[moby] Re: [MOBY-dev] lease versus agent for registry updating

[Paul Gordon]

I would go for the server polling the RDFs option.  In that way, there 
could potentially be more than one MOBY Central (e.g. private ones) that 
could simply get the provider RDF URL list from the "Master" MOBY 
Central, and replicate the service registry (in whatever underlying data 
store they like).  Decentralizing is good.


>Ah... I missed the bit about a service being flagged as "temporarily
>unavailable" rather than just flagged in general.  The reason we are
>loathe to do that is it makes assumptions about the underlying data
>store being able to capture that information (or at least, forces
>queries on the underlying data store to then be passed through a post-
>retrieval "available" filter implemented by the data adaptor)... 
>
>We're trying to make as few assumptions about the underlying store as
>possible  - a minimum of information about the core functionality of a
>service (i.e. at this point, the overlap between the MOBY and the Feta
>data models)
>
>M
>
>
>On Fri, 2005-08-12 at 16:50 -0300, Boris Steipe wrote:
>  
>
>>Why not put the burden of the lease on the agent to combine the 
>>advantages of both models? I.e. if service is down for less then a 
>>specific time, it might not get deregistered but only flagged as 
>>temporarily unavailable ... then un-flagged as it comes up again, 
>>except if it's down for, say > 1week, then it gets deregistered.
>>
>>$0.02
>>
>>Boris
>>
>>On Friday, Aug 12, 2005, at 16:38 Canada/Atlantic, Mark Wilkinson wrote:
>>
>>    
>>
>>>Hi all!
>>>
>>>Eddie and I are spending the day working on MOBY Central architecture
>>>issues.  We've run into a question that has so many pros and cons that
>>>we decided to toss it out to the list for other opinions.
>>>
>>>Keeping MOBY Central up-to-date:
>>>
>>>Method 1:  Agent
>>>
>>>An agent retrieves the list of SignatureURL's from the registry, and
>>>crawls around retrieving the RDF from each of those URLs.  The RDF is
>>>compared to what is in the registry, and updates/deletions are made.
>>>
>>>Consequence to service provider: a service providers machine goes down,
>>>the service is deregistered (the agent can't retrieve the URL) and the
>>>service provider must then actively re-register their services
>>>
>>>
>>>Method 2:  Lease
>>>
>>>Services have a time-stamp in the registry and expire after X time.
>>>They must then be actively re-registered.
>>>
>>>Consequence to service provider:  Service providers must set up a cron
>>>(or whatever) that is aware of all of their *current* Signature URL's
>>>and can call MOBY Central to re-register their services on a regular
>>>basis.
>>>
>>>
>>>Both solutions seem to put an unwanted burden on the service providers,
>>>but the burdens are different in nature and frequency.
>>>
>>>Which of these seems preferable?  Are there solutions we haven't 
>>>thought
>>>of?
>>>
>>>???
>>>
>>>Mark & Eddie
>>>
>>>
>>>-- 
>>>"Ontologists do it with the edges!"
>>>
>>>Mark Wilkinson
>>>Asst. Professor
>>>Dept. of Medical Genetics
>>>University of British Columbia
>>>PI in Bioinformatics
>>>iCAPTURE Centre
>>>St. Paul's Hospital
>>>Rm. 166, 1081 Burrard St.
>>>Vancouver, BC, V6Z 1Y6
>>>tel: 604 682 2344 x62129
>>>fax: 604 806 9274
>>>
>>>_______________________________________________
>>>MOBY-dev mailing list
>>>MOBY-dev at biomoby.org
>>>http://www.biomoby.org/mailman/listinfo/moby-dev
>>>      
>>>