W3C home > Mailing lists > Public > ietf-http-wg@w3.org > July to September 2007

revised I-D draft-decroy-http-progress-01

From: Adrien de Croy <adrien@qbik.com>
Date: Fri, 03 Aug 2007 13:17:23 +1200
Message-ID: <46B28223.2050000@qbik.com>
To: ietf-http-wg@w3.org

greatly simplified, and deals now purely with progress notifications.

Regards

Adrien

P.S, I'm still working on discussion paper on intercepting proxies.  
Also affects reverse proxies, as this is also a case of a proxy being 
involved when the client thinks it's talking to a server.

-- 
Adrien de Croy - WinGate Proxy Server - http://www.wingate.com



Network Working Group                                            de Croy
Internet-Draft                                                      QBIK
Intended status: Standards Track                          August 1, 2007
Expires: January 3, 2008


                      Progress notifications for HTTP
                       draft-decroy-http-progress-01

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on January 3, 2008.

Copyright Notice

   Copyright (C) The Internet Society (2007).
















de Croy                 Expires January 3, 2008                 [Page 1]

Internet-Draft                http-progress                  August 2007


Abstract

   This document specifies extenions to HTTP to allow progress messages
   for user-agents during lengthy transactions, and to allow better 
   flow-control of large message body submission in cases where HTTP
   authentication is required by servers and/or intermediaries.

Table of Contents

   1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction and motivation  . . . . . . . . . . . . . . . . .  4
     2.1 The need for progress information. . . . . . . . . . . . . .  4
     2.2 Aim of this document . . . . . . . . . . . . . . . . . . . .  4
   3.  Header Field Definitions . . . . . . . . . . . . . . . . . . .  5
     3.1 Progress . . . . . . . . . . . . . . . . . . . . . . . . . .  5
       3.1.1 Client request . . . . . . . . . . . . . . . . . . . . .  5
       3.1.2 1xx Responses. . . . . . . . . . . . . . . . . . . . . .  6
   4.  Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.1 Progress Intervals . . . . . . . . . . . . . . . . . . . . .  7
   5.  Example. . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   6.  Compatibilty issues. . . . . . . . . . . . . . . . . . . . . .  9
   7.  Implementation Notes . . . . . . . . . . . . . . . . . . . . . 10
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   9.  Notes & TODO . . . . . . . . . . . . . . . . . . . . . . . . . 12
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 13
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 14
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15
   Intellectual Property and Copyright Statements . . . . . . . . . . 16






















de Croy                 Expires January 3, 2008                 [Page 2]

Internet-Draft                http-progress                  August 2007


1.  Terminology

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT"
   and "MAY" that appear in this document are to be interpreted as
   described in [RFC2119]














































de Croy                 Expires January 3, 2008                 [Page 3]

Internet-Draft                http-progress                  August 2007


2.  Introduction and motivation

2.1 The need for progress information

   Increasingly, resource transfers using HTTP are subject to ever-
   more complex processing, particularly by proxy servers.  Processing 
   such as scanning resources for viruses at an HTTP proxy creates 
   special problems that cannot be resolved cleanly with the current 
   specification of HTTP.

   Many types of processing require access to an entire message body.
   This can take considerable time to accumulate depending on upstream 
   link bandwidth and/or other factors.  It may not be safe to send 
   any part of the resource to the client until processing is complete.

   Frequently problems occur where human users of client agents give up
   waiting for visible progress, typically resulting in retries wasting
   time and network resources.

   Furthermore, some automated clients will give up waiting when no
   resource data is received within a certain timeframe.

   There is a clear need for upstream agents to be able to provide 
   timely progress notifications to downstream agents to enable them to
   make proper decisions about whether it is appropriate to keep 
   waiting.


2.3 Aim of this document

   This document aims to solve this problems by providing a defined 
   mechanism whereby intermediaries or server agents can provide visible
   progress notifications back to the client agent (and the human user),
   thereby avoiding inappropriate timeouts, and retries;

















de Croy                 Expires January 3, 2008                 [Page 4]

Internet-Draft                http-progress                  August 2007


3 Header field definitions

   This document defines a new header field to indicate progress.  
   This field allows optional textual state indication as well as 
   requiring numeric indication of completeness.

3.1 Progress

   The Progress field MAY appear in any request message sent by a client
   or in any server or proxy-generated 1xx series of response messages.  
   The Progress field MUST not appear in any other series of response 
   messages.

   A server that complies with this document upon receiving a request 
   containing a Progress field MUST provide an interim response message 
   (1XX) within a reasonable time period AND provide further periodic 
   updates until the final response to the request is sent.  
   
   A proxy that complies with this document upon receiving a request
   containing a Progress field MUST forward the tag unchanged to any
   upstream agent.  The proxy however is responsible for providing
   progress messages to the client, and in the event that no upstream
   notifications are available, it MUST satisfy the client progress
   notifications whilst it is still prepared to process the request.
   
   The proxy SHOULD pass any 1XX messages back through to the 
   client unchanged.  

   Progress indication is worthless if it is not timely.  A discussion
   of timing is in section 4


   The form of the field is defined below

3.1.1 Client request

   Progress = "Progress" ":" SP interval

   interval = the time in seconds in which the client expects a response

   Example:
   
   Progress: 10








de Croy                 Expires January 3, 2008                 [Page 5]

Internet-Draft                http-progress                  August 2007


3.1.2 1xx Responses

   Progress         = "Progress" ":" SP numeric [";" SP textual] 

   textual          = any text valid in a header

   numeric          = (percent | bytes-processed "/" bytes-total)

   percent          = "%" number

   bytes-processed  = number
   
   bytes-total      = number | "UNKNOWN"

   The textual information is intended to be displayed verbatim to a
   user in an area usually associated with progress indication.  The 
   numeric-progress field can be used to display a progress bar and/or
   show how much data has been received by an upstream proxy.
   
   the language of the text information SHOULD be the same language
   as indicated as preferred by the client in its original request, e.g.
   by using the values from the Accept-Language: header in the request

   Examples of its use are:

      Progress: 20480/UNKNOWN; Generating content

   This could be sent by a server to indicate progress of generation of
   content.

