DISTRIBUTED COMPUTING

( PLEASE ANSWER WITH THIS POST, can not post mulitple items. THANK YOU FOR YOUR HELP!)

Look up the online API specification for Java (20 points)

Choose the link for the Runnable interface and then the Thread class. Browse each carefully, reading the specifications for the methods of each.

According to the specification, which of the two, Runnable interface and Thread class, is preferred if you only intend to implement the run method? Why?

What does the Thread class method sleep do? Write a Java statement(s) that appears in the code for a thread to suspend the execution of the execution of the thread for 5 seconds.

What does the Thread class method activeCount do? What should the method return in a program where three threads are spawned?

How do you use a Runnable interface to create a Thread? Explain.

Naming (10 points)

Complete the following table:

IP address	Domain name	Class of address (A-E)	Net ID (in dotted decimal notation)	Host ID )in dotted decimal notation)
18.181.0.31
129.65.2.119
204.198.135.62
224.0.1.24

HINT: use nslookup in command prompt to look for the Domain Name corresponding to IP address.

Consider this URI: http://www.someSite.org:8081/foo/index.htm

What is the protocol specified?

What is the host name of the service?

What is the port number of the process that provides the service?

Where is the document located?

Process A sends a single message to process B using connectionless IPC. To do so, A issues a send operation (specifying the message as argument) sometime during its execution, and B issues a receive operation. Suppose the send operation is blocking and the receive operation is non-blocking. Draw an event diagram (not sequence diagram) for each of the following scenario: (20 points)

Process A issues its send operation prior to process B issues its receive operation.

Process B issues its receive operation prior to process A issues its send operation.

In the context of IPC: (20 points)

a) What is meant by data marshaling? (There are two components to data marshalling; name and describe each.) Why is it necessary?

b) What is meant by object serialization?

c) How does the two components of data marshalling apply to (i) an array of integers, and (ii) an object? (Describe in general terms what needs to be flattened and encoded in each case.)

5. Consider the Simple Mail Transfer Protocol (SMTP). An excerpt from the RFC for this protocol provides the following sample session. (10 points) 

 R: 220 USC-ISI.ARPA Simple Mail Transfer Service Ready 

 S: HELO LBL-UNIX.ARPA 

 R: 250 USC-ISI.ARPA 

 S: MAIL FROM: 

 R: 250 OK 

 S: RCPT TO: 

 R: OK 

 S: DATA 

 R: 354 Start mail input; end with . 

 S: Blah blah blah... 

 S: ...etc. etc. etc. 

 S: . 

 R: 250 OK 

 S: QUIT 

R: 221 USC-ISI.ARPA Service closing transmission channel

Use a sequence diagram to describe the interactions among the participating processes.