Web Server Design

Assignment #3: Transfer Encoding & Content Negotiation

Due: 03/24/2010Old Dominion University

Department of Computer ScienceCS 495/595 Spring 2010

Martin Klein <mklein@cs.odu.edu>

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:

– email the class list– mimic the behavior of a well known Apache server

(e.g., www.cs.odu.edu)

Methods to Support

• Same as assignments 1 & 2

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 that

match the requested q values

Request Headers

• Same as assignments 1 & 2• and add:

– Accept– Accept-Charset– Accept-Encoding– Accept-Language– User-Agent– Referer– Negotiate

Response Headers• Same as assignments 1 & 2, but add:

– Vary– Content-Language– Content-Location– Content-Encoding– “Transfer-Encoding: chunked”– Alternates– TCN

• Modified– Content-type

• add charset after type if not ISO-8859-1 (ASCII)– see week 8 slides for examples

MIME Types

• Same as assignment #1

Encoding Types

• compress, gzip, deflate, identity, chunked– (see week 7 lecture)

Further Guidance

• Use “chunked” transfer encoding for any dynamically generated server response– i.e., directory listings and 3xx, 4xx, 5xx html snippets– 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”

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 structured ETags on selected representation as per RFC-2295 (section 9.2)

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 OR

the client sends a “Negotiate: 1.0” request header– 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

302 Redirection

## Incoming RE 302 URI# (this overwrites the redirection from A2)#

^(.*)/galaxie(.*) $1/fairlane$2

Keep in mind:Status report in 2 weeks!

START NOW!!!