Content Discovery

Searching for content is a functionality that is primarily supported by Coordinating Nodes, programmatically through the CN_read.search method, and through a web browser interface that connects through a user interface implemented by Mercury which utilizes a SOLR index to support search operations.

This document describes the properties of the SOLR index, how it is populated, and how it can be used to support programmatic search and introspection into the DataONE holdings.

The SOLR index is populated from content that is copied to Coordinating Nodes, that is System Metadata, Science Metadata and Resource Maps. Each index entry represents information about the information referenced by a single identifier (PID). For PIDs that refer to science data objects the index entry will be constructed from system metadata and zero or more resource maps that reference the object. If a PID identifies a science metadata object, the index entry will have fields populated with content extracted from the system metadata for the object, the science metadata document and zero or more resource maps that reference the science metadata. Similarly, if the PID identifies a resource map, then the index entry fields for that PID will be populated by the System Metadata and resource map values for that PID.

The general sequence for indexing content is illustrated in Figure 1 below.

The general process of indexing content involves retrieving a System Metadata document, parsing system metadata properties such as permission rules to generate a SOLR index document, then optionally adding to the document if the PID refers to a science metadata or resource map object. The general sequence of operations is outlined in Figure 1. If the PID refers to a resource map, then it is necessary to update the documents and isDocumentedBy properties of the Science Metadata and data objects that appear in the data package defined by the Resource Map.

../_images/index_sequence.png

A full list of index fields is provided in Table 4 below.

Querying the SOLR Index

The SOLR query syntax is based on the Lucene query syntax and adds a couple of extensions. The SOLR search index is exposed directly as a SOLR search service with the base url of:

http(s)://server.name/solr/

System Metadata Index Properties

The main goals for indexing system metadata include:

  1. Support access control rules for search results
  2. Support efficient discovery of objects by their properties

Table 1 provides a list of SOLR attributes that are populated by values taken from System Metadata.

Table 1. Elements derived from System Metadata and available for all objects. “Multi” fields may be populated with more than a single value per document (PID) indexed.

System
Attribute Type Multi? Content Origin
blockedReplicationMN string Yes Types.ReplicationPolicy.blockedMemberNode
checksum string No Types.SystemMetadata.checksum
checksumAlgorithm string No Types.Checksum.algorithm
dataUrl string No Resolve REST URL created from PID
datasource string No Types.SystemMetadata.originMemberNode
dateUploaded date No Types.SystemMetadata.dateUploaded
dateModified date No Types.SystemMetadata.dateSysMetadataModified
id string No Types.SystemMetadata.identifier
numberReplicas string No Types.replicationPolicy.numberReplicas
formatId string No Types.SystemMetadata.formatId
obsoletes string No Types.SystemMetadata.obsoletes
preferredReplicationMN string Yes Types.ReplicationPolicy.preferredMemberNode
replicationAllowed boolean No Types.ReplicationPolicy.replicationAllowed
rightsHolder string No SystemMetadata.rightsHolder
size long No Types.SystemMetadata.size
submitter string No Types.SystemMetadata.submitter
authoritativeMN string No Types.SystemMetadata.authoritativeMemberNode
replicaMN string Yes Types.Replica.replicationMemberNode
readPermission string Yes Types.AccessRule.subject where permission = read
writePermission string Yes Types.AccessRule.subject where permission = write
changePermission string Yes Types.AccessRule.subject where permission = changePermission
isPublic boolean No Public User

Populating Permission Fields

This process is fairly straight forward, and requires simply de-duping entries so that each of the permission fields contains a distinct list of subjects granted that permission. If the DataONE public user is present in the read permissions, then the isPublic field is set to True.

Example Queries

The following provide some example queries that may be issued directly against the SOLR index operating on the Coordinating Nodes. Note that search terms must be properly escaped for the SOLR query syntax, and additionally if submitted directly as part of a URL, must also be properly URL escaped.

