i. Abstract

This document is the specification for the OpenSearch extension for Earth Observation collections and products search.

This standard is intended to provide a very simple way to make queries to a repository that contains Earth Observation information and to allow syndication of repositories.

ii. Keywords

The following are keywords to be used by search engines and document catalogues.

ogcdoc, OGC document, OpenSearch, Earth Observation Extension, OpenSearch Earth Observation Service, EO Collection, EO Product, ISO19115, INSPIRE, OGC O&M EOP

iii. History

The first release of the document was the result of work undertaken within the GENESI-DR (Ground European Network for Earth Science Interoperations - Digital Repositories) project funded by the 7th Framework program of the European (EC Grant Agreement no. 212073), the follow-up project GENESI-DEC (Ground European Network for Earth Science Interoperations -Digital Earth Community) funded by the same program (Contract nº RI-261623). This document was initially produced during the ESA HMA (Heterogeneous Missions Accessibility) initiative [RD.25] and related projects.

iv. Preface

The recent release of the document is the result of work sponsored by EUMETSAT and ESA in the context of the continuation of the ESA HMA (Heterogeneous Missions Accessibility) initiative [RD.25].

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The Open Geospatial Consortium shall not be held responsible for identifying any or all such patent rights.

Recipients of this document are requested to submit, with their comments, notification of any relevant patent claims or other intellectual property rights of which they may be aware that might be infringed by any implementation of the standard set forth in this document, and to provide supporting documentation.

v.  Submitting organizations

The following organizations submitted this Document to the Open Geospatial Consortium (OGC):

EUMETSAT

European Space Agency (ESA)

con terra GmbH

Spacebel s.a.

Terradue SRL

The editors would like to acknowledge that this work is the result of collaboration and review of many organizations and would like to thank for the comments and contributions from:

CEOS/WGISS

NASA

AIRBUS

CGI

EOX GmbH

Luciad

Terradue

VITO

Note: this collaboration not imply a complete endorsement by these organizations.

vi.  Submitters

All questions regarding this submission should be directed to the editor or the submitters:

vii.  Future Work

In a future release of OGC 10-032, that standard should include things which are specified for the time being within this document:

• Encoding of paging (using atom:link rel="prev", rel="next",…) and OS metadata (such as os:totalResults).

1.    Scope

The OpenSearch specification originated in a community effort built around Amazon's A9.com. The specification was intended to allow syndication of search results that could then be aggregated by one large index. OpenSearch provides a simple to use description of the search interface, which is called an OpenSearch Description document (OSDD). A client (e.g., a browser) can use this description to check which response formats are supported and how a query/filter can be formulated.

The OpenSearch specification [RD.15] is made available under the Creative Commons Attribution-Sharealike 2.5 license (http://www.opensearch.org/Specifications/License).

Earth Observation (EO) products have specific characteristics that follow a specific logic inherent to the EO community of users of satellite datasets. Typically, an EO product contains information regarding:

• The platform or satellite from where it originates (e.g. SPOT, ENVISAT);
• The sensor used to acquire the data;
• The processing centre responsible for its elaboration together with the date and software used for the processing; and
• Specific satellite orbit information like the orbit number, wrsLatitudeGrid, and direction.

The OSDD format permits the use of extensions that allow search engines to inform clients about specific and contextual query parameters and response formats. This OGC standard specifies an Earth Observation extension to OpenSearch that defines query parameters that permit the filtering of search results with those fields and a search response model supporting different search response encodings.

This specification is complementary to the OpenSearch Geo and Time Extensions (OGC 10-032 [RD.3]) and recommends its use for spatial and temporal queries. Further the standard defines a default response encoding based on Atom 1.0/XML [RD.22].

Other formats may be supported by the server as well. One of these formats is GeoJSON(-LD) as defined in the document OGC 17-047 [RD.6]. The document does not (re)define the OpenSearch search parameters as these are already defined in this specification. Their mapping to the GeoJSON response format is included that document.

This document incorporates feedback from developers in the open source geospatial community and includes several annexes showing result sets in several possible formats and giving details that reflect a sample implementation.

Services that support the OpenSearch Specification and the Earth Observation extension defined in this document are called OpenSearch Earth Observation Services (OpenSearch-EO).

2.    Conformance

Conformance with this standard shall be checked using all the relevant tests specified in Annex A (normative) of this document. Annex C presents the different RELAX-NG schemas for the OpenSearch Description and the Atom Response Documents. The framework, concepts, and methodology for testing, and the criteria to be achieved to claim conformance are specified in the OGC Compliance Testing Policies and Procedures and the OGC Compliance Testing web site[1].

To conform to this OGC standard, a software implementation shall implement the Core conformance class and may implement any other of the conformance classes specified in Table 1. The implementation can be validated with the conformance tests defined in Annex A (normative). An implementation candidate to conformance shall minimally pass all applicable tests specified in the Abstract Test Suite belonging to core conformance class (minimal support).

The mappings between the conformance classes and the requirement classes are shown in Table 1.

Note 1: If a requirement class r11 depends on another requirement class r1 then also r1 must be implemented.

Note 2: Every requirement class (except the Core requirement class) depends on the Core requirement class.

All requirements-classes, conformance-classes and conformance tests described in this document are owned by the specification identified as http://www.opengis.net/spec/opensearcheo/1.0.

For each conformance class listed in Table 1 there is a corresponding requirement class with the same name. Table 2 lists each requirement classes and the set of requirements that correspond to each requirement class. Furthermore, each requirement in Table 2 is covered by a test in the conformance tests defined in Annex A: Abstract Test Suite (Normative).

The mappings between the requirements and the associated requirement class are shown in the table below.

3.    References

3.1 Normative References

The following normative documents contain provisions that, through reference in this text, constitute provisions of this document. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the normative document referred to applies.

[RD.1] OGC: OGC 06-121r9 - OpenGIS® Implementation Standard: OGC Web Services Common Standard, 2010

[RD.2] OASIS: OASIS OpenSearch - searchRetrieve: Part 4. APD Binding for OpenSearch Version 1.0, OASIS Standard, 2013, http://docs.oasis-open.org/search-ws/searchRetrieve/v1.0/searchRetrieve-v1.0-part4-opensearch.html

[RD.3] OGC: OGC 10-032r8 - OpenGIS® Implementation Standard: OpenSearch Geo and Time Extensions, 2014

[RD.4] OGC: OGC 10-157r3 – OpenGIS® Implementation Standard: Earth Observation Metadata profile of Observations & Measurements, V 1.0, 2012

[RD.5] OGC: OGC 10-157r4 – OpenGIS® Implementation Standard: Earth Observation Metadata profile of Observations & Measurements, V 1.1, 2016

[RD.6] OGC: OGC 17-047 – OGC OpenSearch-EO GeoJSON(-LD) Response Encoding Standard, 2019

[RD.7] OGC: OGC 17-003 – OGC EO Dataset Metadata GeoJSON(-LD) Encoding Standard, 2019

[RD.8] W3C: Linked Data Platform Paging 1.0, W3C Working Group Note, 2015, http://www.w3.org/TR/ldp-paging/

[RD.9] CEOS: CEOS OpenSearch Best Practice, Issue 1.2, 2017.

[RD.10] The Library of Congress – Information Resource Retrieval Protocols: SRU/SRW (Search and Retrieve URL/Web Service) DC Schema for SRU (http://www.loc.gov/standards/sru/recordSchemas/dc-schema.html)

[RD.11] OGC: OGC 12-084r2 – OGC OWS Context Atom Encoding Standard, V 1.0, 2013

[RD.12] OGC: OGC 13-043 – OGC Download Service for Earth Observation Products, OGC Best Practice, V 1.0, 2014

[RD.13] OGC: OGC 06-141r6 - Ordering Services Framework for Earth Observation Products Interface Standard (OSEO), V 1.0, 2012

[RD.14] OGC: OGC 13-043 – OGC Download Service for Earth Observation Products Best Practice (ROSEO), V 1.0, 2014

[RD.15] OpenSearch.org: OpenSearch - http://www.opensearch.org/Specifications/OpenSearch/1.1, 2018

[RD.16] OGC: OGC GeoRSS Community standard, V 1.0, OGC 17-002r1, 2017 http://www.opengeospatial.org/standards/georss.

[RD.17] OpenSearch.org: OpenSearch Parameter Extension - http://www.opensearch.org/Specifications/OpenSearch/Extensions/Parameter/1.0/Draft_2

[RD.18] OpenSearch.org: OpenSearch SRU Extension - http://www.opensearch.org/Community/Proposal/Specifications/OpenSearch/Extensions/SRU/1.0/Draft_1

[RD.19] European Commission: INSPIRE Metadata Implementing Rules: Technical Guidelines based on EN ISO 19115 and EN ISO 19119, 2013 (http://inspire.ec.europa.eu/Technical-Guidelines2/Metadata/6541)

[RD.20] European Commission: Technical Guidance for the implementation of INSPIRE Discovery Services, 2011 (http://inspire.ec.europa.eu/documents/technical-guidance-implementation-inspire-discovery-services-0)

[RD.21] RSS Advisory Board: Media RSS Specification, Version 1.5.1, 2009 http://www.rssboard.org/media-rss

[RD.22] IETF: Atom - The Atom Syndication Format (IETF RFC4287), 2005

[RD.23] no longer assigned.

[RD.24] no longer assigned.

[RD.25] ESA HMA (Heterogeneous Missions Accessibility). http://www.esa.int/About_Us/ESA_Publications/ESA_TM-21_Heterogeneous_Missions_Accessibility

[RD.26] ISO: ISO 19115:2003, Geographic Information – Metadata, 2003

[RD.27] ISO: ISO/TS 19139:2007, Geographic information -- Metadata -- XML schema implementation, 2007

[RD.28] ISO: ISO19115-2:2009, Geographic information – Metadata – Part 2: Extensions for imagery and gridded data, 2009

[RD.29] ISO: ISO/TS 19139-2:2012, Geographic information - Metadata - XML schema implementation - Part 2: Extensions for imagery and gridded data, 2012

[RD.30] ISO: ISO 19115-1:2014, Geographic information -- Metadata -- Part 1: Fundamentals, 2014

[RD.31] ISO: ISO/TS 19115-3, Geographic information -- Metadata -- Part 3: XML schema implementation for fundamental concepts, 2016

3.2 Other References

Dublin Core Metadata Initiative term declarations represented in RDF schema language, http://dublincore.org/schemas/rdfs/.

