Are XMPP server implementations of binding not following the standard? - binding

Question

I recently tried binding based on RFC 6120 (9.1.3 pg 132) with:
<iq id='tn281v37' type='set'><bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/></iq>
I would get a response of 'not well formed':
<stream:error xmlns='jabber:client' xmlns:stream='http://etherx.jabber.org/streams'><not-well-formed xmlns='urn:ietf:params:xml:ns:xmpp-streams'/></stream:error>
It took a few days to find out it needed xmlns='jabber:client' :
<iq id='tn281v37' type='set' xmlns='jabber:client'><bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'/></iq>
It doesn't look like RFC 6120 has been superseded and every example of binding I find on the web doesn't have it. Is this due to implementation of the server? At the time I was binding to chinwag.im

Answer 1

This appears to be a misunderstanding of how XML namespaces work. In one of your comments you suggested that you are using a namespace of jabber:socket, but this is not a namespace that is defined anywhere in the XMPP specs and I could not find any reference to it online. Instead, you want to use jabber:client (or jabber:server if this were a server-to-server connection). A quick overview of XML namespaces is below:
All XML elements have a "name", this name is made of two parts: the local name and the namespace. The namespace is defined using an xmlns attribute, for example the following are different elements, they do not have the same name:
<iq xmlns="jabber:client"/>
<iq xmlns="jabber:server"/>
Namespaces declared using an xmlns attribute are inherited by their child elements (unless that element has its own xmlns attribute), therefore in the following:
<session xmlns="jabber:client">
<iq/>
<foo xmlns="bar"/>
</session>
Both the "session" element and the "iq" elements have the namespace "jabber:client" but "foo" has the namespace "bar".
There is also another way to declare a namespace: using a prefix. Prefixes are declared with an "xmlns:prefix" attribute (where "prefix" is the name of the prefix). The list of prefixes is inherited by child elements and don't need to be redeclared, and the namespace defined by the prefix only applies to elements that start with "prefix:". For example:
<stream:stream xmlns="jabber:client"
xmlns:stream="http://etherx.jabber.org/streams">
<iq/>
<stream:error></stream:error>
</stream:stream>
In the above the "stream" element has the namespace "http://etherx.jabber.org/streams", because it has the "stream:" prefix. The "iq" element on the other hand has the "jabber:client" namespace because it inherits it from the parents "xmlns" attribute. Finally, the "error" element also has the "http://etherx.jabber.org/streams" namespace because it uses the "stream:" prefix as well. Notice that it did not have to redeclare the stream prefix because it also inherits a list of prefixes from its parent elements, so just applying the prefix without re-defining it is okay.
It's impossible to tell from the level of detail you provided, but chances are you need to add xmlns="jabber:client" to your root element. If you don't have a root element to add it to (ie. when you're using the websocket protocol that sends lot of separate XML documents instead of one long stream), you will have to apply it separately to the root element in every frame you send.