United States Geoscience Information Network
Glossary
This page defines terms as they are used within the context of the United States Geoscience Information Network (USGIN). Instanced terms that are used only in a specialized context (such as a specific tutorial or a specific State Geothermal Data content model) are not defined here, but are instead defined within the specific instance. Likewise, geoscience vocabulary is not defined here.
ArcGIS
Proprietary geographic information system (GIS) software created by ESRI.
Attribute (GIS)
Within the context of geographic information systems, an attribute describes a feature. For example: attributes of a fault feature might include the latitude and longitude coordinates for each fault, as well as the fault's age, dip, and slip. Attributes can be expressed in elements in a markup language document or in database fields in a database.
Attribute (Markup Language)
Within the context of a markup language, attributes modify markup language tags, like so:
- <tag attribute="value" />
For more information, see the markup language Element entry in this glossary. For a much more detailed overview of attributes, see the USGIN XML Tutorial.
Binding
An explicit logical association between any two things. For example, a binding can exist between two resources; a binding can also exist between a location and the resource found there.
Content Model
Within the context of USGIN and the State Geothermal Data (SGD) project, content models are Excel workbooks which contain template spreadsheets. Content models provide a model for SGD schemas that are designed to facilitate interoperability. Any data submitted for the State Geothermal Data project by Arizona Geological Survey subrecipients must be formatted according to the State Geothermal Data project content models.
Data
Data describes something in the real world. In the USGIN framework, data often describes a resource. Though the terms data and information are often used interchangeably, it should be noted that data technically indicates raw observations; information is interpreted observations. A discrete cluster of related data is known as a dataset.
Data Consumer
Any USGIN user who browses, discovers, downloads, accesses, and explores USGIN data is a data consumer. USGIN data consumers who host or submit data according to USGIN specifications may also be USGIN data providers.
Data Provider
Any USGIN user who submits, hosts, serves, or otherwise produces USGIN data according to USGIN specifications is a USGIN data provider. USGIN data providers who access or explore USGIN data can also be USGIN data consumers.
Database
A method of storing data. In a database, data is divided up into database records; in turn, database records are divided up into database fields. The advantage of a database is that it can be sorted and searched by field contents. Though modern databases are usually digital, a physical example of a database is a card catalog in a public library. In a card catalog, data is divided up into individual cards, which are directly analagous to database records. Each card (record) in the catalog corresponds with and describes a book (in this case, books constitute resources). The information about each book is divided up into fields: title; authoer; subject; publication date; etc. Digital databases can be in tabular format (that is, a table) in which rows represent individual records and columns constitute fields; or they can be viewed record-by-record.
Database Field
A subdivision of a database record in which a specific type of data is entered. Using the analogy of a card catalog in a public library: if the card catalog is directly analagous to a database, and if the cards in the catalog are directly analagous to database records, then the different subdivisions of information found in each card in the catalog (title, author, publishing date, etc.) are all database fields.
Database fields are functionally similar to markup language elements.
Database Key
A database field designed to contain values that are used to organize and maintain the uniqueness of records within a database. Database keys can be used to identify records in such way that they can be referenced by other databases. Database keys allow databases to refer to records in other databases.
Database Record
A subdivision of a database. Using the analogy of a card catalog in a public library, each record in a database is analogous to an index card in the card catalog; each card (record) corresponds with and describes an individual book. Database records are further subdivided into fields, which contain specific kinds of data.
Dataset
A discrete cluster of related data. For example: data regarding all oil and gas wells in the state of Arizona would constitute a dataset.
Dereference
Verb. To display the data associated with a reference. Dereferencing usually takes place in a web browser.
Element
Elements are logical document components found in markup languages such as XML and HTML. Elements simultaneously define the structure and content of a document; they are constituted by two markup language tags and the content between the two. For example:
- <tag>content</tag>
The two tags and their content form an element. In a more concrete example, HTML uses the <i> tag to demarcate text that should be Italicized. So, an Italicized element of an HTML document would appear as follows:
- <i>Italicized content</i>
In a web browser, this element would produce the following result:
- Italicized content
Markup language elements are functionally similar to database fields.