ESA: HMA - Heterogeneous Missions Accessibility – Design Methodology, Architecture and Use of Geospatial Standards for the Ground Segment Support of Earth Observation missions ESA TM-21, 2012 http://www.esa.int/About_Us/ESA_Publications/ESA_TM-21_Heterogeneous_Missions_Accessibility

ISO: ISO 19115:2003/Cor 1:2006, Geographic information – Metadata - Corrigendum 1, 2006

W3C: RDF 1.1 Concepts and Abstract Syntax - Richard Cyganiak, David Wood, Markus Lanthaler, Editors. 2014. W3C Proposed Recommendation. URL: http://www.w3.org/TR/rdf11-concepts/.

RDFS - http://schema.rdfs.org/

IETF: RFC 3339 - Date and Time on the Internet: Timestamps. Internet profile of the ISO 8601 standard for representation of dates and times using the Gregorian calendar, 2002 http://www.ietf.org/rfc/rfc3339.txt

IETF: RFC 5646 - Tags for Identifying Languages, 2009 http://tools.ietf.org/html/rfc5646

IETF: RFC 5988 - Web Linking, 2010 http://tools.ietf.org/html/rfc5988, http://www.iana.org/assignments/link-relations/link-relations.xhtml

4.    Terms and Definitions

This document uses the terms defined in Sub-clause 5.3 of [RD.1], which is based on the ISO/IEC Directives, Part 2, Rules for the structure and drafting of International Standards. In particular, the word "shall" (not "must") is the verb form used to indicate a requirement to be strictly followed to conform to this standard.

For the purposes of this document, the following additional terms and definitions apply.

4.1       Collection

A Collection or a Dataset Series (in short Series) defines a container for a list of Products (or datasets) that have common properties. Products inherit all the Collection properties that are not explicitly overridden.

4.2       Product

A Product or a Dataset corresponds to an identifiable collection of data under one single identifier. It is independent of a physical form or an encoding even if it is normally distributed in a single file.

4.3       OpenSearch

Draft specification for web search syndication, originating from Amazon’s A9 project and given a corresponding interface binding by the OASIS Search Web Services working group.

4.4       OpenSearch Geospatial Service

Defines services that comply with the OpenSearch Specification and the Geo extension defined in OGC 10-032 [RD.3]

4.5       OpenSearch GeoTemporal Service

Defines services that comply with the OpenSearch Specification, the Geo and Time extensions defined in OGC 10-032 [RD.3]

4.6       OpenSearch Description Document (OSDD)

An XML document available at a consistent location describing metadata for the service and providing templates for queries.

4.7       OpenSearch Earth Observation Service

Defines services that comply with the OpenSearch Specification and the Earth Observation extension defined in this document.

4.8       Search feed

The response document of search service request containing zero or several entries.

4.9       Entry

An element of the search response representing a catalogued resource.

5.    Conventions

5.1    Abbreviated terms

Some of the abbreviated terms listed in Subclause 5.1 of the OWS Common Implementation Specification [RD.1] apply to this document, plus the following:

ATS                   Abstract Test Suite

CEOS                   Committee on Earth Observation Satellites

DM                   Download Manager

EC                  European Commission

EO                  Earth Observation

EOP                Earth Observation Product

ESA                European Space Agency

GML                   Geography Markup Language

HMA                   Heterogeneous Missions Accessibility

HTTP                   HyperText Transfer Protocol

IRI                   Internationalised Resource Identifier

ISO                   International Organisation for Standardisation

OASIS                   Advancing Open Standards for the Information Society

OGC                   Open Geospatial Consortium

OSDD                  OpenSearch Description Document

O&M                  Observations and Measurements

OWC                   OGC Web Services Context

RDF                   Resource Description Framework

RDFS                  RDF Schema

REST                   Representational State Transfer

SRU                  Search/Retrieval via URL

SWS                  Search Web Services

UML                   Unified Modelling Language

UMM                   Unified Metadata Model

URI                   Uniform Resource Identifier

URL                   Uniform Resource Locator

URN                   Uniform Resource Name

W3C                   World Wide Web Consortium

WGISS                   Working Group on Information Systems and Services

WKT                   Well-Known Text

WMC                   Web Map Context

WMS                   Web Map Service

XML                   eXtensible Markup Language

XSD                   XML Schema Definition Language

5.2    Namespace prefix conventions

Table 3 lists the namespaces used in this document and the specifications in which they are defined. The prefixes are not normative and are merely chosen for convenience; they may appear in examples without being formally declared, and have no semantic significance. The namespaces to which the prefixes correspond are normative, however.

6.   OpenSearch-EO - Overview

As the OpenSearch specification [RD.15] is defined in the OASIS SWS bindings [RD.2], this document is confined to the OpenSearch Earth Observation extension (OpenSearch-EO). This standard is complementary to the OpenSearch Geo and Time Extensions (OGC 10-032 [RD.3]) and recommends its use for spatial and temporal queries especially for EO collection and EO product metadata. Further it defines a default response encoding based on Atom 1.0/XML [RD.22].

OpenSearch-EO specifies a series of parameters that can be used to constrain search results. These are discussed in more detail in section 7.2. In short, provision is made to filter results by sensor information, acquisition, processing parameters and other information. The purpose of OpenSearch-EO is to make sure that OpenSearch parameters are aligned with OGC 10-157r4 [RD.5] that describes EO products metadata and with ISO19115(-1) [RD.26, RD.30]/ISO19115-2 [RD.28] that is used for describing EO collection metadata (see 6.1). An OpenSearch Earth Observation Service is not expected to support all the elements defined here, but use them in accordance with a given use case and search service contents.

Further an important aspect is the definition of search responses supporting best practices which are relevant in the context hypermedia web guidelines such as HATEOAS (Hypermedia As The Engine Of Application State).

6.1    Collections and Products

An EO Collection (i.e., dataset series) is defined as a set of EO Products (i.e., datasets), sharing a common specification or characteristics. Below are a few examples on how to define an EO Collection:

• EO products of the same platform (e.g.; Sentinel-1) and the same instrument (C-SAR sensor) acquired over a specific Area of Interest (AOI) and Time of Interest (TOI);
• EO products of several SAR instruments over AOI and TOI (e.g., Time series with ENVISAT ASAR, Sentinel-1A/b, TSX); and
• EO products acquired from a combination of platforms/instrument (e.g., Sentinel-1/SAR, Sentinel-2/MSI and SMOS/MIRAS) over AOI and TOI to address specific purposes. Definition of a "Thematic Collection" would permit the users to get direct access to EO products, necessary for specific application domains (e.g., Forestry, land monitoring, Emergency, ice monitoring, etc.), instead of searching in all the collections for different satellite products.

Definition of flexible EO collections that are as close as possible to users’ needs requires the possibility to associate a specific EO product to more than one EO Collection.

6.2 Two Step Search

In a typical search scenario, a client will first request for a catalogue´s OpenSearch Description Document - OSDD (see Figure 1), which will detail the catalogue’s support for searching for collections. Then, the client will submit a query searching for EO collections, according to allowed search parameters specified in this OSDD (See 7.2), and will receive the results in XML encoding (e.g., atom). In the search response, the user will find the details of the collections that match the search, these can be used to select a collection of interest and to identify how to request its specific search support (e.g., via the identifier or the hyperlink to the OSDD for the collection). This OSDD can then be retrieved and used to search for products of interest in this EO products collection.

7.    OpenSearch-EI Search Service

The OpenSearch Description Document (OSDD) allows clients to retrieve service metadata from a server. The response to a request for a Description shall be an XML document in the form specified by the SWS OpenSearch bindings published by OASIS. A brief summary of the Description’s requirements is provided in OGC 10-032 [RD.3].

The OpenSearch Earth Observation Extension is designed to provide a search facility of Earth Observation metadata to the OpenSearch protocol. One namespace is provided for use in URL templates that form part of the OSDD (see Example 1, below), published by the server in XML at a stable URL.

A server provides an OSDD that a client reads to determine the response formats available and how to formulate a search/retrieve request. The OSDD includes a mandatory URL element containing a mandatory request template. Where several request templates are provided, a client may choose the one offering the most useful format (specified by MIME-type defined in the type attribute of the element) as shown in Example 1 below.

EXAMPLE 1        The following XML document provides a sample response to a request for an OpenSearch Description Document from a repository supporting the Earth Observation Extension. Note that the response type is given in the type attribute and not implicitly on the URL path

<OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/" xmlns:eo="http://a9.com/-/opensearch/extensions/eo/1.0/">
	<ShortName>Web Search</ShortName>
	<Description>Use Example.com to search the Web.</Description>
	<Contact>admin@example.com</Contact>
	<Url type="application/atom+xml" template="http://example.com/myatom/?q= {searchTerms}&pw={startPage?}&platform={eo:platform?}"/>
	<Url type="application/geo+json" template="http://example.com/geojson/?q= {searchTerms}&pw={startPage?}&platform={eo:platform?}"/>
	<Url type="text/html" template="http://example.com/?q= {searchTerms}&platform={eo:platform?}&pw={startPage?}"/>
	<LongName>Example.com Web Search</LongName>
	<Query role="example" searchTerms="cat" eo:platform="ENVISAT"/>
	<Attribution>Copyright 2005, Example.com, Inc.</Attribution>
	<SyndicationRight>open</SyndicationRight>	
</OpenSearchDescription>

7.2 Search operation request

7.2.1 Fundamental search request parameters to search by time and space

The time and geo extensions defined in OGC10-032 [RD.3] give a list of fundamental search parameters sufficient to constrain a search by time and space. This OpenSearch Extension for EO complements those extensions with optional parameters specific to EO data.

<param:Parameter name="radius" value="{geo:radius}" title="Expressed in meters. Default value is 10000"/>

7.2.2 Concept of search request parameters for the Earth Observation Extension

This Earth Observation Extension defines in Table 4, Table 5, Table 6 and Table 7 an extensive list of OpenSearch parameters that can (all parameters are optional) be supported by a search engine when searching via EO-related attributes. It is not expected or advisable for an OpenSearch Earth Observation Service to support all the parameters. Their use is largely dependent on the search engine contents and capabilities.

If a search engine use case is for the discovery of collections, typically the parameters of tables 4-6 are relevant. Those tables include parameters like: platform, orbitType, instrument, sensorType, spectralRange, processingLevel or compositeType. Table 6 includes the parameters which are aligned with the INSPIRE requirements like title, topicCategory, organisationName, useLimitation or accessConstraint.

Conversely, if the search engine use case is for the discovery of products (usually when a collection was already identified and afterwards a subset of interesting products of that collection shall be selected), it is recommended to select relevant parameters e.g., from: orbitNumber, orbitDirection, wrsLatitudeGrid, archivingCenter, processingCenter, processingSoftware, processingDate, cloudCover, snowCover as defined in Table 7.

