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To: cs551@merlot.usc.edu
Subject: Re: CS551 - Final Project - Question on Grading guidelines 
Date: Fri, 20 Apr 2007 15:14:49 -0700
From: william@bourbon.usc.edu

Someone wrote:

  >   	From your response to the question below, what I understand from
  > this particular test case is that there is only one copy (same nonce, sha1,
  > filename) of the file "blondie1.mp3" stored in the network when user invoked
  > 
  > in 1st window, type:
  >   store blondie1.mp3 1 title="Heart of Glass"
  > 
  > 	At this point, node at 3rd window should have this file in its cache
  > space. After it searches and gets 3 responses, no matter if user does "get 1
  > 2 or 3", this should always succeed and hence make a copy of the file in CWD
  > because:
  > 	1. If the file corresponding to 'get' number is a local copy, it
  > should simply move it to permanent space.
  > 	2. If the file comes from the other two nodes, it should check
  > before attempting to store and find that it already has a copy of the same
  > file, and discard the response.
  > 	So the permanent space should NEVER be exceeded in this case since
  > there is only one file in the network, and a node MUST always have only one
  > copy of the file. I suspect that the person who got the storage exceeded
  > must not check for file duplicate before he attempts to store the received
  > file. Please let me know what you think.

Your analysis is correct!  I'm reverting the grading guidelines
back to the previous version!

Sorry about my confusion!
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>



	
	

  -----Original Message-----
  From: william@bourbon.usc.edu [mailto:william@bourbon.usc.edu] 
  Sent: Friday, April 20, 2007 2:40 PM
  To: cs551@merlot.usc.edu
  Subject: Re: CS551 - Final Project - Question on Grading guidelines
  
  Someone wrote:
   
    > For Test Case (A) Beacon-only networks -> (2) Network with 3 beacon nodes
    >  
    > The configuration parameters are set with CacheSize=600 and PermSize=600
    > (These are in KB).
    >  
    > For the following part of the test case:
    >  
    >                 in 3rd window, type:
    >   (+1 points)
    >   search filename=blondie1.mp3
    >                              should get three responses, then do
    >   (+1 points)
    >   get 1
    >                              "blondie1.mp3" should be created in the
    >                              current directory
    >  
    >                 in the 4th window, type at the UNIX prompt:
    >                              "ls -l blondie1.mp3"
    >                                  (file size should be 474736)
    >                              "openssl sha1 blondie1.mp3"
    >                                  (should be
    >                              ffd3b197e1c0f0c27e7bdc219f553a3e6b139dfb)
    >                              "rm blondie1.mp3"
    >  
    >  
    >  
    > =========================> At this point 400 KB of the Perm space is used
    > up; which mean approx 200 KB of perm space is available. If the following
    > "get" commands are executed, then the node at window 3 will not be able to
    > save the file in the permanent area (due to lack of free space 400KB >
    > 200KB) and hence will not be able to provide the file to the user. So are
    > the subsequent steps correct?
    >  
    >                 in 3rd window, type:
    >   (+1 points)
    >   get 2
    >                              "blondie1.mp3" should be created in the
    >                              current directory
    >  
    >                 in the 4th window, type at the UNIX prompt:
    >                              "ls -l blondie1.mp3"
    >                              "openssl sha1 blondie1.mp3"
    >                              "rm blondie1.mp3"
    >  
    >                 in 3rd window, type:
    >   (+1 points)
    >   get 3
    >                              "blondie1.mp3" should be created in the
    >                              current directory
    >  
    >                 in the 4th window, type at the UNIX prompt:
    >                              "ls -l blondie1.mp3"
    >                              "openssl sha1 blondie1.mp3"
    >                              "rm blondie1.mp3"
  
  You are correct.  I have just changed the grading guidelines
  to say that "get 2" should not succeed and I removed "get 3"
  and move the +1 point to "get 1".
  
  Thanks for catching the bug!
  --
  Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>