The ArcGIS Server and Image Server architecture

LegacyLegacy:

ArcGIS 10 is the last release of the stand-alone ArcGIS Image Server product. The image service definition (.ISDef) has been replaced by an improved geodatabase data model—the mosaic dataset—which can be published as an image service using the ArcGIS Server Image extension.

ArcGIS Server is capable of serving different GIS services such as the map service, geodata service, and image service. Map services are created from a map document (.mxd), geodata services are created from a geodatabase, and image services are created from raster datasets. With the ArcGIS Image Server extension, ArcGIS Server can serve image services created from image service definitions. An image service definition can contain large numbers of raster datasets, along with properties defining how they will be processed and mosaicked. Image service definitions are authored using the Image Service Definition Editor toolbar in ArcMap.

When ArcGIS Image Server is used as an extension in ArcGIS Server, it becomes part of the ArcGIS Server system architecture. There are four components that are installed with ArcGIS Image Server: Service Editor, Image Server Manager, service provider (SP), and server (AIS). Additionally, there are several clients that can be installed on client applications. These components and clients are depicted below as part of the ArcGIS Server system architecture.

ArcGIS Server and ArcGIS Image Server architecture
ArcGIS Server and ArcGIS Image Server architecture

This architecture is made up of the following components:

GIS server

The GIS server hosts your GIS resources, such as maps, globes, image services, and address locators, and exposes them as services to client applications.

The GIS server itself is composed of two distinct parts: the server object manager (SOM) and server object containers (SOCs). As the name implies, the SOM manages the services running on the server. When a client application requests the use of a particular service, the SOM provides it.

The SOM connects to one or more SOCs. The SOC machines—also referred to as container machines—contain, or host, the services that the SOM manages. Depending on your configuration, you can run the SOM and SOC on different machines and also have multiple SOC machines. The figure above shows a SOM machine connected to two SOC machines.

Data server

The data server contains the GIS resources that have been published as services on the GIS server. These resources can be map documents, address locators, globe documents, geodatabases, toolboxes, raster datasets, and image service definitions.

ArcGIS Image Server extension

The ArcGIS Image Server extension is composed of two parts, the server (AIS) and service providers (SP).

The server is registered with the SOM. It acts as the request broker for ArcGIS Image Server connections. It provides load balancing and failover support of connection requests between different service providers.

The service provider is the central processing unit (CPU) that processes the components of the image service definition and distributes the data to the client. Service providers perform on-the-fly processing defined in the image service definition. ArcGIS Image Server scales to support heavier loads by using additional service providers that run in parallel. Each service provider can provide multiple image services. The service provider's architecture is multithreaded, with each request running in its own thread, so multiple requests are processed simultaneously on multicore machines.

Managers and ArcCatalog administrators

ArcGIS Server administrators can use either ArcGIS Server Manager or ArcCatalog to publish their GIS resources as services. ArcGIS Server Manager is a Web application that supports publishing services, administering the GIS server, creating Web applications, and publishing ArcGIS Explorer maps on the server. ArcCatalog includes a GIS Servers node that you can use to add connections to GIS servers for either general server usage or administration of a server's properties and services.

When using the ArcGIS Image Server extension, ArcGIS Server Manager or ArcCatalog can publish image service definitions as image services.

Image Server Manager is used to configure and manage the server and service providers. This application has tools that allow an administrator to configure, view the status of, and start and stop the image servers and service providers, as well as export or review log files.

NoteNote:

When ArcGIS Image Server is used as a stand-alone server, Image Server Manager publishes the image services from the image service definitions; however, when used as an extension with ArcGIS Server, ArcGIS Server Manager or ArcCatalog is used to publish image services.

ArcGIS Desktop content authors

To author the GIS resources, such as maps, geoprocessing tools, and globes, that will be published to your server, use ArcGIS Desktop applications such as ArcMap, ArcCatalog, and ArcGlobe. If you're creating a cached map service, use ArcCatalog to create the cache, whereas if you're creating an image service definition, use the Image Service Definition Editor toolbar in ArcMap.

Web server

The Web server hosts Web applications and Web services that use the resources running on the GIS server.

Clients

Web client applications are Web, mobile, and desktop applications that connect over Hypertext Transfer Protocol (HTTP) to ArcGIS Server Internet services. Such services are served via the Web server, SOM, and SOC. When Web clients make image service requests, the requests are processed by the SOM. Requests for image services that are defined by image service definitions are forwarded to the server (AIS), which processes the request on the appropriate service provider. Desktop applications that use local services over a local area network (LAN) or wide area network (WAN) utilize the AIS directly, as do direct-connect ArcGIS Image Server clients. Direct-connection clients for ArcGIS Image Server include ArcMap applications as well as third-party applications, such as AutoCAD, MicroStation, MapInfo, and GeoMedia.

Service Editor

Image service definitions are created and edited in ArcMap using the tools and functions on the Image Service Definition Editor toolbar.

Image Service Definition Editor toolbar

The Image Service Definition Editor toolbar is used to accomplish the following:

Learn about working with the Image Service Definition Editor toolbar

Learn about creating a new image service definition

Image service definitions

The image service definition (.ISDef) file contains references to the raster data that is to be served; defines the properties of the service, such as the spatial reference and metadata; defines the image-processing steps to be applied to the raster data; and defines information about the output image rendering, presentation, and properties, such as the mosaic order and which images will be displayed at which resolutions.

The links to the raster data from the image service definition are in a raster process definition (.RPDef) file, which contains specific information about each raster dataset used in the image service, such as the pixel size, spatial reference, extent, and raster-specific processing to be applied.

The raster datasets are defined as raster types, such as QuickBird Basic, QuickBird Standard, Landsat ETM 1G, TIFF, United States Geological Survey (USGS) digital orthophoto quadrangle (DOQ), and USGS digital elevation models (DEM). Generally, for every raster data type, there is associated metadata, either as a header or as part of an associated file. This metadata can contain basic information about the raster, such as its coordinate system, pixel size, number of rows and columns, and number of bands, or more detailed information, such as the date of acquisition, cloud cover, and data provider's name. The raster data and any associated files should be stored together or in the same file folder structure as the data exists in when provided from a data vendor. For example, .tif files using the information in a world file should have the .tfw file stored in the same folder.

The raster data can be stored on a local disk, on a network, on a removable disk drive, or in a database—raster data can be stored anywhere as long as it can be readily accessed by ArcGIS Image Server. The speed of reading the data affects the performance.

The image service definition is created and edited in ArcMap using tools on the Image Service Definition Editor toolbar. The image service definition appears in ArcMap as a custom layer containing one to four of the following layers:

The image service definition is a folder with the extension .ISDef containing the footprint shapefile, a service table that is part of the footprint shapefile, a boundary shapefile, the ImageService.ISDef, a subfolder with the raster process definitions, and a seamline shapefile (if it is created). These contents are compiled, creating a single file used by ArcGIS Server with the extension .ISCDef.

Direct-connection client applications

The ArcGIS Image Server extension has direct-connection clients that are supported by the following applications:

These client applications allow you to directly change some of the image properties, such as the spatial reference, compression, and mosaic method of the image data you receive. They also allow you to view associated metadata and export the image data to a file.

Related Topics

An overview of ArcGIS Image Server
System requirements for ArcGIS Image Server

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4/19/2011