This article provides instructions to configure the cache directory to display a 'Data not available' tile for empty map cache areas or when tiles are missing from the cache service.
A 'Data not available' tile can be useful if a user pans to the edge of the map, or navigates to an area that has not completed caching or where cache tiles are missing.
Configuring the server to return a 'Data not available' tile yields better user experience than returning nothing in some cases.
The following instructions are for use with ArcGIS Server 9.3.1 and later versions, for both the .NET and Java platforms.
For ArcGIS Server for the Microsoft .NET Framework 9.3 and previous versions, follow the instructions in ArcGIS Blog: Configuring your server to display a "Data not available" tile for empty map cache areas.
Note: • Use missing.png or blank.png if the cache tile format is PNG and if transparency is required. • Use missing.jpg or blank.jpg if the cache tile format is JPEG and if transparency is not required. • Use blank.png instead if a clear blank tile is needed. This is also used for overlay services that require transparency.
Additionally, the ArcGIS Server cache directory must be configured without specifying a virtual directory. This forces clients to use the tile handler to request tiles (instead of directly requesting tiles from the virtual directories) which retrieves missing.jpg (or missing.png) when a cache tile is not found.
Alternatively, for .NET Web ADF Applications, a custom error response on the virtual cache directory can be configured for HTTP Error 404: 'Not Found'. Instead of an error message, the web server returns the tile. This approach is discussed in the ArcGIS Server blog thread provided in the Related Information section below. This method is used in ArcGIS Server 9.3 and previous versions.