unordered delivery

7
Summary of Last Lecture

• Multiplexing and demultiplexing
• Receiving host demultiplexing
• Sending host multiplexing
• Connectionless demultiplexing
• Identified by two-tuple
• (dest IP, dest port)
• Connection-oriented demultiplexing
• Identified by four-tuple
• (source IP, source port, dest IP, dest port)