Main Components
===============

A common need for a feature is the ability to interact with the DOM, somewhere
at the root of the web client. For example, the notification service want to
include a component somewhere to be able to display notifications. Or maybe the
discuss code will need the ability to display chat windows.

The Odoo javascript framework provides a way to do that, with the idea of
``main components``. These are component classes (NOT instances) that are registered
in the ``mainComponentRegistry``. For example:

.. code-block:: ts

   class MyComponent extends Component {
       ...
   }

   componentRegistry.add("myaddon.MyComponent", MyComponent);

When the web client is rendered, it will iterate over all these Component and
add them to a ``div`` inside its template.

Notes:


* like usual, it is a convention to prefix the registry keys with the name of
  the odoo addon that register it, in order to lessen the risk of name collision.
* Since these components are rendered when the Web client is started, they can
  actually delay the rendering (if they implement ``willStart`` ). Therefore, one
  need to be cautious. If possible, try to keep them synchronous.