The generic dataflow layer provides concepts which are applicable to different dataflow frameworks, and can be used to develop generic dataflow code. Generic dataflow code (such as Dataflow.Blueprint) can be built on top of these concepts, and then work with any dataflow framework whose elements model the concepts (such as Dataflow.Signals).

Following is a gentle introduction to the various concepts addressed. More detail can be found in the concepts documentation, as well as the reference for implemented templates, classes and functions.

Frameworks

A dataflow framework is a collection of types and functions which can be used to move and process data in a dataflow network. Diffirent frameworks work in different ways, and use different mechanisms to transport data. For example, Boost.Signals offers transfer of data through function calls, while VTK offers a number of classes which are meant to be connected in a pipline (e.g., starting with the data source, manipulating it, and finally displaying it on the screen).

In the Dataflow library, a framework typically has a Tag, which is then used to tag its Ports and Components and allow them to interoperate.

Ports

A point of data production or consumption in a dataflow framework is called a port. Two complementary ports that produce / consume the same type of data using the same mechanism can typically be connected/disconnected, or data can be extracted from one port to another.

Ports are captured more formally by the Port concept.

Components

A component is the fundamental data processing element of a dataflow network. It can have multiple ports, for example a video filter component might have one consumer port (consuming video to be processed) and one producer port (producing filtered video).

Components are captured more formally by the Component concept.

Operations

To establish a flow of data in a dataflow program, we typically connect producers and consumers using some type of connection. In C++, this is usually done through a pointer-like mechanism. For example, a boost::signal can be used by a producer to dissiminate data to multiple consumers which have been connected to the signal. Or, a consumer class might have a pointer to a variable which it collects data from.

Operations between two ports such as connect, connect_only, disconnect, and extract are captured by the BinaryOperable concept. Operations on a single port such as disconnect_all are covered by the UnaryOperable concept. Operations on components are covered by the ComponentOperable concept.