ixampl is an implementation of ixml, implemented in the the VHLPL ABC. It consists of two parts: A bootstrap parser, that has the definition of ixml built in, parses the input and serialises it (in memory) into the form expected by part 2, which is an Earley parser that accepts a grammar in ixml, and parses input using that grammar, and then serialises the result to XML.
You can try it out here.