In some situations, it may happen that for the selection of a subset of interesting products all parameters of tables 4-7 may become relevant. This is the case for example:

• when there is no strict separation between collections and products (e.g., because products are described and indexed by parameters which include those which are typically only used for collections); and
• for "thematic collections" in cases where:
  • products in a collection are of various types/sensors/missions/... ("a logical collection could be defined as a group of products from a given number of collections…"); and
  • the same product belongs to several collections.

7.2.3 Informing clients about constraints on search request parameters

To inform clients about permitted values (supported value list, range, ...) for a given parameter an OpenSearch Earth Observation Service should make use of the OpenSearch Parameter Extension [RD.17]. The Parameter Extension explicitly advertises the valid lists and ranges of search parameters. Thus, it allows reducing ambiguities and errors dramatically.

The following example provides a sample response to a request for an OpenSearch Description from a repository supporting the Earth Observation and Temporal Extensions. The OpenSearch Parameter extension elements are used to suggest to clients the possible values for temporal range and acquisition station names

Example 2: OpenSearch Desction Document supporting the OpenSearch Parameter extension

<?xml version="1.0" encoding="UTF-8"?> 
<OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/" 
    xmlns:eo="http://a9.com/-/opensearch/extensions/eo/1.0/"
    xmlns:param="http://a9.com/-/spec/opensearch/extensions/parameters/1.0/"
    xmlns:time="http://a9.com/-/opensearch/extensions/time/1.0/">
    
    <ShortName>Web Search</ShortName> 
    <LongName>Example.com Web Search</LongName> 
    <Description>Use Example.com to search the Web.</Description> 
    <Tags>example web</Tags> 
    <Contact>admin@example.com</Contact> 
    <Url type="application/atom+xml" template="http://example.com/myatom/?pw={startPage?}&acq={eo:acquisitionStation?}&start={time:start?}&end={time:end?}"> 
        
        <param:Parameter name="start" value="{time:start}" minimum="0" 
            minInclusive="2011-01-01T00:00:00Z" maxExclusive="2012-01-01T00:00:00Z"/>
        
        <param:Parameter name="end" value="{time:end}" minimum="0"
            minInclusive="2011-01-01T00:00:00Z" maxExclusive="2012-01-01T00:00:00Z"/>
        
        <param:Parameter name="acq" value="{eo:acquisitionStation}" minimum="0" 
            title="Acquisition Station">
            <param:Option value="PDHS-K" label="Kiruna"/>
                <param:Option value="PDHS-E" label="ESRIN"/>
        </param:Parameter>
    </Url>
    <Attribution>Copyright 2005, Example.com, Inc.</Attribution> 
    <SyndicationRight>open</SyndicationRight> 
</OpenSearchDescription>

For conveying the server’s search support condition on ranges and sets (used in request parameters to express that a set or a whole range of values are accepted) the Parameter Extension can be used as well.

8.    OpenSearch Earth Observation operation

8.1    Search operation request

8.1.1    Search request parameters

An OpenSearch Earth Observation Service should use the time and geo extensions defined in OGC10-032 when supporting the search respectively by acquisition times and acquisition footprint. This Earth Observation Extension defines in Table 3, Table 4, Table 5 and Table 6 an extensive list of OpenSearch parameters that can be supported by a search engine.

It is not expected or advisable for an OpenSearch Earth Observation Service to support all the elements defined in this specification. The elements defined should be used to constrain search results and their use is largely dependent on the search engine contents and capabilities (see also 6).

If a search engine use case is for the discovery of collections, it is recommended to use the elements of Table 3 and Table 4 that include parameters like: platform, orbitType, instrument, sensorType, spectralRange, processingLevel, compositeType, organisationName, useLimitation or accessConstraint. If the search engine is obliged to be aligned with INSPIRE requirements it SHALL support the elements of Table 4.

Conversely, if the search engine use case is for the discovery of products[2] associated to a single collection, it is recommended to select additional relevant parameters e.g. from: orbitNumber, orbitDirection, track, frame, archivingCenter, processingCenter, processingSoftware, processingDate, cloudCover and snowCoveras shown in Table 5. The specific parameters related to the acquisition of Earth Observation products are shown on Table 6.

To suggest clients of the possible values of a given parameter an OpenSearch Earth Observation Service should make use of the OpenSearch Parameter Extension.

EXAMPLE 2        The following XML document provides a sample response to a request for an OpenSearch Description from a repository supporting the Earth Observation and Temporal Extensions. The OpenSearch Parameter extension elements are used to suggest clients the possible values for temporal range and acquisition station names:

<?xml version="1.0" encoding="UTF-8"?>
<OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/"
xmlns:eo="http://a9.com/-/opensearch/extensions/eo/1.0/"
xmlns:param="http://a9.com/-/spec/opensearch/extensions/parameters/1.0/"
xmlns:time="http://a9.com/-/opensearch/extensions/time/1.0/">
 
<ShortName>Web Search</ShortName>
<LongName>Example.com Web Search</LongName>
<Description>Use Example.com to search the Web.</Description>
<Tags>example web</Tags>
<Contact>admin@example.com</Contact>
<Url type="application/atom+xml" 
    template="http://example.com/myatom/? pw={startPage?}&acq={eo:acquisitionStation?}&start={time:start?}& end={time:end?}">
 
<param:Parameter name="start" value="{time:start}" minimum="0"
   minInclusive="2011-01-01T00:00:00Z" maxExclusive="2012-01-01T00:00:00Z"/>
 
<param:Parameter name="end" value="{time:end}" minimum="0"
   minInclusive="2011-01-01T00:00:00Z" maxExclusive="2012-01-01T00:00:00Z"/>
 
<param:Parameter name="acq" value="{eo:acquisitionStation}" minimum="0"
   title="Acquisition Station">
<param:Option value="PDHS-K" label="Kiruna"/>
          <param:Option value="PDHS-E" label="ESRIN"/ >
</param:Parameter>
</Url>
<Attribution>Copyright 2005, Example.com, Inc.</Attribution>
<SyndicationRight>open</SyndicationRight>
</OpenSearchDescription>

All parameters of the OpenSearch query should be mapped to the appropriate catalogue or metadata fields of the underlying metadata management system. Annex D shows the suggested mappings for

• Earth Observation Metadata profile of Observations & Measurements (OGC 10-157)
• ISO 19115 / ISO19115-2 Geographic information – Metadata
• OGC Catalogue Services Standard 2.0 Extension Package for ebRIM Application Profile Earth Observation Products (OGC 06-131)
• OGC I15 (ISO19115 Metadata) Extension Package of CS-W ebRIM Profile (OGC 13-084)
• OGC Catalogue Services Specification 2.0 Extension Package for ebRIM Application Profile: SensorML (OGC 09-163)

8.1.2    Search request KVP encoding (mandatory)

Note that for the given key-value pairs, the key can be an arbitrary string, specified by one given instance of an OpenSearch repository. For example, one Description may provide a URL template asking for platform={eo:platform}, another specifying plat={eo:platform}. It is the responsibility of the client application to parse the URL template and create the appropriate keys for each key-value pair. These parameter sets are templates from which URLs can be constructed. The search client must replace every instance of a template parameter with a value before the search request is performed. If a search engine wishes to indicate that a template parameter is optional and can be replaced with the empty string, then the "?" notation described in the section on optional template parameters should be used. Clients should take special consideration to the fact that according to the OpenSearch specification the OpenSearch parameters usage is not restricted to the URL query string and can be used as templates values in any of URL components (e.g. path, host).

EXAMPLE 3        A search operation URL template with the OpenSearch parameter as a query string parameter and the corresponding request:

<Url template="http://foo.com/atom/?count={count?}&st={startIndex?}& platform={eo:platform}" type="application/atom+xml" />
 
http://foo.com/atom/?count=&st=&platform=ENVISAT

<Url template="http://foo.com/{eo:platform}/atom/?count={count?}& st={startIndex?}" type="application/atom+xml" />
 
http://foo.com/ENVISAT/atom/?count=&st=

8.2    Search operation response

8.2.1    Normal response parameters

The normal response to a valid Search operation request shall be in one of several formats that are specified in the OpenSearch Description for a given instance. The mandatory response format is Atom but the server may support other formats.

8.2.2    Normal response XML encoding

The normative response format for an OpenSearch service using Earth Observation Extension shall be ATOM 1.0. The properties shown in the Atom and OpenSearch namespaces are those mandated by the core specification.

Following the Atom format the response is made of a atom:feed element that may contain several atom:entry elements. While the latter describe the returned resources that respect the query performed the first describes the discovery service or search engine.

In the atom:feed element the response should include the elements listed in Table 7and the atom:entry elements should include the elements listed in Table 8. The metadata for each item in the result set should provide a link to a "full" view of the result, where more detailed metadata according to OGC O&M EOP (OGC 10-157r3, OGC 10-157r4), ISO19115(-1|-2|-3)/ISO19139(-2), SensorML 1.0 (OGC 07-122r2), SensorML 2.0 (OGC 12-000) or Dublin Core Schema for SRU (http://www.loc.gov/standards/sru/recordSchemas/dc-schema.html) can be provided (see 8.2.4) and, when available, a direct link to the resource using the atom:link element.

8.2.3    Search context propagation to external end points

If the resource described in the response entry aggregates other resources (e.g. is a collection or a search service) it should possess an atom:link with the relation "search" [RFC 5988]. This feature can be used to define recursive searches where the search context (e.g. queriables) is propagated to an internal or external service (see e.g. 6.2). It can also allow the aggregation of entries into collections or groups.

EXAMPLE 5        Defining access to the product file of the atom:entry

<atom:link rel="search" type="application/opensearchdescription+xml" 
    href="http://search.acme.com/osd.xml" title="Search this resource" />

When an entry contains a link with the rel attribute equal to "search" and the type attribute equal to "application/opensearchdescription+xml" clients are recommended to propagate the query parameters to the search engine described by the OpenSearch description document located on the href attribute value using the original query parameters.

8.2.4    Linking entry with metadata

If possible, the access to the original authoritative metadata source of the entry should be given using one atom:link element with the atom:rel equal to "via" [RFC5988] with the corresponding format announced in the type attribute.

If the information of this entry is available in other metadata encodings, then a server can include atom:link elements for each format using the "alternate" [RFC 5988] relation name and corresponding format in the type attribute.

