External plugins are standalone, executable programs, that can be written
in any language. When ikiwiki starts up, it runs the program, and
-communicates with it using [XML RPC][xmlrpc]. If you want to [[write]] an external
-plugin, read on..
+communicates with it using [XML RPC][xmlrpc]. If you want to [[write]] an
+external plugin, read on..
[xmlrpc]: http://www.xmlrpc.com/
XML RPC has a limitation that it does not have a way to pass
undef/NULL/None. There is an extension to the protocol that supports this,
-but it is not yet available in the [[!cpan XML::RPC]] library used by
-ikiwiki.
+but it is not yet available in all versions of the [[!cpan XML::RPC]] library
+used by ikiwiki.
Until the extension is available, ikiwiki allows undef to be communicated
over XML RPC by passing a sentinal value, a hash with a single key "null"