Dataflow programming
在学习TensorFlow时，知道他是基于dataflow architecture的，所以对Dataflow programming进行了一些了解。
wikipedia Dataflow programming
In computer programming, dataflow programming is a programming paradigm that models a program as a directed graph of the data flowing between operations, thus implementing dataflow principles and architecture.
NOTE: TensorFlow就是典型的基于dataflow的。TensorFlow中的directed graph被称为computational graph。
Dataflow programming languages share some features of functional languages, and were generally developed in order to bring some functional concepts to a language more suitable for numeric processing.
NOTE: 本段所讨论的是dataflow language 和 functional language。
Some authors use the term Datastream instead of Dataflow to avoid confusion with Dataflow Computing or Dataflow architecture, based on an indeterministic machine paradigm.
NOTE: Dataflow architecture是CPU architecture。
Dataflow programming was pioneered by Jack Dennis and his graduate students at MIT in the 1960s.
Properties of dataflow programming languages
Traditionally, a program is modeled as a series of operations happening in a specific order; this may be referred to as sequential,[1]:p.3 procedural,[2] Control flow[2] (indicating that the program chooses a specific path), or imperative programming(命令式编程). The program focuses on commands, in line with the von Neumann[1]:p.3 vision of sequential programming, where data is normally "at rest"[2]:p.7
In contrast, dataflow programming emphasizes the movement of data and models programs as a series of connections. Explicitly defined inputs and outputs connect operations, which function like black boxes.[2]:p.2 An operation runs as soon as all of its inputs become valid.[3] Thus, dataflow languages are inherently parallel and can work well in large, decentralized systems.[1]:p.3[4] [5]
NOTE: 上面这段话对dataflow programming language和寻常的imperative programming的对比是非常好的。关于它们的差异，在工程machine-learning的
Programming\TensorFlow\Implementation的TensorFlow VS compiler章节中也进行了讨论。
wisegeek What Is Dataflow Programming?
Dataflow and stream
dataflow其实就是一种stream，TensorFlow的中，显然它的stream的单位是tensor。关于stream，参见工程discrete的Relation-structure-computation\Model\Stream章节。