  1. Index entries that match PID (should be at most one match):

    id:"PID"

    where PID = identifier of object being located

  2. Index entries with PID that starts with “some_prefix”:

    id:"some_prefix*"

  3. Index entries that match a particular format id:

    formatId:"format_a"

    where format_a = the formatId being located

  4. Entries with formatId matching “fmtid_1” or “fmtid_2”:

    formatId:"fmtid_1" || formatId:"fmtid_2"

  5. Entries with byte size less than or equal to 10000:

    size:[* TO 10000]

  6. Entries with byte size less than 10000:

    size:{* TO 10000}

  7. Objects modified before 09:56:04 on 2012-01-03 UTC:

    datemodified:{* TO 2012-01-03T09:56:04.000Z}

  8. Objects modified less than 10 minutes ago:

    datemodified:[NOW-10MINUTE TO *]

  9. Objects of a formatId equal to “format_a” and modified within one day:

    formatId:"format_a" AND datemodified:[NOW-1DAY TO *]

  10. Metadata associated with data objects of relevance to Photosynthesis:

    photosynthesis AND documents:[* TO *]

Properties of the Index Derived from Resource Maps

Table 2 provides a list of SOLR attributes that are populated by values obtained by parsing resource map objects.

Table 2. Elements derived from Resource Map documents. “Multi” fields may be populated with more than a single value per document (PID) indexed.

Resource
Attribute Type Multi? Content Origin
SearchMetadata.isDocumentedBy string Yes  
SearchMetadata.documents string Yes  
SearchMetadata.resourceMap string Yes  

Populating Object Relation Fields

The fields resourceMap, documents, and isDocumentedBy contain identifiers of other objects in the DataONE system related to the subject of the current record. These relationships are recorded in OAI-ORE resource map documents as described in the section Data Packaging. Since the values for these fields are contained in resource maps, it is necessary to build these fields in progression as additional resource maps are synchronized with the coordinating nodes.

For each object, a query is issued against the index to retrieve the list of resource maps in which the object identifier is present, enabling population of the resourceMaps field for the object. Each of those resource maps is examined to obtain the list of identifiers for the documents field if the object is science metadata, and the isDocumentedBy field if the object is data.

Example Sequence for Index Population

The following sequence steps through the generation of index entries for three data packages, providing an example of how the index entries are updated depending on relationships between the objects being added.

Adding Package 1

digraph RM1 { graph [rankdir="LR", label="Package 1"]; A [shape=folder]; B [shape=note]; C [shape=oval]; A -> B; A -> C; }

A simple data package with a Resource Map A indicating that the metadata document B and the data object C together form a data package, and that B documents C and that C isDocumentedBy B.

Index entries after Package 1 is added.

PID resourceMaps documents isDocumentedBy
A      
B A C  
C A   B

Adding Package 2

digraph RM1 { graph [rankdir="LR", label="Package 2"]; D [shape=folder]; B [shape=note]; E [shape=oval]; D -> B; D -> E; }

A simple data package with a Resource Map D indicating that the metadata document B and the data object E together form a data package, and that B documents E and that E isDocumentedBy B. Note that the metadata document B is also used in Package 1.

Index entries after package 2 is added. New entries and changes to existing are indicated in bold.

PID resourceMaps documents isDocumentedBy
A      
B A, D C, E  
C A   B
D      
E D   B

Adding Package 3

digraph RM1 { graph [rankdir="LR", label="Package 3"]; F [shape=folder]; G [shape=note]; D [shape=folder]; F -> G; F -> D; }

A data package that references another, already indexed data package (represented by the Resource Map D) as its data object.

Index entries after package 3 is added. New entries and changes to existing are indicated in bold.

PID resourceMaps documents isDocumentedBy
A      
B A, D C, E  
C A   B
D F   G
E D   B
F      
G F D  

Limitations of Multi-Valued Fields in SOLR

Multi-valued fields in SOLR have an internal representation that can be likened to a delimited concatenation of all the values for the field. The fields have a configurable limit to the maximum field size, and this limit may be encountered in the various entries such as the permission fields or object relation fields where a potentially large number of subjects or identifiers may be stored. Further research has indicated this problem is unlikely since simply increasing the SOLR maxFieldLength configuration value will enable larger field content, with examples in the wild of several thousand entries equivalent to DataONE identifiers in a single field.

Values Extracted from Science Metadata

Indexing the system metadata entries provides a mechanism for selection of content using low level attributes of the objects such as the type, size and relationships, however is not useful for locating content relevant to a particular topic or purpose. The science metadata contains such information and the index records associated with these documents contain additional information described below.

