5.3 Geospatial Services Taxonomy Structures
5.3.5 Spatial Data Infrastructure: Cookbook
6
The SDI Cookbook identifies existing and emerging standards, open-source and commercial 7
standards-based software solutions, supportive organizational strategies and policies, and best 8
practices. “The SDI Cookbook wiki is intended as a ‘living document’ which provides information 9
on standards and best practices for implementing a Spatial Data Infrastructure.” 10
The SDI Cookbook defines services as: 11
“… self-contained, self-describing, modular applications consisting of collections
12
of operations, accessible through interfaces, which allow clients to evoke
13
behaviors of value to the user. Clients can invoke services from across a network
14
using standardized protocols independently of platform, language, or object
15
model on which the services or the client were deployed.”
16
The OGC Service Framework groups geospatial services into five categories corresponding to the 17
OGC services taxonomy top-level domains described in OGC’s Service Architecture Abstract 18
Specification (also ISO 19119104). The SDI Cookbook provides a summary of these categories
19
(below), and when available, includes implementation specifications for these services: 20
103 The information in this section is taken directly from SDI Cookbook, Global Spatial Data Infrastructure, GSDIWiki, last updated 5
June 2014. Available at http://www.gsdidocs.org/GSDIWiki/index.php/Main_Page
104 ISO 19119:2005 Geographic information – Services. “ISO 19119:2005 identifies and defines the architecture patterns for service
interfaces used for geographic information, defines its relationship to the Open Systems Environment model, presents a geographic services taxonomy and a list of example geographic services placed in the services taxonomy. It also prescribes how to create a platform-neutral service specification, how to derive conformant platform-specific service specifications, and provides guidelines for
• Catalogue Services – respond to requests for metadata in a Catalogue that comply 1
with certain browse or search criteria. Geospatial data that are stored for use in 2
local databases can often be used in external applications once they are published. 3
In this chapter, the concepts and implementation of geospatial data catalogues are 4
presented as a means to publish descriptions of your geospatial data holdings in a 5
standard way to permit search across multiple servers. 6
◦ Note: A Catalogue is a single collection of metadata entries that are managed 7
together. 8
• Geospatial Data Services - provide access to a wide range of collections of 9
geospatial data stored in distributed repositories and databases. Examples of data 10
services include: 11
◦ Feature Access Services: provide access and management of feature stores. 12
Applicable implementation specification: OGC Web Feature Service
13
(WFS; http://www.opengeospatial.org/standards/wfs 14
http://www.opengis.org/docs/02-058.pdf)
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◦ Coverage Access Services: provide access and management of coverage stores. 16
Applicable implementation specification: OGC Web Coverage Service
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(WCS; http://www.opengeospatial.org/standards/wcs)
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◦ Sensor Collection Services: provide access, manipulation and collection of sensor 19
observations. Applicable implementation specification: OGC Sensor Collection
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Service (SCS; http://www.opengis.org/docs/02-028.pdf)
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◦ Image Archive Services: provide access and management of large sets of digital 22
images and related metadata 23
• Data services also provide access to location-based data in the form of the following 24
services (Applicable implementation specification: OGC Location Services OLS;
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http://www.opengeospatial.org/standards/ols ): 26
◦ Directory Services: provide access to online directories to find the locations of 27
specific or nearest places, products or services 28
◦ Geocoding Services: transform a description of a location (place name or street 29
address) into a normalized description of the location 30
◦ Navigation Services: determine travel routes and navigation between two points 31
◦ Gateway Services: fetch the position of a known mobile terminal from the 32
network 33
the selection and specification of geographic services from both platform-neutral and platform-specific perspectives.” INCITS approved ISO 19119:2005 as an American National Standard.
• Portrayal services – provide visualization of geospatial information. Given one or 1
more inputs, portrayal services produce rendered outputs (maps, perspective views 2
of terrain, annotated images, etc.). They can be tightly or loosely coupled with 3
other services such as the Data and Processing services, and can transform, 4
combine, or create portrayed outputs. Examples of such services include: 5
◦ Map Portrayal Services 6
◦ Coverage Portrayal Services: Applicable implementation specification: OGC
7
Coverage Portrayal Service (CPS; http://www.opengis.org/docs/02-019r1.pdf)
8
◦ Mobile Presentation Services 9
• Processing services – unlike data services, are not associated with specific datasets. 10
Instead, they provide operations for processing or transforming data in a manner 11
determined by user specified parameters. Processing services can be tightly or 12
loosely coupled with other services such as the Data and Processing Services. The 13
most common examples of processing services are: 14
◦ Coordinate Transformation Services: convert geospatial coordinates from one 15
reference system to another. Applicable implementation specification: Coordinate
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Transformation Services (CTS; http://www.opengeospatial.org/standards/ct)
17
◦ Image Processing Services, detailed in OGC’s Abstract Specification Topic 15 18
http://www.opengeospatial.org/standards/as, include: 19
• Image Manipulation Services - manipulate images (resizing, changing color and 20
contrast values, applying various filters, manipulating image resolution, etc.) and 21
are used for conducting mathematical analyses of image characteristics (computing 22
image histograms, convolutions, etc.). 23
• Image Exploitation Services - support the photogrammetric analysis of remotely 24
sensed and scanned imagery and the generation of reports and other products 25
based on the results of the analysis. 26
• Image Synthesis Services - create or transform images using computer-based spatial 27
models, perspective transformations, and manipulations of image characteristics to 28
improve visibility, sharpen resolution, and/or reduce the effects of cloud cover or 29
haze. 30
• Geospatial Analysis Services: exploit information available in a Feature or Feature 31
Collection to derive application-oriented quantitative results that are not available 32
from the raw data itself. 33
• Gazetteers: provide access to geospatial data indexed by place name rather than by 34
coordinate locations. Applicable Gazetteer Service – Application profile of the Web
35
Feature Service Best Practice 1.0 (http://www.opengeospatial.org/standards/bp)
•Service Chaining – can be considered as a special case of processing services, 1
enabling the combination or pipelining of results from different services in response 2
to clients’ requests. Efficient service chaining is critical to the ability to leverage and 3
combine multiple information sources hosted by various service providers. Service 4
chaining is required when a task needed by a client cannot be provided by a single 5
service, but rather by combining or pipelining results from several complementary 6
services. Most GIS applications will require the chaining of multiple geospatial and 7
non-geospatial services. 8