Cloud computing is utility computing. No up front commitment
required. You buy only what you need, and when you do not need it any more you
do not pay for it.
There are three basic cloud computing scenarios:
infrastructure scenarios, application delivery scenarios, and scaling
scenarios. These scenarios are not independent, one or all of them can come into
play. Each, however, has different
technological implications.
The three basic scenarios are: infrastructure, application
delivery, or the need to reach internet scale.
Fundamentally, cloud computing is a software delivery
platform. Are the economics of working with the cloud cheaper than doing it
yourself? Doing it yourself could mean self-hosting, or traditional delivery of
desktop software. Self-hosting could be in your own data center, or in a
hosting facility.
Not needing to build to your peak capacity drives the
infrastructure scenarios. This is not an all or nothing proposition.
Some small and medium sized companies may decide they do not
want to run their own data centers. The savings in terms of not having to buy
machines and pay employees is enormous. This money could be put to use in
building better applications. This might be the entire compute infrastructure,
or just running an email server.
Other companies may have an occasional need for massive
computation. Say you have to do a stress analysis of a new airplane wing, or a
geographical routing of a complicated delivery, decide among alternative new financial models, or even a human genome search. Any of the classic grid
computations fall into this category. Your existing infrastructure is just fine, but for these not
every day scenarios (they might actually be frequent) it makes sense to rent
space in the cloud to do the computations.
A related scenario is cloud-bursting. You can handle your
everyday computing demands, but occasionally you get a burst of orders that
overwhelms your system. Ticket agencies are a classic example when tickets for a popular event first go on sale. So are stores
around the holidays. Here you use the cloud to handle the overflow so that
people wanting to order do not get unresponsive web pages, or busy signals on
the telephone.
Small divisions in large companies may find the cloud appealing
for prototyping, or even developing certain applications. Their central IT may
be unresponsive or slow to respond to their needs. It is well within the
capacity of a departmental budget to rent space in the cloud.
The next post will explore the other two scenarios, and look
at how the various vendor options would meet your needs.