XPath in XmlStream.addObserver doesn't work the way it should

Question

What I want to do is to react only on specified root elements. For example, if user sends XmlStream that looks like:

<auth>
    <login>user</login>
    <pass>dupa.8</pass>
</auth>

My method ._auth should be executed. I've done it with addObserver method called inside connectionMade method.

self.addObserver("/auth", self._auth)

AFAIK XPath - if I write "/auth" it means that I want my root element to be "auth", so that message:

<longtagislong>
    <auth>...</auth>
</longtagislong>

... should be rejected, because auth isn't root.

But Twisted however doesn't work the way I thought it should - my _auth method is executed when second message appears (with auth element inside the tree), not the first one - with auth element as a root.

So, my question is: how to tell Twisted and addObserver method that I want to react only if root element's name is "auth"?

Answer 1

Ok, finally I got the answer. It's because of XmlStream itself. Connection is active as long as main root element is not closed (for example: <stream/>). Everything inside it is root element for XPath, that's why "/auth" means <stream><auth></auth></stream>.