[glue-wg] Usage of GLUE2 XML realization

[Weijian Fang]

Hi,

In our previous post, we raised the questions about Glue2 XML
realization's capability to update part of the information, say,
Domains/AdminDomain/Service. Because Glue2 XML schema only defines a
single element <Domains>, there is no way to define a "Service"
element purely based on the Glue2 XML schema. Here we try to figure
out how to define a Glue2 "service" element with a minimum extension
to the Glue2 XML schema.

We have to define our own <Service> element which has a type of
"glue:Service_t".

======== Glue2 Service XSD definition begins ========
<schema xmlns="http://www.w3.org/2001/XMLSchema"
	targetNamespace="http://www.omii.ac.uk/glue2/service"
	xmlns:g2s="http://www.omii.ac.uk/glue2/service"
	xmlns:glue="http://schemas.ogf.org/glue/2008/05/spec_2.0_d42_r01"
	elementFormDefault="qualified">
	
	<import namespace="http://schemas.ogf.org/glue/2008/05/spec_2.0_d42_r01"
		schemaLocation="http://schemas.ogf.org/glue/2008/05/spec_2.0_d42_r01"/>
	
	<element name="Service" type="glue:Service_t"></element>
</schema>
======== Glue2 Service XSD definition ends ========

Based on the XSD defined above, we are able to define a "Service"
element that conforms to the GLUE2 XSD.

======== Glue2 Service element begins ========
<g2s:Service xmlns:g2s="http://www.omii.ac.uk/glue2/service"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.omii.ac.uk/glue2/service glue2service.xsd"
	BaseType="Service">
	<ID>http://tempuri.org</ID>
	<Type>Type</Type>
	<QualityLevel>production</QualityLevel>
</g2s:Service>
======== Glue2 Service element ends ========

But we still have two problems here. First, now the "Service" element
falls in our own namepace instead of the Glue2 namespace,  though this
"Serivce" element is semantically equivalent to the Glue2 "Service"
type. Second, the Glue2 "Service" type lacks information about which
AdminDomain this Service should belong to, it is uncertain for the
Glue Information Service on how to incorporate this Service into the
current information tree.

Again it seems to us the current Glue2 XSD makes partially updating
quite difficult. Is this partial updating NOT a requirement that is
supported by GLUE2?

Thanks.

--
Dr. Weijian Fang
OMII-UK
4067 Building 32
School of Electronics and Computer Science
University of Southampton
Southampton SO17 1BJ
United Kingdom



2009/11/3 Weijian Fang <wf at ecs.soton.ac.uk>:
> Hi,
>
> We are looking at GLUE2 XML realizations, i.e., the official but a
> little obsolete one
> (http://schemas.ogf.org/glue/2008/05/spec_2.0_d42_r01) and the
> NorduGrid one (http://svn.nordugrid.org/trac/nordugrid/browser/arc1/trunk/doc/tech_doc/infosys/GLUE2.xsd.
> (We are also aware of the TeraGrid GLUE2 XML schema.)
>
> The official schema and the NorduGrid schema are similar. Both define
> only a single XML element: <Domains>. And all the other entities are
> defined as XML types instead of elements. Thus they can be included in
> <Domains> but can never stand on their own. Therefore, under this
> design, in order to update a single piece of information, for
> instance, Domains/AdminDomain/Services/ComputingService/RunningJobs,
> one has to re-publish the whole AdminDomain.
>
> Our observation is that the current design of GLUE2 XML schema is not
> optimised for updating part of the information. Is this because
> updating part of the information is never an intended usage pattern of
> GLUE? A validity attribute is defined for each entity. We assume the
> intended usage pattern of GLUE information model (including the XML
> realization) is to PERIODICALLY publish ALL the information once the
> validity period expires. Are we correct? Many thanks!
>
> --
> Dr. Weijian Fang
> OMII-UK
> 4067 Building 32
> School of Electronics and Computer Science
> University of Southampton
> Southampton SO17 1BJ
> United Kingdom
>