EXAMPLE 6        Defining the access to authoritative source and alternative representations of the atom:entry

<atom:link rel="alternate" type="application/gml+xml;profile=http://www.opengis.net/spec/EOMPOM/1.1" 
    title="EOP O&M Metadata" href="http://site.com/eo/asarimageEOOM.xml" length="1245"/>
<atom:link rel="via" type="application/vnd.iso.19139+xml" length="845" 
    title="ISO 19139 Metadata" href="http://site.com/eo/asarimageISO.xml"/>

If a server allows to obtain metadata inline, it can advertise that it supports the sru:recordSchema (see Table 3) and use the parameter extension to say which ones.

EXAMPLE 7        Defining metadata inline

    <georss:where><gml:Polygon><gml:exterior><gml:LinearRing><gml:posList 
    srsDimension="2">42.2879 128.7535 42.4897 127.4932 41.4254 127.1936 41.2326 128.3991 42.2879 128.7535
    </gml:posList></gml:LinearRing></gml:exterior></gml:Polygon></georss:where>
…
<eop:EarthObservation xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation=http://www.opengis.net/opt/2.1 ../xsd/opt.xsd
xmlns:eop="http://www.opengis.net/eop/2.1"    … gml:id="eo_ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1">
    <om:phenomenonTime><gml:TimePeriod
gml:id="tp_ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1">
            <gml:beginPosition>2010-01-22T01:44:41.316Z</gml:beginPosition>
…

EXAMPLE 8        Use of parameter extension for sru:recordSchema

<param:Parameter name="rec" value="{sru:recordSchema}" minimum="0" 
    title="Metadata model in which additional metadata should be provided inline">
              <param:Option value="http://www.isotc211.org/2005/gmi" label="ISO19115-2/ISO19139-2"/>
</param:Parameter>

Advertising sru:recordSchema means it can provide metadata inline in the Atom response.  Not advertising it means it cannot do this but will provide the available alternative atom:links instead. A server supporting sru:recordSchema can also support providing alternate links instead - support for both mechanisms by a single server are not mutually exclusive (the client can then decide what he wants by using or not using the sru:recordSchema parameter). 

8.2.5    Linking an entry with its thumbnail, quicklook or masks

To define the reference to a resource representing a quicklook, browse image or cloud mask that represents the entry, the "Media RSS Specification" should be used [Media RSS].  Each of the images should be included as a separate media:content element.  Multiple elements (e.g. Quicklook and cloud mask) for the same entry single entry should be included in the same media:groupelement.

The scheme parameter in the media:category element should reflect a thesaurus/codelist covering the various possibilities, e.g. the values allowed in the OGC 10-157r4 codelist for browse/BrowseInformation/type (THUMBNAIL, QUICKLOOK, ALBUM) and mask/MaskInformation/type (SNOW, CLOUD, QUALITY).

EXAMPLE 9        Defining the reference to the quicklook image of the atom:entry

<feed xmlns="http://www.w3.org/2005/Atom
xmlns:media="http://search.yahoo.com/mrss/" …>
…
<entry>
…
   <media:group>
      <media:content url="http://mda.com/browse/RADARSAT-2/2012/08/01/PASS_RS2_210671_3_32488_1.jpg" type="image/jpeg" medium="image">   
         <media:category scheme="http://www.opengis.net/spec/EOMPOM/1.1">QUICKLOOK</media:category>
      </media:content>
…
     </media:group>
</entry>

8.2.6    Error handling

The Atom and the OpenSearch specifications do not directly specify how to deal with server and request errors. It is recommended that an OpenSearch Earth Observation Service use the HTTP error codes for client (4xx) and server (5xx) errors. In particular, it is recommended to use the following error codes in the particular situations of client error:

• 400 Bad Request: The request has an invalid syntax (i.e. badly formatted geometry)
• 413 Request Entity Too Large: The request originates too many returnable hits

For server side errors the following error codes are recommended:

• 500 Internal Server Error: Default code for the server side for an execution error.
• 501 Not Implemented: When requesting an unimplemented feature.
• 503 Service Unavailable: When the search service is temporarily not available (due to overload or other reasons)
• 504 Gateway Timeout: When the search engine is a broker or aggregator to other services that fail to produce a answer within a giving time frame.

EXAMPLE 10      Response example for a bad request (incorrect eo:orbitNumber format)

HTTP/1.1 400 Bad Request
Content-Type: text/plain
Date: Mon, 6 Feb 2012 14:27:37 GMT
Content-Length: 56
 
Bad Request - Wrong orbitNumber format (number or range)

Annex A

Conformance Class Abstract Test Suite (Normative)

A.1     Conformance Test Class Core (/conf/Core)

A.2     Conformance Test Class EarthObservationForeignElement (/conf/EarthObservationForeignElement)

A.3     Conformance Test Class Suggestions (/conf/Suggestions)

A.4     Conformance Test Class INSPIRE (/conf/INSPIRE)

Annex B: XML Schema Documents

B.1     Atom Schema (schemas/atom/2005/rfc4287.rnc)[4]

# -*- rnc -*-
# RELAX NG Compact Syntax Grammar for the
# Atom Format Specification
# Taken from http://tools.ietf.org/html/rfc4287#page-35
# Defined a new constructor for Atom Feed and Entry
namespace atom = "http://www.w3.org/2005/Atom"
namespace xhtml = "http://www.w3.org/1999/xhtml"
namespace s = "http://purl.oclc.org/dsdl/schematron"
namespace local = ""  
start = atomFeed | atomEntry
 
# Common attributes
atomCommonAttributes = attribute xml:base { atomUri }?,
                        attribute xml:lang { atomLanguageTag }?, undefinedAttribute*
 
# Text Constructs
atomPlainTextConstruct = atomCommonAttributes,
      attribute type { "text" | "html" }?, text
atomXHTMLTextConstruct = atomCommonAttributes, attribute type { "xhtml" }, xhtmlDiv
atomTextConstruct = atomPlainTextConstruct | atomXHTMLTextConstruct
 
# Person Construct
atomPersonConstruct = atomCommonAttributes,
      (element atom:name { text } & element atom:uri { atomUri }?
       & element atom:email { atomEmailAddress }?  & extensionElement*)
 
# Date Construct
atomDateConstruct = atomCommonAttributes, xsd:dateTime
 
# atom:feed
atomFeed =  [
    s:pattern [ name="check authors"
     s:rule [ context = "atom:feed"
       s:assert [test = "atom:author or not(atom:entry[not(atom:author)])"
               "An atom:feed must have an atom:author unless all"
               ~ "of its atom:entry children have an atom:author."]]]]
      element atom:feed { atomFeedConstruct }
  
atomFeedConstruct =
         atomCommonAttributes, (atomAuthor* & atomCategory* & atomContributor*
         & atomGenerator? & atomIcon? & atomId & atomLink* & atomLogo? & atomRights? &
atomSubtitle? & atomTitle & atomUpdated & extensionElement*), atomEntry*
     
# atom:entry
atomEntry = [
    s:pattern [ name="check entry’s alternate link"
      s:rule [ context = "atom:entry" s:assert [
               test = "atom:link[@rel=’alternate’]"
               ~ "or atom:link[not(@rel)] or atom:content"
               "An atom:entry must have at least one atom:link element"
               ~ "with a rel attribute of ‘alternate’ or an atom:content."
            ]]]
    s:pattern [ name="check entry’s author"
      s:rule [ context = "atom:entry" s:assert [
               test = "atom:author or ../atom:author or atom:source/atom:author"
               "An atom:entry must have an atom:author if its feed does not."
            ]]]]
      element atom:entry { atomEntryConstruct }
  
atomEntryConstruct =
         atomCommonAttributes,
         (atomAuthor* & atomCategory* & atomContent? & atomContributor*
          & atomId & atomLink* & atomPublished? & atomRights? & atomSource?
          & atomSummary? & atomTitle & atomUpdated & extensionElement*)
         
# atom:content
atomInlineTextContent = element atom:content { atomCommonAttributes,
         attribute type { "text" | "html" }?, (text)* }
 
atomInlineXHTMLContent = element atom:content { atomCommonAttributes,
         attribute type { "xhtml" }, xhtmlDiv }
 
atomInlineOtherContent = element atom:content { atomCommonAttributes,
         attribute type { atomMediaType }?, (text|anyElement)*}
 
atomOutOfLineContent = element atom:content { atomCommonAttributes,
         attribute type { atomMediaType }?, attribute src { atomUri }, empty }
 
atomContent = atomInlineTextContent | atomInlineXHTMLContent
                    | atomInlineOtherContent | atomOutOfLineContent
 
atomAuthor = element atom:author { atomPersonConstruct }
 
atomCategory =
      element atom:category { atomCommonAttributes, attribute term { text },
         attribute scheme { atomUri }?, attribute label { text }?,
         undefinedContent }
 
atomContributor = element atom:contributor { atomPersonConstruct }
 
atomGenerator = element atom:generator { atomCommonAttributes,
      attribute uri { atomUri }?, attribute version { text }?, text }
 
atomIcon = element atom:icon { atomCommonAttributes, (atomUri) }
 
atomId = element atom:id { atomCommonAttributes, (atomUri) }
 
atomLogo = element atom:logo { atomCommonAttributes, (atomUri)}
 
atomLink =
      element atom:link { atomCommonAttributes, attribute href { atomUri },
         attribute rel { atomNCName | atomUri }?, attribute type { atomMediaType }?,
 attribute hreflang { atomLanguageTag }?, attribute title { text }?,
 attribute length { text }?, undefinedContent }
 
atomPublished = element atom:published { atomDateConstruct }
 
atomRights = element atom:rights { atomTextConstruct }
 
atomSource = element atom:source {
         atomCommonAttributes, (atomAuthor* & atomCategory* & atomContributor* &
 atomGenerator? & atomIcon? & atomId? & atomLink* & atomLogo? & atomRights?
          & atomSubtitle? & atomTitle? & atomUpdated? & extensionElement*)}
 
atomSubtitle = element atom:subtitle { atomTextConstruct }
 
atomSummary = element atom:summary { atomTextConstruct }
 
atomTitle = element atom:title { atomTextConstruct }
 
atomUpdated = element atom:updated { atomDateConstruct }
 
# Low-level simple types
atomNCName = xsd:string { minLength = "1" pattern = "[^:]*" }
 
# Whatever a media type is, it contains at least one slash
atomMediaType = xsd:string { pattern = ".+/.+" }
 
# As defined in RFC 5646
atomLanguageTag = xsd:string { pattern = "[A-Za-z]{1,8}(-[A-Za-z0-9]{1,8})*"}
 
# Unconstrained; it’s not entirely clear how IRI fit into
# xsd:anyURI so let’s not try to constrain it here
atomUri = text
 
