1. Java Socket Programming and Java RMI CS 15-440 Recitation 1, Sep 8, 2011 Majd F. Sakr, Vinay Kolar, Mohammad Hammoud

2. Today… Announcements All programs run on Unix cluster Use any editor/file-transfer you want Project 1 Java Socket Programming Java RMI

3. Project 1 Learning objective: Apply the knowledge of Process and Communication and Naming to design a Distributed File System. Duration: 3 weeks Solo project

4. Project Objectives Design a Distributed File System called File Stack using RMIs Functions provided: Create/Read/Write files and directories Meta-operations: list files, size

5. Components Storage Servers: Stores Files Naming Server: Maps a file to storage server Clients: Contact Naming to get storage server Carry out file operation on storage server

6. Design Storage Server Registration Storage Servers register to Naming on boot Client functions Contact naming to get a file-handle to access a file Perform file operation All functionalities through RMI Stubs/Skeletons Serialization

7. Design/Implementation hints Remote Method Invocation (RMI) heavy We have an excellent start-up code Read “Design guidelines” and “Implementation hints” Come back to us Earlier the better

8. Java Socket Programming Sockets: An API for using underlying networks An abstraction like “File” Request-response

9. Java Socket Programming IP Address To name a machine/host Port Port maps to one connection-end-point For your apps: Use ports 49152 through 65535 Types of Sockets UDP (Datagram) vs TCP (Conn-oriented)

10. java.net class A package that provide base classes and API for Socket programming Open/close socket Accept Read/Write Send/Receive

11. TCP Sockets Classes java.net.ServerSocket, java.net.Socket DataInputStream, DataOutputStream

12. TCP Socket Server Client 1.Socket client = new Socket(server, port_id); 2.DIS/DOS  Same as in server 3.Read/Write  Same as in server 4.Close  Same as in server 1.ServerSocket server = new ServerSocket( PORT ); 2.Socket client = server.accept(); 3.DataInputStream is = new DataInputStream(client.getInputStream()); 4.DataOutputStream os = new DataOutputStream(client.getOutputStream()); 5.String line = is.readLine(); 6.os.writeBytes(“Hello\n”); 7.client.close();

13. Exercise Write a simple chat server and client using TCP Sockets (Estimated time: 20 mins) Step 1: Client connects to server. Sends a message Server sends back all the message that it has received from all clients Step 2: One client should not block the server

14. Java RMI What is RMI? What do we need Where is the server? Which object/method should I call? What if I do not know the server object definition? How to communicate?

15. Java RMI How do we implement? Look-up for server/object RMI Registry Remote interface Extend Remote interface Throw RemoteException Make it accessible How does the magic happen? Stub/Skeleton, Serialize

16. References http://www.buyya.com/java/Chapter13.pdf http://www.generalsoftwares.co.uk/remote-services.html