[Smwg] Approaches for Implementing the SM Info Entity "Stereotype" in XML Schema

[John Pietras]

Anthony,
Your summary of each approach is right on the mark. The primary (perhaps only)  "advantage" of the second approach is that it does most-accurately reflect the UML model. My reason for exploring that approach is that there has been a fair amount of email discussion about that way of modeling the abstraction, so I thought that I would see how such a model could be most closely preserved in XML schema. If reflecting the UML model is important, then there is a way to do it. But the question is whether it is indeed important to do so. If not, then the first approach is probably simpler, as you point out.

John

From: Anthony Crowson [mailto:anthony.crowson at telespazio-vega.de]
Sent: Wednesday, January 28, 2015 5:27 AM
To: John Pietras; CCSDS SMWG ML (smwg at mailman.ccsds.org)
Subject: RE: [Smwg] Approaches for Implementing the SM Info Entity "Stereotype" in XML Schema

John,

A couple of initial thoughts:

To me, your second XML approach corresponds as closely as possible within Schema constraints to Colin's UML. The "potential issue" (mixing incompatible subtypes of header/body) would turn up in other languages as well, and I don't think it is necessarily a problem. This is conceptually the most accurate reflection of the UML. In principle it might help support more flexible/generic software handling multiple info entities.

On the other hand approach 1 is simpler. The "construction rules" needed for approach 1 govern schema construction only, while those for approach 2 govern instance construction - i.e. approach 1 does seem to give less opportunity for making mistakes. I would hope that people reference the BB rather than the schema  for general understanding of the spec, so a schema which doesn't reflect the precise UML relationships shouldn't actually be problematic.

The instance documents will probably not look hugely different either way.

Anthony

From: smwg-bounces at mailman.ccsds.org<mailto:smwg-bounces at mailman.ccsds.org> [mailto:smwg-bounces at mailman.ccsds.org] On Behalf Of John Pietras
Sent: 27 January 2015 21:37
To: CCSDS SMWG ML (smwg at mailman.ccsds.org<mailto:smwg at mailman.ccsds.org>)
Subject: [Smwg] Approaches for Implementing the SM Info Entity "Stereotype" in XML Schema

CSSMWG colleagues ---
As you know, over the past few weeks there has been discussion on various aspects
of the "standard header" for the SM Information Entities. In particular, the standard header is really more like a standard stereotype: three abstract classes (SvcMgtInfoEntity, SvcMgtHeader, and SvcMgtData) in a defined interrelationship that is inherited by every SM Information Entity that we will define.

Over the past few days, I started looking into how this stereotype relationship might be represented in the XML schemas for those Info Entities. I explored two possible approaches (there may be more) and put together a set of slides that I had hoped to be able to present at today's telecon, but we ran out of time. Selection of one of these approaches (or some alternative) will govern how the XML schemas for our Info Entity schemas will be developed.

I've posted the presentation in the CWE > Cross Support Services Area (CSS)<http://cwe.ccsds.org/css> > Documents<http://cwe.ccsds.org/css/docs/Forms/AllItems.aspx?View=%7B8045374D%2DF8E0%2D4356%2D83CA%2D993252A38FE8%7D&> > CSS-SM<http://cwe.ccsds.org/css/docs/Forms/AllItems.aspx?RootFolder=%2Fcss%2Fdocs%2FCSS%2DSM&View=%7B8045374D%2DF8E0%2D4356%2D83CA%2D993252A38FE8%7D&> > CWE Private<http://cwe.ccsds.org/css/docs/Forms/AllItems.aspx?RootFolder=%2Fcss%2Fdocs%2FCSS%2DSM%2FCWE%20Private&View=%7B8045374D%2DF8E0%2D4356%2D83CA%2D993252A38FE8%7D&> > Draft Schemas  folder at URL
http://cwe.ccsds.org/css/docs/CSS-SM/CWE%20Private/Draft%20Schemas/XmlSchemasForInfoEntities-150127.pptx

I hope that we can discuss these approaches at a telecon in the near future. In the meantime, please feel free to look at the briefing and offer comments and criticisms.

Best regards,
John
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