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What is Cloud?
A datacenter hardware and software that are used to offer computing resources and services
What does Cloud Computing refer to?
applications delivered as services
data center hardware and software that provide those services
TF
Cloud computing is the transformation of applications/IT being delivered as products to being delivered as services
T
Types of cloud (3)
Public cloud
Private cloud
Hybrid cloud
Public cloud
cloud is made available to public
in a pay-as-you-go manner
service sold is utility computing
Customers share same infrastructure, but they are isolated
Private Cloud
internal data-centers of organizations not available to public
managed internally or by third-party providers
Involves CapEx
Hybrid Cloud
leverage both models
seamlessly migrate data/app between private and public
Cloud Economics – for Users
Demand for service vary with time
Demand is unknown
Computation intensive
TF
There is a minimum/upfront cost for cloud computing
F
TF
There is a predictable peak and trough demand for
servers in cloud computing
T
TF
Using 1000 servers for 1 hour costs the same as 1 server for 1 hour
F
Economies of scale:
Purchasing, powering & managing machines at scale gives lower per-unit
costs than customers’
Speed of iteration
Software as a service means faster time-to-market, updates, and detailed monitoring/feedback
Cloud service models
Infrastructure-as-a-service
Server-less
Platform-as-a-service
Infrastructure-as-a-service
basic computing resources
users control the software stack from the kernel upward
provider cannot offer scalability and fail over
Server-less
application domain specific platform (AppEngine)
request-reply based
automatic scaling, high availability
not suitable for general purpose computing
Platform-as-a-service
supports general purpose computing
user can choose language but not libraries, OS
automatic scaling but requires configuration by users
Signal
software interrupts to process
TF
Process can react to a signal or choose to ignore
T
Use command ‘____’ to send a signal to a process
kill
‘kill -9 pid’
kills the specified process; cannot be caught
‘kill -15 pid’
terminates the specified process; can be caught and some
actions can be taken before terminating
Regular Expression (regex)
A pattern matched against a text
consists of sequence of characters
Fundamental building block of regex
an exp that matches a character
dot:
matches any single character other than \n
\w:
Any word character
bracket expression
set of characters – any one is matched
ex range: [a-h]
^:
exclusion operator
-[^a] matches with anything other than a
anchor
specify where the next character in the pattern must
be seen
^, $: begin of line, end of line
\b: word boundary
sequence
2 patterns with one right after the other
ab, [a-z][0-9]
alternation ‘|’
One or more alternatives.
LINUX|linux
repetition:
expression immediately before the repetition may
be repeated.
“b{m,n}
Shortened forms of repetition:
, +, ?: BA*, BA+, .+, [0-9]?
group ( )
(ab)* matches ab, abab, ababab
Note 
Flashcard (51)