1. Web Server Design Assignment #3: Transfer Encoding & Content Negotiation
Old Dominion University
Department of Computer Science
CS 495/595 Spring 2006
Michael L. Nelson

2. Grading
To be done by an automated program that will test most (all?) combinations
assignment is listed under the day it is to be demoed in class
each group will give a 3-4 minute status report the week before an assignment is due!
If you have a question:
the class list
mimic the behavior of a well known Apache server (e.g.,

3. Methods to Support
Same as assignments 1 & 2

4. Status Codes to Support
Same as assignments 1 & 2, plus:
300 Multiple Choice
use if there are > 1 possible representations
provide html list for a user to pick from
406 Not Acceptable
use if there are no possible representations

5. Request Headers Same as assignments 1 & 2 and add: Accept
Accept-Charset
Accept-Encoding
Accept-Language
User-Agent
Referer

6. Response Headers Same as assignments 1 & 2, but add: Modified Vary
Content-Language
Content-Location
“Transfer-Encoding: chunked”
Modified
Content-type
add charset after type if not ISO (ASCII)
see week 10 slides for example

7. MIME Types
Same as assignment #1

8. Encoding Types compress, gzip, deflate, identity, chunked
(see week 8 lecture)

9. Further Guidance
Use “chunked” transfer encoding for any non-200 response code
use 2 lines as the “chunk”
Use these language encodings
en, es, de, ja, ko, ru
Use these non-ASCII charset encodings
“.jis” -> “iso-2022-jp”
“koi8-r” -> “koi8-r”
“euc-kr” -> “euc-kr”

10. Further Guidance Build “Vary” response header as:
Vary: negotiate, header1, header2, …, headerN
use the “Vary” header only if content negotiation has been performed
No “default” q values in content negotiation
remember: content negotiation only happens if the request would have generated a 404 without content negotiation
Generate ETags on selected representation
we will not do structured ETags as described in RFC-2295

11. Status Code Definition
Generate a 200:
if there is only a single representation as a result of Accept headers and q values
Generate a 300:
if there are multiple representations that “tie” in q values
generate an HTML list showing possible options
Generate a 406:
if no representations are suitable given Accept headers and q values
generate an HTML list showing closest options