Node

Table of Contents

• Worker Thread
• Node States

Nodes, also known as "modules" in flow-based programming, are the primary encapsulation mechanism inside INSTINCT. A Node can provide one or more input and/or output Pins . Matching pins can be linked in the GUI to provide nodes a mean to exchange data with each other.

Worker Thread

Each node starts a thread during its Constructor which handles state transitions. Later on the thread will also handle data processing.

Node States

The State enum defines all possible state a node can be in within its lifetime. To change from one state to the next, the user can call certain functions:

• doInitialize(bool wait) : Initializes the node by calling initialize() . Also tries to initialize all nodes which are connected over none Flow input pins as the node depends on the pin data.
• doDeinitialize(bool wait) : Deinitializes the node by calling deinitialize() . Also deinitializes all nodes which are connected over none Flow output pins as they depend on the pin data.
• doReinitialize(bool wait) : Calls doDeinitialize(bool wait) and afterwards doInitialize(bool wait) .
• doDisable(bool wait) : Disables the node. Also performs deinitialization first and therefore can wait for it to finish.
• doEnable() : Enables the node. Enabling is not handled by the worker thread, so this function does not need to wait.
• Transition into the Shutdown state is done by the program automatically in its Destructor. It can be performed from any previous state.

Usually the user only calls the doInitialize(bool wait) or doDeinitialize(bool wait) as the other functions can be triggered over the GUI.

An overview when which function can be called and which state transition is performed can be seen in the following graph.

The doReinitialize(bool wait) function takes a slightly different state transition route.

The doDisable(bool wait) function can transition from Deinitialized state but also from Initialized as follows