[OSGeodata] RE: Ready for a lean and mean Catalogue Service Protocol Spec.?

[Jody Garnett]

He he - my turn.

CSW-2 is fine (aka very similar to WFS but allows separation of data 
returned from data queried in case we care):
- query - filter 1.1 is good, think they even made a BNF text format for 
it right?
- query model? query against something really simple. uDig uses 
something like minimal Dublin core with no multiplicity
- data returned? something really simple ... OWSContext contains some 
basic direct elements which are good.

Cheers,
Jody
>
> Many thanks for your many reactions. It seems that I hit a need and 
> that there is some sort of (implicit) agreement that we need a lean 
> and mean Catalogue Service Protocol Spec but - sigh: where to begin 
> and how to reach consensus here?
>
>  
>
> To clarify this at this place: Presumably no one wants to reimplement 
> the wheel and OGC needs to be kept in the loop. My short term goal is 
> to define a thesis project to contribute an implementation of such a 
> service.
>
>  
>
> I'm still thinking forth and back what's better: Either to profile WFS 
> (as well as profiling the ISO 19115/19119 information model), or to 
> extend general search protocols like OpenSearch - thus becoming 
> interoperable with library and search community (did anyone really try 
> to understand OAI-PMH?) - or ...?
>
>  
>
> Next I will try to summarize the discussion with requirements, current 
> implementations and proposals.
>
>  
>
> -- Stefan
>
>  
>
> > -----Original Message-----
>
> > From: Panagiotis (Peter) A. Vretanos [mailto:pvretano at cubewerx.com 
> <mailto:pvretano at cubewerx.com>]
>
> > Sent: Donnerstag, 20. Juli 2006 23:40
>
> > Subject: Re: Ready for a lean and mean Catalogue Service Protocol Spec.?
>
> >
>
> > Stefan,
>
> >
>
> > The HTTP protocol binding from CSW2 is already heavily based on WFS and
>
> > includes KVP encodings for most of the requests.   Here are some 
> examples:
>
> >
>
> >
>
> > a) Get a capabilities document:
>
> >
>
> > http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetCapabilities
>
> >
>
> > b) Describe the information model(s) that the catalog uses:
>
> >
>
> > http://www.pvretano.com/cwwrs/cwwrs.cgi?request=DescribeRecord
>
> >
>
> > c) Execute a query that does searches the record descriptions:
>
> >
>
> > http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRecords&typeNames=Extrinsic 
> <http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRecords&typeNames=Extrinsic>
>
> > Object&ConstraintLanguage=Filter&Constraint=%3Cogc:Filter%20xmlns:ebxml=%22urn 
>
>
> > :oasis:names:tc:ebxml-
>
> > regrep:rim:xsd:2.5%22%20xmlns:gml=%22http://www.opengis.net/gml%22%20xmlns:ogc 
>
>
> > =%22http://www.opengis.net/ogc%22%3E%3Cogc:PropertyIsLike%20escape=%22\%22%20s 
>
>
> > ingleChar=%22_%22%20wildCard=%22%25%22%20matchCase=%22false%22%3E%3Cogc:Proper 
>
>
> > tyName%3E/ExtrinsicObject/Description/LocalizedString/@value%3C/ogc:PropertyNa 
>
>
> > me%3E%3Cogc:Literal%3E%25bird%25%3C/ogc:Literal%3E%3C/ogc:PropertyIsLike%3E%3C 
>
>
> > /ogc:Filter%3E
>
> >
>
> > d) Get the repository item associated with the record found in (c)
>
> > (analogous to fetching the book from the library shelf):
>
> >
>
> > http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRepositoryItem&id=urn:uuid 
> <http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRepositoryItem&id=urn:uuid>:
>
> > 9f818e6a-08b0-11db-8378-0010dcf5553d
>
> >
>
> > e) Get a specific record from the catalog:
>
> >
>
> > http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRecordById&id=urn:uuid:3748 
> <http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRecordById&id=urn:uuid:3748>
>
> > cfea-17f9-11db-b340-0010dcf5553d
>
> >
>
> > f) Get the repository item associated with the record from (d):
>
> >
>
> > http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRepositoryItem&id=urn:uuid 
> <http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRepositoryItem&id=urn:uuid>:
>
> > 3748cfea-17f9-11db-b340-0010dcf5553d
>
> >
>
> >
>
> > Your specific proposal (i.e. ISO19115/ISO19119 and WFS) would be very
>
> > close to the existing ISO profile of the CSW2 specification.    The ISO
>
> > profile uses the HTTP protocol binding from CSW2 as the API and
>
> > ISO19115/ISO19119 as the information models.
>
> >
>
> > Personally, I think what makes the current CSW specification "heavy
>
> > weight" is the KVP encoding for the query operation (GetRecords) and the
>
> > fact that the client needs to know the catalog's information model
>
> > fairly well to even formulate a query.  Not to mention, be familiar with
>
> > the Filter syntax.
>
> >
>
> > What I think needs to happen is the addition of a new "simplified" query
>
> > request to the CSW specification leaving GetRecords as the "advanced"
>
> > query operation.
>
> >
>
> > I have been experimenting with a simpler query request whose KVP
>
> > encoding looks something like this (equivalent to (c)):
>
> >
>
> > http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRecordsBasic&fulltext=birds 
> <http://www.pvretano.com/cwwrs/cwwrs.cgi?request=GetRecordsBasic&fulltext=birds>
>
> >
>
> > NOTE:  My experimental name for the request is GetRecordsBasic and at
>
> > the moment the request returns an XML fragment which may not validate in
>
> > your browser.  So, you may have to view the source to see what was
>
> > generated by the catalogue.
>
> >
>
> > Other parameters on the GetRecordsBasic request include:
>
> >
>
> > BBOX, CLASSIFICATIONNODE, OBJECTTYPE, KEYWORDS, OUTPUTSCHEMA, Temporal
>
> > Operators
>
> >
>
> > The advantage of this request is that the client does not need to be too
>
> > familiar with the catalog's information model in order to formulate a 
> query.
>
> >
>
> > Comments welcome.
>
> >
>
> > Ciao.
>