The initial web user interface to DataONE utilizes the Mercury system. This in turn relies upon a SOLR index to support the search, faceting, and sub-setting operations that are exposed through Mercury. The underlying SOLR index is also exposed through as an API, so other clients (such as the file system driver) can leverage the search capabilities thus provided.

The remainder of this document describes the search properties that are extracted from the various formats and syntaxes of of science metadata that are supported by the DataONE indexing system.

Table 3. Index fields populated from science metadata documents. “Multi” fields may be populated with more than a single value per document (PID) indexed.

Resource
Field Type Multi? Description
SearchMetadata.abstract text No The full text of the abstract as provided in the science metadata document.
SearchMetadata.author string No Principle Investigator (PI) / Author as listed in the metadata document.
SearchMetadata.authorLastName string Yes The LAST name(s) of the author(s)
SearchMetadata.beginDate date No The starting date of the temporal range of the content described by the metadata document.
SearchMetadata.class string Yes Taxonomic class name(s)
SearchMetadata.contactOrganization string No Name of the organization to contact for more information about the dataset
SearchMetadata.decade string No The latest decade that is covered by the dataset, expressed in the form “1999-2009”
SearchMetadata.eastBoundCoord sfloat No Eastern most longitude of the spatial extent, in decimal degrees, WGS84
SearchMetadata.edition text No The version or edition number of the item described.
SearchMetadata.endDate date No The ending date of the temporal range of the content described by the metadata document.
SearchMetadata.family string Yes Taxonomic family name(s)
SearchMetadata.fileID string No Contains the CNRead.resolve() URL for the object ONLY if the object is a science metadata object.
SearchMetadata.fullText text No Full text of the metadata record, used to support full text searches
SearchMetadata.gcmdKeyword text Yes Keywords drawn from the GCMD controlled vocabulary
SearchMetadata.genus string Yes Taxonomic genus name(s)
SearchMetadata.geoform string No The name of the general form in which the item’s geospatial data is presented
SearchMetadata.geohash_1 string Yes An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_2 string Yes An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_3 string Yes An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_4 string Yes An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_5 string Yes An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_6 string Yes An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_7 string Yes An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_8 string Yes An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_9 string Yes An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.investigator string Yes Name of the investigator(s) responsible for developing the dataset and associated content.
SearchMetadata.isSpatial string No Set to “Y” for records that contain spatial information
SearchMetadata.keywords string Yes Keywords recorded in the science metadata document. These may be controlled by the generator of the metadata or by the metadata standard of the document, but are effectively uncontrolled within the DataONE context.
SearchMetadata.kingdom string Yes Taxonomic kingdom(s)
SearchMetadata.LTERSite string No Data provider organization identifier, for sources within the LTER network.
SearchMetadata.noBoundingBox string No Set to “Y” if there is no bounding box information available (i.e., the east, west, north, south most coordinates)
SearchMetadata.northBoundCoord sfloat No Northern most latitude of the spatial extent, in decimal degrees, WGS84
SearchMetadata.ogcUrl text No URL for Open Geospatial Web service if available.
SearchMetadata.order string Yes Taxonomic order name(s)
SearchMetadata.origin string Yes Investigator or Investigator organization name.
SearchMetadata.originator string Yes Investigator or Investigator organization name. Derived by normalizing origin.
SearchMetadata.parameter string Yes A characteristic, or variable, that is measured or derived as part of data-collection activities.
SearchMetadata.phylum string Yes Taxonomic phylum (or division) name(s)
SearchMetadata.placeKey text Yes A place name keyword, assigned by the metadata creator. It is one keyword from the thesaurus named in <placekt>
SearchMetadata.presentationCat string No Type of data being preserved (maps, text, etc.)
SearchMetadata.project string No The authorized name of a research effort for which data is collected. This name is often reduced to a convenient abbreviation or acronym. All investigators involved in a project should use a common, agreed-upon name.
SearchMetadata.pubDate date No Publication date for the dataset (this may or may not be coincident with when the content is added to DataONE).
SearchMetadata.purpose text No The “Purpose” describes the “why” aspects of the data set (For example, why was the data set created?).
SearchMetadata.sensor string Yes Also called “instrument.” A device that is used for collecting data for a data set.
SearchMetadata.site string Yes The name or description of the physical location where the data were collected
SearchMetadata.source string Yes Also called “platform.” The mechanism used to support the sensor or instrument that gathers data
SearchMetadata.southBoundCoord sfloat No Southern most latitude of the spatial extent, in decimal degrees, WGS84
SearchMetadata.species string Yes Taxonomic species name(s)
SearchMetadata.term string Yes A secondary subject area within which parameters can be categorized. Approved terms include “agricultural chemicals” and “atmospheric chemistry,” among many others. When entering a term in the LandVal Metadata Editor, users should select a standard expression from the pick list for terms if at all possible.
SearchMetadata.title string No Title of the dataset as recorded in the science metadata.
SearchMetadata.topic string Yes The most general subject area within which a parameter is categorized. Approved topics include “agriculture,” “atmosphere,” and “hydrosphere,” among others.
SearchMetadata.webUrl string Yes Link to the investigator’s web-site.
SearchMetadata.westBoundCoord sfloat No Western most longitude of the spatial extent, in decimal degrees, WGS84
SearchMetadata.keyConcept string Yes Terms drawn from a controlled vocabulary of concepts that are applicable to the content described by the metadata document.
SearchMetadata.namedLocation string Yes The name of the location(s) relevant to the content described by the metadata document.
SearchMetadata.relatedOrganizations string Yes Organizations that played an indirect role in the development of the data set and metadata that should be cited or mentioned as contributing to the development of the data or metadata.
SearchMetadata.scientificName string Yes Taxonomic scientific name(s) at the most precise level available for the organisms of relevance to the dataset

