Known Proxy/Caching Problems

From: John Dilley (jad@granite.hpl.hp.com)
Date: Mon Apr 19 1999 - 18:47:24 MDT


        I have begun creating a template for the known problems document
discussed at the Minneapolis WREC WG meeting. I would like to solicit
input from the WREC group on this first draft. My goal is to have the
template firm and presentable by the Oslo IETF meeting, and to solicit
input from the WG attendees. I hope we can also have a first pass at
the high-profile known problems to (1) provide a good example of what
this document should contain, and (2) to prevent duplication of effort
of multiple people sending in the same high-profile known problems.

Please provide feedback by email on the following points:

    - Does the template look reasonable? How would you improve it?
    - Do the classifications look reasonable? What would you add/remove?

In addition, feel free to begin a discussion of known problems; once we
get a template we are satisfied with I will advertise it more widely,
and publish it in a more appropriate location (the WREC page perhaps)?

        This memo mentions the taxonomy work in progress. How is that
coming along, Ingrid and Gary? Did you get the comments I sent just
after Minneapolis? I looked for a new version of the document on the
web but did not find one. I'd like to make sure these two memos fit
together well. I would also like to make sure this memo dovetails into
Joe's Research Topics memo. There will likely be a grey area between
known problems and research topics, which Joe and I will work to keep as
clean as possible.

        I appreciate your comments and suggestions! Best regards,

                             -- jad --

        John Dilley <jad@hpl.hp.com>
        Hewlett-Packard Laboratories
        1501 Page Mill Road MS 1U-17
        Palo Alto, CA 94304 // USA

        Voice +1 650 857-8146
        Fax +1 650 857-5100

        The known problems draft is attached in text below, or you can
find it on the web at the following URL: (sorry for its length)

http://www.hpl.hp.com/personal/John_Dilley/caching/draft-wrec-known-prob-00.html


                      HTTP Proxy/Caching Known Problems

Status of this Memo

This memo provides information for the Internet community. It does not
specify an Internet standard of any kind. Distribution of this memo is
unlimited.

Introduction

This memo catalogs a number of known problems with World Wide Web proxy and
cache servers. The goal of the document is to provide a discussion of the
problems and proposed workarounds, and ultimately to improve conditions by
illustrating problems. The construction of this document is a joint effort
of the web caching community. It is being done under the auspices of the
IETF Web Replication and Caching working group. We gratefully acknowledge
RFC 2525, which helped define the initial format for this known problems
list.

This memo discusses problems both with Proxy servers, which act as
application-level gateways for web requests, as well as Cache servers, which
hold copies of previously requested documents in the hope of saving future
network bandwidth and latency for users. Proxies often perform a caching
function, but the two are not necessarily linked. Refer to the work in
progress Internet Web Replication and Caching Taxonomy for definitions of
proxy and cache terminology used in this memo.

No individual or organization has complete knowledge of the know problems in
web caching. If you know of a problem that is not documented on this list
you are encouraged to send it to the WREC mailing list for discussion or to
the memo's editor for review and inclusion in the list.

Problem Template

Each problem is defined in a standard format, summarized in the table below
with each item described more fully in the following list.
----------------------------------------------------------------------------

    Name: short, descriptive name of the problem (3-5 words)
    Classification: classifies the problem: performance, security, etc
    Description: describes the problem succinctly
    Significance: magnitude of problem, environments where it exists
    Implications: the impact of the problem on systems and networks
    Indications: states how to detect the presence of this problem
    Solution(s): describe the solution(s) to this problem, if any
    Workaround: practical workaround for the problem
    Contact: contact name and email address for this section

----------------------------------------------------------------------------

Name
     A short, descriptive name (3-5 words) name associated with the problem.
     In this memo, the name is used as a subsection heading.

Classification
     Problems are grouped into categories of similar problems for ease of
     reading of this memo. Choose the category that best describes the
     problem. Suggested categories are as follows:
       1. Performance: perceived latency or server demand
       2. Administration: care and feeding of caches
       3. Network: impact on local, global networks
       4. Security: privacy, authentication
     This is the first draft of this memo. The classification structure is
     subject to revision. In the published drafts of the memo the
     classification structure should be fixed but may be revised from time
     to time.

Description
     A definition of the problem, succinct but including necessary
     background material.
     Note that problems that are particular to a single product's
     implementation are not appropriate. The IETF will not endorse or
     condemn any vendor's product. (How are we going to manage this?)
    
Significance (High, Medium, Low)
     May include a brief summary of the environments for which the problem
     is significant.
    
Implications
     Why the problem is viewed as a problem. What inappropriate behavior
     results from it? This section should substantiate the magnitude of any
     problem indicated with High significance.
    
Indications
     How to detect the presence of the problem. This may include references
     to one or more substantiating documents that demonstrate the problem. This
     should include the network configuration that led to the problem such
     that it can be reproduced. Problems that are irreproduceable will not
     appear in this memo.
    
Solution(s)
     Solutions that fix the problem, if known. Note: only well-know problems
     with little known solutions should be in this memo. Problems with
     well-known solutions are unnecessary to document here.
    
Workaround
     Practical workaround if no solution is available or usable. The
     workaround should have sufficient detail for someone experiencing the
     problem to get around it.
    
Contact
     Contact name and email address of the person who supplied the
     information for this section. If you would prefer to remain anonymous
     the editor's name will appear here instead, but we believe in credit
     where credit is due.

Known Problems

This is the first draft of the memo. Rather than prejudice the readers with
the editor's opinion of the current problems with caching, this memo
solicits input from the community on current proxy/caching problems. First
we must address the classification; are those the right categories for
problems? Without a set of problems to classify it is a difficult to say,
but how does it look for a start? Please send initial input to
jad@hpl.hp.com. I will summarize the inputs, and refine the categorization
based upon the initial set of problems. Thank you!



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