[Zope] Generating unique keys

[Michel Pelletier]

Stuart 'Zen' Bishop wrote:
> 
> I need to generate unique ID's for objects I'll be creating from DTML. This
> of course needs to be thread safe. Although I can't do this out of the box
> from within DTML (that I know of), I could get thread safety using an
> external method, or a persistant object written in Python, and using locks
> provided by the Python thread module. I think a persistant object (lets call
> it ZSequence) would be best.
> 
> However, all this falls down if we want the code to run under ZEO in the
> future. And using a SEQUENCE in my Oracle database might work for me, but
> I want avoid using my RDBMS if possible.
> 
> Can I use the Transaction system? I don't want to do a full commit, as this
> would have unknow effects on whatever is referencing this object. Can I
> commit changes to a dirty object, without affecting the rest of the
> transaction? (I've looked at cPersistence.c, which did nothing but remind we
> why I havn't programmed in C for years :-) )
> 
> Any thoughts? Have I missed some fundamental ZODB concept that solves
> these issues?

No.  No one has had the need to solve the problem yet concerning the ZEO
issue.  For a single process space Zope (ie, intra-thread but
inter-process) there is a how-to on how to generate unique ides.  For a
zeo envorinment, I would suggesting using Apache's unique ID module
which passes in a unique id with an environment variable for each
request, guarenteed (or at least odds in the billions to one against it
not being) unique across a set of machines which synchronize via Network
Time Protocol.

-Michel

> 
>  ___
>    //     Zen (alias Stuart Bishop)     Work: zen@cs.rmit.edu.au
>   // E N  Senior Systems Alchemist      Play: zen@shangri-la.dropbear.id.au
>  //__     Computer Science, RMIT         WWW: http://www.cs.rmit.edu.au/~zen
> 
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