# Whatever an email address is, it contains at least one @
atomEmailAddress = xsd:string { pattern = ".+@.+" }
 
# Simple Extension
simpleExtensionElement = element * - atom:* { text }
 
# Structured Extension
structuredExtensionElement = element * - atom:* {
         (attribute * { text }+, (text|anyElement)*)
       | (attribute * { text }*, (text?, anyElement+, (text|anyElement)*))}
 
# Other Extensibility
extensionElement = simpleExtensionElement | structuredExtensionElement
 
undefinedAttribute = attribute * - (xml:base | xml:lang | local:*) { text }
 
undefinedContent = (text|anyForeignElement)*
 
anyElement = element * { (attribute * { text } | text | anyElement)* }
 
anyForeignElement = element * - atom:* { (attribute * { text } | text | anyElement)* }
 
# XHTML
anyXHTML = element xhtml:* { (attribute * { text } | text | anyXHTML)* }
 
xhtmlDiv = element xhtml:div { (attribute * { text } | text | anyXHTML)* }
 
# EOF

B.2     OpenSearch Atom Schema (schemas/opensearch/1.1/osatom.rnc)

# -*- rnc -*-
   # RELAX NG Compact Syntax Grammar for
   # Atom encoding and foreign elements for OpenSearch   
namespace s = "http://purl.oclc.org/dsdl/schematron"
namespace atom = "http://www.w3.org/2005/Atom"
namespace os = "http://a9.com/-/spec/opensearch/1.1/"
 
# Redefine atom:feed to include new OpenSearch elements
atomFeedConstruct &= osQuery ? & osTotalResults? &osStartIndex? &osItemsPerPage?                      
osQuery = element os:Query { undefinedAttribute*, ( osQueryAttr ) }
osTotalResults = element os:totalResults { xsd:int }
osStartIndex = element os:startIndex { xsd:int }
osItemsPerPage = element os:itemsPerPage { xsd:int }
 
include "osquery.rnc"
 
# Replacing definitions on RFC4287
# relative path schemas/atom folder
include "../../atom/2005/rfc4287.rnc"{
      # Redefine the Simple Extension to exclude os:* elements
      simpleExtensionElement = element * - (atom:* | os:*) { text }
      # Redefine the Structured Extension to exclude os:* elements
      structuredExtensionElement = element * -
          (atom:* |  os:* ) { (attribute * { text }+,(text|anyElement)*)
           | (attribute * { text }*, (text?, anyElement+, (text|anyElement)*))}
 
      # Redefine Atom rules   
      atomFeed = [
       s:rule [ context = "atom:feed"
         s:assert [ test = "atom:author or not(atom:entry[not(atom:author)])"
           "An atom:feed must have an atom:author unless all"
           ~ "of its atom:entry children have an atom:author."]]     
       ]
       element atom:feed { atomFeedConstruct }    
      
      atomEntry =[
       s:pattern [ name="check entry content"
        s:rule [ context = "atom:entry"
         s:assert [ test = "atom:content"
          "An atom:entry must have one atom:content MUST have content"
          ~ "element in a format understandable by generic Atom readers"
          ~ " ( @type equal to ‘html’ is recommended)"]]]
        
      ]
      element atom:entry { atomEntryConstruct }
}
# EOF

B.3     OpenSearch Description Document Schema (schemas/opensearch/1.1/osdd.rnc)

# -*- rnc -*-
   # RELAX NG Compact Syntax Grammar for
   # OpenSearch Description Document
  
namespace os = "http://a9.com/-/spec/opensearch/1.1/"
namespace s = "http://purl.oclc.org/dsdl/schematron"
namespace local = ""  
start = osDocument
 
osDocument = element os:OpenSearchDescription { osDocumentConstruct }
 
osDocumentConstruct =
      element os:ShortName { xsd:string { maxLength = "16" } }
      & element os:Description { xsd:string { maxLength = "1024" } }
      & element os:Url { osdUrlAttr } *
      & element os:Contact { xsd:string {pattern=".+@.+"}}?
      & element os:Tags { text }? & element os:LongName { xsd:string {maxLength="48"}}?
      & element os:Image { osdImage } *
      & element os:Query { undefinedAttribute*, ( osQueryAttr ) }*
      & element os:Developer { xsd:string { maxLength = "64" } }?
      & element os:Attribution { xsd:string { maxLength = "256" } }?
      & element os:SyndicationRight { osdSyndicationRightValues } ?
      & element os:AdultContent { "false" | "true" } ?
      & element os:Language {xsd:string { pattern="[A-Za-z]{1,8}(-[A-Za-z0-9]{1,8})*"}}?
      & element os:InputEncoding { text } ? & element os:OutputEncoding { text } ?
      & undefinedAttribute*
      & extensionElement*
 
osdUrlAttr = attribute template { text }, attribute type { text },
            attribute rel { osdRelationValues }?, attribute indexOffset { xsd:int }?,
         attribute pageOffset { xsd:int }?, undefinedAttribute*, extensionElement*
 
osdImage = attribute height {xsd:int}, attribute width {xsd:int},
           attribute type {xsd:string}, text
 
include "osquery.rnc"
   
osdRelationValues = "results" | "suggestions" | "self" | "collection"
osdSyndicationRightValues = "open" | "limited" | "private" | "closed"
 
# Simple Extension
simpleExtensionElement = element * - os:* { text }
 
# Structured Extension
structuredExtensionElement = element * - os:* {
         (attribute * { text }+, (text|anyElement)*)
       | (attribute * { text }*, (text?, anyElement+, (text|anyElement)*))}
 
# Other Extensibility
extensionElement = simpleExtensionElement | structuredExtensionElement
undefinedAttribute = attribute * - (local:* ) { text }
undefinedContent = (text|anyForeignElement)*
anyElement = element * { (attribute * { text } | text | anyElement)* }
anyForeignElement = element * - os:* { (attribute * { text } | text | anyElement)* }
 
 
# EOF

B.4     OpenSearch Query Element Schema (schemas/opensearch/1.1/osquery.rnc)

# -*- rnc -*-
   # RELAX NG Compact Syntax Grammar for
   # OpenSearch Query element
 
namespace os = "http://a9.com/-/spec/opensearch/1.1/"
namespace s = "http://purl.oclc.org/dsdl/schematron"
namespace local = ""
 
osQueryAttr = attribute role { osQueryRoleValues },
     attribute title { xsd:string { maxLength="256"}}?, attribute searchTerms { text }?,
     attribute totalResults { xsd:int }?, attribute count { text }?,
     attribute startIndex { text }?, attribute startPage { text }?,
     attribute inputEncoding { text }?, attribute outputEncoding { text }?,
        attribute language { text }?
   
osQueryRoleValues = "request" | "example" | "related" | "correction" | "subset" | "superset"  
 
# EOF

B.5     GeoRSS Schema (schemas/georss/1.1/georss.rnc)

# -*- rnc -*-
   # RELAX NG Compact Syntax Grammar for the GEORSS
   # This defines the conformance to the rules of GEORSS
  
namespace georss="http://www.georss.org/georss"
namespace gml="http://www.opengis.net/gml"
namespace local = ""
 
georssElement = ( georssSimple | georssWhere)
     
georssWhere = element georss:where { gmlAttribute*, gmlElement }
 
georssSimple = georssPoint | georssLine | georssPolygon | georssBox | georssCircle
               | georssFeatureTypeTag | georssFeatureName | georssElev | georssFloor
 
georssPoint = element georss:point { list { xsd:decimal, xsd:decimal } }
georssLine = element georss:line { list { (xsd:decimal, xsd:decimal)+ } }
georssPolygon = element georss:polygon { list { (xsd:decimal, xsd:decimal)+ }  }
georssBox = element georss:box {
      list { (xsd:decimal, xsd:decimal, xsd:decimal, xsd:decimal) } }
georssCircle = element georss:circle { 
      list { (xsd:decimal, xsd:decimal, xsd:decimal) } }
georssFeatureTypeTag = element georss:featureTypeTag { text }
georssRelationshipTag = element georss:relationshipTag { text }
georssFeatureName = element georss:featureName { text }
georssElev = element georss:elev {xsd:decimal}
georssFloor = element georss:floor {xsd:decimal}
georssRadius = element georss:radius {xsd:decimal}
            
gmlAttribute = attribute (xml:base | xml:lang | local:* | gml:* ) { text }
  
gmlElement = (gmlPointElement | gmlLineStringElement |
                    gmlPolygonElement | gmlEnvelopeElement )
     
gmlPointElement =
      element gml:Point { gmlAttribute*,
        element gml:pos  { gmlAttribute*, list { xsd:decimal, xsd:decimal }}}
  
gmlLineStringElement = element gml:LineString { gmlAttribute*,
      element gml:posList  {gmlAttribute*, list { (xsd:decimal, xsd:decimal)+ }}}
            
gmlPolygonElement = element gml:Polygon { gmlAttribute*,
        element gml:exterior  { gmlAttribute*,
          element gml:LinearRing { gmlAttribute*,
            element gml:posList  { gmlAttribute*,
                                   list { (xsd:decimal, xsd:decimal)+ }}}}}
     
gmlEnvelopeElement = element  gml:Envelope { gmlAttribute*,
           (  element gml:lowerCorner { gmlAttribute*, 
                                        list { xsd:decimal, xsd:decimal } }
             & element gml:upperCorner { gmlAttribute*,
                                        list { xsd:decimal, xsd:decimal } }) }
            
# EOF

B.6     Earth Observation Extension Description Document Schema (schemas/opensearch/extensions/eo/1.0/osddeo.rnc)

# -*- rnc -*-
   # RELAX NG Compact Syntax Grammar for OpenSearch Description Documents
   # as defined in OGC 13-026 
namespace s = "http://purl.oclc.org/dsdl/schematron"
namespace local = ""
namespace os = "http://a9.com/-/spec/opensearch/1.1/"
namespace time = "http://a9.com/-/opensearch/extensions/time/1.0/"
namespace geo = "http://a9.com/-/opensearch/extensions/geo/1.0/"
namespace eo = "http://a9.com/-/opensearch/extensions/eo/1.0/"
 
include "eo.rnc"
 
# Redefine the foreign attribute to exclude eo:* elements
# relative path schemas/opensearch/1.1/ folder
include "../../../1.1/osdd.rnc"{
     undefinedAttribute = attribute * - (local:* | eo:* ) { text }
 
        osDocument = [
s:pattern [ name="check Atom template"
 s:rule [ context = "os:OpenSearchDescription"
              s:assert [ test = "os:Url[@type=’application/atom+xml’]"
               "An OpenSearch Description Document must have a Url template with"
               ~ " type of Atom document." ]]]]
              element os:OpenSearchDescription { osDocumentConstruct }
}
 
#EOF

B.7     Earth Observation Extension Query Element Schema (schemas/opensearch/extensions/eo/1.0/eo.rnc)

# -*- rnc -*-
   # RELAX NG Compact Syntax Grammar
   # OpenSearch Query Element as defined in OGC 13-026 for the eo extension
 
namespace eo = "http://a9.com/-/opensearch/extensions/eo/1.0/"
 
 # from Table 3
 osQueryAttr &=
      attribute eo:productType { text }?
    & attribute eo:doi { text }?
    & attribute eo:platform { text }?
    & attribute eo:platformSerialIdentifier { text }?
    & attribute eo:instrument { text }?
    & attribute eo:sensorType  { text }?
    & attribute eo:compositeType { text }?
    & attribute eo:processingLevel { text }?
    & attribute eo:orbitType { text }?
    & attribute eo:spectralRange { text }?
    & attribute eo:wavelength {intValueOrSetOrRange }?
    & attribute eo:hasSecurityConstraints { text }?
    & attribute eo:dissemination { text }?
    & attribute sru:recordSchema { text }?
 
