1. Hydrologic Vocabularies Thursday, April 14

2. Discussion questions (and some answers… more below) What vocabularies are available and in what formats. Which vocabularies you actually use and why – Many vocabularies to choose from; 700 vocabularies of units (Rob) What are the gaps; where additional vocabularies are needed – Depends on the conceptual model, so this is where we start How are the vocabularies structured (hierarchy, synonyms, etc.) – How vocabularies are defined, and exposed How we reconcile upper level and domain vocabularies, and how we handle mappings Architecture/infrastructure issues Where we need to make progress over the next year, to support WaterML2 work, IEs, others. – what services should we use for distributing vocabularies, and creating and managing links between vocabularies, – how should we reconcile/document what is required for minimal exchange of water info to a more complete description.

3. Agenda I-Lin: modeling vocabularies as DAGs Boyan: How we reconcile upper level and domain vocabularies, and how we handle mappings DaveV, Ilya: vocabularies and ontologies in CUAHSI HIS ---------------------------- lunch break--------------- Rob: vocabulary aspects of cross-domain model integration; delivering referencable definitions from formal domain models; governance of mappings between alternative representations Discussion

4. Additional Discussion Issues (as prompted by I-Lin’s and Boyan’s talks) Do we want a semantics-focused group (somehow instituted? As IE?) within HDWG What is a vocabulary (set of terms): what is a formal definition, canonical description What is a definition of mapping between vocabularies – Federation of subscriptions Governance of vocabularies, policies – In a dynamic system; delegation of mapping maintenance; how vocabularies are exposed How to handle multiple languages

5. Main points from Boyan Glossaries/thesauri are insufficient because their representations don't allow for basic reasoning required in water infrastructures, thus need ontologies Need to separate concepts from terms: e.g. the terms "water" and "eau“ refer to the same concept. Development of concepts and relations (ontologies) is a priority, followed by assignment to them of multi- lingual terms OWL provides a basic language not only for representing items in schemas, but also for simple mappings between them

6. Use cases Expose vocabularies – how? – To be used in filters (Eric) Matching vocabularies to properties Core use case: getObservations?site=[…] – Components of the contract: (1) manage variations of “site” (diff languages and conventions), (2) list of instances, (3) list of parameters (in addition to “site”: medium, data category, parameter, etc.) Main issues: – Information model – Architecture to manage/govern differences from the canonical inform model

7. How to expose semantic info Schema (service registry) Domain of values Mappings Governance: responsibilities Need one standard way of exposing semantic info

8. Action Items - 1 Harmonization report? Here are a few interesting efforts: – BODC has done review of options for vocab services – extend it – French geol survey with INSPIRE – BOM: WaterML and Geosciences vocab services – Model registry (Rob) – Linked Open Data (they have really interesting stuff) – Mediator in GWIE (a’la GEON) – CUAHSI ontology work – --------------- – Figure out common patterns and gaps – Get OGC mandate to do it (geosemanticsWG?)

9. Action Items - 2 Report it as a current problem with OGC architecture NGA interested? – Cross-domain; water security; situation awareness – JeremyT Would OGC be interested in finding sponsors for an effort to fill this gap in architecture White paper: – Use cases; common issues; common gaps Get on IE agendas