Send/Receive IQ Stanzas#

Unlike Message and Presence stanzas which only use text data for basic usage, Iq stanzas require using XML payloads, and generally entail creating a new Slixmpp plugin to provide the necessary convenience methods to make working with them easier.

Basic Use#

XMPP’s use of Iq stanzas is built around namespaced <query /> elements. For clients, just sending the empty <query /> element will suffice for retrieving information. For example, a very basic implementation of service discovery would just need to be able to send:

<iq to="" type="get" id="1">
  <query xmlns="" />

Creating Iq Stanzas#

Slixmpp provides built-in support for creating basic Iq stanzas this way. The relevant methods are:

These methods all follow the same pattern: create or modify an existing Iq stanza, set the 'type' value based on the method name, and finally add a <query /> element with the given namespace. For example, to produce the query above, you would use:


Sending Iq Stanzas#

Once an Iq stanza is created, sending it over the wire is done using its send() method, like any other stanza object. However, there are a few extra options to control how to wait for the query’s response, as well as how to handle the result.

send() returns an Future object, which can be awaited on until a result is received.

These options are:

  • timeout: When using the blocking behaviour, the call will eventually timeout with an error. The default timeout is 30 seconds, but this may be overidden two ways. To change the timeout globally, set:

    self.response_timeout = 10

    To change the timeout for a single call, the timeout parameter works:

  • callback: When not using a blocking call, using the callback argument is a simple way to register a handler that will execute whenever a response is finally received.

  • timeout_callback: A callback to execute when the provided timeout is reached before an answer is received.


Both callback and timeout_callback can be effectively replaced using await, and standard exception handling (see below), which provide a more linear and readable workflow.

Properly working with Iq stanzas requires handling the intended, normal flow, error responses, and timed out requests. To make this easier, two exceptions may be thrown by send(): IqError and IqTimeout. These exceptions only apply to the default, blocking calls.

    resp = await iq.send()
    # ... do stuff with expected Iq result
except IqError as e:
    err_resp =
    # ... handle error case
except IqTimeout:
    # ... no response received in time

If you do not care to distinguish between errors and timeouts, then you can combine both cases with a generic XMPPError exception:

    resp = await iq.send()
except XMPPError:
    # ... Don't care about the response

Advanced Use#

Going beyond the basics provided by Slixmpp requires building at least a rudimentary Slixmpp plugin to create a stanza object for interfacting with the Iq payload.

The typical way to respond to Iq requests is to register stream handlers. As an example, suppose we create a stanza class named CustomXEP which uses the XML element <query xmlns="custom-xep" />, and has a plugin_attrib value of custom_xep.

There are two types of incoming Iq requests: get and set. You can register a handler that will accept both and then filter by type as needed, as so:

    'CustomXEP Handler',

# ...

def _handle_custom_iq(self, iq):
    if iq['type'] == 'get':
        # ...
    elif iq['type'] == 'set':
        # ...
        # ... This will capture error responses too

If you want to filter out query types beforehand, you can adjust the matching filter by using @type=get or @type=set if you are using the recommended StanzaPath matcher.

    'CustomXEP Handler',

# ...

def _handle_custom_iq_get(self, iq):
    assert(iq['type'] == 'get')