# from Table 4
osQueryAttr &=
    attribute eo:title  { text }?
    & attribute eo:topicCategory  { text }?
    & attribute eo:keyword  { text }?
    & attribute eo:abstract  { text }?
    & attribute eo:denominator { intValueOrSetOrRange }?
    & attribute eo:distanceValue { floatValueOrSetOrRange }?
    & attribute eo:distanceUOM { text }?
    & attribute eo:organisationName { text }?
    & attribute eo:organisationRole { text }?
    & attribute eo:publicationDate { dateValueOrSetOrRange }?
    & attribute eo:lineage { text }?
    & attribute eo:useLimitation { text }?
    & attribute eo:accessConstraint { text }?
    & attribute eo:otherConstraint { text }?
    & attribute eo:classification { text }?
    & attribute eo:language { text }?
    & attribute eo:specificationTitle { text }?
    & attribute eo:specificationDate { dateValueOrSetOrRange }?
    & attribute eo:specificationdateType { text }?
    & attribute eo:degree { text }?
 
# from Table 5
osQueryAttr &=
    attribute eo:parentIdentifier { text }?
  & attribute eo:productionStatus { text }?
  & attribute eo:acquisitionType { text }?
  & attribute eo:orbitNumber { intValueOrSetOrRange }?
  & attribute eo:orbitDirection { orbitDirection }?
  & attribute eo:track { text }?
  & attribute eo:frame { text }?
  & attribute eo:swathIdentifier { text }?
  & attribute eo:cloudCover { intValueOrSetOrRange }?
  & attribute eo:snowCover { intValueOrSetOrRange }?
  & attribute eo:lowestLocation { floatValueOrSetOrRange }? 
  & attribute eo:highestLocation { floatValueOrSetOrRange }? 
  & attribute eo:productVersion { text }?
  & attribute eo:productQualityStatus { text }?
  & attribute eo:productQualityDegradationTag { text }?
  & attribute eo:processorName { text }?
  & attribute eo:processingCenter { text }?
  & attribute eo:creationDate { dateValueOrSetOrRange }?
  & attribute eo:modificationDate { dateValueOrSetOrRange }?
 
  & attribute eo:processingDate { dateValueOrSetOrRange }?
  & attribute eo:sensorMode  { text }?
  & attribute eo:archivingCenter { text }?
  & attribute eo:processingMode { text }?
 
 
# from Table 6
 
osQueryAttr &=
attribute eo:availabilityTime
& attribute eo:acquisitionStation { text }?
& attribute eo:acquisitionSubType { text }?
& attribute eo:startTimeFromAscendingNode { intValueOrSetOrRange }?
& attribute eo:completionTimeFromAscendingNode { intValueOrSetOrRange }?
& attribute eo:illuminationAzimuthAngle { floatValueOrSetOrRange }?
& attribute eo:illuminationZenithAngle { floatValueOrSetOrRange }?
& attribute eo:illuminationElevationAngle { floatValueOrSetOrRange }?
& attribute eo:polarisationMode { polarisationMode }?
& attribute eo:polarizationChannels { text }?
& attribute eo:antennaLookDirection { antennaLookDirection }?
& attribute eo:minimumIncidenceAngle { floatValueOrSetOrRange }?
& attribute eo:maximumIncidenceAngle { floatValueOrSetOrRange }?
& attribute eo:dopplerFrequency { floatValueOrSetOrRange }?
& attribute eo:incidenceAngleVariation { floatValueOrSetOrRange }?
 
 
polarisationMode = "S" | "D" | "T" | "Q" | "UNDEFINED"
antennaLookDirection = "LEFT" | "RIGHT"
orbitDirection = "DESCENDING" | "ASCENDING"
 
# Ranges value|\{value(,value)*\}|[\]\[\(\)]value,value[\]\[\(\)]
 
intValueOrSetOrRange = xsd:string { pattern ="[\+\-]?[\d]*|\{[\+\-]?[\d]*(,[\d]*)*\}|[\]\[\(\)]?[\+\-]?[\d]*,[\+\-]?[\d]*[\]\[\(\)]?" }
 
floatValueOrSetOrRange = xsd:string { pattern ="[\+\-]?[\d]*(.[\d]+)?|\{[\+\-]?[\d]*(.[\d]+)?(,[\+\-]?[\d]*(.[\d]+)?)*\}|[\]\[\(\)]?[\+\-]?[\d]*(.[\d]+)?,[\+\-]?[\d]*(.[\d]+)?[\]\[\(\)]?" }
 
dateValueOrSetOrRange = xsd:string { pattern="[0-9]{4}-[0-9]{2}-[0-9]{2}(T[0-9]{2}:[0-9]{2}:[0-9]{2}(\.[0-9]+)?(Z|[\+\-][0-9]{2}:[0-9]{2}))?|\{[0-9]{4}-[0-9]{2}-[0-9]{2}(T[0-9]{2}:[0-9]{2}:[0-9]{2}(\.[0-9]+)?(Z|[\+\-][0-9]{2}:[0-9]{2}))?(,[0-9]{4}-[0-9]{2}-[0-9]{2}(T[0-9]{2}:[0-9]{2}:[0-9]{2}(\.[0-9]+)?(Z|[\+\-][0-9]{2}:[0-9]{2}))?)*\}|[\]\[\(\)][0-9]{4}-[0-9]{2}-[0-9]{2}(T[0-9]{2}:[0-9]{2}:[0-9]{2}(\.[0-9]+)?(Z|[\+\-][0-9]{2}:[0-9]{2}))?,[0-9]{4}-[0-9]{2}-[0-9]{2}(T[0-9]{2}:[0-9]{2}:[0-9]{2}(\.[0-9]+)?(Z|[\+\-][0-9]{2}:[0-9]{2}))?[\]\[\(\)]"}
 

B.8     Earth Observation Extension Atom Response Schema (schemas/opensearch/extenstions/eo/1.0/atomeo.rnc)

# -*- rnc -*-
   # RELAX NG Compact Syntax Grammar for Atom encoding and foreign elements
   # as defined in OGC 13-026 for the eo extension
  
namespace s = "http://purl.oclc.org/dsdl/schematron"
namespace atom = "http://www.w3.org/2005/Atom"
namespace os = "http://a9.com/-/spec/opensearch/1.1/"
namespace eo = "http://a9.com/-/opensearch/extensions/eo/1.0/"
namespace eop = "http://www.opengis.net/eop/2.1"
namespace opt = "http://www.opengis.net/opt/2.1"
namespace sar = "http://www.opengis.net/sar/2.1"
namespace atm = "http://www.opengis.net/atm/2.1"
namespace alt = "http://www.opengis.net/alt/2.1"
namespace lmb = "http://www.opengis.net/lmb/2.1"
namespace ssp = "http://www.opengis.net/ssp/2.1"
namespace local = ""
 
# Redefine atom:entry to include the EO elements  defined in OGC 10-157r4
atomEntryConstruct &= eopElements ?
eopElements =  eopElement | optElement | sarElement | atmElement | altElement
               | lmgElement | sspElement
eopElement = element eop:EarthObservation { anyChildren }
optElement = element opt:EarthObservation { anyChildren }
sarElement = element sar:EarthObservation { anyChildren }
atmElement = element atm:EarthObservation { anyChildren }
altElement = element alt:EarthObservation { anyChildren }
lmgElement = element lmb:EarthObservation { anyChildren }
sspElement = element ssp:EarthObservation { anyChildren }
 
anyChildren =  undefinedAttribute*, extensionElement*
 
include "eo.rnc"
 
# Replacing definitions on RFC4287 plus OpenSearch
# relative path schemas/opensearch/1.1/ folder
include "../../../1.1/osatom.rnc"{
      undefinedAttribute = attribute * - (xml:base | xml:lang | local:* | eo:* ) { text }
# Redefine the Simple Extension to exclude owc:* elements
      simpleExtensionElement = element * -
          (atom:* | os:* | eop:EarthObservation| opt:EarthObservation |
           sar:EarthObservation | atm:EarthObservation | alt:EarthObservation |
           lmb:EarthObservation | ssp:EarthObservation) { text }
 
      # Redefine the Structured Extension to exclude owc:* elements
      structuredExtensionElement = element * -
          (atom:* |  eop:EarthObservation | opt:EarthObservation | sar:EarthObservation |
           atm:EarthObservation | alt:EarthObservation | lmb:EarthObservation |
           ssp:EarthObservation | os:* ) {
             (attribute * { text }+,(text|anyElement)*)
           | (attribute * { text }*, (text?, anyElement+, (text|anyElement)*))}
 
      # Redefine Atom rules   
      atomFeed = element atom:feed { atomFeedConstruct }    
      atomEntry =element atom:entry { atomEntryConstruct }
}
# EOF

B.9     Parameter Extension Query Element Schema (schemas/opensearch/extensions/parameter/1.0/parameter.rnc)

