Rainbow Unit: Networks Big and Small
1B: Connecting Our Electronic ‘Thing’ to a Wider World
Technical Overview
As we saw at the end of the Orange and Blue Units, there are many ways to provide data communications between devices. In the Orange Unit, we learned more about the ports available on our computers, such as the and ports, that provide ways for us to connect external devices such as keyboards, mice, and monitors. And in the Blue Unit, we learned about serial data communications interfaces such as the interface we’ve been using to transmit and receive data between the Raspberry Pi and the screen or PuTTY console of our laptop, and between the Circuit Playground Express and our Raspberry Pi. While technically a keyboard and a computer or a microcontroller and a microcomputer are two separate devices, via the software we use, they work as one unified system. They are our computer. They are our counterstory trumpet.
But underlying the concept of the Internet of Things—which today is often popularly referred to as Smart Devices coming together to create Smart Homes, Smart Grids, Smart Cities, and more—is an interconnection of electronics. A mechanical keyboard connected to a personal computer is not an IoT device. But a programmable keyboard that uses machine learning to predict changing contexts based on data from a range of local IoT devices and functionally evolve accordingly would be an IoT keyboard. It is to create an Internet of Things, whether or not this is connected to the physical Internet. There are actually many choices that can be made regarding this interconnectivity, only some of which make use of the Internet Protocol, something we’ll learn more about in session two of the Rainbow Unit.
Data Transport
As the evolution of computer networking continued into the 1970s, a number of different government- and corporate-sponsored programs led to the development of protocols, standards, and frameworks for data, information, and communication distribution between computers. This included CYCLADES in France, NPL network in the UK, and ARPANET in the United States. Through extended work by international bodies such as the International Organization for Standardization (ISO) and the Telecommunications Standardization Sector of the International Telecommunication Union (ITU-T), an Open Systems Interconnection (OSI) reference model was created and formally published in 1984 as both ISO 7498 and X.200. A key component of the OSI is a seven-layer model.
With regard to the Internet, these layers are practically combined into four groups, as follows:
| Application & Presentation Layers | Provide the physical client/server (e.g. web browser client/, server and , database server) or (e.g., Bittorrent, Bitcoin) applications with which end users work & the data translation and representation used in support of those applications |
| Session & Transport Layers |
Provide interhost communication and connections using protocols such as the and . While T