Cloud computing, or something within the cloud, is an expression used to describe a variety of computing concepts that involve a large number of computers connected through a real-time communication networks such as the Internet. A detailed explanation of various types of cloud and various advantages and disadvantages of cloud computing.

1. CLOUD COMPUTING: SOME BASIC
CONCEPTS

2. CLOUD COMPUTING
CLOUD COMPUTING, OR SOMETHING WITHIN THE CLOUD, IS AN EXPRESSION USED
TO DESCRIBE A VARIETY OF COMPUTING CONCEPTS THAT INVOLVE A LARGE NUMBER
OF COMPUTERS CONNECTED THROUGH A REAL-TIME COMMUNICATION NETWORKS
SUCH AS THE INTERNET.
IN SCIENCE, CLOUD COMPUTING IS A SYNONYM FOR DISTRIBUTED COMPUTING
OVER A NETWORK, AND MEANS THE ABILITY TO RUN A PROGRAM OR APPLICATION
ON MANY CONNECTED COMPUTERS AT THE SAME TIME.
THE PHRASE ALSO MORE COMMONLY REFERS TO NETWORK-BASED SERVICES,
WHICH APPEAR TO BE PROVIDED BY REAL SERVER HARDWARE, AND ARE IN FACT
SERVED UP BY VIRTUAL HARDWARE, SIMULATED BY SOFTWARE RUNNING ON ONE OR
MORE REAL MACHINES.

3. HISTORY OF CLOUD COMPUTING
The 1950’s
THE UNDERLYING CONCEPT OF CLOUD COMPUTING DATES BACK TO THE 1950S,
WHEN LARGE-SCALE MAINFRAME COMPUTERS BECAME AVAILABLE IN ACADEMIA
AND CORPORATIONS, ACCESSIBLE VIA THIN CLIENTS/TERMINAL COMPUTERS,
BECAUSE THEY WERE USED FOR COMMUNICATIONS BUT HAD NO INTERNAL
PROCESSING CAPACITIES.
TO MAKE MORE EFFICIENT USE OF COSTLY MAINFRAMES, A PRACTICE EVOLVED
THAT ALLOWED MULTIPLE USERS TO SHARE BOTH THE PHYSICAL ACCESS TO THE
COMPUTER FROM MULTIPLE TERMINALS AS WELL AS TO SHARE THE CPU TIME.
THE PRACTICE OF SHARING CPU TIME ON A MAINFRAME BECAME KNOWN IN THE
INDUSTRY AS TIME-SHARING.

4. The 1960s–1990s
JOHN MCCARTHY(AN AMERICAN COMPUTER SCIENTIST) OPINED IN THE 1960S
THAT "COMPUTATION MAY SOMEDAY BE ORGANIZED AS A PUBLIC UTILITY.“
OTHER SCHOLARS HAVE SHOWN THAT CLOUD COMPUTING'S ROOTS GO ALL THE
WAY BACK TO THE 1950S WHEN SCIENTIST HERB GROSCH (THE AUTHOR OF
GROSCH'S LAW) POSTULATED THAT THE ENTIRE WORLD WOULD OPERATE ON
DUMB TERMINALS POWERED BY ABOUT 15 LARGE DATA CENTERS.
DUE TO THE EXPENSE OF THESE POWERFUL COMPUTERS, MANY CORPORATIONS
AND OTHER ENTITIES COULD AVAIL THEMSELVES OF COMPUTING CAPABILITY
THROUGH TIME SHARING AND SEVERAL ORGANIZATIONS, SUCH AS GE'S GEISCO,
IBM SUBSIDIARY THE SERVICE BUREAU CORPORATION (SBC, FOUNDED IN 1957),
TYMSHARE(1966), DIAL DATA (BOUGHT BY TYMSHARE IN 1968),ETC.

5. THE 1990’S
IN THE 1990S, TELECOMMUNICATIONS COMPANIES BEGAN OFFERING
VIRTUAL PRIVATE NETWORK (VPN) SERVICES WITH COMPARABLE QUALITY OF
SERVICE, BUT AT A LOWER COST.
BY SWITCHING TRAFFIC AS THEY SAW FIT TO BALANCE SERVER USE, THEY
COULD USE OVERALL NETWORK BANDWIDTH MORE EFFECTIVELY.
THEY BEGAN TO USE THE CLOUD SYMBOL TO DENOTE THE DEMARCATION
POINT BETWEEN WHAT THE PROVIDER WAS RESPONSIBLE FOR AND WHAT
USERS WERE RESPONSIBLE FOR. CLOUD COMPUTING EXTENDS THIS
BOUNDARY TO COVER SERVERS AS WELL AS THE NETWORK INFRASTRUCTURE.

6. SINCE 2000
AMAZON PLAYED A KEY ROLE IN ALL THE DEVELOPMENT OF CLOUD
COMPUTING BY MODERNIZING THEIR DATA CENTERS, WHICH, LIKE MOST
COMPUTER NETWORKS, WERE USING AS LITTLE AS 10% OF THEIR CAPACITY AT
ANY ONE TIME.
IN EARLY 2008, OPENNEBULA, ENHANCED IN THE RESERVOIR EUROPEAN
COMMISSION-FUNDED PROJECT, BECAME THE FIRST OPEN-SOURCE
SOFTWARE FOR DEPLOYING PRIVATE AND HYBRID CLOUDS, AND FOR THE
FEDERATION OF CLOUDS.
ON MARCH 1, 2011, IBM ANNOUNCED THE IBM SMARTCLOUD FRAMEWORK
TO SUPPORT SMARTER PLANET. AMONG THE VARIOUS COMPONENTS OF THE
SMARTER COMPUTING FOUNDATION, CLOUD COMPUTING IS A CRITICAL
PIECE.

