Add docs on using Iq stanzas.

1 files changed, 180 insertions, 0 deletions

diff --git a/docs/getting_started/iq.rst b/docs/getting_started/iq.rst
index 7ac1508c..98e0bdaf 100644
--- a/docs/getting_started/iq.rst
+++ b/docs/getting_started/iq.rst
@@ -1,2 +1,182 @@
 Send/Receive IQ Stanzas
 =======================
+
+Unlike :class:`~sleekxmpp.stanza.message.Message` and
+:class:`~sleekxmpp.stanza.presence.Presence` stanzas which only use
+text data for basic usage, :class:`~sleekxmpp.stanza.iq.Iq` stanzas
+require using XML payloads, and generally entail creating a new
+SleekXMPP plugin to provide the necessary convenience methods to
+make working with them easier.
+
+Basic Use
+---------
+
+XMPP's use of :class:`~sleekxmpp.stanza.iq.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:
+
+.. code-block:: xml
+
+    <iq to="user@example.com" type="get" id="1">
+      <query xmlns="http://jabber.org/protocol/disco#info" />
+    </iq>
+
+Creating Iq Stanzas
+~~~~~~~~~~~~~~~~~~~
+
+SleekXMPP provides built-in support for creating basic :class:`~sleekxmpp.stanza.iq.Iq`
+stanzas this way. The relevant methods are:
+
+* :meth:`~sleekxmpp.basexmpp.BaseXMPP.make_iq`
+* :meth:`~sleekxmpp.basexmpp.BaseXMPP.make_iq_get`
+* :meth:`~sleekxmpp.basexmpp.BaseXMPP.make_iq_set`
+* :meth:`~sleekxmpp.basexmpp.BaseXMPP.make_iq_result`
+* :meth:`~sleekxmpp.basexmpp.BaseXMPP.make_iq_error`
+* :meth:`~sleekxmpp.basexmpp.BaseXMPP.make_iq_query`
+
+These methods all follow the same pattern: create or modify an existing 
+:class:`~sleekxmpp.stanza.iq.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:
+
+.. code-block:: python
+
+    self.make_iq_get(queryxmlns='http://jabber.org/protocol/disco#info',
+                     ito='user@example.com')
+
+
+Sending Iq Stanzas
+~~~~~~~~~~~~~~~~~~
+
+Once an :class:`~sleekxmpp.stanza.iq.Iq` stanza is created, sending it
+over the wire is done using its :meth:`~sleekxmpp.stanza.iq.Iq.send()`
+method, like any other stanza object. However, there are a few extra
+options to control how to wait for the query's response.
+
+These options are:
+
+* ``block``: The default behaviour is that :meth:`~sleekxmpp.stanza.iq.Iq.send()`
+  will block until a response is received and the response stanza will be the
+  return value. Setting ``block`` to ``False`` will cause the call to return
+  immediately. In which case, you will need to arrange some way to capture
+  the response stanza if you need it.
+
+* ``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:
+
+    .. code-block:: python
+
+        self.response_timeout = 10
+
+  To change the timeout for a single call, the ``timeout`` parameter works:
+
+    .. code-block:: python
+        
+        iq.send(timeout=60)
+
+* ``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. Using this method, there
+  is no timeout limit. In case you need to remove the callback, the
+  name of the newly created callback is returned.
+
+    .. code-block:: python
+
+       cb_name = iq.send(callback=self.a_callback) 
+
+       # ... later if we need to cancel
+       self.remove_handler(cb_name)
+
+Properly working with :class:`~sleekxmpp.stanza.iq.Iq` stanzas requires
+handling the intended, normal flow, error responses, and timed out
+requests. To make this easier, two exceptions may be thrown by
+:meth:`~sleekxmpp.stanza.iq.Iq.send()`: :exc:`~sleekxmpp.exceptions.IqError`
+and :exc:`~sleekxmpp.exceptions.IqTimeout`. These exceptions only
+apply to the default, blocking calls.
+
+.. code-block:: python
+
+    try:
+        resp = iq.send()
+        # ... do stuff with expected Iq result
+    except IqError as e:
+        err_resp = e.iq
+        # ... handle error case
+    except IqTimeout:
+        # ... no response received in time
+        pass
+
+If you do not care to distinguish between errors and timeouts, then you
+can combine both cases with a generic :exc:`~sleekxmpp.exceptions.XMPPError`
+exception:
+
+.. code-block:: python
+
+    try:
+        resp = iq.send()
+    except XMPPError:
+        # ... Don't care about the response
+        pass
+
+Advanced Use
+------------
+
+Going beyond the basics provided by SleekXMPP requires building at least a
+rudimentary SleekXMPP plugin to create a :term:`stanza object` for
+interfacting with the :class:`~sleekxmpp.stanza.iq.Iq` payload.
+
+.. seealso::
+
+    * :ref:`create-plugin`
+    * :ref:`work-with-stanzas`
+    * :ref:`using-handlers-matchers`
+    
+
+The typical way to respond to :class:`~sleekxmpp.stanza.iq.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 :attr:`~sleekxmpp.xmlstream.stanzabase.ElementBase.plugin_attrib` value
+of ``custom_xep``.
+
+There are two types of incoming :class:`~sleekxmpp.stanza.iq.Iq` requests:
+``get`` and ``set``. You can register a handler that will accept both and then
+filter by type as needed, as so:
+
+.. code-block:: python
+
+    self.register_handler(Callback(
+        'CustomXEP Handler',
+        StanzaPath('iq/custom_xep'),
+        self._handle_custom_iq))
+
+    # ...
+
+    def _handle_custom_iq(self, iq):
+        if iq['type'] == 'get':
+            # ...
+            pass
+        elif iq['type'] == 'set':
+            # ...
+            pass
+        else:
+            # ... This will capture error responses too
+            pass
+
+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
+:class:`~sleekxmpp.xmlstream.matcher.stanzapath.StanzaPath` matcher.
+
+.. code-block:: python
+
+    self.register_handler(Callback(
+        'CustomXEP Handler',
+        StanzaPath('iq@type=get/custom_xep'),
+        self._handle_custom_iq_get))
+
+    # ...
+
+    def _handle_custom_iq_get(self, iq):
+        assert(iq['type'] == 'get')