Essential GIS services vocabulary

Below are some of the most common terms you will encounter when using GIS services.

Geoservices

Often used to refer to Web-based GIS services. These are Web services that are served from a GIS. In ArcGIS Desktop, users create a number of important geographic elements, such as map documents, geodatabases, geoprocessing models, and image catalogs. Each of these can be published on the Web as a geoservice.

Cached map services

An ArcGIS map service where the map has been precomputed to speed up performance and increase the scalability of Web map services. Typically, the precomputed map is created for many map scales and is stored as a series of map tiles. Here are some example tiles for two map scales of a multiscale cached map service:

Dynamic map service

An ArcGIS map service whose map display is computed at the time that the map is requested. Dynamic map services are useful for portraying the most up-to-date information in your map service. However, they can take more time to display and may not scale to as many simultaneous users as cached map services.

Image service

A rendered image, which can include the pixel information within it, that users access from the server. Image services can combine any set of rasters into an integrated service, treating the services as if they were a single data source. The image service appears to the user as a virtual image. See Adding image services for more information.

REST

REST, shorthand for Representational State Transfer, is used as a mechanism to identify and work with any Web resource, such as Web pages and Web resources. Essentially, REST enables users to issue a series of operations or commands against URLs and other Web resources (for example, URIs). This allows users to combine and mash up information and resources from many Web sites within simple applications. Scripting environments, such as HTTP, JavaScript, Adobe Flex, Silverlight, and Python, can leverage "RESTful" Web services and resources.

All services created using ArcGIS Server have REST interfaces, enabling them to be combined in exciting and interesting ways.

Web map

One or more Web map services that are combined together to create a useful map experience for ArcGIS users. Web maps have a number of key map properties and are saved and shared as Web URLs.

They can be shared (for example, e-mailed) and opened in a wide range of ArcGIS clients.

Key Web map properties	Shared as
Map title, summary, description, and so on A set of one of more map service URLs that comprise the basemap The ordered list of Web map URLs used as operational layers A list of tasks (for example, whether a layer can be queried) A set of widgets to use the operational layers (for example, for editing or for time-aware layers)	Web map (JSON format), which can be opened and used in ArcGIS Desktop ArcGIS Explorer Online Windows Mobile applications Apple iPhone applications ArcGIS Web map applications ArcGIS for Flex ArcGIS for SharePoint

List of key Web map properties and their applications

See Using ArcGIS Web maps for more information.

Web service

A software component accessible over the World Wide Web for use in other applications. Web services are built using industry standards such as XML, REST, and SOAP and thus are not dependent on any particular operating system or programming language, allowing access to them through a wide range of applications.

XML

XML is short for Extensible Markup Language. It is a standard from the World Wide Web Consortium (W3C) and is used for sharing information on the Web.

XML is used for information formats, complex documents, and data structures and provides a framework for creating standard information formats using customized tags. This enables open sharing of both the format and the data across applications.