Active (classical) FBP components

[trustmaster]

Currently GoFlow components are reactive: we program them as reactions to data arriving at inports.

In classical FBP, a component's process is sitting in its own thread receiving data on its inports and sending output in a loop.

Implementing active components in GoFlow is relatively easy but requires some changes to the library:

• Active components should have Loop() method which is called in a separate goroutine when the process is activated.
• Within the Loop() method it uses Go channel operators (<-, = <- and select) to receive data from inports, send data to outports, etc.
• Hybrid active/reactive components are currently unsupported.
• All the other GoFlow things like Graphs, Connections and run-time capabilities don't require any changes to support Active components.
• For Loopers Loop() is called when the network is started. Non-loopers are currently unsupported in favor of reactive components.