For a much more detailed overview of elements, see the USGIN XML Tutorial.
Feature
The word feature may be used to indicate geologic feature, such as a fault, formation, or dike. Alternatively, a feature can be a GIS representation of a real-world object on a map. GIS features do not always correspond with geologic features because GIS software can be used to represent anthropogenic objects such as buildings, roads, or canals. The definition of the term feature therefore depends on its context: it can be used to mean either a geologic feature or an GIS feature.
GIS features are often described by attributes.
Feature Class
A feature class can be either a method of storing GIS features of the same geometry type within a geodatabase, or it can be discretionary or subjective grouping of homogenous GIS features. For example, "highways, primary roads, and secondary roads can be grouped into a line feature class named also" (Source: Wade, Tasha and Shell.y Sommer. A to Z GIS. Redlands, CA. ESRI Press. 2006)
Field (Database)
See Database Field.
Geographic Information Systems (GIS)
A system designed to capture, store, manipulate, analyze, manage, and present all types of geographically referenced data (Source: "Geographic Information Systems as an Integrating Technology: Context, Concepts, and Definitions")
HTML
HTML stands for Hypertext Markup Language. HTML is the predominant language in which web pages are written.
HTTP
HTTP stands for Hypertext Transfer Protocol. HTTP is the networking protocol that is used to transfer information over the World Wide Web.
Identifier
An identifier is used to distinguish one thing from another. For example, names are identifiers: a person's name is used to distinguish one person from another. A URI identifies a resource and distinguishes one resource from another.
Note: an identifier can identify a resource without being a URI. To be a URI, an identifier must conform to URI syntax.
Interoperability
The capability to communicate, execute programs, or transfer data among various functional units in a manner that requires the user to have little or no knowledge of the unique characteristics of those units. ISO/IEC 2382-01 (SC36 Secretariat, 2003).
Markup Language
Markup languages, such as HTML and XML use elements to annotate text in such a way that the structure of the document is distinguishable from the contents of the document. Consequently, markup language documents are very good for storing data, since the distinction between structure and content is transparent and immediately discernable.
Metadata
Literally, data about data. Metadata is used to organize, categorize, browse, and discover data resources. For more information, see the USGIN Metadata Tutorial.
Model
In the context of USGIN, a model is a theoretical framework for data, of which a schema is a representation. For practical purposes, the structure of a given schema is determined by the model that schema represents.
Open-Source
Software can be considered open-source when it complies with the crieteria of the Open Source Initiative. Briefly summarized: to be considered open-source, the software or license must...
- ...be distributable and redistributable free of charge
- ...be distributed with uncompiled source code
- ...allow modifications and derived works
- ...restrict modifications and derived works only in the event of further development by the original author
- ...not discriminate against any person or group
- ...not discriminate against any field, profession, or endeavor
- ...be usable without acquisition of an additional license
- ...not be restricted to use as part of a larger software package
- ...not restrict the use of other software
- ...not be predicated on any individual technology or style of interface
A more detailed list of these conditions may be found here.
Protocol
In the context of computing, a protocol is a special set of rules that enable communication between two computers. A useful physical analogy is a traffic light: on green lights, cars pass through intersections; on red lights, cars are not permitted to pass through an intersection. The rules represented by traffic lights can be considered traffic protocols; the rules for data transfer are computing protocols. HTTP is one example of a computing protocol.
Record (Database)
See Database Record.
Resolve
Verb. See dereference.
Resource
An identifiable thing that fulfills a requirement. Though resources are often placed into categories (such as data resources, geophysical resources, or computing resources), these categories are nonexclusive and usually demonstrate significant overlap (for example, wood can be both a construction resource and a fuel resource). Consequently, almost anything can be a resource as long as it is identifiable and fulfills a requirement.
Schema
A schema is the framework for a data model or collection of attributes that describe something. For practical purposes, schemas dictate where and how data from a dataset should be entered into a document.
Service
See Web Service.
String
A sequence of alphanumeric characters.
