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Mapping and visualization
Working with web maps in ArcGIS
Using OGC Services
This topic was updated for 9.3.1.
The Open Geospatial Consortium, Inc. (OGC), Web Map Service (WMS) is a map portrayal service that is used to publish a collection of map layers to embed in your interactive Web maps. ArcMap, ArcScene, and ArcGlobe support WMS. The WMS specification expresses the map contents as map layers using XML. WMS's primary use is to openly serve interactive map images on the Internet.
WMS client support in ArcGIS allows you to access these services over the Internet and add them to your maps as layers.
The organization of WMS map layers and sublayers in ArcMap
After connecting to a WMS server, a WMS service is shown on the Add Data dialog box with this icon:
. You can add the entire service to ArcMap, in which case the first 20 layers will be turned on automatically, since a WMS service doesn't define which of its layers are visible. In this way, you are likely to see something useful when you first add the service to a map, without having a large number of individual layers to turn on or off. When you initially zoom in on WMS services, bear in mind that you won't necessarily see more detail unless the layers providing more detailed data happen to be in those first 20 layers. Similarly, if you preview a WMS service in ArcCatalog, you will see the first 20 layers in the service.
When added to ArcMap, the WMS service layer's entry in the table of contents is contracted to save space, but you can expand it and its groups to see the individual layers it contains.
A WMS service layer is made up of three entries that are arranged hierarchically in the table of contents. At the top is the name of WMS service , which holds all the WMS map layers. The next level is WMS group layers, whose only function is to organize WMS sublayers into related groups. There is at least one WMS group layer, but there can be can be any number of WMS group layers (and even nested groups within groups). WMS group layers do not hold any map layers—it is the third group, WMS sublayers, that actually contains the map layers.
Each of these types of WMS layers has its own Layer Properties dialog box with different options available. The properties for WMS service layers, group layers, and sublayers are described in the subsections below.
You can add a WMS group layer or individual WMS sublayers to ArcMap using the Add Data dialog box or by dragging and dropping them onto the map from ArcCatalog. WMS group layers and sublayers are always part of a WMS service. When you add individual WMS sublayers, you will create one WMS service entry in the table of contents for each sublayer you add. Additional service layers require additional requests to the server, which can affect performance. In order to minimize these requests, you may want to add a single WMS sublayer. You can use the Layers tab of the service Layer Properties dialog box to add additional WMS sublayers to an existing WMS map layer in ArcGIS.