.. _lifecycle:

=====================
 Component Lifecycle
=====================

|project| components :ref:`(not nodes!) <components>` maintain a lifecycle, that
is specific to the AMARSi learning domain.

The lifecycle maintains the component state and handles changing between those
states. The basic lifecycle is:

.. image:: images/lifecycle.png
  :width: 500px
  :align: right
  :target: _images/lifecycle.png

A component author can hook into the lifecycle by implementing the following
process methods of the component states and the methods called when changing
the state. *All hooks are optional an can be left unimplemented.*

Execution
=========

**Execution** is the main state of a component. The hooks are:

* ``onStartExecution()`` - called once when entering this state
* ``onProcess()`` - called every time when the :ref:`procstrat` triggers processing
* ``onStopExecution()`` - called once when leaving this this state

Online Learning
===============

**Online Learning** is for online learning of an adaptive component. The hooks
are:

* ``onStartLearnOnline()`` - called once when entering this state
* ``onLearnOnlineBeforeProcess()`` - called every time when the :ref:`procstrat`
  triggers processing. This method is called **right before** onProcess() in
  case needed for the online learning method. The main computation of the online
  learning step should go in *onLearnOnlineBeforeProcess()*.
* ``onProcess()`` - called every time when the :ref:`procstrat` triggers processing
* ``onLearnOnlineBeforeProcess()`` - called every time when the :ref:`procstrat`
  triggers processing. This method is called **right after** onProcess(). The
  main computation of the online learning step should go here.
* ``onStopLearnOnline()`` - called once when leaving this this state

Offline Learning
================

**Offline Learning** is for offline learning of an adaptive component. The hooks
are:

* ``onStartLearnOffline()`` - called once when entering this state
* ``onLearnOffline()`` - called every time when the :ref:`procstrat` triggers
  processing
* ``onStopLearnOffline()`` - called once when leaving this this state

Recording
=========

*to come …* (`#448 <https://redmine.amarsi-project.eu/issues/448>`_)