tilecache(8)							   GIS Utilities						      tilecache(8)

NAME

       tilecache - Cache and serve map tiles

DESCRIPTION

       TileCache  is  a BSD licensed tile caching mechanism.  The goal is to make it easy to set up a WMS or TMS frontend to any backend data ser-
       vices you might be interested in, using a pluggable caching and rendering mechanism.

       TileCache was developed by MetaCarta Labs and released to the public under a BSD license.

       The TileCache was designed as a companion to OpenLayers, the BSD licensed web mapping interface. If you are using TileCache  with  OpenLay-
       ers,  please read the section of this readme which describes how to do so. For additional help with setting up TileCache for use with Open-
       Layers, please feel free to stop by #openlayers, on irc.freenode.net, or to send email to tilecache@openlayers.org.

RUNNING UNDER CGI

       o TileCache should have a cgi installed under /usr/lib/cgi-bin, called tilecache.cgi.  This  is	accessible  from  http://yourmachine.exam-
	 ple.com/cgi-bin/tilecache.cgi.

       o Edit  /etc/tilecache.cfg  to  point the DiskCache to the location you wish to cache tiles, and the layers to point to the map file or WMS
	 server you wish to cache.

       o Visit:

	 http://yourmachine.example.com/cgi-bin/tilecache.cgi?LAYERS=basic&SERVICE=WMS&BBOX=-180,-90,0,90

       o Or visit:

	 http://yourmachine.example.com/cgi-bin/tilecache.cgi/1.0.0/basic/0/0/0.png

       o If you see a tile, TileCache is working correctly.

RUNNING UNDER MOD_PYTHON
       o Edit /etc/tilecache.cfg to point the DiskCache to the location you wish to cache tiles, and the layers to point to the map  file  or  WMS
	 server you wish to cache.

       o Add the following to your Apache configuration:

	 Alias /tiles /var/lib/python-support/python2.4/tilecache/
	 <Directory /var/lib/python-support/python2.4/>
	      SetHandler python-program
	      PythonHandler TileCache.Service
	      PythonOption TileCacheConfig /etc/tilecache.cfg
	 </Directory>

       o Visit one of the URLs described above, replacing tilecache.cgi with tilecache.py

       o If you see a tile you have set up your configuration correctly. Congrats!

RUNNING STANDALONE (UNDER WSGI)
       TileCache includes standalone HTTP server which uses the WSGI handler. This implementation depends on Python Paste , which can be installed
       via the python-paste package.

       For versions of Python earlier than 2.5, you will also need to install wsgiref:

       http://cheeseshop.python.org/pypi/wsgiref

       Once you have all the prerequisites installed, simply run:

       /usr/sbin/tilecache_http_server

       This will start a webserver listening on port 8080 (by default), after which you should be able to open:

       http://yourmachine.example.com:8080/1.0.0/basic/0/0/0.png

       to see your first tile.

RUNNING UNDER FASTCGI

       TileCache includes a fastcgi implementation. In order to use this implementation, you will need to install flup, available from:

       http://trac.saddi.com/flup

       This implementation also depends on Python Paste, which can be downloaded via the python-paste package:

       Once you have done this, you can configure your fastcgi server to use tilecache.fcgi.

       Configuring FastCGI is beyond the scope of this documentation.

CONFIGURATION

       TileCache is configured by a config file, defaulting to tilecache.cfg.  There are several parameters to control TileCache layers  that  are
       applicable to all layers:

       bbox   The  bounding box of the Layer. The resolutions array defaults to having resolutions which are equal to the bbox divided by 512 (two
	      standard tiles).

       debug  Whether to send debug output to the error.log. Defaults to "yes", can be set to "no"

       description
	      Layer description, used in some metadata responses. Default is blank.

       extension
	      File extension of the layer. Used to request images from WMS servers, as well as when writing cache files.

       layers A string used to describe the layers. Typically passed directly to the renderer. The WMSLayer sends this in the  HTTP  request,  and
	      the  MapServerLayer chooses which layer to render based on this string. If no layer is provided, the layer name is used to fill this
	      property.

       levels An integer, describing the number of 'zoom levels' or scales to support. Overridden by resolutions, if passed.

       mapfile
	      The absolute file location of a mapfile. Required for MapServer and Mapnik layers.

       maxResolution
	      The maximum resolution. If this is set, a resolutions array is automatically calculated up to a number of levels controlled  by  the
	      'levels' option.

       metaTile
	      set to "yes" to turn on metaTiling. This will request larger tiles, and split them up using the Python Imaging library.  Defaults to
	      "no".

       metaBuffer
	      an integer number of pixels to request around the outside of the rendered tile. This is good to combat edge effects in  various  map
	      renderers. Defaults to 10.

       metaSize
	      A  comma	separated pair of integers, which is used to determine how many tiles should be rendered when using metaTiling. Default is
	      5,5.

       resolutions
	      Comma separate list of resolutions you want the TileCache instance to support.

       size   Comma separated set of integers, describing the width/height of the tiles. Defaults to 256,256

       srs    String describing the SRS value. Default is "EPSG:4326"

       type   The type of layer. Options are: WMSLayer, MapnikLayer, MapServerLayer, ImageLayer

       url    URL to use when requesting images from a remote WMS server. Required for WMSLayer.

       watermarkImage
	      The watermarkImage parameter is assigned on a per-layer basis.  This is a fully qualified path to an image you would like  to  apply
	      to  each tile. We recommend you use a watermark image the same size as your tiles.  If using the default tile size, you should use a
	      256x256 image.  NOTE: Python Imaging Library DOES NOT support interlaced images.

       watermarkOpacity
	      The watermarkOpacity parameter is assigned on a per-layer basis.	This configures the opacity of the watermark over the tile, it	is
	      a floating point number between 0 and 1. Usage is optional and will otherwise default.

       extent_type
	      Setting  this to 'loose' will allow TileCache to generate tiles outside the maximum bounding box. Useful for clients that don't know
	      when to stop asking for tiles.

       tms_type
	      Setting this to "google" will cause tiles to switch vertical order (that is, following the Google style x/y pattern).

