Subject: [core] Resource Directory: Pagination (?page/?count)

From: Carsten Bormann <[email-masked]>
Date: Wed, 9 Jan 2019 16:12:23 +0100

During a recent discussion of the specification and of implementation efforts for the CoRE resource directory, the question came up whether there really is a good reason to have the pagination mechanism described in:

https://core-wg.github.io/resource-directory/draft-ietf-core-resource-directory.html#rfc.section.6.2.p.2

This provides query parameters to the lookup interface, where a “count” query parameter can be given that limits the number of items returned (returning a “page” of items), and a “page” query parameter to skip a number of pages.

Christian noticed that the implementation of this was pretty much equivalent in implementation effort to simply supporting the block-wise transfer mechanism (RFC 7959).
(There is a small difference in that a block-wise transfer skips forwards in units of bytes in the representation, while page/count can skip forward in items, which is closer to the application.  E.g., it might be possible to implement page/count just with SQL parameters, while block-wise is most efficient with a result cache and cursors.)

What do other implementers think?  Any SDOs that already have adopted page/count for RD?

Grüße, Carsten