OGC and ESIP Discoveryor

Can’t we all just get along??

Christopher Lynnes

The Players• ESIP Discovery Cluster– Informal working group of server and client developers

• Open Geospatial Consortium (OGC)– Formal, addresses many communities– Draft documents available only to OGC partners

• Open Source Geospatial Foundation (OSGeo)– Leading OpenSearch spec. development in OGC

• GENESI-DR– 13 Orgs with Earth Observation repositories– Implementing and promoting OpenSearch for Earth

Observations along OSGeo lines

Documents• ESIP– DCP-1: Codifies basic response. Status=approved– DCP-2: Proposed extension of rel field to codify

OPeNDAP links. Status = withdrawn– DCP-3: Rework of DCP-1 and DCP-2. Reverts to IANA

standards for rel, but adds new attributes to codify specific links. Status=under debate

• OGC– OpenSearch Geospatial Extensions Draft

Implementation Standard• Version 0.0.1 available, but superseded• Version 0.0.2 moving toward approval, but not available

Key Similarities between OGC and ESIP Discovery Approaches

• Basis in OpenSearch• Emphasis on Atom response format• Incorporation of geospatial query element• Incorporation of geospatial response element• Incorporation of temporal query element• Recursive search supported– But not called out as such in OGC spec

Key Differences in Atom ResponseFeature ESIP Approach OGC Approach

Time Repurpose temporal extension to OpenSearch: <time:start>2011-01-01</time:start><time:end>2011-01-02</time:end>

Dublin core:<dc:date>2011-01-01/2011-01-02</dc:date>

Paging no recommendation recommended

Link identification

ESIP namespace... IANA-based, except OGC namespace for OGC services

Link Identification• DCP-1 (to be deprecated)• DCP-2 (withdrawn)• DCP-3 (under debate)• mime-type approach (new! and improved?)

Link Identification• DCP-1 (to be deprecated)• DCP-2 (withdrawn)• DCP-3 (under debate)• mime-type approach (new! and improved?)

Approach: ESIP-specific value for rel attribute:

Data:<link href="http://host.com/my/file.nc”rel="http://esipfed.org/ns/discovery/1.1/data#” type="application/x-netcdf" />

OPeNDAP:<link href="http://host.com/opendap/file.hdf.nc”rel="http://esipfed.org/ns/discovery/1.1/data#” type="application/x-netcdf" />

Link Identification• DCP-1 (to be deprecated)• DCP-2 (withdrawn)• DCP-3 (under debate)• mime-type approach (new! and improved?)

Approach: Define new ESIP-specific value for rel attribute:

Data:<link href="http://host.com/my/file.nc”rel="http://esipfed.org/ns/discovery/1.1/data#” type="application/x-netcdf" />

OPeNDAP:<link href="http://host.com/opendap/file.hdf.nc”rel=“http://xml.opendap.org/ns/DAP/3.3#” type="application/x-netcdf" />

Link Identification• DCP-1 (to be deprecated)• DCP-2 (withdrawn)• DCP-3 (under debate)• mime-type approach (new! and improved?)Approach: Return to IANA rel + Add ESIP-specific attributes

Data:<link href="http://host.com/my/file.nc”rel=”enclosure” esip:subrel=“http://esipfed.org/ns/discovery/1.1/data#type="application/x-netcdf" />

OPeNDAP:<link href="http://host.com/opendap/file.hdf.nc”rel=“enclosure” esip:subrel=“http://esipfed.org/ns/discovery/1.1/data#esip:serviceProtocol=“http://xml.opendap.org/ns/DAP/

3.3#”type="application/x-netcdf" />

Link Identification• DCP-1 (to be deprecated)• DCP-2 (withdrawn)• DCP-3 (under debate)• mime-type approach (new! and improved?)

Approach: Return to IANA rel + extend typeData:

<link href="http://host.com/my/file.nc”rel=”enclosure”type="application/x-netcdf" />

OPeNDAP:<link href="http://host.com/opendap/file.hdf.nc”rel=“enclosure” type="application/opendap+x-netcdf" />

Link Identification• DCP-1 (to be deprecated)• DCP-2 (withdrawn)• DCP-3 (under debate)• mime-type approach (new! and improved?)

Approach: Return to IANA rel + Add ESIP-specific attributes + extend typeData:

<link href="http://host.com/my/file.nc”rel=”enclosure” esip:subrel=“http://esipfed.org/ns/discovery/1.1/data#type="application/x-netcdf" />

OPeNDAP:<link href="http://host.com/opendap/file.hdf.nc”rel=“enclosure” esip:subrel=“http://esipfed.org/ns/discovery/1.1/data#esip:serviceProtocol=“http://xml.opendap.org/ns/DAP/

3.3#”type="application/opendap+x-netcdf" />

Decisions, Decisions

1. Change time in Atom response to use Dublin Core?

2. Add ESIP-Specific attributes to <link>?3. Extend mime-type to indicate service?4. Work more directly with OGC?

N.B.: their constituency is a superset of our constituency, BUT their tools are a subset of our tools

5. Work more directly with OS Geo or GENESI-DR?