Managing the GeoStream Cache

A map layer presented using the GeoStream server consists of a collection of individual .png image 'tiles' (with a default size of either 300 x 300 or 600 x 600 pixels, depending on the display DPI detected). When these images are tiled together, a complete map layer is formed.

These tiles are typically cached on the server in the 'GeoStreamData\Cache' folder rather than being re-created every time they are needed, reducing the time needed to display a complete map.

Under some circumstances it may be desirable (for example when updating to new GBFS file versions) or necessary (if storage space is limited) to delete some or all of the contents of the GeoStreamData folder.

On a GeoStream server the GeoStreamData\Cache directory is typically found at one of the following locations:

• C:\ProgramData\GeoStreamData\Cache

• C:\GeoStreamData\Cache

Note
The GeoStreamData folder location is specified during initial installation. Its location will differ if the installer's default Server Cache Location is not used. See the Installing GeoStream topic for more information. The Server Cache Location can also be manually changed by editing the 'GeoStreamDataFolder' key in the Web.Config file.

The GeoStreamData Cache folder's contents are structured as follows:

<Hash of Map Style>\<Hash of Data Sets>\GBMapTiles-<Tiles Per Super Tile>-<Tile Size>[-<Display Scale, if not 1>]\<Zoom>\<Super Tile X Coordinate>\<Super Tile Y Coordinate>\<Tile X Coordinate>.<Tile Y Coordinate>_<Basemap Layer Suffix>.png

For example:

105E703FA832C3E38CC9592EB88A30A6\B9578968\GBMapTiles-4-300\128\22\50\3.3_1.png

Note
The basemap layer suffix is either _1 for auxiliary layers (see Auxiliary Layers), or _flat for all others.

Note
For explanations of Tile Size, Zoom and X/Y, see the GeoStream Tile Coordinates topic.

The <Hash of Data Sets> folder is named using a unique hash obtained from the current working set of GBFS map data files.

Note
When displaying Web Map Services (WMS) layers, such as weather or topographical imagery, additional folders will be created to house these tiles and any related images, rather than a <Hash of Data Sets> folder.

If your GeoStream server has multiple users with access to different subsets of GBFS files, the hash used to name this folder will be different for each combination of data. In other words, if three users have access to only UK and Ireland map data, then they will share a common cache folder, but if another user has access to UK, Ireland and France, then they will have a different cache folder. This may result in some duplication of tiles across folders.

If and when a GBFS file is updated (for example from 14Q1 to 14Q2), then the hash of the GBFS sets will change, and a new folder named using this hash will be created. This effectively means the cache is being restarted for sets containing that GBFS, and the old folder and its tiles can be deleted.

The <Hash of Map Style> folder allows tiles to be simultaneously cached for multiple map styles. If you are not using custom map styles, then you will probably only see separate folders used here for the satellite tiles. Note that upgrading your GeoBase version may change the default Map Style, which will result in this hash folder changing. When this occurs, you can safely delete the old folder and its tiles.

Note
The GeoStreamData folder may contain additional sub-folders, other than the Cache folder. These folders do not contain image files and are used for statistical logging (see GeoStream Statistics), and for storing other information depending on the GeoStream logging options enabled (see Configuring the server).