7. TYPES OF CLOUD
• PRIVATE CLOUD : PRIVATE CLOUD IS CLOUD INFRASTRUCTURE OPERATED
SOLELY FOR A SINGLE ORGANIZATION, WHETHER MANAGED INTERNALLY
OR BY A THIRD-PARTY AND HOSTED INTERNALLY OR EXTERNALLY.
• PUBLIC CLOUD : A CLOUD IS CALLED A 'PUBLIC CLOUD' WHEN THE SERVICES
ARE RENDERED OVER A NETWORK THAT IS OPEN FOR PUBLIC USE.
• COMMUNITY CLOUD : A COMMUNITY CLOUD BASICALLY SHARES
INFRASTRUCTURE BETWEEN SEVERAL ORGANIZATIONS FROM A SPECIFIC
COMMUNITY WITH COMMON CONCERNS (SECURITY, COMPLIANCE,
JURISDICTION, ETC.), WHETHER MANAGED INTERNALLY OR BY A THIRD-
PARTY AND HOSTED INTERNALLY OR EXTERNALLY.

8. • HYBRID CLOUD : HYBRID CLOUD IS A COMPOSITION OF TWO OR MORE
CLOUDS (PRIVATE, COMMUNITY OR PUBLIC) THAT REMAIN UNIQUE
ENTITIES BUT ARE BOUND TOGETHER, OFFERING THE BENEFITS OF MULTIPLE
DEPLOYMENT MODELS.
• DISTRIBUTED CLOUD : CLOUD COMPUTING CAN ALSO BE PROVIDED BY A
DISTRIBUTED SET OF MACHINES THAT ARE RUNNING AT DIFFERENT
LOCATIONS, WHILE STILL CONNECTED TO A SINGLE NETWORK OR HUB
SERVICE. EXAMPLES OF THIS INCLUDE DISTRIBUTED COMPUTING
PLATFORMS SUCH AS BOINC AND FOLDING@HOME.

9. PROTOCOLS USED FOR CLOUDCOMPUTING
NUMEROUS INITIATIVES AND STANDARDS BODIES ARE ADDRESSING THE STANDARDS
RELATED TO CLOUD COMPUTING. FROM THE NETWORKING SIDE, THE IEEE IS
WORKING ON NEW PROTOCOLS AND THE ENHANCEMENT OF EXISTING PROTOCOLS
FOR DATA CENTERS. THESE ENHANCEMENTS ARE PARTICULARLY USEFUL IN DATA
CENTERS WITH CONVERGED NETWORKS—THE AREA IS OFTEN KNOWN AS
CONVERGENCE ENHANCED ETHERNET (CEE).
THE IEEE IS WORKING TO ENABLE FCOE(FIBRE CHANNEL OVER ETHERNET) THROUGH
AN ETHERNET LINK IN WHAT IS KNOWN AS "LOSSLESS ETHERNET“.

10. PROS AND CONS OF CLOUD COMPUTING

11. PROS
• COST REDUCTION : CLOUD COMPUTING REDUCES PAPERWORK, LOWERS
TRANSACTION COSTS, AND MINIMIZES THE INVEST IN HARDWARE. MOVING YOUR
BUSINESS TO ‘THE CLOUD’ ALSO REDUCES THE NEED FOR AN IT STAFF.
• IT’S SCALABLE : LIKE ELECTRICITY AND WATER, SOME CLOUD COMPUTING
SERVICES ALLOW BUSINESSES TO ONLY PAY FOR WHAT THEY USE. AND AS YOUR
BUSINESS GROWS, YOU CAN ACCOMMODATE BY ADDING MORE SERVER SPACE.
• LEVELS THE PLAYING FIELD : CLOUD COMPUTING PROVIDERS OFFERS SMALL AND
MID-SIZE BUSINESSES ACCESS TO MORE SOPHISTICATED TECHNOLOGY AT LOWER
PRICES.
• EASIER COLLABORATION : SINCE SERVICES IN THE CLOUD CAN BE ACCESSED
ANYTIME FROM ANY COMPUTER, IT’S EASY TO COLLABORATE WITH EMPLOYEES IN
DISTANT LOCATIONS.

12. CONS
• TECHNICAL ISSUES : THOUGH IT IS TRUE THAT INFORMATION AND DATA ON THE CLOUD
CAN BE ACCESSED ANYTIME AND FROM ANYWHERE AT ALL, THERE ARE TIMES WHEN
THIS SYSTEM CAN HAVE SOME SERIOUS DYSFUNCTION. BESIDES, YOU WILL NEED A VERY
GOOD INTERNET CONNECTION TO BE LOGGED ONTO THE SERVER AT ALL TIMES.
• SECURITY IN THE CLOUD : BEFORE ADOPTING THIS TECHNOLOGY, YOU SHOULD KNOW
THAT YOU WILL BE SURRENDERING ALL YOUR COMPANY’S SENSITIVE INFORMATION TO
A THIRD-PARTY CLOUD SERVICE PROVIDER. THIS COULD POTENTIALLY PUT YOUR
COMPANY TO GREAT RISK. HENCE, YOU NEED TO MAKE ABSOLUTELY SURE THAT YOU
CHOOSE THE MOST RELIABLE SERVICE PROVIDER, WHO WILL KEEP YOUR INFORMATION
TOTALLY SECURE.
HOWEVER, THE ADVANTAGES OF CLOUD COMPUTING OVERWEIGHS ALL ITS
DISADVANTAGES !