Date Representations in Science Metadata Documents

The following are examples of date values extracted from FGDC, ISO-19115, and EML science metadata documents currently in use. The literal value appearing in the document and the interpreted date value are shown.

Examples of date values appearing in FGDC <pubdate>:

Value Interpreted Value
Unknown Null
unknown Null
Unpublished material Null
unpublished material Null
1993 1993-01-01 00:00:00Z
199607 1996-07-01 00:00:00Z
20000101 2000-01-01 00:00:00Z
19981231 1998-12-31 00:00:00Z
196820405 1968-01-01 00:00:00Z
1992 onwards 1992-01-01 00:00:00Z
1989 and 1990 1989-01-01 00:00:00Z
varies Null
Present Null
1995/1996 1995-01-01 00:00:00Z
1991-1992 1991-01-01 00:00:00Z
variouis Null
April 1999 1999-04-01 00:00:00Z
1980 on 1980-01-01 00:00:00Z
2005-06-24 2005-06-24 00:00:00Z
NA Null
1990- [unpublished annual reports] 1990-01-01 00:00:00Z
November, 1994 1994-11-01 00:00:00Z

Examples of date values appearing in ISO-19115 <gco:Date>:

Value Interpreted Value
1999 1999-01-01 00:00:00Z
2010-03-03 2010-03-03 00:00:00Z

Examples of date values appearing in EML <calendarDate>:

Value Interpreted Value
2002-06-20 2002-06-20 00:00:00Z
1998 1998-01-01 00:00:00Z
2004-02-13 2004-02-13 00:00:00Z

Attribute Descriptions and Notes

A list of all fields in search index, their origin and brief description. Source column indicates which DataONE content the values are retrieved from: Y = System Metadata, S = Science Metadata, R = Resource Map, and C = copied internally by the search index.

