[glue-wg] XML rendering style

[Warren Smith]

I've been meaning to follow up our last conference call with an email about the "style" of the XML rendering. You all probably know that I prefer the flat style over the hierarchical. The current hybrid schema is a compromise between these two approaches (I think it's great that people are willing to compromise, btw), but what I mentioned on the call is that I think I prefer the flat (https://github.com/OGF-GLUE/XSD/blob/master/schema/teragrid_glue_2.0_r01.xsd) or hierarchical (https://forge.ogf.org/sf/docman/do/downloadDocument/projects.glue-wg/docman.root.drafts/doc15515) styles to the hybrid (https://github.com/OGF-GLUE/XSD/blob/master/schema/GLUE2.xsd) one. I've seen a couple of comments that make me wonder if I'm not alone in this.

One of the high-level concern that I have with the hybrid approach is that a GLUE2 entity can appear in several different places in a GLUE2 document (this is why it is a hybrid approach, of course). For example, a document could only have a ComputingActivity, it could be ComputingActivities -> ComputingActivity, or ComputingEndpoint -> ComputingActivities -> ComputingActivity. As was mentioned on the call, you can search the document for that element name, but that seems a bit inelegant to me and implies that the hierarchical structure of the document doesn't even matter.

Another high-level concern is linking of entities. The hierarchical approach linked many entities via parent-child in the XML hierarchy. A flat approach links them using IDs to refer to each other. With a hybrid approach something like both of these need to be supported and this seems a bit confusing - the ID references will be in the schema, but only needed if a particular XML document doesn't use a hierarchy. This could lead to confusion when creating/parsing documents.

I have some other comments about the current hybrid schema, but I'll send separate emails about those.


Do we need a discussion about these three different styles? There seems to be an assumption that there is agreement on the compromise hybrid style, but I'm not sure that is the case...


Warren


-----Original Message-----
From: glue-wg-bounces at ogf.org [mailto:glue-wg-bounces at ogf.org] On Behalf Of david.meredith at stfc.ac.uk
Sent: Wednesday, June 13, 2012 11:14 AM
To: navarro at mcs.anl.gov; glue-wg at ogf.org
Subject: Re: [glue-wg] OGF 35 meeting and preparation reminder

Hi everyone,
Regarding the XML rendering:  for me the most important agenda item is to make a decision between the flattened document style (e.g. like the Teragrid rendering), or a nested/hierarchical approach (the current style described in the word doc), or somewhere between.  Both styles render associations using their own 'identifier' elements that reference the IDs of associated elements. 

Until last phone meeting, I had not seen the Teragrid rendering which looks good to me. This approach may be preferable compared to defining deeply nested element trees. Therefore, I think the agenda item iii) needs to come first before the substitution group stuff.  

Regardless of the preferred style, I still think we need to cater for sub-typing of the core entities by future profiles at the outset.  I am pretty sure the abstract-element/substitution group approach may also be useful to the flattened style. For example, maybe the global 'Entities' element could define abstract elements such as 'AbstractService' so that concrete specialisations can be substituted in place (e.g. Service, ComputingService, StorageService and potentially any future profiled service that can substitute for AbstractService).  Same sort of thing could apply to abstract Domain and AdminDomain/UserDomain etc.

Cheers
David 

> -----Original Message-----
> From: glue-wg-bounces at ogf.org [mailto:glue-wg-bounces at ogf.org] On 
> Behalf Of JP Navarro
> Sent: 13 June 2012 11:02
> To: OGF GLUE WG
> Subject: [glue-wg] OGF 35 meeting and preparation reminder
> 
> Dear GLUE WG,
> 
> Just a reminder of our OGF 35 GLUE2 working group meeting this coming 
> Sunday June 17th 13:30-15:00 Central European Time.
> 
> http://ogf.org/gf/event_schedule/index.php?id=2530
> 
> Our agenda:
> 
> i) Substitution group discussion and agreement
> ii) EGI service names and types discussion
> iii) Globalized schema and cross-references
> iv) Future directions discussion: JSON rendering, etc.
> 
> Recent action items to prepare for this meeting:
> 
> Action Item: Provide a slide for OGF on how to implement the Glue 
> Entities Bag high-level element, probably with example: Assigned to: 
> David Action Item: A slide will be presented in next OGF to explain 
> the problem in greater detail. Assigned to: Warren, JP
> 
> We will post meeting call-in information when it's available.
> 
> Regards,
> 
> JP
> _______________________________________________
> glue-wg mailing list
> glue-wg at ogf.org
> https://www.ogf.org/mailman/listinfo/glue-wg
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