Earth Data Open Search Specifications Doug Newman (NASA ECHO) CWIC January 2014

The specifications

Open Search Still in draft?!!! Open Search descriptor document URL element, template attribute Query element Request HTTP GET URL with standard query parameters Constructed programmatically from URL element definition in OSDD Response ATOM feed response with zero or more entries Links to metadata, data, browse, more searches

The base extensions Geo extension - Spatial constraint by point, box, circle and WKT (line polygon etc) Spatial constraint by place name Spatial constraint relation * Search constraint by uid?!! * Spatial extent via GeoRSS elements Time extension - Temporal constraint by start and end date using RFC-3339 No temporal extent guidelines Parameter extension - A more formalized specification of search parameters Permissible ranges Pattern matching for permissible values Relevancy extension - Ranking your results * Recently we see that the GEO extension has been augmented by the OGC specification

The OGC specification Candidate standard Rel=‘via’ still in examples - ^&#$#()))_!!!! Elements of this standard have crept into the geo extension Navigation by links (prev, self and next)

The ESIP best practices Dynamic, bespoke OSDDs Nested discovery via hypermedia Link ‘rel’ mapping (augmented by media type) data – enclosure metadata – describedBy documentation – describedBy browse – icon OSDD – search OpenDAP Spatial extent as minimum bounding rectangle Temporal extent as dublin core date

Navigating this mine field 7

Insert cheeky graphic here… Attribution: Open Search Specs

The hierarchy OGC Specification ESIP Best Practices CEOS Best Practices Geo Extension Time Extension Parameter Extension Relevancy Extension Open Search Specification via describedBy

The CEOS best practices 1.Conform to the Open Search Specification 2.Conform to the OGC Specification 3.Take pertinent ideas from ESIP best practices 4.Add our own recommendations Such as, Make best attempt at coercing clients to provide client ids Extend ESIP ‘two step’ idea to link IDN dataset -> CWIC granule searching Embrace hypermedia Navigation by ‘self’, ‘next’, ‘prev’ Media types Achieve a ‘programmatic client’ where possible. Relevance Utilizing the parameter extension for better clarity of service Spatial (MBR+) and temporal (Dublin Core) extent representation

How it will look in theory

Visualization HTTP Response CWIC Dataset 1 CWIC Dataset 2 Metadata Link Data Link Search Link Metadata Link Data Link Search Link HTTP GET Request IDN CWIC OSDD HTTP Response Granule 1 Granule 2 Metadata Link Data Link Browse Link Metadata Link Data Link Browse Link HTTP GET Request CWIC OSDD for dataset 1

Open Search Descriptor Document ‘We essentially ignore everything except the URL element’ Chris Lynnes, ESIP Winter 2014 IDN - one OSDD exposing CWIC datasets (dynamic*) CWIC one OSDD for general granule queries one OSDD per dataset (dynamic*) for IDN coupling Obtain OSDD by URL with mandatory client id parameter Should we exercise draft 2 of the Open Search parameter extension? * Dynamic with respect to client id HTTP GET domain/opensearch/resource(s)/descriptor_document.xml?clientId=d

Request HTTP GET domain/opensearch/resource(s).atom Free text os:searchTerms datasets.atom?keyword=MODIS Spatial geo:box, (geo:geometry) granules.atom?boundingBox=-180.0,-90.0,180.0,90.0 granules.atom?geometry=POINT (-5 -5) granules.atom?geometry=LINESTRING (5 5, 4 4) granules.atom?geometry=POLYGON ((30 10, 10 20, 40 40, 30 10)) Temporal time:startTime, time:endTime datasets.atom?startTime= T22:00:00Z datasets.atom?endTime= T22:00:00Z Traversal os:pageNumber, os:numberOfResults granules.atom?pageNumber=1&numberOfResults=10

Response (1 of 3) Navigation

Response (2 of 3) Navigation … cwic.gov/opensearch/granules/ descriptorDocument?datasetId=1234&client=d … …

Response (2 of 3) Content ID – resolvable URI cwic.gov/foo?uid=Landsat_8:LC LGN00 Spatial Extent – MBR bounding box Temporal Extent – Dublin Core date T03:11:45Z/ T03:12:17Z Links – Data: – Metadata: – Browse: – Documentation: – Alternate:

Challenges Maintaining coupling between IDN and CWIC Interpretation of existing Open Search implementations Handling specification divergence Programmatic client from specification- compliant implementations Should we use the parameter extension? Ranking

Questions