.
Index Field Multi? Source Description
SearchMetadata.abstract
 No S The full text of the abstract as provided in the science metadata document.
SearchMetadata.author
 No S Principle Investigator (PI) / Author as listed in the metadata document.
SearchMetadata.authoritativeMN
 No Y The node Id of the authoritative Member Node for the object.
SearchMetadata.authorLastName
 Yes S The LAST name(s) of the author(s)
SearchMetadata.beginDate
 No S The starting date of the temporal range of the content described by the metadata document.
SearchMetadata.blockedReplicationMN
 Yes Y A multi-valued field that contains the node Ids of member nodes that are blocked from holding replicas of this object.
SearchMetadata.changePermission
 Yes Y List of subjects (groups and individuals) that have change permission on PID.
SearchMetadata.checksum
 No Y The checksum for the object
SearchMetadata.checksumAlgorithm
 No Y Algorithm used for generating the object checksum
SearchMetadata.class
 Yes S Taxonomic class name(s)
SearchMetadata.contactOrganization
 No S Name of the organization to contact for more information about the dataset
SearchMetadata.contactOrganizationText
 No C Copy from contactOrganization
SearchMetadata.datasource
 No Y The node Id of the member node that originally contributed the content.
SearchMetadata.dataUrl
 No Y The URL that can be used to resolve the location of the object given its PID.
SearchMetadata.dateModified
 No Y The date and time when the object system metadata was last updated.
SearchMetadata.dateUploaded
 No Y The date and time when the object was uploaded to the Member Node.
SearchMetadata.decade
 No S The latest decade that is covered by the dataset, expressed in the form “1999-2009”
SearchMetadata.documents
 Yes R Lists all PIDs that this object describes. Obtained by parsing all resource maps in which this object is referenced. Not set for data or resource map objects.
SearchMetadata.eastBoundCoord
 No S Eastern most longitude of the spatial extent, in decimal degrees, WGS84
SearchMetadata.edition
 No S The version or edition number of the item described.
SearchMetadata.endDate
 No S The ending date of the temporal range of the content described by the metadata document.
SearchMetadata.family
 Yes S Taxonomic family name(s)
SearchMetadata.fileID
 No S Contains the CNRead.resolve() URL for the object ONLY if the object is a science metadata object.
SearchMetadata.formatId
 No Y The format identifier indicating the type of content this record refers to.
SearchMetadata.fullText
 No S Full text of the metadata record, used to support full text searches
SearchMetadata.gcmdKeyword
 Yes S Keywords drawn from the GCMD controlled vocabulary
SearchMetadata.genus
 Yes S Taxonomic genus name(s)
SearchMetadata.geoform
 No S The name of the general form in which the item’s geospatial data is presented
SearchMetadata.geohash_1
 Yes S An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_2
 Yes S An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_3
 Yes S An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_4
 Yes S An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_5
 Yes S An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_6
 Yes S An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_7
 Yes S An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_8
 Yes S An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.geohash_9
 Yes S An encoded string that represents the geographic coordinates of the centroid of a spatial extent. This can be used for searching and plotting.
SearchMetadata.id
 No Y The identifier of the object being indexed.
SearchMetadata.identifier
 No C Copy from id
SearchMetadata.investigator
 Yes S Name of the investigator(s) responsible for developing the dataset and associated content.
SearchMetadata.investigatorText
 Yes C Copy from investigator
SearchMetadata.isDocumentedBy
 Yes R Lists all PIDs that describe this object. Obtained by parsing all resource maps in which this object is referenced.
SearchMetadata.isPublic
 No Y Set to True if the DataONE public user is present in the list of subjects with readPermission on PID.
SearchMetadata.isSpatial
 No S Set to “Y” for records that contain spatial information
SearchMetadata.keyConcept
 Yes S Terms drawn from a controlled vocabulary of concepts that are applicable to the content described by the metadata document.
SearchMetadata.keywords
 Yes S Keywords recorded in the science metadata document. These may be controlled by the generator of the metadata or by the metadata standard of the document, but are effectively uncontrolled within the DataONE context.
SearchMetadata.keywordsText
 Yes C Copy from keywords
SearchMetadata.kingdom
 Yes S Taxonomic kingdom(s)
SearchMetadata.LTERSite
 No S Data provider organization identifier, for sources within the LTER network.
SearchMetadata.namedLocation
 Yes S The name of the location(s) relevant to the content described by the metadata document.
SearchMetadata.noBoundingBox
 No S Set to “Y” if there is no bounding box information available (i.e., the east, west, north, south most coordinates)
