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Best practices for tile caches

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Hosted tile layers run quickly on the web, but it takes an investment of server power, time, and storage space to build and maintain the tile cache. When you host your tile layers on ArcGIS Online, acquiring server power is not as big a concern as it would be if you were creating the tiles on-premises. Esri maintains the server and is responsible for completing your tile creation. However, you need to prepare for the time that it takes to build a cache. You also need to anticipate the amount of disk space the cache will use.

In general, the time it takes to generate the tiles for a particular map is based on the spatial extent of the map to be cached, the number of layers in the map, and the load on the system at the time that the map is being processed. ArcGIS Online is designed to scale automatically (by adding computing power) as load increases. However, lags are possible in the cases where the system experiences drastic load.

When ArcGIS Online creates tiles, it partitions the map into spatial extents that are drawn in parallel. If your data contains many extents, the entire process may take minutes or hours to complete. The process is asynchronous, which means the caching process continues if you close the application from which the publication was performed.

View cache status

Anytime after you start creating tiles, you can display a scale-by-scale progress report of the percentage of cache your server has generated. Right-click your hosted tile layer in the Catalog tree in ArcMap and click View Cache Status. You'll immediately notice that the larger cache scales take much longer to cache than the smaller scales.

You can alternatively see the cache status in the My Content page of the ArcGIS.com website by clicking the Manage Tiles link.

Build tiles strategically

Your organization has purchased a finite number of credits that can be exchanged for ArcGIS Online services such as building and storing tiles. The number of credits remaining for your account is visible to administrators in the My Organization page under the Subscription Status menu. If you exhaust all your credits while creating tiles, the server stops the tile creation, and you will need to acquire more credits or use only the tiles that have been built already.

By default, tiles are created for the full extent of the map. If you're creating tiles for a large geographic entity that is not rectangular, you can conserve time and service credits by interactively defining the area of interest to cache. To constrain tile creation to a smaller extent instead of creating tiles for the full extent of the map, use the Manage Map Server Cache Tiles geoprocessing tool in ArcMap to digitize an area of interest polygon on the map. The extent of this polygon is used for cache creation.

Build a cache for hosted tiles

You can choose to build a cache on your tiles automatically when publishing, or build the cache manually after publishing. When you first start publishing, it is easier to build the cache automatically. Your tiles are created for you by ArcGIS Online. You don't have to take any further action other than optionally monitoring the cache progress.

As soon as you become familiar with what your caching needs are, though, Esri recommends that you build the cache manually. Caches that are automatically generated may be larger than you need. The larger the cache, the longer time it takes to build. Building a larger cache also uses more credits.

If you choose to build a cache manually after publishing your tile layer, you can launch the cache jobs from My Content. Display the item page for your tiles, click the Settings tab, and click the Manage Tiles button in the Tile Layer (Hosted) Settings section. This displays a window allowing you to create tiles and view the status of each scale level.

Tip:

You can also modify the visible scale range in the Tile Layer (Hosted) Settings section of the Settings tab.

Alternatively, you can launch the tile creation from ArcMap, which gives you more control over the geographic area cached. The following steps explain how to build the cache from ArcMap:

  1. Start ArcMap.

    Optionally open the map document from which you originally published the service. Opening the map document is necessary only if you want to interactively define an area of interest for tile creation.

  2. Sign in to ArcGIS Online..
    1. Click File > Sign In.
    2. Type your organizational user name and password and click Sign In.
  3. Open the Catalog window and expand My Hosted Services.
  4. Right-click your hosted tile layer and click Manage Cache > Manage Tiles.

    The Manage Map Server Cache Tiles tool dialog box appears. This tool creates tiles for tile layers.

  5. Set the tool parameters as desired.

    Note the Area Of Interest parameter, which allows you to interactively digitize a polygon to define where tiles are created.

    If you need help understanding any of the other tool parameters, click Show Help in the tool dialog box.

  6. Click OK to begin creating tiles.

    Tip:

    To view a scale-by-scale progress report of cache tile creation, right-click your hosted tile layer in the Catalog tree and click View Cache Status. To learn more, see Viewing cache completion status.

The tiles are created and stored on the ArcGIS Online servers.

If you ever want to delete tiles, you can run this same tool with the Update Mode parameter set to Delete Tiles.