[ee122] Assignment writeup for first phase of Project 1 updated

Merry Choi merry_c at berkeley.edu
Fri Sep 21 23:30:24 PDT 2007


(I only ask about the constant reconnection because I don't think that's how
jaguar.icir.org on port 7 works. jaguar seems to never terminate the
connection.)



-----Original Message-----
From: ee122-bounces at ICSI.Berkeley.EDU
[mailto:ee122-bounces at ICSI.Berkeley.EDU] On Behalf Of Merry Choi
Sent: Friday, September 21, 2007 11:04 PM
To: 'Vern Paxson'; ee122 at ICSI.Berkeley.EDU
Subject: Re: [ee122] Assignment writeup for first phase of Project 1 updated

Just a clarification. After a server finishes receiving/sending one message
to one client, it should close the connection? So a client is constantly
reconnecting for every line (url) from stdin?



-----Original Message-----
From: ee122-bounces at ICSI.Berkeley.EDU
[mailto:ee122-bounces at ICSI.Berkeley.EDU] On Behalf Of Vern Paxson
Sent: Friday, September 21, 2007 1:01 AM
To: ee122 at ICSI.Berkeley.EDU
Subject: [ee122] Assignment writeup for first phase of Project 1 updated

We have updated the writeup in an attempt to clarify a few things:

	- The server closes the connection.
	- The server must handle multiple clients and partial request
	  lines from clients.
	- What the server echoes to the client, and what it prints
	  to standard output.

Appended are "diffs" showing exactly what was changed.

		Vern


Index: Project1A.tex
===================================================================
--- Project1A.tex	(revision 30)
+++ Project1A.tex	(revision 42)
@@ -136,11 +136,16 @@
 \item The server listens for TCP connections on a port, specified as a
        command line argument on startup.
 
-\item The server echoes back whatever data it receives on a TCP connection.
+\item The server echoes back the first line it receives on the TCP
connection, prints
+  the line to standard output, and prints the components of the request or
prints an
+  appropriate error for invalid requests.
 
+\item The server closes the connection with the client.
+
 \item The server must be able to handle concurrent connections from
multiple
        clients.  This will entail use of {\tt select()}, as will be
-       discussed in section.
+       discussed in section. The server cannot wait on a single client to
finish
+       sending while ignoring the other clients.
 
 \end{enumerate}
 
@@ -182,11 +187,13 @@
 \tt
 \begin{tabular}{rcl}
 Request-Line & = & Method +Space Request-URI +Space HTTP-Version *Space
CRLF \\
-Method & = & "GET" \\
+Method & = & "GET" \\ \\
+
 Request-URI & = & Absolute-Path \\
-HTTP-Version & = & "HTTP" "/" +DIGIT "." +DIGIT \\ \\
 Absolute-Path & = & "/" *FileNameChar \\
 FileNameChar & = & ALPHA | DIGIT | "." | "-" | "\_" | "/" \\ \\
+
+HTTP-Version & = & "HTTP" "/" +DIGIT "." +DIGIT \\ \\
 Space & = & SP | TAB
 \end{tabular}
 }
@@ -222,15 +229,14 @@
 the socket and determine which lines, if any, are legal HTTP GET requests.
 For each line of input, your program should:
 \begin{packed_list}
-\item Echo the line of input ({\it i.e.}, print the line of input to
-       the screen).
-\item For valid requests, list on subsequent lines the components of
-       the request.
-\item For invalid requests, print out an error message indicating
+\item Echo the line of input to both the client, and standard output.
+\item For valid requests, print to standard output the components of the
request (these
+  should appear after the line of input).
+\item For invalid requests, print an error message on standard output
indicating
        which token is missing or illformed.
 \end{packed_list}
 
-For a valid request, the output would be ({\it i.e.,} the server should
return):
+For a valid request, the output to standard output would be ({\it i.e.,}
the server should return):
 
 {\tt
 GET /Research/Areas/OSNT/index.html HTTP/1.0 \\
@@ -251,6 +257,12 @@
 \end{tabular}
 
 
+\vspace{2mm}
+The server needs to be able to handle multiple clients connected
simultaneously. This means
+that if you only receive part of a message, you must store it and handle
other clients. You can't
+receive a partial message and keep attempting to receive from that client,
while ignoring
+the other clients.
+
 \subsubsection*{Client Behavior}
 The client program at this stage will be a
 program that requests an object from a web server and echoes the
@@ -304,8 +316,7 @@
 server. The client need not do any other processing of the message other
 than echo them to standard output.
 
-After processing the response received from the server, the client should
-close the socket to the server and read the next full URL from standard
+After the server closes the connection, read the next full URL from
standard
 input. When end-of-file is reached on standard input, the client program
 should terminate.
 
@@ -378,7 +389,7 @@
 
        \item Copy all the files that you wish to submit to this directory.
 
-       \item Change to the parent directory: {\tt \% cd ..}
+%       \item Change to the parent directory: {\tt \% cd ..}
 
        \item Run the submit program: {\tt \% submit proj1a}
 
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