SearchMetadata.northBoundCoord
 No S Northern most latitude of the spatial extent, in decimal degrees, WGS84
SearchMetadata.numberReplicas
 No Y Requested number of replicas for the object
SearchMetadata.obsoletes
 No Y If set, indicates the object that this record obsoletes.
SearchMetadata.ogcUrl
 No S URL for Open Geospatial Web service if available.
SearchMetadata.order
 Yes S Taxonomic order name(s)
SearchMetadata.origin
 Yes S Investigator or Investigator organization name.
SearchMetadata.originator
 Yes S Investigator or Investigator organization name. Derived by normalizing origin.
SearchMetadata.originatorText
 Yes C Copy from originator
SearchMetadata.originText
 Yes C Copy from origin
SearchMetadata.parameter
 Yes S A characteristic, or variable, that is measured or derived as part of data-collection activities.
SearchMetadata.parameterText
 Yes C Copy from parameter
SearchMetadata.phylum
 Yes S Taxonomic phylum (or division) name(s)
SearchMetadata.placeKey
 Yes S A place name keyword, assigned by the metadata creator. It is one keyword from the thesaurus named in <placekt>
SearchMetadata.preferredReplicationMN
 Yes Y A list of member node identifiers that are preferred replication targets for this object.
SearchMetadata.presentationCat
 No S Type of data being preserved (maps, text, etc.)
SearchMetadata.project
 No S The authorized name of a research effort for which data is collected. This name is often reduced to a convenient abbreviation or acronym. All investigators involved in a project should use a common, agreed-upon name.
SearchMetadata.projectText
 No C Copy from project
SearchMetadata.pubDate
 No S Publication date for the dataset (this may or may not be coincident with when the content is added to DataONE).
SearchMetadata.purpose
 No S The “Purpose” describes the “why” aspects of the data set (For example, why was the data set created?).
SearchMetadata.readPermission
 Yes Y List of subjects (groups and individuals) that have read permission on PID.
SearchMetadata.relatedOrganizations
 Yes S Organizations that played an indirect role in the development of the data set and metadata that should be cited or mentioned as contributing to the development of the data or metadata.
SearchMetadata.replicaMN
 Yes Y One or more node Ids holding copies of the object.
SearchMetadata.replicationAllowed
 No Y True if this object can be replicated.
SearchMetadata.resourceMap
 Yes R List of resource map PIDs that reference this PID.
SearchMetadata.rightsHolder
 No Y The Subject that acts as the rights holder for the object.
SearchMetadata.scientificName
 Yes S Taxonomic scientific name(s) at the most precise level available for the organisms of relevance to the dataset
SearchMetadata.sensor
 Yes S Also called “instrument.” A device that is used for collecting data for a data set.
SearchMetadata.sensorText
 Yes C Copy from sensor
SearchMetadata.site
 Yes S The name or description of the physical location where the data were collected
SearchMetadata.siteText
 Yes C Copy from site
SearchMetadata.size
 No Y The size of the object, in bytes.
SearchMetadata.sku
 No C Copy from id
SearchMetadata.source
 Yes S Also called “platform.” The mechanism used to support the sensor or instrument that gathers data
SearchMetadata.sourceText
 Yes C Copy from source
SearchMetadata.southBoundCoord
 No S Southern most latitude of the spatial extent, in decimal degrees, WGS84
SearchMetadata.species
 Yes S Taxonomic species name(s)
SearchMetadata.submitter
 No Y The Subject name of the original submitter of the content to DataONE.
SearchMetadata.term
 Yes S A secondary subject area within which parameters can be categorized. Approved terms include “agricultural chemicals” and “atmospheric chemistry,” among many others. When entering a term in the LandVal Metadata Editor, users should select a standard expression from the pick list for terms if at all possible.
SearchMetadata.termText
 Yes C Copy from term
SearchMetadata.text
 Yes C contactOrganization, datasource, decade, features, fileID, fullText, gcmdKeyword, geoform, id, includes, investigator, keywords, LTERSite, manu, name, origin, originator, parameter, placeKey, presentationCat, project, purpose, sensor, site, source, term, title, topic
SearchMetadata.title
 No S Title of the dataset as recorded in the science metadata.
SearchMetadata.titlestr
 No C Copy from title
SearchMetadata.titleText
 No C Copy from title
SearchMetadata.topic
 Yes S The most general subject area within which a parameter is categorized. Approved topics include “agriculture,” “atmosphere,” and “hydrosphere,” among others.
SearchMetadata.topicText
 Yes C Copy from topic
SearchMetadata.updateDate
 No C Copy from dateuploaded
SearchMetadata.webUrl
 Yes S Link to the investigator’s web-site.
SearchMetadata.westBoundCoord
 No S Western most longitude of the spatial extent, in decimal degrees, WGS84
SearchMetadata.writePermission
 Yes Y List of subjects (groups and individuals) that have write permission on PID.

