Towards Integration
===================
:date: Spring 2023
:author: Ichthyostega

//Menu: label Integration

The Lumiera project creates innovative software, geared towards professional, high-quality work;
it aims at high flexibility, offering user-control over a broad spectrum of configurable parameters,
and with smooth workflows that scale well to larger and more intricate projects. Building such
software involves some degree of exploration and search for adequate methods to reconcile
conflicting goals. There is no ready-made blueprint that just needs implementation -- rather,
we have to resort to a sequence of integration efforts, aimed at establishing core tenets
of the envisioned architecture.


Vertical Slices
---------------

TIP: A »https://en.wikipedia.org/wiki/Vertical_slice[vertical slice]« is an integration effort
     that engages all major software components of a software system. It is defined and used as
     a tool to further and focus the development activity towards large scale integration goals.


Populate the Timeline in the UI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
✔ link:https://issues.lumiera.org/ticket/1014[#1014 »TimelinePopulation«]: +
Send a description of the model structure in the form of a _population diff_ from the Session
in Steam-Layer up through the UI-Bus. When received in the UI-Layer, a new Timeline tab will be
allocated and populated with appropriate widgets to create a GUI-Timeline-View. The generated
UI structures will feature several nested tracks and some placeholder clips, which can be
dragged with the mouse. Moreover, the nested track structure is visualised by _custom drawing_
onto a _canvas widget,_ and the actual colours and shades for this drawing operations will be
picked up from the current desktop theme, in combination with an CSS application stylesheet.


Commands and State Messages via UI-Bus
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
✔ link:https://issues.lumiera.org/ticket/1099[#1014 »Demo GUI Roundtrip«]: +
Set up a test dialog in the UI, which issues test/dummy commands. These are propagated
to a dispatcher in Steam-Layer and by special rigging reflected back as _State Mark Messages_
over the UI-Bus, causing a visible state change in the _Error Log View_ in the UI.


Play a clip
~~~~~~~~~~~
🗘  link:https://issues.lumiera.org/ticket/1221[#1221 »PlaybackVerticalSlice«]: +
This vertical slice drives integration of Playback and Rendering.
While the actual media content is still mocked and hard wired, we get a simple playback control
in the GUI connected to some suitable display of video. When activated, an existing _ViewConnection_
is used to initiate a _Play Process_; the _Fixture_ data structure established between high-level-Model
(Session) and low-level-Model (Render nodes) will back a _Frame Dispatcher_ to generate _Render Jobs,_
which are then digested and activated by the _Scheduler_ in the Vault-Layer, thereby
_operating the render nodes_ to generate video data for display.

