mod_mrf

An apache module that serves tiles directly from a local MRF, 2D or 3D. This module takes two apache configuration directives:

MRF On|Off

Defaults to on if the MRF_ConfigurationFile is provided

MRF_ConfigurationFile Filename

Points to a text file that contains lines, where the first word on a line is a directive, followed by parameters

• Empty lines, lines that start with # are considered comments
• Unknown directives are ignored
• Known directives for this module are:

Size X Y Z C

• Mandatory, at least x and y, the size in pixels of the input MRF. Z defaults to 1 and C defaults to 3 (these are usually not meaningful)

DataFile string

• Mandatory, the path to the data file of the MRF.

RegExp

• Optional, a regular expression that must match the request URL for it to be considered a tile request. By default all URLs are considered tile requests. This directive can appear multiple times. If there are multiple RegExp lines, at least one has to match the request URL.

PageSize X Y 1 C

• Optional, the pagesize in pixels. X and Y default to 512. Z has to be 1 if C is provided, which has to match the C value from size

IndexFile string

• Optional, The index file name. If not provided it uses the data file name if its extension is not three letters.
  Otherwise it uses the datafile name with the extension changed to .idx

MimeType string

• Optional. Defaults to autodetect.

EmptyTile Size Offset FileName

• Optional. By default it ignores the request if a tile is missing. First number is assumed to be the size, second is offset. If filename is not provided, it uses the data file name.

SkippedLevels N

• Optional, how many levels to ignore, at the top of the MRF pyramid. For example a GCS pyramid will have to skip the one tile level, so this should be 1

ETagSeed base32_string

• Optional, 64 bits in base32 digits. Defaults to 0.
  The empty tile ETag will be this value but bit 64 (65th bit) is set. All the other tiles have 64 bit ETags that depend on this value.

Redirect path

• Optional, if the data file is on an object store

For better performance on local files, the httpd source against which this module is compiled should include support for random file access optimization. A patch file for libapr is provided, see apr_FOPEN_RANDOM.patch

For better performance when using object stores, the mod_proxy should be patched to reuse connections on subrequests. A patch file is included, see mod_proxy_httpd.patch