Creating Citations from Index Fields

Table 3. Cross reference of index fields and elements useful in citation best practices as exemplified in the interagency data stewardship wiki page of ESIP. * = Mandatory (if applicable). COinS tags provide a mechanism of embedding Z39.88-2004 elements in HTML for consumption by citation manager tools.

Citation Element FGDC CSDGM field DataCite Metadata Scheme ID and Property DataONE Index Field COinS Tag
Author or Creator* idinfo > citation > citeinfo > “origin” 2 Creator* author rft.creator
Release Date* idinfo > citation > citeinfo > “pubdate” and sometimes “othercit” 5 PublicationYear* datePublished rft.date
Title* idinfo > citation > citeinfo > “title” and possibly “edition” 3 Title* title rft.title
Version*   15 Version See notes below.  
Archive and/or Distributor* idinfo > citation > citeinfo > “publish” 4 Publisher* See notes below. rft.publisher
Locator, Identifier, or Distribution Medium* idinfo > citation > citeinfo > “othercit” or “onlink” 1 Identifier* pid rft.identifier
Access Date and Time* not applicable 8 Date perhaps dateUploaded  
Subset Used not applicable 12 RelatedIdentifier DataCite recommends obtaining an identifier for any subset that needs to be cited as well as an identifier for the larger whole. perhaps a reference to the resource map?  
Editor or Other Important Role idinfo > citation > citeinfo > “origin” 7 Contributor See notes below. rft.source
Publication Place idinfo > citation > citeinfo > “pubplace” 17 Description See notes below.  
Distributor, Associate Archive, or other Institutional Role idinfo > citation > citeinfo > “othercit” 7 Contributor or possibly 4 Publisher “http://dataone.org“  
Data Within a Larger Work idinfo > citation > citeinfo > “othercit” or “lworkcit” 12 RelatedIdentifier perhaps a reference to the resource map?  
      keyWord rft.subject
      abstract rft.description
      object format name, or “data” | “metadata” | “resource map” rft.type
      object format type rft.format
      constructed from bounding box rft.coverage

Notes

Version:There is no clear recommendation on how to express version. For an object with a linear revision history (A is obsoleted by B is obsoleted by C), object C might be considered to have a version of “2”. However, it is possible for an object to have a tree lineage (A1 and A2 are obsoleted by B1, and B1, A3 and Z are obsoleted by C). A suggestion for a version indicator in this case may be the total number of parent objects, 5 in this case. Another option may be to indicate the number of contributing objects at each revision, 1.1 in the first case, and 2.3 in the second.
Publisher:The publisher in DataONE may in some cases be the origin member node, however this will not always be the case. For example, many data sets in the KNB are published by LTER, though KNB would be the member node. Where possible the publisher information should be pulled from the science metadata, though this may be complicated where multiple data and metadata entries occur within a data package and there are several publishers listed. In this case, a simple concatenation of the publishers (semi-colon + space delimited) may be sufficient.
Date:In the DataCite 2.2 document, a mapping between Date and the dcterms:date is suggested. The description of dcterms:date is “A point or period of time associated with an event in the lifecycle of the resource.” In DataONE there are two main dates related to an object, when the content is added to the system, and when the properties of the object (access control, and so forth) are modified. Since the content of the object does not change once submitted to DataONE, the SystemMetadata.dateUploaded value seems appropriate here, expressed as dateUploaded in the search index.
Subset Used:DataONE does not provide a mechanism for identifying sets of information other than through resource maps which describe data packages. It is possible that a resource map may contain references to additional resource maps, conceptually equivalent to subsets of content. The simplest option here would be to use the identifier of the resource map object describing the package in question.
Contributor:Described in DataCite 2.2 as “The institution or person responsible for collecting, creating, or otherwise contributing to the development of the dataset”, this optional element can be populated by the citeinfo/origin element from FGDC.
Publication Place:
 In CSDGM, “the name of the city (and state or province, and country, if needed to identify the city) where the data set was published or released”.
Data Within a Larger Work:
 This is similar to the “Subset Used” entry except in the other direction of containment. The identifier of the containing resource map relevant to the current package should be used.

This material is based upon work supported by the National Science Foundation under Grant Numbers 083094 and 1430508.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.