Network Working Group                                          M. Kerwin
Internet-Draft
Intended status: Standards Track                           July 28, 2014
Expires: January 29, 2015


                            HTTP/2 Segments
                     draft-kerwin-http2-segments-00

Abstract

   This document introduces the concept of "segments" to HTTP/2, and
   adds a flag to the DATA frame type to allow the expression segments.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   2
   2.  Segments  . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  SEGMENT_CONTINUES Flag  . . . . . . . . . . . . . . . . . . .   2
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   3

1.  Introduction

   This document extends HTTP/2 [I-D.ietf-httpbis-http2] by introducing
   the concept of "segments" to HTTP/2, as a mechanism to combat the
   effects of fragmentation within a stream.  It does this by adding a
   new flag to the DATA frame type ([I-D.ietf-httpbis-http2],
   Section 6.1).

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.  Segments

   A "segment" is a contiguous region of a HTTP/2 message's payload data
   which can be freely fragmented and recombined.  A segment is
   expressed by marking all but the final frame in the segment with the
   "SEGMENT_CONTINUES" flag (Section 3).  Any data-bearing frame that
   does not have the "SEGMENT_CONTINUES" flag set, and does not follow
   one that does, comprises a single segment.

   Segments can be used to mitigate the effects of fragmentation within
   a stream.  For example, an endpoint may have a large chunk of data
   which it has to transmit via multiple DATA frames in order to comply
   with frame size limits.  It can mark those frames as a single segment
   so that any downstream peer without the same frame size restrictions
   knows that it can safely coalesce the frames.

3.  SEGMENT_CONTINUES Flag

   The following new flag is defined for the "DATA" frame
   ([I-D.ietf-httpbis-http2], Section 6.1):

   o  "SEGMENT_CONTINUES" (0x10): Bit 5 being set indicates that the
      current segment continues after the current frame (see Section 2).



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      Intermediaries MUST NOT coalesce frames across a segment boundary
      and MUST preserve segment boundaries when forwarding frames.

4.  Security Considerations

5.  IANA Considerations

   This document has no actions for IANA.

6.  Normative References

   [I-D.ietf-httpbis-http2]
              Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer
              Protocol version 2", draft-ietf-httpbis-http2-13 (work in
              progress), June 2014.

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

Author's Address

   Matthew Kerwin

   Email: matthew@kerwin.net.au
   URI:   http://matthew.kerwin.net.au/


























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