In Chapter 3, Building Your First Mobile ArcGIS Application, we added a layer of data provided by an ArcGIS feature service. This is a special type of service where the raw layer data is passed to the mobile browser for rendering. This is different to the other commonly used ArcGIS map services—dynamic and tiled—that provide map images. You can interact directly with features generated by an ArcGIS feature service programmatically. Using feature layers, and setting the correct "Mode", can avoid the need for a round-trip request-response to ArcGIS when we pan, zoom, or wish to see a features attribute.

The following screenshot illustrates the various types of layers in ArcGIS:

ArcGIS layer types

Avoiding server requests has potential advantages, particularly relating to performance. In this chapter, we will remain focused on feature layers most of the the code examples take advantage of in-memory feature layer data.