Strategies for creating map cache tiles
There are two ways to add tiles to your cache.
One way is to precreate tiles so that they will be available when the first users start navigating the map. The geoprocessing tool Manage Map Server Cache Tiles can help you precreate some or all of the tiles for your cache.
A second way is to create tiles on demand, meaning that tiles for an area will not be created until the map is viewed. Previewing the map in ArcCatalog or opening the map in ArcMap or the Web Mapping Application starts the on-demand map caching process. With on-demand caching, the first visitor to an area will have to wait for the map to draw and be added to the cache, but subsequent visitors can take advantage of the cached tile.
An effective caching strategy is to precreate tiles for heavily visited areas of your map and create tiles on demand for rarely visited areas. The diagram below shows how you could apply this strategy to the prairie provinces of central Canada. Most of the population lives in the southern part of the provinces, as evidenced by the roads and towns there. You can precreate these tiles so that most users will immediately get the benefit of the cache.
The tiles for the rest of the map can be created on demand, since fewer users are likely to navigate there. The cost of creating, storing, and maintaining the cache for these vast uninhabited areas would outweigh the benefit of fast navigation for the first visitor.
Precreating tiles based on feature extents
How do you designate the portion of your map that will be precached? The simplest way is to precreate only the tiles that fall within the features of a given feature class. The caching tools allow you to choose a feature class for this purpose. In the example above, you might provide a feature class containing one feature that covers all of southern Canada. Alternatively, you could provide a feature class of major urban area boundaries in Canada. That way you could avoid precreating tiles for all uninhabited areas of Canada.
On-demand caching creates all the tiles that are included in and around the map view, so the first time you visit an area with on-demand caching enabled, the map may actually take longer to draw than if you were viewing the service dynamically.