Re: What's the difference between dyngroup and dynlist overlay

["Pierangelo Masarati" <ando@sys-net.it>]

> Hello all,
>
>     I would like to know the difference between dyngroup and dynlist
> overlay.

dyngroup first appeared as a means to define "dynamic groups", i.e. group
objects whose members are URLs that dynamically expand to the list of
members.  So the search defined by each URL is performed, and the DN of
each resulting search entry is turned into a member of the original group.
 It only implements the compare operation, so the generation of the listof
member never actualy occurs; basically, as soon as compare results into
TRUE the lookup of the dynamically generated list ends.

dynlist first appeared as a means to dynamically merge the contents of
entries; so static "list" entries allow to define dynamic members in form
of URLs; these URLs describe a search, which is dynamically expanded, and
the selected attributes of the resulting search entries are merged
(subjected to constraints: a single-valued attribute stops after merging
the first value; duplicate values are listed once only, and so).  If no
attributes are specified, all attrs are merged.  Note that you cannot
search for the resulting merged entry: if the search filter uses some of
the attributes resulting from the merge, the search will fail because
merging occurs while sending the search results.  As you can see, this is
quite different from dyngroup; however, there were enough similarities to
allow dynlist to behave in a special mode (see slapo-dynlist(5) for
details) that is essentilly equivalent to dyngroup; only, dynlist also
allows to present the fully expanded list of group members as the result
of a search operation.

>
>     Does dynlist overlay reuse the sourcode of dyngroup and it's an
> enganced dyngroup?

No, it's been entirely rewritten.

> So we usually use dynlist instead of dyngroup. Right?

No.  If the functionality of dyngroup is enough, I don't see any reason to
use dynlist instead.

> And which protocol is it according to? RFC2589?

No; the dynamic group entry is static for both overlays, and, according to
rfc 2589 (3.1):

   The support of dynamic attributes of an otherwise static object, are
   outside the scope of this document.

so neither of them has anything to do with that rfc.  None of the two
overlays is based on, or complies with, any rfc, AFAIK.  They're OpenLDAP
extensions.

p.



Ing. Pierangelo Masarati
Responsabile Open Solution
OpenLDAP Core Team

SysNet s.n.c.
Via Dossi, 8 - 27100 Pavia - ITALIA
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