.. _migration:

=============
 Migration
=============

Migrating from |project| 0.3 to |project| 0.4
=============================================

|project| is under continuous development, sometimes resulting in API changes
between minor versions, as happened between |project| 0.3 to |project| 0.4.

This page helps by pointing to the most prominent API changes. Examples for all
of the aspects can be found :ref:`here <examples>`. 

Node / Component base class names
---------------------------------

The base classes for :ref:`Nodes and Components <component>` were renamed
consistently (see API documentation):

* ``CCANode`` => ``Node``
* ``BaseComponent`` => ``Component``

Initial component state
-----------------------

While in |project| 0.3 components were initialized *stopped*, which seemed like
an unconvenient default, in |project| 0.4 the initial state of a component can
be specified. It is now *executing* by default and can be set via an optional
second parameter in the component constructor::

  // MyDefaultComponent will be initialized executing
  class MyDefaultComponent : cca::Component {
    MyDefaultComponent() // Constructor
        : cca::Component("Default Component") {
        ...
  }

  // MyStoppedComponent will be initialized stopped
  class MyStoppedComponent : cca::Component {
    MyStoppedComponent() // Constructor
        : cca::Component("Stopped Component", ComponentState::STOPPED()) {
        ...
  }
  
see also: :ref:`lifecycle`.

Ports are named and typed 
-------------------------

Component and node :ref:`Ports <ports>` are now typed and provide their own
API for sending and receiving data, which was formerly done through the API
of the node or component. Ports are meant to be class members now and are
registered to the node / component by a name for configuration.

Publishing data through a port is now::

  OutputPort<int>::Ptr PORT;
  ...
  OutputPort<int>::DataPtr data = ...
  OUT->publish(data);  

Receiving data now became significantly easier. Since the ports are typed, manual
casting is no longer required:: 

  InputPort<int>::Ptr PORT;
  ...
  InputPort<int>::DataPtr data = IN->get();

Processing strategy class names and helper methods
--------------------------------------------------

The classes of the standard :ref:`Processing Strategies <procstrat>` were
renamed for the sake of brevity (see API documentation):

* ``TimedProcessing`` => ``Timed``
* ``ModerateProcessing`` => ``Moderate``
* ...

The static helper methods to create shared pointers were renamed to be more
specific (see API documentation):

* ``TimedProcessing::create(2)`` => ``Timed::samplerate(2)``
* ``ModerateProcessing::create(0)`` => ``Moderate::noTimeout()``
* ``PortTriggeredProcessing::create(0)`` => ``PortTriggered::port("feedback")``
* ...

Printing nodes and components
-----------------------------

Printing component information is now accessible over the print() method::

  std::cout << myNode->print() << std::endl;