AP Computer Science Principles Big Idea 4

computing device

a physical device that can run a program. i.e. a phone, tablet, computer, router, or smart sensor.

computing system

a group of computing devices working together for a common purpose.

computer network

a group of interconnected computing devices capable of sending and receiving data.

path

between two computing devices on a computer network (a sender and a receiver) is a sequence of directly connected computing devices that begins at the sender and ends at the receiver.

Routing

the process of finding a path from sender to receiver.

bandwidth

maximum amount of data that can be sent in a fixed amount of time. usually measured in bits per second (bps)

protocol

an agreed-upon set of rules that specify the behavior of a system. the internet uses open protocols, allowing users to easily connect other devices to the internet. i.e. IP TCP UDP

scalability

the capacity for the system to change in size and scale to meet new demands. for example when 8 bits is not enough to support every IP address, more bits get added. the internet was designed to be scalable.

data stream

the method of passing information in the internet which contains chunks of data, which are encapsulated in packets.

packets

contain a chunk of data and metadata used for routing the packet between the origin and the destination on the Internet, as well as for data reassembly.

redundancy

inclusion of extra components that can be used to mitigate failure of a system if other components fail. having more than one path between any two connected devices allows for redundancy.

fault-tolerant

when a system can support failures and still continue to function. this is important because elements of complex systems fail at unexpected times, often in groups, and fault tolerance allows users to continue to use the network.

sequential computing

a computational model in which operations are performed in order one at a time. it takes as long as it would to complete all tasks in order.

parallel computing

a computational model where the program is broken into multiple smaller sequential computing operations, some of which are performed simultaneously. takes as long as the sequence plus the longest parallel chunk.

distributed computing

a computational model in which multiple devices are used to run a program. allows easier access of processing tasks because of storage space or processing speed that wouldn't be good enough on a single computer; therefore, allowing much larger tasks to be solved quicker than it would've with a single computer.

"speedup"

measured in the time it took to complete the task sequentially divided by the time it took to complete the task when done in parallel.

Topic 4.1

explains how computer systems and networks facilitate the transfer of data. also explains the difference between the internet and the world wide web: WWW uses the internet and HTTP is a protocol the WWW uses.

Topic 4.2

redundancy allows computer systems to maintain fault tolerant, which is important for a server to keep working despite problems with certain paths.

Topic 4.3

Parallel and distributed computing leverage multiple computers to more quickly solve complex problems or process large data sets. although parallel computing decreases the time spent on a certain tasks, the efficiency of a solution is still limited by the sequential portion. this means that at some point, adding parallel portions will no longer meaningfully increase efficiency.