If <DATA Or filename> is pseudo-code, then your error is that Data____ should be __DATA__. Once you fix that, things look fine.

By the way, the join is superfluous; joining a one-element list (or a scalar in list context) gives you the scalar back.

Update: Things look fine in the sense that the code will compile, not that reading from DATA in scalar context will read the whole XML file. I missed that in my first answer. You'll need to slurp the entire file somehow.