Subrecipient
Subrecipients are the State Geological Surveys (or state agency that houses the geologic/mineral resource agency for the state) that are subcontracted by the Arizona Geological Survey (AZGS) under the Department of Energy (DOE) contract No. DE-EE0002850 for the National Geothermal Data Service (NGDS) project to perform the subcontract requirement to make "at risk" geothermal data available online to promote geothermal development throughout the Unites States.
Syntax
A ruleset that governs the construction of phrases in a human- or machine-readable language.
Template
A blank form that is formatted in the correct schema.
Token
A token is a discrete, logical, non-elementary component of an information stream (here, non-elementary means that a token is not irreducible and can be reduced to smaller components). For example, a sentance is an information string; words are non-elementary components of a sentence and therefore tokens.
Computing information streams, such as URIs can also be broken down into tokens. For example, USGIN URIs conform to the following syntax:
- http://host/uri-gin/authority/resource_type/resource_specific/
...wherein the following tokens exist:
- http://
- host/
- uri-gun/
- authority/
- resource_type/
- resource_specific/
For more information about USGIN URIs, see the USGIN URI tutorial.
Uniform Resource Identifier (URI)
Uniquely identifies a resource. See the USGIN URI Tutorial for more information about URIs.
Web Service
Under the client-server relationship, a web service is a protocol for requesting data from a server; data requests and responses made in accordance with this protocol are standardized. In other words: by using standardized data requests and responses, client software can make requests for data regardless of server configuration.
Matters are complicated slightly by the fact that “hosting data as a service” is considered synonymous with “hosting data in accordance with a web service protocol.” Likewise, data hosted in accordance with a web service protocol is often referred to as a web service.
The Open Geospatial Consortium has produced several different flavors of web service that are relevant to geographic information systems, USGIN, and the State Geothermal Data project. These include:
- Catalog Service – Web (CSW): Not to be confused with web coverage services (WCS), catalog services are designed to query databases containing metadata about other services, thereby allowing users to discover and access services more easily
- Web Coverage Service (WCS): Not to be confused with catalogue service - web (CSW), web coverage services are designed to publish continuous data sets. Continuous data sets are so named because the data they display does not have discrete boundaries. Consequently, continuous data sets are unsuited to vector images (each vector object necessitating a discrete boundary) and are instead stored as raster images. For example, data about oceanic temperature is a continuous data set, since it is difficult to establish clear boundaries in a body of water. Consequently, data about oceanic temperature would be stored as a raster image and published as a web coverage service
- Web Feature Service (WFS): Web feature services serve data from shapefiles as vector-based features that may be queried for associated attributes (and therefore compared with other data published as web feature services). For example: if data from a shapefile containing information about rivers were published as a WFS, clients attempting to access this service would receive a map in which individual rivers could be queried for any attributes associated with them (such as average flow rate, average depth, etc.). Owing to the large amount of data associated with WFS, these services tend to require fast Internet connections
- Web Map Service (WMS): Web map services display data from a source shapefile or feature class as a static raster image, regardless of whether or not the source data contains features that may be queried for attributes. For example: if a shapefile containing a geologic map of Arizona were published as a WMS, clients attempting to access this web service would receive a raster image suitable for printing, display, or visual analysis
XML
XML stands for Extensible Markup Language. USGIN specifies the usage of XML documents as an interchange format for database records, owing to the ability for XML elements to emulate database fields. To use XML documents as an interchange format, USGIN defines XML schemas in which each XML document corresponds with a specific database record and each element corresponds with data entered in a database field. In these documents, tags define the database fields.
For example: well_name is a field within the WellHeader content model. Any known oil and gas well names go in the well_name field. An XML schema for expressing database records within the WellHeader content model might appear as follows:
- <content_model_name>WellHeader</content_model_name>
-
<database_record>
- <well_name>Union Oil Company of California-South 7 Veysey</well_name>
In this example, the Union Oil Company of California-South 7 Veysey well name constitutes the content delineated by the <well_name> tag.
For a much more detailed overview of XML, see the USGIN XML Tutorial.