Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved.
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Get the service capabilities: retrieval of the supported version, the supported operations, etc.
o Order options retrieval scene selection options, processing options, media
definition, subscription sub-setting, etc.. o
Order Quotation: for getting a quotation of the order going to be submitted. o
Order submission o
Order monitor: to check the status of submitted orders. o
Order Cancellation: to cancel an on-going order. o
Retrieval of on-line available products. During the order execution the user can query the status of his her orders or also cancel
the orders. The services should verify any constraints that may be imposed on users, and report
status and relevant information back to the user
9.7 Online Data Access services
Various on-line data access services provide access to ordered datasets via the Internet. Such services typically use the File Transfer Protocol FTP for allowing access to EO
data, but also more advanced methods such as OGC Web Services for data delivery and visualization: Web Coverage Services WCS, Web Map Services WMS, Web Feature
Services WFS and Sensor Observation Services SOS.
9.7.1 Files Transfer Protocol
FTP or File Transfer Protocol from IETF is used to transfer data from one computer to another over the Internet, or through a network.
Specifically, FTP is a commonly used protocol for exchanging files over any network that supports the TCPIP protocol such as the Internet or an intranet.
9.7.2 OGC Web Map Service
An OGC Web Map Service WMS produces maps of spatially referenced data dynamically from geographic information. This international standard defines a map to
be a portrayal of geographic information as a digital image file suitable for display on a computer screen.
A map is not the data itself. WMS-produced maps are generally rendered in a pictorial format such as PNG, GIF or JPEG, or occasionally as vector-based graphical elements in
Scalable Vector Graphics SVG or Web Computer Graphics Metafile WebCGM
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Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved.
formats. This is in contrast to a Web Coverage Service WCS, which returns actual raster data.
WMS defines three operations: o
GetCapabilities, which returns service-level metadata. o
GetMap, which returns a map whose geographic and dimensional parameters are well-defined.
o GetFeatureInfo, which returns information about particular features shown on
a map optional.
9.7.3 OGC Web Coverage Service
The Web Coverage Service is an Open Geospatial Consortium standard web service for exchanging geospatial raster data.
WCS provides available data together with their detailed descriptions; allows complex queries against these data; and returns data with its original semantics instead of
pictures which can be interpreted, extrapolated, etc. -- and not just portrayed. This is in contrast to a Web Map Service WMS which produces a digital image file.
WCS provides three operations: o
GetCapabilities, which returns XML document describing the data collections available via WCS.
o DescribeCoverage, which returns details about a specified data collection.
o GetCoverage, which returns the data in a well known format.
9.7.4 OGC Web Feature Service
The Web Feature Service is an Open Geospatial Consortium standard web service for defining interfaces for data access and manipulation operations on geographic features
using HTTP as the distributed computing platform. Via these interfaces, a web user or service can combine, use and manage geodata
– the feature information behind a map image
– from different sources by invoking the following WFS operations on geographic features and elements :
o Create a new feature instance,
o Delete a feature instance,
o Update a feature instance,
o Lock a feature instance,
o Get or query features on spatial and non-spatial constraints.