# -*- rnc -*-
# RELAX NG Compact Syntax Grammar for
# OpenSearch Description Parameter Extension
namespace s = "http://purl.oclc.org/dsdl/schematron"
namespace local = ""
namespace os = "http://a9.com/-/spec/opensearch/1.1/"
namespace param = "http://a9.com/-/opensearch/extensions/param/1.0/"
 
parameterConstruct =  attribute name { xsd:token }?,
                                      attribute value { xsd:token }?,
                                      attribute minimum { xsd:unsignedInt }?,
                                      attribute maximum { xsd:unsignedInt }?,
                                      attribute pattern { text }?,
                                      attribute title {  xsd:string { maxLength = "1024" } }?,
                                      attribute minExclusive { xsd:decimal | xsd:dateTime }?,
                                      attribute maxExclusive { xsd:decimal | xsd:dateTime }?,
                                      attribute minInclusive { xsd:decimal | xsd:dateTime }?,
                                      attribute maxInclusive { xsd:decimal | xsd:dateTime }?,
                                      attribute step { xsd:decimal }?,
                                      undefinedAttribute*,
                                      element param:Option { paramOption }*
 
paramMethod = "OPTIONS" | "GET" | "HEAD" | "POST" | "PUT" | "DELETE" | "TRACE" | "CONNECT"
 
paramOption = attribute value { xsd:string },
               attribute label { xsd:string }, undefinedAttribute*
 
paramUrl = attribute param:method { paramMethod }?
            & attribute param:enctype {  xsd:string { pattern = ".+/.+" } }?
             &  element param:Parameter { parameterConstruct } *
 
#extend the Url definition here
osdUrl &= paramUrl
         
# Redefine the foreign attribute to exclude param:* elements
# relative path schemas/opensearch/1.1/ folder
include "../../../1.1/osdd.rnc"{
              # Simple Extension
              simpleExtensionElement = element * - ( os:* | param:* ){ text }
              # Structured Extension
              structuredExtensionElement = element * - ( os:*  | param:* ) {
                       (attribute * { text }+, (text|anyElement)*)
                     | (attribute * { text }*, (text?, anyElement+, (text|anyElement)*))}
             
              # Other Extensibility
              undefinedAttribute = attribute * - ( local:* | param:* ) { text }
              anyForeignElement = element * - ( os:*  | param:* ) { (attribute * { text } | text | anyElement)* }
                     
           osDocument = [ s:rule [ context = "os:OpenSearchDescription"
              s:assert [ test = "os:Url/param:Parameter"
               "This URL template does not contain a Parameter element." ]]]
              element os:OpenSearchDescription { osDocumentConstruct }
}
# EOF

Annex C (informative): Example XML Documents

C.1 OpenSearch Description with Earth Observation Extension

<?xml version="1.0" encoding="UTF-8"?>
<OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/"
xmlns:eo="http://a9.com/-/opensearch/extensions/eo/1.0/"
xmlns:param="http://a9.com/-/opensearch/extensions/param/1.0/"
xmlns:time="http://a9.com/-/opensearch/extensions/time/1.0/"
xmlns:geo="http://a9.com/-/opensearch/extensions/geo/1.0/">
 
<ShortName>Web Search</ShortName>
<LongName>Example.com Web Search</LongName>
<Description>Use Example.com to search the Web.</Description>
<Tags>example web</Tags>
<Contact>admin@example.com</Contact>
<Url type="application/atom+xml" template="http://example.com/myatom/?pw={startPage?}&amp;acq={eo:acquisitionStation?}&amp;bbox={geo:box?}&amp;start={time:start?}&amp;end={time:end?}">
 
   <param:Parameter name="start" value="{time:start}" minimum="0"
      minInclusive="2011-01-01T00:00:00Z" maxExclusive="2012-01-01T00:00:00Z"/>
 
   <param:Parameter name="end" value="{time:end}" minimum="0"
      minInclusive="2011-01-01T00:00:00Z" maxExclusive="2012-01-01T00:00:00Z"/>
 
   <param:Parameter name="acq" value="{eo:acquisitionStation}" minimum="0"
      title="Acquisition Station">
     <param:Option value="PDHS-K" label="Kiruna"/>
     <param:Option value="PDHS-E" label="ESRIN" />
   </param:Parameter>
</Url>
<Attribution>Copyright 2005, Example.com, Inc.</Attribution>
<SyndicationRight>open</SyndicationRight>
 
</OpenSearchDescription>

C.2      Atom Output of Earth Observation Metadata

<?xml version="1.0" encoding="utf-8"?>
<feed xml:lang="en" xmlns="http://www.w3.org/2005/Atom" xmlns:time="http://a9.com/-/opensearch/extensions/time/1.0/"
xmlns:os="http://a9.com/-/spec/opensearch/1.1/" xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:georss="http://www.georss.org/georss" xmlns:gml="http://www.opengis.net/gml"
xmlns:geo="http://a9.com/-/opensearch/extensions/geo/1.0/" >
  <title>Catalogue Search Feed for ASAR Image Mode source packets Level 0 (ASA_IM__0P)</title>
  <subtitle type="html">The ASAR Image Mode source packets Level 0 data product offers Level 0 data for possible images processing on an other processing site. It includes some mandatory information for SAR processing. The Image Mode Level 0 product consists of time-ordered Annotated Instrument Source Packets (AISPs) collected while the instrument is in Image Mode. The echo samples contained in the AISPs are compressed to 4 bits/sample using Flexible Block Adaptive Quantisation (FBAQ). This is a high-rate, narrow swath mode so data is only acquired for partial orbit segments and may be from one of seven possible image swaths. The Level 0 product is produced systematically for all data acquired within this mode. This product provides a continuation of the ERS-SAR_RAW product.</subtitle>
  <generator uri="http://www.terradue.com" version="1.4.0">Terradue CAS</generator>
  <updated>2013-03-24T17:54:40Z</updated>
  <id>http://eo-virtual-archive4.esa.int/search/ASA_IM__0P/atom/</id>
  <link rel="self" type="application/atom+xml" href="http://eo-virtual-archive4.esa.int/search/ASA_IM__0P/atom//?startIndex=0&amp;start=2010-01-01&amp;stop=2010-01-31&amp;bbox=125,39.9,132.7,43.5"/>
    <link rel="search" type="application/opensearchdescription+xml" href="http://eo-virtual-archive4.esa.int/search/ASA_IM__0P/description"/>
  <os:totalResults>1</os:totalResults>
  <os:startIndex>0</os:startIndex>
  <os:itemsPerPage>20</os:itemsPerPage>
  <os:Query role="request" startIndex="0" time:start="2010-01-01" time:end="2010-01-31" geo:box="125,39.9,132.7,43.5"/>
  <georss:where><gml:Polygon><gml:exterior><gml:LinearRing>
      <gml:posList>39.9 125 43.5 125 43.5 132.7 39.9 132.7 39.9 132.7</gml:posList>
  </gml:LinearRing></gml:exterior></gml:Polygon></georss:where>
    <author><name>GEOSS Supersites</name></author>
  <entry>
    <id>http://eo-virtual-archive4.esa.int/search/ASA_IM__0P/ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1/atom</id>
    <title>ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1</title>
    <dc:identifier>ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1</dc:identifier>
    <published>2012-03-06T00:10:33.000Z</published>
    <updated>2013-05-16T22:25:57.124Z</updated>
    <dc:date>2010-01-22T01:44:41.316Z/2010-01-22T01:44:57.596Z</dc:date>
    <georss:where><gml:Polygon><gml:exterior><gml:LinearRing><gml:posList srsDimension="2">42.2879 128.7535 42.4897 127.4932 41.4254 127.1936 41.2326 128.3991 42.2879 128.7535
    </gml:posList></gml:LinearRing></gml:exterior></gml:Polygon></georss:where>
    <link rel="alternate" type=" application/gml+xml;profile=http://www.opengis.net/spec/EOMPOM/1.1" title="EOMPOM 1.1 file" href="http://eo-virtual-archive4.esa.int/search/ASA_IM__0P/ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1/xml"/>
    <link rel="alternate" type="text/html" title="HTML page" href="http://eo-virtual-archive4.esa.int/search/ASA_IM__0P/ASA_IM__0CNPDE20100122_014441_ 000000162086_00146_41282_7918.N1/html"/>
    <link rel="via" type="application/rdf+xml" title="RDF metadata entry" href="http://eo-virtual-archive4.esa.int/search/ASA_IM__0P/ASA_IM__ 0CNPDE20100122_014441_000000162086_00146_41282_7918.N1/rdf"/>
    <link rel="enclosure" type="application/binary" length="157076059" title=" File ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1 in the N1 (ENVISAT) format" href="https://eo-virtual-archive4.esa.int/supersites/ASA_IM__ 0CNPDE20100122_014441_000000162086_00146_41282_7918.N1"/>
    <content type="html">
       &lt;ul&gt;    &lt;li&gt; &lt;b&gt;Date&lt;/b&gt;: 2010-01-22 &lt;br/&gt;
       (2010-01-22T01:44:41.316Z / 2010-01-22T01:44:57.596Z) &lt;/li&gt;
       &lt;li&gt; &lt;b&gt;Orbit Number&lt;/b&gt;: 41282 &lt;/li&gt;
       &lt;li&gt; &lt;b&gt;Processing Center&lt;/b&gt;: PDHS-E &lt;/li&gt;        
       &lt;li&gt; &lt;b&gt;Processing Date&lt;/b&gt;: 2010-01-22 &lt;/li&gt;
       &lt;br/&gt;
       &lt;a href="https://eo-virtual-archive4.esa.int/supersites/ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1"&gt;Product Download &lt;/a&gt;
       &lt;/ul&gt;
</content>
<eop:EarthObservation xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.opengis.net/opt/2.1 ../xsd/opt.xsd"
xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:gml="http://www.opengis.net/gml/3.2" xmlns:eop="http://www.opengis.net/eop/2.1" xmlns:swe="http://www.opengis.net/swe/1.0" xmlns:om="http://www.opengis.net/om/2.0"
    gml:id="eo_ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1">
    <om:phenomenonTime><gml:TimePeriod
gml:id="tp_ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1">
            <gml:beginPosition>2010-01-22T01:44:41.316Z</gml:beginPosition>
            <gml:endPosition>2010-01-22T01:44:57.596Z</gml:endPosition>
        </gml:TimePeriod></om:phenomenonTime><om:resultTime>
        <gml:TimeInstant
  gml:id="ad_ ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1">
            <gml:timePosition>2010-01-22T02:35:06.000Z</gml:timePosition>
        </gml:TimeInstant></om:resultTime>
    <om:procedure>
        <eop:EarthObservationEquipment
gml:id="eq_ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1">
            <eop:platform><eop:Platform><eop:shortName>ENVISAT</eop:shortName>
</eop:Platform></eop:platform>
            <eop:instrument><eop:Instrument><eop:shortName>ASAR</eop:shortName>
                </eop:Instrument>
            </eop:instrument>
            <eop:sensor><eop:Sensor><eop:sensorType>RADAR</eop:sensorType>
</eop:Sensor></eop:sensor>
        </eop:EarthObservationEquipment>
    </om:procedure>
    <om:observedProperty xlink:href="#params1"/>
    <om:featureOfInterest>
        <eop:Footprint gml:id="fp_ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1">
            <eop:multiExtentOf><gml:MultiSurface gml:id="ms_ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1" srsName="EPSG:4326"><gml:surfaceMember><gml:Polygon gml:id="p_ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1">
              <gml:exterior><gml:LinearRing>
                <gml:posList>42.2879 128.7535 42.4897 127.4932 41.4254 127.1936 41.2326 128.3991 42.2879 128.7535</gml:posList>
               </gml:LinearRing></gml:exterior></gml:Polygon>
           </gml:surfaceMember></gml:MultiSurface></eop:multiExtentOf>
        </eop:Footprint>
    </om:featureOfInterest>
    <om:result></om:result>
    <eop:metaDataProperty>
        <eop:EarthObservationMetaData>
           <eop:identifier> ASA_IM__0CNPDE20100122_014441_000000162086_00146_41282_7918.N1 </eop:identifier>
            <eop:acquisitionType>NOMINAL</eop:acquisitionType>
            <eop:productType>ASA_IM__0P</eop:productType>
            <eop:status>ARCHIVED</eop:status>
            <eop:downlinkedTo><eop:DownlinkInformation>
                    <eop:acquisitionStation>PDHS-E</eop:acquisitionStation>
            </eop:DownlinkInformation></eop:downlinkedTo>
            <eop:processing><eop:ProcessingInformation>
                    <eop:processingCenter>PDHS-E</eop:processingCenter>
            </eop:ProcessingInformation></eop:processing>
        </eop:EarthObservationMetaData>
    </eop:metaDataProperty>
</eop:EarthObservation>
 