      Progress: 20480/UNKNOWN; Download in progress

   Could be sent by an upstream proxy that is retrieving a message body,
   has received 20480 bytes, and doesn't know the content length.  

      Progress: 1200000/1200000; Download complete, scanning

   Could be sent by an upstream proxy that has just completed retrieving 
   a message body, has received 1200000 of 1200000 bytes, and is about 
   to scan the content before sending it on to the client.

      Progress: %25; Scanning content for viruses

   Could be sent by an upstream proxy that is currently 25% through 
   virus scanning of a message body.

      Progress: %45; Enumerating mail folders

   could be sent by a webmail server opening a user mailbox 


de Croy                 Expires January 3, 2008                 [Page 6]

Internet-Draft                http-progress                  August 2007


4.  Timing
   
4.1 Progress intervals
   
   The client Progress header indicates a time in seconds which is the
   time within which it expects a response (either final or interim
   containing progress information).  The server or proxy SHOULD use 
   this specified time as the initial time and periodic time for
   updates, or choose another time.   If the server chooses to use 
   another periodic interval, this should be one chosen with regard to
   the usefulness of the interval to a waiting human, and it is 
   suggested that an interval of about 5 - 10 seconds would be 
   appropriate.

   Agents generating progress notifications MAY choose to send a 
   notification whenever any significant change in state occurs.  
   
   However in the interests of bandwidth, agents SHOULD NOT send 
   progress notifications more frequently than once per second.
   This includes an intermediary which may be generating notifications
   and relaying notifications from upstream.

   It is left up to the implementor of intermediaries to choose which 
   notifications they may choose to relay or generate themselves, 
   remembering that this is intended for a human user, but will be 
   useful to automated agents as well.

























de Croy                 Expires January 3, 2008                 [Page 7]

Internet-Draft                http-progress                  August 2007


5.   Example

   +-------------------+------------------------+--------------------+
   |       Client      |      Intermediary      |       Server       |
   +-------------------+------------------------+--------------------+

   Connects to intermediary
   
   ->
   GET http://www.wingate.com/bigfile.zip HTTP/1.1
   Host: www.wingate.com
   Progress: 10

                        ->
                        GET /bigfile.zip HTTP/1.1
                        Host: www.wingate.com
                        Progress: 10

                                             <-
											 HTTP/1.1 200 OK
                                             Content-Length: 20000000
											 ...

                           time elapses
						<-
                        HTTP/1,1 102 Processing
						Progress: 1000000/20000000; Downloading

                           time elapses
						<-
                        HTTP/1,1 102 Processing
						Progress: 20000000/20000000; Downloaded, Scanning

                           time elapses
						<-
                        HTTP/1,1 102 Processing
						Progress: %25; Scanning

                           time elapses
						<-
                        HTTP/1,1 102 Processing
						Progress: %75; Scanning

                        <-
                        HTTP/1.1 200 OK
                        Content-Length: 20000000
                        ...
						Transfers resource to client.



de Croy                 Expires January 3, 2008                 [Page 8]

Internet-Draft                http-progress                  August 2007


6. Compatibilty issues.

   None identified.  RFC2616 already mandates that any agent must be 
   able to cope with multiple interim responses.

   A server not understanding the Progress header in a request will
   not generate progress notifications.

   A client unaware of this document will not generate requests with
   the Progress header.

   A proxy not understanding the Progress header already should be 
   passing unknown headers through to upstream, and also passing back 
   1XX responses.





































de Croy                 Expires January 3, 2008                 [Page 9]

Internet-Draft                http-progress                  August 2007


7.  Implementation Notes

   Most user agents provide screen real-estate to display progress, 
   often in the "status bar" of the window.  It is envisaged that the
   progress notifications outlined in this document would be shown in
   there.

   











































de Croy                 Expires January 3, 2008                [Page 10]

Internet-Draft                http-progress                  August 2007


8.  Security Considerations

   No security issues identified with use of this proposal.
















































de Croy                 Expires January 3, 2008                [Page 11]

Internet-Draft                http-progress                  August 2007


9.  Notes & TODO

   * modified from version 00 to remove sections on flow control issues.
















































de Croy                 Expires January 3, 2008                [Page 12]

Internet-Draft                http-progress                  August 2007


10. IANA Considerations

   None.
















































de Croy                 Expires January 3, 2008                [Page 13]

Internet-Draft                http-progress                  August 2007


11.  References

11.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC4234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 4234, October 2005.

   [RFC4559]  Brezak, J. "SPNEGO-based Kerberos and NTLM HTTP 
              authentication in Microsoft Windows", RFC 4559, June 2006



































de Croy                 Expires January 3, 2008                [Page 14]

Internet-Draft                http-progress                  August 2007


Author's Address

   Adrien de Croy
   Qbik New Zealand Limited
   PO Box 3548
   Shortland St
   Auckland
   New Zealand

   Email: adrien@qbik.com
   URI:   http://www.wingate.com/








































de Croy                 Expires January 3, 2008                [Page 15]

Internet-Draft                http-progress                  August 2007


Full Copyright Statement

   Copyright (C) The Internet Society (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.


Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).





de Croy                 Expires January 3, 2008                [Page 16]
Received on Friday, 3 August 2007 01:17:04 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 27 April 2012 06:50:15 GMT