HTTP MIME Type Handler Detection
RFC 2936

Document Type RFC - Informational (September 2000; No errata)
Last updated 2013-03-02
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Network Working Group                                         D. Eastlake
Request for Comments: 2936                                       Motorola
Category: Informational                                          C. Smith
                                                     Royal Bank of Canada
                                                                D. Soroka
                                                                      IBM
                                                           September 2000

                    HTTP MIME Type Handler Detection

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.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   Entities composing web pages to provide services over the Hypertext
   Transfer Protocol (HTTP) frequently have the problem of not knowing
   what Multipurpose Internet Mail Extensions (MIME) types have handlers
   installed at a user's browser.  For example, whether an Internet Open
   Trading Protocol (IOTP) or VRML or SET or some streaming media
   handler is available.  In some cases they would want to display
   different web pages or content depending on a MIME handler's
   availability.  This document summarizes reasonable techniques to
   solve this problem for most of the browsers actually deployed on the
   Internet as of early 2000.  It is intended to be of practical use to
   implementors during the period before the wide deployment of superior
   standards based techniques which may be developed.

Acknowledegements

   Helpful comments by Tony Lewis of Visa have been incorporated.

Eastlake, et al.             Informational                      [Page 1]
RFC 2936            HTTP MIME Type Handler Detection      September 2000

Table of Contents

   1. Introduction.................................................  2
   2. The HTTP 'Accept' Header.....................................  2
   3. JavaScript...................................................  3
   4. ActiveX and the Windows Registry.............................  4
   5. ECML, The Electronic Commerce Modeling Language..............  4
   6. Putting It All Together......................................  5
   7. Future Development...........................................  5
   8. Security Considerations......................................  5
   9. IANA Considerations..........................................  6
   References......................................................  6
   Appendix A: Browser Version Sniffer Code........................  8
   Authors' Addresses.............................................. 12
   Full Copyright Statement........................................ 13

1. Introduction

   Entities composing web pages to provide services over [HTTP]
   frequently have the problem of not knowing what [MIME] types have
   handlers installed at a user's browser.  For example, whether an
   [IOTP] or VRML or [SET] or some streaming media handler is available.
   In many cases they would want to display different web pages or
   content depending on a MIME handler's availability.  Sending a
   response with a MIME type that is not supported frequently results in
   interrupting the flow of the user experience, browser queries as to
   what to do with the data being provided, and, of course, failure to
   provide the behavior that would have occurred had the correct MIME
   type handler been installed.

   This document describes reasonable techniques to solve this problem
   for most of the browsers actually deployed on the Internet as of
   early 2000.  It is intended to be of practical use to implementors
   during the period before the wide deployment of superior standards
   based techniques which may be developed.  It is written in terms of
   determining whether a handler for application/iotp or application/x-
   iotp exists but is equally applicable to other MIME types.

2. The HTTP 'Accept' Header

   The problem should be solved by the Hyper Text Transport Protocol
   [HTTP] request "Accept" header which lists accepted [MIME] types.
   This header is present in both Version 1.0 and 1.1 of HTTP and its
   content is supposed to be a list of MIME types and subtypes that are
   accepted.  The only problem is that many browsers just send "*/*" or
   the like.

Eastlake, et al.             Informational                      [Page 2]
RFC 2936            HTTP MIME Type Handler Detection      September 2000

   If the particular MIME type you are looking for is specifically
   present in the Accept header, it is generally safe to assume that a
   handler for it is actually installed or part of the browser.

   NOTE: Although not part of the main topic of this document, if you
   are designing MIME type handler software and have access to a browser
   interface that allows you to request the insertion of the MIME type
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