[glue-wg] Endpoints and ComputingService, relationships between services. Some thoughs

[Etienne URBAH]

Florido,

Concerning the publication of 2 RELATED services using the GLUE 2.0 
schema and its XML rendering(s) :


I suggest to :

-  begin by searching solutions at the conceptual level using the GLUE 
2.0 schema,

-  and only then to look for practical solutions using an XML rendering.


GLUE 2.0 schema
---------------
It is easy to define 1 single Endpoint exposing 2 Services.

Any information consumer will then know that these 2 Services are 
somehow related, and the precise relationship may be inferred from :

-  the respective values of the Capability Attribute for the 2 Services 
:  For example 'security.delegation' and 'executionmanagement.jobmanager',

-  the value of 1 occurrence of the Service.ID value of one Service : 
This value is the ID of the other Service.

So, the GLUE 2.0 schema seems to permit the above solution.


XML renderings
--------------
-  A flat XML rendering, having NO presupposed hierarchy, should permit 
the practical implementation of the above solution.

-  Any XML rendering having a presupposed hierarchy is a conceptual 
mistake.  Your example is a clear Use Case proving this.


Best regards.

-----------------------------------------------------
Etienne URBAH         LAL, Univ Paris-Sud, IN2P3/CNRS
                       Bat 200   91898 ORSAY    France
Tel: +33 1 64 46 84 87      Skype: etienne.urbah
Mob: +33 6 22 30 53 27      mailto:urbah at lal.in2p3.fr
-----------------------------------------------------


On Mon, 20/08/2012 12:01, Florido Paganelli wrote:
> Hi all,
>
> I am in the situation that I would like to have a simple Endpoint
> published within a ComputingService. However, besides UML inheritance
> might allow this, the hierarchic xsd schema does not allow that, it only
> allows ComputingEndpoints to be nested within ComputingServices.
>
> I don't know it this is good or bad; for you to understand how I got
> here, I can give you this little problem to solve:
>
> Suppose the same machine hosts two RELATED services, that is, one needs
> the other one for proper functionality. For example a delegation service
> is needed to submit a job to a job execution service.
>
> Is there a way for an information consumer to infer/understand this
> relationship? Can a client understand that (1) the services are related
> and (2) that they are running in the same machine just by looking at the
> GLUE2 records?
>
> One might think of associations, but it can easily be shown that they
> don't solve the problem. We don't really have service-to-service
> associations, just some kind of hierarchy between services.
>
> What do you think?

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