20 January 2017

What Have I Been Doing Lately?

My last posting was in October of 2016, and since then I have been working on moving the code and lessons I learned from the razmq project to a new project called Python Banyan. The code has been complete for some time now, but I have been struggling to get it documented. I am pleased to say that the documentation is well under way and hopefully will be complete in about 2 weeks time (hopefully shorter). You can view a draft of  the User's Guide here, but be mindful it is subject to change. 

WHAT IS PYTHON BANYAN?

Python Banyan is a lightweight, reactive framework used to create flexible, non-blocking, event driven, asynchronous applications. It was designed primarily to implement physical computing applications for devices such as the Raspberry Pi and Arduino, but it is not limited to just that domain, and may be used to create application in any domain.

Most traditional physical computing libraries or frameworks use an object oriented model that results in a single, tightly coupled, monolithic executable image. Python Banyan uses an extension of the object oriented model, called the component based model. A component based application is comprised of a set of independent, loosely coupled modules. Functionality is easily added to a Python Banyan application, and in fact it may be added to a fully running system without the need to recompile or reboot.

Because each module is a self contained entity, applications can be created with a set of modules that use different versions of Python, and in fact, you can even add modules written in other computer languages.

In addition, the modules may be run on a single computer, or may be distributed across multiple  computers running different operating systems, without having to change a single line of code.

A Little More Detail

The Python Banyan Framework consists of a single, simple base class. All Banyan compatible components inherit from this class. When a Banyan component is first invoked, it automatically connects to a common shared software backplane. All of the complexity of managing connections is hidden within and handled by the base class. All Banyan modules exchange information with each another by sending or publishing user defined protocol messages via the backplane. All routing and message buffering is automatically handled by the Framework. Each Banyan component can "publish" messages, "subscribe" to receive specific messages or both publish and subscribe messages. A Banyan component is not limited as to how many types of messages it may subscribe to.

Because Banyan messages are not computer language specific, components written in other computer Languages, such as JavaScript, can be used within a Python Banyan application. A simple JavaScript demo is provided in the examples section below.

Python Banyan takes full advantage of the ZeroMQ networking library that not only provides connectivity, but in addition acts as a concurrency framework. All of this is handled transparently by the Python Banyan base class. If your application requires additional concurrency support, you are free to choose whatever works best for your application, such as a multi-threading or a Python asyncio approach. User defined messages are prepared for transport across the network by wrapping them in theMessage Pack format.

The complexities of MessagePack are handled transparently by the base class, both for transmitting and receiving messages.

A User's Guide Is Provided. Here is what the guide covers:

Chapter 1 is an introduction to developing with Python Banyan. An application tailored specifically for this purpose will be presented in detail.

In chapter 2, a demonstration of, and a discussion about creating physical computing components with Python Banyan.

To demonstrate Python Banyan's flexibility, applications will be built from Python 2 components, Python 3 components and even a JavaScript component, all cooperating and communicating with each other within a single Python Banyan application.

Python Banyan applications may be distributed across multiple computers, all without changing a single line of code. Using the components created in this guide, all of the components will first be launched to run on a Raspberry Pi, and then then the components will be re-distributed across a Linux Unbuntu PC, a Windows PC and the Raspberry Pi without having to change a single line of code.

In Chapter 3, we will add components to control an 8x8 bicolor LED matrix connected to a Raspberry Pi. A demonstration of using Python Banyan to control an i2c device will be presented.

If you need to control multiple i2c devices sharing the same i2c pins, Python Banyan provides the concurrency support for you to do so.

Chapter 4 will discuss how to use Python's setup tools to convert a Banyan component into an executable file and have it automatically installed on the execution path.