Week 8: SELF-PACED READING Flashcards
_ is the world’s largest coding community for children and a coding language with a simple visual interface design to gentle introduction of programming concepts.
Scratch
_ is an increasingly popular choice as a first programming language in computer science curricula.
Python
In addition to the three-tier model, other types of distributed computing include:
- Client-server architectures. These use smart clients that contact a server for data, and then format and display that data to the user.
- N-tier system architectures. Typically used in application servers, these architectures use web applications to forward requests to other enterprise services.
- Peer-to-peer architectures. These divide all responsibilities among all peer computers, which can serve as clients or servers.
_ is a general term for anything that involves delivering hosted services over the internet.
Cloud computing
_ is a special case of a more common mechanism called a multicast in which a value is sent to a subset of nodes.
Broadcasting
✓ It has one sender and multiple receivers.
_ is the collection of information from several sources into one sink (as in the fan-in tree)
Convergecast
✓ is a fundamental operation of distributed systems, and is commonly used in sensor networks in which the information from several sensors must be aggregated into a node.
✓ the idea is similar to a multicast, in that a tree is employed, this time to move information from the leaves to the root.
_ has one/more senders and one/more recipients participate in data transfer traffic.
Multicasting
✓ It has one or more senders and multiple receivers.
The _ is a package that supports spawning processing using API similar to the threading module.
tree
The _ is an important interconnection network in modern computing systems.
bus
_ have additional circuitry via which the gate outputs can be enabled or disabled.
Tri-state gates
A _ is a group of computers connected through wires, optical fibres, or optical links so that various devices can interact with each other through a network.
Computer Network
- The aim of the computer network is the sharing of resources among various devices.
- In the case of computer network technology, several types of networks vary from simple to complex level
_ defines the structure of the network of how all the components are interconnected to each other.
Topology
Two types of topology
physical and logical topology
_ is the geometric representation of all the nodes in a network.
Physical topology
_ refers to the way data is transmitted from one node to another on a network.
Logical Topology
_ is designed in such a way that all the stations are connected through a single cable known as a backbone cable.
BUS TOPOLOGY
- The configuration of a bus topology is quite simple as compared to other topologies.
- The backbone cable is considered as a “single lane” through which the message is broadcast to all the stations.
- The most common access method of the bus topologies is CSMA (Carrier Sense Multiple Access).
The most common access method of the bus topologies is _.
CSMA (Carrier Sense Multiple Access)
Advantages of bus topology
- Low-cost cable
- Moderate Data Speeds
- Familiar Technology
- Limited Failure
It is a media access control used to control the data flow so that data integrity is maintained, i.e., the packets do not get lost.
CSMA (Carrier Sense Multiple Access)
There are two alternative ways of handling the problems that occur when two nodes send messages simultaneously.
- CSMA CD: CSMA CD (Collision detection) is an access method used to detect the collision. Once the collision is detected, the sender will stop transmitting the data. Therefore, it works on “recovery after the collision”.
- CSMA CA: CSMA CA (Collision Avoidance) is an access method used to avoid collision by checking whether the transmission media is busy or not. If busy, then the sender waits until the media becomes idle. This technique effectively reduces the possibility of a collision. It does not work on “recovery after the collision”.
_ is an access method used to detect the collision. Once the collision is detected, the sender will stop transmitting the data. Therefore, it works on “recovery after the collision”.
CSMA CD (Collision detection)
_ is an access method used to avoid collision by checking whether the transmission media is busy or not. If busy, then the sender waits until the media becomes idle. This technique effectively reduces the possibility of a collision. It does not work on “recovery after the collision”.
CSMA CA (Collision Avoidance)
_ is like a bus topology, but with connected ends.
RING TOPOLOGY
- The node that receives the message from the previous computer will retransmit to the next node.
- The data flows in one direction, i.e., it is unidirectional.
- The data flows in a single loop continuously known as an endless loop.
- It has no terminated ends, i.e., each node is connected to another node and has no termination point.
- The data in a ring topology flow in a clockwise direction.
- The most common access method of the ring topology is token passing.
It is a network access method in which a token is passed from one node to another node.
Token passing
It is a frame that circulates the network.
Token
The message-passing paradigm is a powerful concept for problem-solving from small clusters to extreme-scale supercomputers.
THE MESSAGE-PASSING CONCEPT
- Is a standardized interface for exchanging messages between multiple computers running a parallel program across
Two main communication mechanisms are:
- Point-to-point communication: allows pairwise data exchanges, while a collective communication coordinates data exchange and synchronization across many processes in a single operation.
- Collective communications: Communication groups, called communicators, can be defined in order to partition the possible destinations that processes can send to. Only processes that belong to a communicator can send to other processes in that communicator. This is a very useful concept when multiple MPI instances need to be used simultaneously.
Allows pairwise data exchanges, while a collective communication coordinates data exchange and synchronization across many processes in a single operation.
Point-to-point communication
Communication groups, called communicators, can be defined in order to partition the possible destinations that processes can send to. Only processes that belong to a communicator can send to other processes in that communicator. This is a very useful concept when multiple MPI instances need to be used simultaneously.
Collective communications
MPI defines this communicator as MPI _ COMM _ WORLD, and in practice, many applications use MPI _ COMM _ WORLD as their communicator. (NO SPACE IN UNDERSCORE)
One of the most important operations for a distributed process computation is the ability to synchronize all of the processes at a given point during execution. Similarly to shared memory threading models, a barrier operation forces all of the processes to report that they have arrived at the barrier point in the code. After all of the processes have arrived at the barrier, the processes are then permitted to continue execution.
Noted
One way to reduce the communication time.
Cloud Computing
A synchronization operation that ensures all processes reach a common synchronization point before proceeding.
Barrier
Communication routines that involve all processes
Collective operation
In multiprocessing, processes are spawned by creating a process object that calls its _
start() method
The barrier is called a _ because all processes, rather than a single send-receive pair, participate.
collective operation
Types of collective operations
- Broadcast (one to all)
- Gather (get data from all other processes)
- Scatter (sends data from one task to all other tasks in a group)
- Reduce (combines values from all processes into a single value, e.g., an addition)
- All-to-all (every process broadcast).
