RWP04: Registry Replication

[Tony Linde]

Comments embedded...

> -----Original Message-----
> From: Keith Noddle [mailto:ktn at star.le.ac.uk] 
> Sent: 28 April 2003 12:23
> To: IVOA Registry mailing list
> Subject: Re: RWP04: Registry Replication
> 
> 
> On Fri, 2003-04-25 at 18:32, Roy Williams wrote:
> > > > How about if we have three types of registry:
> > > >
> > > > 1. full: will attempt to maintain a full list of all 
> resources on 
> > > > the VO 2. limited: lists only resources of interest to 
> a specific 
> > > > community 3. private: only lists the resources at that 
> location; 
> > > > not queryable
> > 
> > There is a smooth transition here to what we might call type 4: a 
> > service
> 
> I am slightly uneasy about different registry "types" as that 
> potentially leads to management and hierarchy issues. I 
> prefer the notion of a self regulating network of registries 
> which "do the right thing" among themselves. Building upon 
> previous discussions, I'd like to float the following:
> 
>       * A registry is viewed just another a resource

Correct.

>       * By definition, resource entries in a registry include a
>         description of themselves (note: fine grained vs 
> coarse grained
>         resource metadata? This proposal requires fine grained)

We should not dictate the content or structure of registries. I'm not sure
why 'requires fine grained'.

>       * The description of the content of a registry grows as other
>         resources are added to it, BUT:
> 
>       * It is only necessary to add the "new" metadata from the added
>         resource to the registry description (the goal being that the
>         registry description contains the scope of the resources it
>         holds but not the detail, that is in the individual resource
>         descriptions)

I'm lost. What is 'scope of the resources'?

>       * All registries mirror all other registries

In content? Or just mirrors the list of registries?

>       * A registry only actions queries against resources for which it
>         is authoritative (i.e. not resources for which it is 
> a mirror),

If it mirrors the resource metadata, why shouldn't it answer the queries?

>         BUT:
> 
>       * A registry can initiate a query requesting it be actioned
>         against mirrored resources (to manage "registry unavailable"
>         problems - this needs further work)

??

'fraid I'm lost here.

> Thus:
> 
>      1. Queries will be targeted to registries which contain relevant
>         resources
>      2. Duplication will be reduced to a minimum
>      3. "Gridiness" will be upheld
>      4. scope={"all","target","this"} will be supported (but 
> "all" will
>         obey [1] above)
>      5. Time-To-Live can be supported
>      6. Queries will never be more than 1 level deep
>      7. Fail-over will be supported.
> 
> Keith.
> 
> -- 
> 
> Keith Noddle			Phone:  +44 (0)116 223 1894
> AstroGrid Technical Lead	Fax:    +44 (0)116 252 3311
> Dept of Physics & Astronomy	Mobile: +44 (0)7721 926 461
> University of Leicester		Email:  ktn at star.le.ac.uk
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>