Computing Systems

• A computing system is when various types of computing devices, such as desktop or laptop computers, tablets, servers, routers, and/or sensors, plus software, work together for a use such as managing the power grid, traffic signals, a smart home, or a network such as the Internet.

• The connections between devices create paths.

• Routers are computing devices along a path that send the information along to the next stop on the path.

• The routing is determined at the moment it is needed, meaning it is dynamic.

How the Internet Works

• The Internet is a network of networks.

• The word Internet came from “interconnection of computer networks.”

• The Internet is very hardware driven with wires, cables, and devices such as routers and servers.

Packets and Data Streams

• Data streams are information transmitted via the Internet.

• The processing of Internet traffic is done at the sending and receiving locations.

• At the sending location, the information to be sent, such as a web page, is broken into smaller packets of the same size (except possibly the last one, which could be smaller).

• Once all packets have arrived at the destination, they are reassembled in order.

  • This is called an end-to-end architecture, because the processing is done at each end.

Protocols

• Every device on a network is called a “host.”

• When a device connects to the Internet, it is given an “address” similar to the idea of a mailing address given to homes and businesses.

• The addresses enable devices to find and communicate with each other.

  • The address is called an Internet Protocol (IP) address.

• Protocols are a set of rules.

  • These are needed so different equipment made by different companies can communicate with each other.

• One of the oldest protocols is TCP/IP.

• TCP creates the packets at the sending location and reassembles them at the receiving one.

  • TCP/IP stands for: Transmission, Control, Protocol/ Internet, Protocol.

• UDP is another common protocol and stands for: User, Datagram, Protocol.

• UDP is also built on top of IP similar to how TCP works with IP.

• UDP does not send a confirmation message back to the sender when packets are received.

Fault-Tolerant

• There is a lot of redundancy or duplication built into the Internet on purpose.

• It is built in by providing multiple paths between devices on the Internet.

• This means that if one point goes down and is not working, then the traffic will be redirected to a different path to get to its ultimate destination.

World Wide Web

• The World Wide Web (WWW) is an application that runs on the Internet.

• The World Wide Web is a collection of web pages, documents, and files, written in hypertext markup language (HTML).

• Web browsers read the HMTL code to know how to display the web page with colors, formatting, images, videos, lists, and more.

Hypertext Transfer Protocol (HTTP)

• HTTP is a protocol used by the World Wide Web.

• It controls how web page data is requested, sent, and received from the browsers and servers where the web pages are stored.

• HTTPS should be used for any secure transaction, such as those involving financial data, medical data, and sites that require a password.

Types of Processing

Sequential Computing Systems

• Most of our day-to-day computational work is done on our local devices in a sequential order, with operations executing one after the other in the specified order.

• This sequential computing model is more than sufficient for what we do.

• Sequential systems cannot scale because each step runs after the one ahead of it finishes.

Parallel Computing Systems

• Sequential processing is too slow to handle these algorithms.

  • That’s when parallel computing can be used to speed up the processing.

• More computers and processors can be added to scale up and further reduce the amount of time it will take to run the program to a certain point.

• The speedup of a parallel process is determined by dividing the time it took to process the problem sequentially by the time it took to complete it in parallel.

Distributed Computing Systems

• This model can handle the speed and memory requirements for heavy-duty processing needs that a single computer cannot due to resource constraints.

• In this case, the data is spread out among multiple computers.

Next Chapter: Chapter 11: Impact of Computing