Page 193 - DCAP609_CLOUD_COMPUTING

Cloud Computing

Notes
websites, for the first generation of HealthyToys.org. When the "flash crowd" hit
HealthyToys.org, the Ecology Center looked for assistance from their web hosting
company, but received nothing but shrugs and empty promises. But by the time anyone
would respond to remedy the problem, media coverage had moved on to other topics,
and the moment had passed.
Not wishing to repeat the previous year's hosting issues, yet uncertain how the second
generation of their website would be received, the Ecology Center was reluctant to invest
in an expensive multi-server, load-balanced system up-front. They needed a system that
could scale up or down easily and affordably, according to need.
The Solution
Cloud computing was the perfect solution for the Ecology Center's situation. The word
has received a lot of press recently, but what is cloud computing?
Large web service companies, such as Amazon, Google, eBay, and so on, require gargantuan
compute and network resources to make their Web-based services widely available at a
usable speed. Their operations are so large, so many computers and internet connections
required, the "economy of scale" enables them to purchase vast amounts computer hardware,
data center space, and network access at very low rates. They can then pass on these
savings and re-sell unused compute time and network bandwidth to third parties who
then have dedicated access to, for example, Amazon's hardware and network. Amazon
refers to their cloud computing service as the "Elastic Compute Cloud," or EC2.

Several features make cloud computing attractive; affordability (it is very competitive
with dedicated hosting for small sites, and much cheaper for large installations);
pro-rated, i.e. compute services are usually charged on a per-hour basis, which makes
companies that require month-or-longer hosting contracts obsolete; scalability – once a
system is set up, it is easy to add or remove servers from your "array" at any time.
However, without a significant time investment, setting up a site to work in a cloud can
take quite a while; the Ecology Center had limited time and budget to spend on systems
administration.
Mouko worked with RightScale Inc. to implement the perfect solution for the Ecology
Center's problem. Using RightScale's pre-configured operating systems, web servers, and
database servers, and sophisticated auto-scaling system, we were able to create a
loadbalanced system where we could specify threshold values for which a web server
array should grow or shrink using server load as the criterion. In anticipation of the site's
launch day, we could pre-allocate compute services (e.g. load would be shared between
ten web servers for the day the site would be announced by the press) or shrink it
significantly once traffic died down.

With a few code changes to support multiple database servers, and just a few hours invested
in learning the RightScale Web-based management interface, the Ecology Center would
have not only a new design for their website, a HealthyToys widget, and updated
information, but also an infrastructure that would scale automatically and that would be
backed up continuously to Amazon's Simple Storage Service (also known as S3).
The Result
The second-generation of HealthyToys.org was a great success and continues to receive
millions of page views. It neither suffered nor suffers from any of the performance issues
of the first generation. The Ecology Center continues to use the Amazon Elastic Compute
Cloud and RightScale for all their sites and Mouko for their web development. This is
likely to continue well into the future.
Contd....

188 LOVELY PROFESSIONAL UNIVERSITY