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| author | Lance Stout <lancestout@gmail.com> | 2011-11-22 15:25:02 -0800 |
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| committer | Lance Stout <lancestout@gmail.com> | 2011-11-22 15:25:02 -0800 |
| commit | 6906c15e8ee20633ae0bf94fee1a99d916ceedc8 (patch) | |
| tree | f933aee58924c878b3fff92823667c4ba68442fb /docs/api/xmlstream/stanzabase.rst | |
| parent | ff5421cefcd2f86fef362d8fd8b387f7e812cc85 (diff) | |
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diff --git a/docs/api/xmlstream/stanzabase.rst b/docs/api/xmlstream/stanzabase.rst new file mode 100644 index 00000000..afed7655 --- /dev/null +++ b/docs/api/xmlstream/stanzabase.rst @@ -0,0 +1,123 @@ +.. _stanzabase: + +========== +stanzabase +========== + +.. module:: sleekxmpp.xmlstream.stanzabase + +The :mod:`sleekmxpp.xmlstream.stanzabase` module provides a wrapper for the +standard :mod:`xml.etree.cElementTree` module that makes working with XML +less painful. Instead of having to manually move up and down an element +tree and insert subelements and attributes, you can interact with an object +that behaves like a normal dictionary or JSON object, which silently maps +keys to XML attributes and elements behind the scenes. + +Overview +-------- + +The usefulness of this layer grows as the XML you have to work with +becomes nested. The base unit here, :class:`ElementBase`, can map to a +single XML element, or several depending on how advanced of a mapping +is desired from interface keys to XML structures. For example, a single +:class:`ElementBase` derived class could easily describe: + +.. code-block:: xml + + <message to="user@example.com" from="friend@example.com"> + <body>Hi!</body> + <x:extra> + <x:item>Custom item 1</x:item> + <x:item>Custom item 2</x:item> + <x:item>Custom item 3</x:item> + </x:extra> + </message> + +If that chunk of XML were put in the :class:`ElementBase` instance +``msg``, we could extract the data from the XML using:: + + >>> msg['extra'] + ['Custom item 1', 'Custom item 2', 'Custom item 3'] + +Provided we set up the handler for the ``'extra'`` interface to load the +``<x:item>`` element content into a list. + +The key concept is that given an XML structure that will be repeatedly +used, we can define a set of :term:`interfaces` which when we read from, +write to, or delete, will automatically manipulate the underlying XML +as needed. In addition, some of these interfaces may in turn reference +child objects which expose interfaces for particularly complex child +elements of the original XML chunk. + +.. seealso:: + :ref:`create-stanza-interfaces`. + +Because the :mod:`sleekxmpp.xmlstream.stanzabase` module was developed +as part of an `XMPP <http://xmpp.org>`_ library, these chunks of XML are +referred to as :term:`stanzas <stanza>`, and in SleekXMPP we refer to a +subclass of :class:`ElementBase` which defines the interfaces needed for +interacting with a given :term:`stanza` a :term:`stanza object`. + +To make dealing with more complicated and nested :term:`stanzas <stanza>` +or XML chunks easier, :term:`stanza objects <stanza object>` can be +composed in two ways: as iterable child objects or as plugins. Iterable +child stanzas, or :term:`substanzas`, are accessible through a special +``'substanzas'`` interface. This option is useful for stanzas which +may contain more than one of the same kind of element. When there is +only one child element, the plugin method is more useful. For plugins, +a parent stanza object delegates one of its XML child elements to the +plugin stanza object. Here is an example: + +.. code-block:: xml + + <iq type="result"> + <query xmlns="http://jabber.org/protocol/disco#info"> + <identity category="client" type="bot" name="SleekXMPP Bot" /> + </query> + </iq> + +We can can arrange this stanza into two objects: an outer, wrapper object for +dealing with the ``<iq />`` element and its attributes, and a plugin object to +control the ``<query />`` payload element. If we give the plugin object the +name ``'disco_info'`` (using its :attr:`ElementBase.plugin_attrib` value), then +we can access the plugin as so:: + + >>> iq['disco_info'] + '<query xmlns="http://jabber.org/protocol/disco#info"> + <identity category="client" type="bot" name="SleekXMPP Bot" /> + </query>' + +We can then drill down through the plugin object's interfaces as desired:: + + >>> iq['disco_info']['identities'] + [('client', 'bot', 'SleekXMPP Bot')] + +Plugins may also add new interfaces to the parent stanza object as if they +had been defined by the parent directly, and can also override the behaviour +of an interface defined by the parent. + +.. seealso:: + + - :ref:`create-stanza-plugins` + - :ref:`create-extension-plugins` + - :ref:`override-parent-interfaces` + + +Registering Stanza Plugins +-------------------------- + +.. autofunction:: register_stanza_plugin + +ElementBase +----------- + +.. autoclass:: ElementBase + :members: + :private-members: + :special-members: + +StanzaBase +---------- + +.. autoclass:: StanzaBase + :members: |