A few exciting ideas related to the on-going evolution of the COSA programming model have been percolating in my mind for quite some time. I wrote a little about them in my recent article, Parallel Computing: Command Hierarchy. These ideas form the basis of a radically new way of looking at software construction that is so intuitive, it promises (or threatens, as the case may be) to reclassify computer programming as a mostly geek-only occupation into something that the average computer user can partake in and enjoy. This multi-part article is an account of the reasoning that led to my current thinking.
Something Is Missing
There is no doubt that the graphical approach to parallel programming can do wonders to productivity and program comprehension. It is true that the use of plug-compatible components in COSA will facilitate drag-and-drop software composition but the simple and intuitive feel that one gets from connecting a sensor to an effector is absent in the realm of high-level components.
Even though looking at a bunch of interconnected COSA components may give one a sense of the various functional parts of a program, the manner in which the parts cooperate to accomplish a task is not obvious. Something is missing.
Masters and Slaves
I realized that the only way to solve the problem is to return to COSA’s roots. The COSA philosophy is that a program is a behaving machine that senses and effects changes in its environment. Of course, there is more to the design of a behaving machine than realizing that programs behave. We, as designers, want the program to behave in a certain way, that is to say, we want control. At the lowest level, we can control the behavior of a program by connecting specific sensors to specific effectors. The applicable metaphor, in this example, is that the sensor is the master or controller and the effector is the slave, i.e., the object that is under control. I rather like the master/slave symbolism because it perfectly illustrates the principle of complementarity. Those of you who have followed my work over the years know that I have always maintained that complementarity is the most important of all the COSA principles because it is the basic underlying principle of every complex organism.
In part II, I will describe how behavior control in COSA works at the elementary level.
How to Solve the Parallel Programming Crisis
Parallel Computing: Why the Future Is Compositional