Introduction to web maps
One type of map that you can work with in the ArcGIS API for Silverlight is a web map. A web map is a map based on the ArcGIS.com map specification, which uses ArcGIS JavaScript Object Notation (JSON) to define a map. For details on the web map specification, see Understanding the map format.
There are three ways to build a web map: using the ArcGIS.com map viewer, ArcGIS Explorer Online, or a Mobile Content Server. Once you've built your web map, you can share it using either ArcGIS.com or your Mobile Content Server. You can make the map publically available and viewable by anyone, or you can limit access to those users you authorize through user groups on ArcGIS.com or permissions on your Mobile Content Server.
As with any type of map, a web map is built by stacking layers. The bottom layer provides the map reader with a geographic reference. The top layers add features of interest to the map reader. See the following illustration:
This example for a water utility shows how three layers are combined into a web map. The top two layers contain features from the water utility network, one for water valves and another for water lines. These top layers are called operational layers because they are part of an organization's operations. The water utility workers can access and update detailed information through these operational layers. Underneath the two operational layers is a basemap layer that provides a background so that the utility workers can locate themselves in the field and know the relationship between features such as streets and buildings to features in the water utility network
The three layers in this example are sandwiched onto one web map. While the basemap always appears in the web map, the operational layers can be turned on and off in the field.
Components of a web map
Web maps are composed of multiple components, including the following:
These components are highlighted in the ArcGIS application for Windows Phone, shown in the following screen shots:
Together these components define a web map. Once you’ve built a web map, it can be used in mobile, web, and desktop clients. The previous screen shots show how the parts of a web map are shown when using the ArcGIS application for Windows Phone. Using the ArcGIS API for Silverlight, you have access to the components of web maps and can create your own user interface for your users to interact with them.
Note:Web maps can also contain time information for a map, as well as bookmarks. However, the ArcGIS API for Silverlight does not currently provide assistance in accessing these components.
Basemap layer
A basemap layer is the reference for your map. A basemap layer typically contains geographic information that provides the cartographic context for your organization’s data. The basemap layer shows common geodata such as roads, buildings, parcels, and terrain. A basemap can be built from multiple layers but is presented as one layer in a web map. Basemap layers are optimized for quick display and cannot be queried or edited.
There are many excellent basemap layers in ArcGIS Online, a repository of professionally prepared map services that are ready to use by anyone. If your application requires common geodata, such as roads, terrain, or topography for a map reference, you will likely find a suitable basemap layer in ArcGIS Online. Using a basemap layer from ArcGIS Online will give your web maps a high-quality cartographic base.
If your organization has special requirements for a basemap layer, you can build a custom basemap layer as an image service or map service from ArcGIS Server. If this is the case, you should do a comprehensive inventory on the available basemap layers to ensure that you won't be doing unnecessary work in building a new basemap layer.
Operational layers
Operational layers are the layers with which your users will interact in the field. They contain the features that are most important to your organization, such as infrastructure for a local government, network assets for a utility, or wildlife observations for an environmental agency. You can find and use a suitable operational layer that's already available on ArcGIS Online, but if your organization has collected extensive data about its infrastructure, you'll want to build an operational layer from your geographic information system (GIS) data.
Operational layers can be queried and edited. Operational layers for display and query are defined from a map service. Operational layers for editing feature are defined from a feature service. You can use one or several operational layers in your web map.
Tasks
Tasks are processes that your users can use to locate and inspect objects in the field. Examples of tasks include queries to find objects based on an attribute or finding a place based on an address. See About queries for details.
Feature collections
Features can be added directly to a web map without using a service to store them. These types of feature layers are useful for displaying information such as events happening within a community or inventory of oil production facilities. They are also an easy way to add a small number of features to a map, for example, the swimming pools managed by your city's parks and recreation department and when you don't have access to ArcGIS Server for creating feature service layers. See Creating editable layers for details.
Pop-up windows
Pop-up windows define information about features that the author of the map wanted to expose to users working with the map. They can be defined on feature collections, as well as on feature layers and dynamic map services hosted on ArcGIS Server. See About displaying attributes with pop-up windows for details.