</entry>
</feed>
 

C.3      Atom Output of Earth Observation Collection Metadata

<atom:feed xml:lang="en" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:gml="http://www.opengis.net/gml" xmlns:georss="http://www.georss.org/georss" xmlns:eop="http://a9.com/-/opensearch/extensions/eo/1.0/" xmlns:eum="http://a9.com/-/opensearch/extensions/eumetsat/1.0/" xmlns:time="http://a9.com/-/opensearch/extensions/time/1.0/" xmlns:geo="http://a9.com/-/opensearch/extensions/geo/1.0/" xmlns:opensearch="http://a9.com/-/spec/opensearch/1.1/" xmlns:kml="http://earth.google.com/kml/2.2">
       <atom:title>EUMETSAT Product Navigator COLOS Adaptor results feed</atom:title>
       <atom:subtitle type="html">Number of results: 58</atom:subtitle>
       <atom:id>http://46.51.189.235:80/atom</atom:id>
       <atom:generator version="2.1" uri="http://46.51.189.235:80">EUMETSAT Product Navigator</atom:generator>
       <atom:author>
              <atom:name>EUMETSAT</atom:name>
       </atom:author>
       <atom:category>climatologyMeteorologyAtmosphere</atom:category>
       <atom:contributor>con terra GmbH</atom:contributor>
       <atom:rights>Copyright</atom:rights>
       <atom:updated>2014-03-14T11:23:28Z</atom:updated>
       <atom:icon>http://46.51.189.235:80/soapServices/feed-icon-14x14.png</atom:icon>
       <atom:logo>http://46.51.189.235:80/soapServices/terraCatalog_feed.png</atom:logo>
       <opensearch:totalResults>58</opensearch:totalResults>
       <opensearch:startIndex>1</opensearch:startIndex>
       <opensearch:itemsPerPage>10</opensearch:itemsPerPage>
       <opensearch:Query role="request" searchTerms="wind" startIndex="1" count="1"/>
       <atom:link title="Product Navigator search" type="application/opensearchdescription+xml" href="http://46.51.189.235:80/soapServices/os-description.xml" rel="search"/>
       <atom:link title="Product Navigator search" type="application/opensearchdescription+xml" href="http://46.51.189.235:80/soapServices/os-description.xml" rel="up"/>
       <atom:link title="self" type="application/atom+xml" href="http://46.51.189.235:80/soapServices/OpenSearch?format=atom&amp;sI=1&amp;c=1&amp;q=wind" rel="self"/>
       <atom:link title="next" type="application/atom+xml" href="http://46.51.189.235:80/soapServices/OpenSearch?format=atom&amp;sI=1&amp;c=1&amp;q=wind&amp;pw=2" rel="next"/>
       <entry xml:lang="en" xmlns="http://www.w3.org/2005/Atom" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:eum="http://www.eumetsat.int/2008/gmi" xmlns:gmi="http://www.isotc211.org/2005/gmi">
              <title>ASCAT AHRPT - Metop</title>
              <category term="climatologyMeteorologyAtmosphere"/>
              <category term="Observation"/>
              <category term="Marine"/>
              <category term="Satellite_Data"/>
              <category term="Sea_Ice"/>
              <id>EO:EUM:DAT:METOP:ASCATAHRPT</id>
              <dc:identifier>EO:EUM:DAT:METOP:ASCATAHRPT</dc:identifier>
              <link href="http://46.51.189.235:80/soapServices/CSWStartup?service=CSW&amp;version=2.0.2&amp;request=GetRecordById&amp;outputSchema=http://www.isotc211.org/2005/gmi&amp;Id=EO:EUM:DAT:METOP:ASCATAHRPT" rel="alternate" type="application/vnd.iso.19139+xml"/>
              <link href="http://46.51.189.235:80/discovery/Start/DirectSearch/DetailResult.do?f(r0)=EO:EUM:DAT:METOP:ASCATAHRPT" rel="alternate" title="ASCAT AHRPT - Metop" type="text/html"/>
              <generator uri="http://navigator.eumatsat.int" version="2.1">EUMETSAT Product Navigator</generator>
              <author>
                      <name>EUMETSAT</name>
                      <email>ops@eumetsat.int</email>
              </author>
              <updated>2010-09-21</updated>
              <summary>The prime objective of the Advanced SCATterometer (ASCAT) is to measure wind speed and direction over the oceans, and the main operational application is the assimilation of ocean winds in NWP models. Other operational applications, based on the use of measurements of the backscattering coefficient, are sea ice edge detection and monitoring, monitoring sea ice, snow cover, soil moisture and land surface parameters.</summary>
              <georss:where>
                      <gml:Polygon srsName="urn:x-ogc:def:crs:EPSG:6.7:4326">
                             <gml:exterior>
                                    <gml:LinearRing>
                                           <gml:posList srsDimension="2">90.0 -180.0 -90.0 -180.0 -90.0 180.0 90.0 180.0 90.0 -180.0</gml:posList>
                                    </gml:LinearRing>
                             </gml:exterior>
                      </gml:Polygon>
              </georss:where>
              <rights>-</rights>
              <link href="http://www.eumetsat.int/Home/Main/Satellites/Metop/Services/SP_2010034162824650?l=en" rel="enclosure" title="Metop Direct Readout Service" type="text/html"/>
              <content type="html"><![CDATA[<a href="http://www.eumetsat.int/Home/Main/Satellites/Metop/Services/SP_2010034162824650?l=en">Metop Direct Readout Service</a>
       <br/>
      
       <a href="http://46.51.189.235:80/discovery/Start/DirectSearch/DetailResult.do?f(r0)=EO:EUM:DAT:METOP:ASCATAHRPT">Metadata (HTML)</a>
       <br/>
       <a href="http://46.51.189.235:80/soapServices/CSWStartup?service=CSW&version=2.0.2&request=GetRecordById&outputSchema=http://www.isotc211.org/2005/gmi&Id=EO:EUM:DAT:METOP:ASCATAHRPT">Metadata (ISO19139 XML)</a>
       <br/>
       <a href="http://46.51.189.235:80/soapServices/OpenSearch?format=atom&id=EO:EUM:DAT:METOP:ASCATAHRPT">ATOM</a>
       <br/>]]></content>
       </entry>
</atom:feed>
 

Annex D (informative): Metadata Mappings

D.1      Mapping for EO Metadata profile of Observations & Measurements

In the table below the informative mappings of the queryables for the Product Search to "Earth Observation Metadata profile of Observations & Measurements" (OGC 10-157r4) are defined.

D.2      ISO 19115 / ISO19115-2 Geographic information – Metadata

In the table below the informative mappings of the queryables for the Collection Search to ISO19115(-2)/ISO19139(-2) are defined.

The table also includes the mappings of the spatial and temporal parameters of the OpenSearch Geo- and Time-Extension to the appropriate XPath in ISO 19115 / ISO 19115-2.

D.3      Mapping for OGC CS Extension Package for ebRIM AP: EO Products

This mapping is based on information from "OGC Catalogue Services Standard 2.0 Extension Package for ebRIM Application Profile Earth Observation Products" (OGC 06-131r6).

D.4      Mapping for OGC CS Extension Package for ebRIM AP: I15

In the table below the informative mappings of the queryables for the Collection Search to the CSW ebRIM I15 Extension Package (OGC 13-084) are defined.

The table also includes the mapping of the spatial and temporal parameters of the OpenSearch Geo- and Time-Extension to the CSW ebRIM I15 Extension Package.

D.5      Mapping for OGC CS Extension Package for ebRIM AP: SensorML

In the table below the informative mappings of the queryables to "OGC Catalogue Services Specification 2.0 Extension Package for ebRIM Application Profile:  SensorML" (OGC 09-163) is defined.

D.6      Response Mapping: EOP O&M / EOP EP to ATOM

Response mapping for Atom encoding to the EO Metadata profile of O&M (OGC 10-157r4)

D.7      Response Mapping: ISO191(15|39)[-2] / I15 EP to ATOM

The following table defines the mappings from ISO191(15|39)[-2] and I15 EP (OGC 13-084) to ATOM response elements.

Annex E: Revision history

[1] www.opengeospatial.org/cite

[2] Including products of logical collections (e.g. containing items of different types, sensor, sensor mode, platforms)

[3] For the identifier see: https://www.loc.gov/standards/sru/recordSchemas/index.html

[4] Note: the official Atom.XSD file used by NASA CWICSmart conformance tests is stricter than this RELAX NG which allows more flexibility. See https://tools.oasis-open.org/version-control/browse/wsvn/cmis/trunk/SchemaProject/schema/ATOM.xsd

[5] Can be applied to gmd:MD_Metadata (ISO19139) and gmi:MI_Metadata (ISO19139-2)

[6] the semantic of atom:rights is not 100%: therefore other mappings (accessConstraints, otherConstraints, useConstratints, classification) may make sense.

[7] Note: it makes sense to provide a gml:Polygon/gml:exterior/gml:LinearRing/gml:posList entry as different clients are able to render this.

[8] An alternative (or in addition to this) is to include gmd:MD_Metadata into the ATOM response (see below).