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

[Eddie Kawas]

I just wanted to say that I agree with Paul. 

I think that when a provider registers a service, the provider enters
a url that causes the service to return something that is commonly
returned by all services that states that the service is running. If
this return value is infact returned, then the service signature is
processed. Otherwise, the offending service is recorded and the
service is not shown to the public until the test passes. If after x
times the test fails, then it is permanently removed.

Eddie


On 8/16/05, Paul Gordon <gordonp at ucalgary.ca> wrote:
> My CAN$0.02 :-)
> 
> >
> >  Paul> A few advantages of the lease are not really advantages in
> >  Paul> practice:
> >
> >  Paul> 1. No one will manually update their lease, they will put it
> >  Paul>    in a cron
> >  Paul> job.  Therefore you either need to edit your crontab, or
> >  Paul> remove from the RDF file in the agent case.  Both are just as
> >  Paul> likely to be ignored by an administrator when a service stops
> >  Paul> working.
> >
> >
> >This is a necessary problem with neither the agent nor the lease. It
> >is a current problem with the implementation of the agent. All you do
> >is add a call back to the service.
> >
> >
> This turns into an issue with the protocol, we would need to require
> (when you register a service) test cases that return predictable,
> non-null value.  This was discussed at the last MOBY meeting, but I
> don't think anything came of it.  Or am I wrong?
> 
> >  Paul> The chief advantages of the agent are:
> >
> >  Paul> 1.  You can trace the registration and deregistration of a
> >  Paul>     service to
> >  Paul> a particular domain name.  It's not great security, but at the
> >  Paul> very least people require some serious work to pose as the
> >  Paul> NCBI on purpose (by hacking their Web domain), and cannot by
> >  Paul> mistake (e.g. "I registered my service using the NCBI
> >  Paul> authority ID because I'm using gi's").
> >
> >Likewise with a lease call back system.
> >
> Like you said, the two approches aren't so different, because fetching
> the RDF from the server is a callback of sorts.
> 
> >Anyway, can you really not
> >determine the start point of a web services call?
> >
> >
> If there are proxies, multiple host names for a machine (e.g. the host
> I'm on right now is www.visualgenomics.ca, moby.ucalgary.ca,
> www.gcbioinformatics.ca, and about 6 other names), it can get complicated.
> 
> >  Paul> 2.  The RDF for the services does not have a single point of
> >  Paul>     failure
> >  Paul> (i.e. the central registry).
> >
> >This is also untrue. There is nothing to stop a lease percolating
> >through a set of federated registries. With the agent, you have to
> >percolate the registered URL's (or the RDF) in the same way.
> >
> >
> True, but the mechanism to exchange a URL list could be simpler than
> mirroring the entire registry, and is less subject to error propagation
> (e.g. don't blindly copy a goof in the main mirror's database system
> because it had network connectivity issues, fetch the RDF yourself) .
> If we're lucky, people will try to outcompete each other creating the
> most robust registry :-)
> 
> >Ultimately, as two systems are doing similar things. It's just that
> >one is push and the other pull.
> >
> >
> >  Paul> The one agent feature I would l;ike though is that I can call
> >  Paul> MOBY Central to tell it that I've changed my RDF, i.e. pushing
> >  Paul> a refresh. It's not critical though. If the agent runs once a
> >  Paul> day, you may get some latency on bad services, but it's not
> >  Paul> the end of the world.  Tim Berners-Lee got a lot of flack for
> >  Paul> his Web idea because it didn't enforce that what people linked
> >  Paul> to existed.  "People won't use it, they may end up at dead
> >  Paul> links!" they said...
> >
> >
> >You still want people to be able to search on the freshness of
> >information though. With a lease, you can add queries to moby-central
> >to say "give me only services with a current lease"--after all the
> >registry is not required to deregister a service when it's lease runs
> >out.
> >
> >
> Would we set a maximum lease?  I'd probably give myself a 1 year lease
> so that I wouldn't be bothered again.  That doesn't make me check that
> the service works throughout the year though. IMHO, having a test case
> checked regularly is what really helps here, not the lease.  A lease is
> someone's word, a test case is action, and actions speak louder than
> words :-)
> 
> >Cheers
> >
> >Phil
> >
> >_______________________________________________
> >moby-l mailing list
> >moby-l at biomoby.org
> >http://biomoby.org/mailman/listinfo/moby-l
> >
> >
> >
> 
> _______________________________________________
> moby-l mailing list
> moby-l at biomoby.org
> http://biomoby.org/mailman/listinfo/moby-l
>