JavaScript SOAP客户端抛出未捕获的类型错误

我正在使用guru4的soap客户端编写一个简单的"Hello world"程序。我从Chrome控制台Uncaught TypeError: Cannot read property 'documentElement' of null得到一个错误。

这是我的JavaScript。

  <script src="soapclient.js"></script>
  <script type="text/javascript">
    function say_hello()
    {
        var pl = new SOAPClientParameters();
        pl.add("name", "john");
        pl.add("times", 2);
        SOAPClient.invoke("http://192.168.1.100:7789/", "say_hello", pl, true, say_hello_callBack);
    }
    function say_hello_callBack(r)
    {
        alert(r);
    }
  </script>

这是我试图与之交互的服务器。

import soaplib
from soaplib.core.service import soap
from soaplib.core.service import DefinitionBase
from soaplib.core.model.primitive import String, Integer
from soaplib.core.server import wsgi
from soaplib.core.model.clazz import Array
'''
This is a simple HelloWorld example to show the basics of writing
a webservice using soaplib, starting a server, and creating a service
client.
'''
class HelloWorldService(DefinitionBase):
    @soap(String, Integer, _returns=Array(String))
    def say_hello(self, name, times):
        '''
        Docstrings for service methods appear as documentation in the wsdl
        <b>what fun</b>
        @param name the name to say hello to
        @param the number of times to say hello
        @return the completed array
        '''
        results = []
        for i in range(0, times):
            results.append('Hello, %s' % name)
        return results
if __name__=='__main__':
    try:
        from wsgiref.simple_server import make_server
        soap_application = soaplib.core.Application([HelloWorldService], 'tns')
        wsgi_application = wsgi.Application(soap_application)
        print "listening to http://0.0.0.0:7789"
        print "wsdl is at: http://127.0.0.1:7789/?wsdl"
        server = make_server('localhost', 7789, wsgi_application)
        server.serve_forever()
    except ImportError:
        print "Error: example server code requires Python >= 2.5"

我有一种感觉，这个错误正在发生，因为我依赖于SOAP客户端内置的XML生成器。