Hi Saranya,

I thought the same thing just a month ago, but elasticity of a PaaS is
something strange. I'll will try to explain, but if I talk something
absurd, please let me know, because I'm new in this context.

So, when we hear about elastic services such as EC2 (just because the name,
it's not a PaaS), Heroku, CloudFoundry, OpenShift, Torquebox and Google
AppEngine, we usually think that the scalability is authomatic. But it

I'm not sure, but the only real elastic solution is Google App Engine,
because they hide from you the resources setup, you build your app inside a
SDK, deploy it to GAE and all the environment is controlled by
Google Engineers.

However, in CloudFoundry, Heroku and EC2 you need to tell them how much
resource you'll expend with your app. Heroku ask you how much machines
(dynos) will you need, for example.

So, CloudFoundry does it in the same way, it asks you how much resources
you need to run your app, and behind the scenes, you need to have a huge
setup with several machines / VMs to support this, and make possible to
expand or shrink your app resources using the vmc. This is the Elasticity
of the CloudFoundry, just like Heroku.

If you refer to the code you can figure out how this happen, the
CloudController asks to Dea if it's possible to expand your app's
resources. But also, think about auto-elasticity and costs. It's possible
to run a code with performance problems, and the PaaS will adjusts the
resources and send you a huge bill $$$, unless you can define a limit for
this, with vmc you can do it, expand and shrink if want, as soon as you
notice that would be necessary.

I hope this was helpful.

Best regards.

Robson Mendonça
Técnico em Análise e Programação Senior
T&T Engenheiros Associados Ltda. <http://tet.com.br/>

2012/8/6 saranya <cmsaranyabe@gmail.com>
I deployed spring web application,which gets the username,password and how
many times want o insert in db for checking scalability

for example

1500 times inserted in mysql db. My configuration is 128mb memory,2
cpu,1024 kb hard disk
upto 127mb memory increased after that 502 Gateway error displayed,whole
record not inserted in DB

It is not automatically use Elastic and Not Expand instance.
Please Help me.


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postedAug 6, '12 at 2:10p
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