Cloud Computing

Question 1

What are features of Cloud Computing?

Answer 1

• System predictable and efficient in growing the application
• In case of failure there is a lot of backup
• Customers share infrastructure
• Compose applications out of services that are loosely coupled
• Applications are decoupled from hardware (Virtualization)
• Scaleable data management

Question 2

What are problems with Cloud Computing?

Answer 2

• Loss of Control of data
• Security and privacy in shared cloud
• Loss of control over performance
• No offline access

Question 3

What is Infrastructure as a Service?

Answer 3

• Cloud Delivery model
• Allows to rent resources as:
• -> Server space
• -> CPU cycles
• -> Memory
• -> Storage space
• Infrastructure can be dynamically scaled up and down
• Example: AWS

Question 4

What is Platform as a Service?

Answer 4

• Provide all resources required to build application
• Run web application code on infrastructure
• Write code once and deploy
• Example: Google App Engine

Question 5

What is software as a service?

Answer 5

• Application is hosted as a service to customers via the internet
• Software managed at central location

Question 6

What is virtualization?

Answer 6

• Separate operating system from underlying platform resource
• Enables high server utilization
• Virtualize hardware of computer(s)

Question 7

What is real time web?

Answer 7

• Many service require instantaneous updates
• Need for massive synchronization of service instances in cloud computing
• Examples: Twitter, Real time search, instant messaging,…

Question 8

What is XMPP?

Answer 8

• Application protocol
• Client server architecture
• Enables full duplex xml streaming

Question 9

How does XMPP communication work?

Answer 9

1) Determine IP address and port to which to connect
2) Open TCP connection
3) Open XML stream over TCP
4) Negotiate TLS for channel encryption
5) Authenticate via SASL mechanism
6) Bind resource to stream
7) Exchange any number of messages
8) Close XML stream
9) Close TCP connection

Question 10

What are XML streams?

Answer 10

Container for exchange of xml elements between two entities of a network.
Bi-directional.
Stream document is the connection transcript.