Subject: [core] #245: Compression vs. Block

From: "core issue tracker" <[email-masked]>
Date: Sun, 30 Sep 2012 13:17:06 -0000

#245: Compression vs. Block

 Klaus Hartke notes:

 The Content-Type option includes the specification of a Content-Encoding
 such as "deflate" or "gzip". When used with block, should each block be
 compressed individually or transfers each block a part of the compressed
 representation?

 If the former, which flush mode should be used, Z_SYNC_FLUSH,
 Z_PARTIAL_FLUSH or Z_FULL_FLUSH?

 Carsten's point of view:

 The intention is to transfer the content-coded representation, which is
 sliced up in blocks.
 The sender (side that does the slicing) may want to do the compression
 incrementally, however, it has to make sure the slices are an exact power
 of two number of bytes.  This makes flushing precisely at the block
 boundaries hard.  (The sender may still want to do flushing, but this is
 an implementation decision.)  The recipient obtains a content-coded
 representation that can be decompressed incrementally, but where the block
 boundaries do not mean anything and therefore don't need to be reproduced
 by flushing.

 This item would benefit from input from implementers that use content-
 coding with CoAP.

-- 
-----------------------------+-------------------------------------
 Reporter:  cabo@…           |      Owner:  draft-ietf-core-block@…
     Type:  other technical  |     Status:  new
 Priority:  minor            |  Milestone:  post-WGLC-1
Component:  block            |    Version:  block-08
 Severity:  In WG Last Call  |   Keywords:
-----------------------------+-------------------------------------

Ticket URL: <http://trac.tools.ietf.org/wg/core/trac/ticket/245>
core <http://tools.ietf.org/core/>