TileCache Caches
================

TileCache offers access to a number of different caches. These caches are used
to store tiles. 

Disk
----
Example Configuration::

  [cache]
  type=Disk
  base=/var/lib/tilecache
  umask=002
  sendfile=yes
  expire=3600

Dependencies: None

The sendfile=yes option instructs TileCache to send an X-SendFile header to
the web server rather than the contents of the image.

See http://blog.lighttpd.net/articles/2006/07/02/x-sendfile and
http://tn123.ath.cx/mod_xsendfile/

GoogleDisk
----
Example Configuration::

  [cache]
  type=GoogleDisk
  base=/var/lib/tilecache

Dependencies: None
Note: A simple subclass of the Disk cache, this switches the Y tile ordering
on the disk, so Google Maps users can easily access tiles directly (e.g. 
bypassing tilecache.py, if all tiles have been pre-rendered) with a simple 
CustomTileUrl function.

Memcached
---------
Example configuration::

  [cache]
  type=Memcached
  servers=127.0.0.1:11211

Dependencies:
 * memcache Python module must be installed on your system path.
   http://code.sixapart.com/svn/memcached/trunk/api/python/memcache.py

Amazon S3
---------
Example configuration::

  [cache]
  type=AWSS3
  access_key=833833ABC88838
  secret_access_key=8234abyi3kdjby8so8idu
  use_tms_paths=true

The use_tms_paths will make the files more accessible to other clients,
though at this time, ACLs are not set on the TMS structure to make them
available publicly.

The use_tms_paths can also be set to "flipped": if so, it will result in
'flipped' TMS, with typical paths like:

  /1.0.0/9/82/63.png

But with 0 starting at the top of the map, instead of the bottom. 

This cache can use one of two libraries:

Boto
____
Available from http://code.google.com/p/boto/, boto is a package that 
wraps the Amazon APIs in a Pythonic wrapper. This is installable on
recent Debian-based distributions as python-boto. It can be installed
via easy_install from setuptools as well: simply easy_install boto.
The boto library is more complete, and is more likely to properly
handle error conditions than the Amazon Example Library.

Amazon Example Library
______________________
Amazon provides an example Python library. This library provides a simple
wrapper around the Amazon web services. The code is available from 
http://developer.amazonwebservices.com/connect/entry.jspa?externalID=134&categoryID=47

You must download, unpack, and place the s3-example-libraries/python/S3.py
file on your PYTHONPATH/sys.path. The source distribution of TileCache
includes this file in the TileCache/Caches/S3.py file. (Packagers are
encouraged to remove this file from distributions and instead depend
on the boto library described above.)

MBTiles
-------

Simple read-only format for MBTiles sqlite databases. Name each database
according to the name of the layer, and place it inside your cache directory,
and provide an extension to your cache.

    [cache]
    type=MBTiles
    base=./tiles
    ext=db

For layer basic, this will attempt to open a sqlite3 database at 
./tiles/basic.db .

See http://mapbox.com/tools/mbtiles for more details.

All Caches
----------

All Caches support the expire option.

The expire=n option instructs TileCache to send an Expires header, with the
date set 'n' seconds into the future.