[Requests] OGC Web Coverage Service - Transaction operation extension - Comment

Peter Baumann p.baumann at jacobs-university.de
Thu Aug 6 06:42:38 EDT 2015



On 2015-08-05 23:56, Simon.Cox at csiro.au wrote:
>
> Ø  Therefore, we have prepared a WCS Extension which I want to propose for
> voting at the Nottingham TC. This extension introduces a very simple concept:
> an XPath expression can be submitted which is evaluated on the Capabilities
> document on server side. This allows applications to get exactly what they
> need, without excess data transfer. If you feel that this is a way forward,
> maybe you want to support this in the upcoming TC meeting - any such support
> is greatly appreciated!
>
> And perhaps better still, submit this idea as an OWS Common CR or as input to
> the upcoming revision.
>

indeed, I mentioned XPath in the OAB discussions, but the OWS Common roadmap
seems still in the make.
-Peter


>  
>
> *From:*Requests
> [mailto:requests-bounces+simon.cox=csiro.au at lists.opengeospatial.org] *On
> Behalf Of *Peter Baumann
> *Sent:* Wednesday, 5 August 2015 5:31 PM
> *To:* Timothy Astle <timothy.astle at caris.com>; requests at lists.opengeospatial.org
> *Subject:* Re: [Requests] OGC Web Coverage Service - Transaction operation
> extension - Comment
>
>  
>
> Dear Timothy,
>
> after completion of the RFC period I'm coming back to your (very thoughtful)
> questions below.
>
> Re Req 8: This actually is a known issue with OWS Common. A service provider
> can decide which elements to expose in a Capabilities document, which has been
> considered sufficient in the past. Alas, it does not solve the issue -
> practice shows that either you get not enough information, or too much (such
> as all coverages listed). In fact, the Capabilities mechanism is way too
> static and inflexible.
>
> OGC has started thinking about how to fix and modernize, but there is no
> relief on the horizon soon. Therefore, we have prepared a WCS Extension which
> I want to propose for voting at the Nottingham TC. This extension introduces a
> very simple concept: an XPath expression can be submitted which is evaluated
> on the Capabilities document on server side. This allows applications to get
> exactly what they need, without excess data transfer. If you feel that this is
> a way forward, maybe you want to support this in the upcoming TC meeting - any
> such support is greatly appreciated!
>
> Re References to grids: Core and extensions have been formulated very
> carefully so as to allow all coverage types defined, which includes point
> clouds and meshes. Currently, there is one extension which specifically refers
> to grids, that is WCS Scaling: change of resolution is an operation meaningful
> on grids only (at least that is my current understanding). Concretely speaking
> about WCS-T, a point cloud (MultiPointCoverage) or mesh (MultiCurveCoverage or
> MultiSurfaceCoverage or MultiSolidCoverage) can be inserted and deleted, and
> can even be updated. Of course, update of a mesh requires more complex
> consistency constraints to be respected, but that is inherent to the
> definition of such mesh types, so does not have to be treated separately here.
>
> Actually, there is nothing in the mask parameter that confines us to a grid.
> Consider a point cloud, for example, The mask in this case will contain the
> direct positions of the points to be updated, associated with a range value of
> "1" (likely in this case the "0" points will simply be left out), and this
> guides the server on the points to be updated - say, with a new temperature
> value. Hence, I'd claim that this definition works on all coverage types -
> kindly let me know should I miss something here, it's a good opportunity to
> catch any and all hiccups.
>
> And obviously there is one: searching for the root cause of your concern I
> find occurrences of "maskGrid", a leftover forgotten in an earlier renaming
> action. I have corrected this, and it actually resolves an inconsistency -
> good catch!
>
> Thank you again for the encouraging assessment and your thoughtful comments.
> Looking forward to further discussion in future.
>
> best regards,
> Peter
>
> On 2015-06-26 20:48, Timothy Astle wrote:
>
>     A couple of questions:
>
>     _Requirement 8 _
>     /After completion of a successful InsertCoverage request, the identifier
>     of the coverage established in the server’s offering shall be listed as an
>     existing coverage in this WCS service’s Capabilities document./
>
>     OGC 06-121r9 (OGC Web Services Common Standard) still allows for the idea
>     of an "otherSource" for finding OWS content.  Is the above requirement
>     mandating thatwhen implementing a WCS-T, you must describe the coverage in
>     the Capabilities' CoverageSummary list?  I'm concerned that when dealing
>     with a large amount of coverages, that could really degrade the
>     performance of a system.
>
>     _References to Grids_
>
>     I definitely see value to this transactional extension to WCS.  I'm
>     definitely interested to watch WCS grow beyond gridded data.  In this
>     particular extension, I seereferences to gridsand grid-related terminology
>     and concepts.  I'm concerned that if / when point clouds or TINsare
>     introduced as extensions, that this specification might not makesense in
>     some contexts.  For example, if a WCS was created that specialized in
>     TINs, the optional grid parameters wouldn't really apply.  Is the intent
>     that this is a "grid transactional operation extension" or a "general
>     coverage operation extension"?  Would a future point cloud transactional
>     extension be created for point cloud operations?  I guess I'm just asking
>     for clarification.
>
>     Thank you for your time and consideration.
>
>     -- 
>
>     Tim Astle
>     Development Manager for Web Technologies
>
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> -- 
> Dr. Peter Baumann
>  - Professor of Computer Science, Jacobs University Bremen
>    www.faculty.jacobs-university.de/pbaumann <http://www.faculty.jacobs-university.de/pbaumann>
>    mail: p.baumann at jacobs-university.de <mailto:p.baumann at jacobs-university.de>
>    tel: +49-421-200-3178, fax: +49-421-200-493178
>  - Executive Director, rasdaman GmbH Bremen (HRB 26793)
>    www.rasdaman.com <http://www.rasdaman.com>, mail: baumann at rasdaman.com <mailto:baumann at rasdaman.com>
>    tel: 0800-rasdaman, fax: 0800-rasdafax, mobile: +49-173-5837882
> "Si forte in alienas manus oberraverit hec peregrina epistola incertis ventis dimissa, sed Deo commendata, precamur ut ei reddatur cui soli destinata, nec preripiat quisquam non sibi parata." (mail disclaimer, AD 1083)
>  
>  

-- 
Dr. Peter Baumann
 - Professor of Computer Science, Jacobs University Bremen
   www.faculty.jacobs-university.de/pbaumann
   mail: p.baumann at jacobs-university.de
   tel: +49-421-200-3178, fax: +49-421-200-493178
 - Executive Director, rasdaman GmbH Bremen (HRB 26793)
   www.rasdaman.com, mail: baumann at rasdaman.com
   tel: 0800-rasdaman, fax: 0800-rasdafax, mobile: +49-173-5837882
"Si forte in alienas manus oberraverit hec peregrina epistola incertis ventis dimissa, sed Deo commendata, precamur ut ei reddatur cui soli destinata, nec preripiat quisquam non sibi parata." (mail disclaimer, AD 1083)


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