[OSGeodata] discovery requirements (some thoughts)

[Kralidis,Tom [Burlington]]

I think some sort of face-to-face would be really helpful.  Perhaps we
can have small presentations from:

Approaches:
 - Tom (owscat)
 - Stefan (OAI approach)
 - Paul Ramsey (Google scraping)
Software:
 - Jeroen (GeoNetwork)
 - someone from deegree?

- discussion of pros and cons of approaches
- timelines
- way forward

Comments?

..Tom

 


________________________________

	From: Stefan F. Keller [mailto:sfkeller at gmail.com] 
	Sent: 22 August, 2006 8:23 PM
	To: geodata at geodata.osgeo.org
	Subject: [OSGeodata] discovery requirements (some thoughts)
	
	
	I just wanted to ask if we still agree in defining an exchange
model and a protocol which of course should be in sync with the metadata
model for geodata?
	
	BTW: A preliminary program of FOSS4GIS is out. Any news about a
BOF session? 
	
	Here are some additional thoughts:
	* Users need search services to discover geographic information.
	* Geodata owners need a metadata management tool (which implies
an internal metadata model).
	* Geodata owners and service providers need (i) a metadata
exchange model, (ii) an encoding of it, as well as (iii) a protocol for
the exchange, dissemination and sharing of metadata. 
	* Metadata should be strictly free (LGPL?).
	
	A preliminary scenario:
	* Users search or browse through metadata records. They use a
web app. or a search component out of a desktop GIS (remark: Users don't
search services per se). 
	* 'Search service providers' enable the discovery of geodata and
'filter services', like transformation services (Note: WMS is a 'data
access service' and belongs to geodata not to filter services)
	* 'Search service providers' gather (harvest) their information
from 'data/filter service providers' and need a protocol to do this. 
	* 'Data/filter service providers' offer metadata over this
protocol. They typically also implement 'data access services' (WMS,
WFS) or they offer 'filter services'.
	
	Building blocks needed:
	1. A geometadata management model ( e.g. internal to
telascience)
	2. Tools to manage the geometadata
	3. A geometadata exchange model
	4. An encoding of the geometadata exchange model (probably XML)
	5. Geometadata exchange protocols
	
	What I am especially interested in is 3 to 5. For the protocols
I see two specifications, both already implemented and ready to go
(given 2. and 3. are determined!): 
	A. Simply publish XML files of geometadata (exchange model) on
the web (=HTTP with autodiscovery).
	B. OAI-PMH which uses geometadata exchange model as its
specialized metadata model type (data providers needed to register but
search services can do better focussed crawling). 
	
	There are some exciting ideas around like embedding hints into
the geometadata exchange model or THUMP from IETF which lead to
something between A. and B.
	
	-- Stefan