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Platform Notes

                             Directory Separators

      JJFMapper uses forward slashes for directory separators throughout.  PHP
  allows this under Windows.  The advantage of using hard coded forward
  slashes rather than the built-in constant DIRECTORY_SEPARATOR is that
  instruction documents that refer to GIS files by path do not need to exist
  in two separate versions.


                                  Endianness

      JJFMapper uses the function "unpack" in the shapefile module.
  Unfortunately this function has no platform independent way of reading
  floating point numbers from binary packed data.  Shapefiles have
  little-endian packed double floats, and unpacking these values only works on
  little-endian processor machines, like Intel x86 family.  I wrote a
  work-around in lib/helpers.php so that the Shapefile module *will* work on
  big endian processor machines, but the performance is lacking.  Therefore
  JJFMapper will probably not run well enough for real-time serving of maps
  over the web on a big-endian processor machine.  Using map caching may solve
  the problem in cases where your maps are relatively static.



  

PHP Version Target Compatibility

  The target compatibility for JJFMapper is currently PHP 4.2.3 and up.





PHP Functions used in JJFMapper


  Function                                   Compatibility
  -----------------------------------------------------------------------------
  call_user_func_array                       (PHP 4 >= 4.0.4, PHP 5)
    Used in jjfmapper::jjfmapper
  preg_match                                 (PHP 3 >= 3.0.9, PHP 4, PHP 5)
    Used in geoformat_shapefile::dbf_stage






PHP Variables


  Preset Variable       Compatibility              Where used
  -----------------------------------------------------------------------------
  $_REQUEST             (PHP 4 >= 4.1.0, PHP 5)    built_in_icons.php







PHP Functions not used in JJFMapper because of portability.


  Function                                   Compatibility
  -----------------------------------------------------------------------------
  dbase_open                                 Requires dbase module
  dbase_numrecords                           ''
  dbase_get_record                           ''
  dbase_close                                ''
          These functions appeared in the earliest PHP version of JJFMapper,
          but the dbase module is not commonly available on webservers, so I
          rewrote the function to read shapefile dbf's such that the parsing
          did not depend on the dbase module.
  file_get_contents                          (PHP 4 >= 4.3.0, PHP 5)
          This is one function I would use if I raised my target
          compatibility, but it alone is not a reason to do so.



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