USING TILECACHE WITH OPENLAYERS

       To run OpenLayers with TileCache the URL passed to the OpenLayers.Layer.WMS constructor must point to  the  TileCache  script,  i.e.  tile-
       cache.cgi  or  tilecache.py. As an example see the example-cgi.html file included in the TileCache distribution, under /usr/share/doc/tile-
       cache/examples/.

       Note: example-cgi.html assumes TileCache is set up under CGI (see above). If you set up TileCache under mod_python you'd  need  to  slighly
       modify  example-cgi.html:  the URL passed to the OpenLayers.Layer.WMS constructor must point to the mod_python script as opposed to the CGI
       script. Similarly, you would need to edit this URL if you were to use TileCache with the standalone HTTP Server or FastCGI.

       The most important thing to do is to ensure that the OpenLayers Layer has the same resolutions and bounding box as  your  TileCache  layer.
       You  can define the resolutions in OpenLayers via the 'resolutions' option or the 'maxResolution' option on the layer. The maxExtent should
       be defined to match the bbox parameter of the TileCache layer.

USING TILECACHE WITH MAPSERVER

       MapServer has a map level metadata option, labelcache_map_edge_buffer, which is set automatically by TileCache to the metaBuffer plus  five
       when metaTiling is on, if it is not set in the mapfile.

       If   you   are	using	MetaTiling,   be   aware   that   MapServer  generates	interlaced  PNG  files,  which	PIL  will  not	read.  See
       http://mapserver.gis.umn.edu/docs/faq/pil_mapscript on how to resolve this.

SEEDING YOUR TILECACHE

       The tilecache_seed utility will seed tiles in a cache automatically. You will need to have TileCache  set  up  in  one  of  the	previously
       described configurations.

   Usage
       /usr/sbin/tilecache_seed <url> <layer> [<zoom start> <zoom stop> [<bbox>]]

   Arguments
       url    http://example.com/yourdir/tilecache.cgi? or http://example.com/yourdir/tilecache.py

       layer  same layer name that is in the tilecache.cfg

       zoom start
	      Zoom level to start the process

       zoom end
	      Zoom level to end the process

       bbox   The bounding box to seed

   Seeding by center point and radius
       If called without zoom level arguments, tilecache_seed.py will assume that it needs to read a list of points and radii from standard input,
       in the form:

       <lat>,<lon>,<radius>
       <lat>,<lon>,<radius>
       <lat>,<lon>,<radius>
       <lat>,<lon>,<radius>
       <ctrl + d>

       The format of this file is:

       lon    the position(s) to seed longitude

       lat    the position(s) to seed latitude

       radius the radius around the lon/lat to seed in degrees

   Examples
       An example with zoom levels 5 through 12 would be like;

       $ /usr/sbin/tilecache_seed "http://example.com/yourdir/tilecache.cgi?" Zip_Codes 5 12 "-118.12500,31.952162238,-116.015625,34.3071438563"

       The bbox can be dropped and defaults to world lonlat(-180,-90,180,90):

       $ /usr/sbin/tilecache_seed.py "http://example.com/yourdir/tilecache.cgi?" Zip_Codes 0 9

       In center point/radius mode, the zoom level range is not specifiable from the command-line. An example usage might look like:

       $ /usr/sbin/tilecache_seed.py "http://example.com/yourdir/tilecache.cgi?" Zip_Codes
       -118.12500,31.952162238,0.05
       -121.46327,32.345345645,0.08
       <Ctrl+D>

       ... the seeding will then commence ...

CLEANING YOUR TILECACHE

       The tilecache_clean utility will remove the least recently accessed tiles from a cache, down to a specified size.

   Usage
       /usr/sbin/tilecache_clean [options] <cache_location>

   Options
       --version
	      show program's version number and exit

       -h , --help
	      show this help message and exit

       -s SIZE, --size SIZE
	      Maximum cache size, in megabytes.

       -e ENTRIES, --entries ENTRIES
	      Maximum cache entries. This limits the amount of memory that will be used to store information about tiles to remove.

   Notes
       The --entries option to tilecache_clean.py is optional, and is used to regulate how much memory it uses to do its bookkeeping. The  default
       value of 1 million will hopefully keep RAM utilization under about 100M on a 32-bit x86 Linux machine. If tilecache_clean.py doesn't appear
       to be keeping your disk cache down to an appropriate size, try upping this value.

       tilecache_clean is designed to be run from a cronjob like so:

       00 05 * * *  /usr/sbin/tilecache_clean.py -s500 /var/www/tilecache

TROUBLESHOOTING

       Occasionally, for some reason, when using meta tiles, your server may leave behind lock files. If this happens, there will be files in your
       cache directory with the extension '.lck'. If you are seeing tiles not render and taking multiple minutes before returning a 500 error, you
       may be suffering under a stuck lock.

       Removing all files with extension '.lck' from the cache directory will resolve this problem.

SEE ALSO

       memcached(8)

       http://tilecache.org/

       http://openlayers.org/

       http://wiki.osgeo.org/index.php/WMS_Tiling_Client_Recommendation

       http://wiki.osgeo.org/index.php/Tile_Map_Service_Specification

AUTHOR

       crschmidt@metacarta.com

COPYRIGHT

       (c) 2006-2007 MetaCarta, Inc.  Distributed under the BSD license.

2.03								    2008-05-19							      tilecache(8)