socket server for parsing streaming xml

iterxml.py

""" socket server for parsing streaming xml

based on
    http://stackoverflow.com/a/2270249/105043 and
    http://eventlet.net/doc/examples.html#echo-server

usage:
    $ python iterxml.py &
    # push two documents to make sure we can start over
    $ cat sample.xml sample.xml |nc localhost 6000
"""


import eventlet
import xml.etree.ElementTree as etree


class DoneParsing(Exception):
    pass


class StreamHandler(object):
    # for example from http://www.w3schools.com/schema/schema_example.asp
    outer_element = 'shiporder'

    def reset(self):
        self.in_document = False
        self.parser = etree.XMLTreeBuilder()
        self.parser._parser.EndElementHandler = self.end_hander

    def handle(self, fd):
        self.reset()
        while True:
            data = fd.read(1)
            if not data:
                break
            if not self.in_document:
                # skip 'junk' betewen documents
                if data != '<':
                    continue
                self.in_document = True

            try:
                self.parser.feed(data)
            except DoneParsing:
                self.reset()

    def end_hander(self, tag):
        node = self.parser._end(tag)
        print node, node.text
        if node.tag == self.outer_element:
            raise DoneParsing()


print "server socket listening on port 6000"
server = eventlet.listen(('0.0.0.0', 6000))
pool = eventlet.GreenPool()
while True:
    try:
        new_sock, address = server.accept()
        print "accepted", address
        handler = StreamHandler()
        pool.spawn_n(handler.handle, new_sock.makefile('rw'))
    except (SystemExit, KeyboardInterrupt):
        break