09 Cloud Computing

8/12/2019 09 Cloud Computing

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95-843 SOAAdapted fromA View of Cloud ComputingUC Berkeley

1Master of Information SystemManagement

95-843 Service Oriented

Architecture

Cloud Computing and SOA

Notes adapted from A View of Cloud Computing, Armbrust,and others -UC Berkeley Reliable, Adaptive, DistributedSystems Laboratory


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Cloud Computing


From A View of Cloud Computing, Armbrust, andothers -UC Berkeley Reliable, Adaptive, DistributedSystems Laboratory


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Suppose you have aninnovative idea

You need a large capital outlay inhardware.

You need talented humans to operate

and maintain the system. There is an over provisioning risk the

new system may not be as popular asyou hoped.

There is an under provisioning risk -missing and losing potential users.

Cloud computing allows you to start

small and grow as needed. 3Master of Information SystemManagement


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Over or Under-Provisioning



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Over or Under-Provisioning


Shaded area is unused capability.Shaded area representsrequests not served.

Less andless

demand.


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Master of Information SystemManagement

Real world estimates

Average server utilization is 5% to20%.

Peak workload exceeds the average byfactors of 2 to 10.

Users provision for the peak.

Peak loads may occur based on the

time of day or based on other factors(e.g. photo sharing after the holidays,drop/add within two weeks of start ofterm, etc.)

6Master of Information System


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Or, suppose you have as

large batch-oriented task? How do we benefit from using a

cloud?

1000 servers for one hour costsnot more than 1 server for 1000hours.

This degree of elasticity may beunprecedented in the history of IT.



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Three new aspects

The illusion of infinite computingresources on demand (no farahead provisioning concerns)

The elimination of up frontcommitment by cloud users (startsmall and grow)

Pay for resources on a short termbasis as needed (rewardconservation)



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Key Enablers

Construction and operation ofextremely large-scale commodity-computer datacenters at low cost

locations

Statistical multiplexing to increaseutilization (to each according to his

needs) varies over time thisdiffers from traditional hosting

Virtualization of computation,

storage, and communication 9Master of Information SystemManagement


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Three Examples

AppEngine(Google) Build scalable webapplications fast. Not for general purposecomputing.

Azure(Microsoft) Use .NET and .NETlibraries as needed. General purposecomputing on a Microsoft platform.

EC2(Amazon) Elastic Compute Cloud

(Choose OS and the entire software stack.General purpose computing



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Three Examples

AppEngine(Google) Least flexible

Application domain-specific platform

Automatic scaling and high availability

Proprietary megastore for data storage Azure (Microsoft) Moderately Flexible

Language independent softwaredevelopment platform

EC2(Amazon) Highly Flexible

Hardware virtual machine

You build from the kernel upward



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Top 10 Obstacles To CloudComputing

1.Business continuity and service

availability

Will the cloud provider remain inbusiness over the long haul?

Can we prevent a single point of

failure by using more than oneprovider?



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2. Data Lock-in

Cloud storage is essentially

proprietary.

SaaS developers cannot easily extract

their data and place it on multiple

clouds.

One solution would be to

standardize data APIs.



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3. Data Confidentiality/Auditability

Security is one of the most

often-cited objections to cloudcomputing.

Think HIPAA regulations and

Sarbanes-OxleyThis is an old and difficult

problem but, in the cloud, more

parties are involved. 14Master of Information SystemManagement

The authorsbelieve this isno moredifficult than

in traditionaldatacenters.


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4. Data transfer bottlenecks


At $100 to $150 per terabyte transferred, costs may quicklyadd up. Shipping disks may be cheaper.

In 2010, the Library of Congress claims to hold 235 terabytes.Wikipedia holds about 5.87 terabytes.Watson, of Jeopardyfame, has 16 terabytes of RAM.

One terabyte is about 1012bytes.


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5. Performance unpredictability


Multiple virtual machines can share CPUs and main memoryvery well in cloud computing. Network and disk I/Osharing is less predictable.

Virtual machines are not new. IBM developed much of this inthe 1980s.

Flash memory preserves information when powered offlike mechanical hard disks. It is much faster to accessand its use may reduce I/O interference.


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6. Scalable storage


An open research question is to create a storage systemthat would not only meet existing programmer expectationsin regard to durability, high availability, and the ability tomanage and query data but combine them with the cloudadvantages of scaling arbitrarily up and down on demand.

AWS uses Amazon Elastic Block Store (EBS) and SimpleDBAzure uses SQL Data Services and Azure Storage ServiceAppEngine uses Megastore/BigTableMany open source NO(Not Only)SQL Projects


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7. Bugs in large scale distributed

systems

News on April 25, 2011:Amazon said it has completed its recovery efforts anda tiny percentage of data lost won't be fully restored.

"We're in the process of contacting these customers,"

Amazon said Monday afternoon on its Web site.

Amazon said it is "digging deeply" into the root causes

behind last week's shutdown and will provide a

"detailed post mortem" in the future.



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8. Scaling quickly


Pay as you go applies to storage and network bandwidth.Simply count byes used.

Google App Engine automatically scales based on loadincreases and decreases.

AWS charges by the hour for the number of instances youoccupy even if your machine is idle.

The challenge is to scale fast (up and down) to save moneywithout violating SLAs.


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9. Reputation fate sharing


One bad apple spoils the bunch.

EC2 IP addresses have beenblacklisted by spam prevention services blocking some goodguys from sending email.

The FBI raided a Dallas data center because a company whoseservices were hosted there was under investigation. Manyinnocent bystanderswere down for days and some wentout of business.


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10. Software licensing


Current practice is to restrict the computer on which thesoftware can run. The software is purchased along with amaintenance fee. This is not the pay-as-you go model.

Microsoft and IBM are now offering pay-as-you go pricing.

In 2011, IBM charges $6.39 per hour for WebSphere withLotus Web Content Management running on EC2.


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95-843 SOAAdapted fromA View of Cloud Computing

SOA and Cloud Computing

22Master of Information SystemM t

While you can certainly leverage a cloud without practicing SOA,and you can leverage SOA without leveraging cloud computing,the real value of cloud computing is the ability to use services,data, and processes that can exist outside of the firewall

From Cloud Computing and SOA Convergence in your Enterpriseby David S. Linthicum

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09 Cloud Computing