[Standards-JIG] JEP-0060 Publisher Model - nodehirarchy

Jean-Louis Seguineau jean-louis.seguineau at laposte.net
Fri May 26 09:16:28 UTC 2006


Bernhard, building the hierarchy is a matter of server implementation. You
can implement a node to be a child of another node without exposing the fact
in the node ID. You could for example implement an indirect index based
reference instead of using building the semantic in the ID.

Having provision for semantic in the IDs is IMHO a major shortcoming of this
JEP. It is opening the Pandora box for all sorts of interpretations of the
standard, and above all reduces XMPP to 'yet another hierarchical pubsub'.
But this is only my strong opinion...

As far as I am concerned, I will not implement hierarchies this way in the
servers I design. Pubsub hierarchies can be expressed as specific cases of
attribute based pubsub systems. But this is only my strong opinion...

Jean-Louis

-----Original Message-----
Message: 5
Date: Thu, 25 May 2006 23:16:13 +0200
From: bernhard <bz at datenkueche.com>
Subject: Re: [Standards-JIG] JEP-0060 Publisher Model	-	nodehirarchy
	permissions
To: Jabber protocol discussion list <standards-jig at jabber.org>
Message-ID: <44761E9D.5060908 at datenkueche.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Bob Wyman wrote:
> Bernhard wrote:
>   
>> ejabberd builds a hierarchy based on the id - this is not specified in 
>> jep-0060.
>>     
> 	If ejabberd "builds a hierarchy based on the id" then that is
> completely *OUTSIDE* JEP-0060. It is a bug. Node IDs in JEP-0060 are
opaque
> and no client or server should ever treat them otherwise.
>   
11.5 Handling Node Hierarchies


NodeIDs MAY have semantic value in implementations of pubsub. If an 
implementation wishes node IDs to have hierarchical meaning (as is shown 
in the examples), that implementation MAY choose any naming scheme which 
is suitable to the hierarchy in question. Identifiers could use slashes, 
periods, or other special characters as the hierarchy separator.

---

As I remember there is written:

collections contains nodes (but no items)
nodes contains nodes and items

Some people tell that jep-0060 says nothing about hierarchy - but that's 
not true.
But there is not written how to configure a node to be a child node of a 
node or a collection.

If there is a usecase how to make the hierarchy, everything is clear - 
otherwise the programmer have to guess.

> 	My personal and very strongly held opinion is that if ejabberd is
> actually doing what you say it is doing, this should be flagged as a bug
and
> the bug should be fixed as soon as possible. It is exceptionally difficult
> to maintain standards if implementers insist on diverging from the
standard.
> Given the prominence of ejabberd, it is likely that people will come to
> perceive this bug to be normal behavior and thus attempt to get others to
> implement the same bug. This is not a good thing.
>   
that's true
> 	Hierarchy in JEP-0060 collections should be established using the
> mechanisms provided in JEP-0060 and those same mechanisms should be used
to
> discover the hierarchy.
Maybe it's hidden - I can't find that.

Bernhard




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