If infrastructure as a service is a way to provide virtual
machines, servers, storage and other infrastructure
services via the cloud, what is platform as a service (PaaS)?
There has long been confusion between the two — and for
good reason.
Both offer computing via the cloud, but at different layers.
The difference is this: The PaaS model provides both a
computing platform, consisting of application building
blocks such as databases and file sharing, along with
applications that run on the platform, while IaaS provides
the infrastructure building blocks only — storage, hardware
and networking components.
Clearly, PaaS and IaaS are closely related, because
applications, platforms and infrastructure can’t work
without each other. This has led some to speculate that the
two eventually will become one layer of service. In the past
year, Microsoft added an IaaS platform on top of its Azure
PaaS platform, while Amazon added PaaS functions to its
IaaS platform.
And just recently, HP announced plans to launch a cloud
service that will combine PaaS, IaaS and SaaS (software
as a service). It will offer both structured and unstructured
databases, along with data analytics as a service. It will also
offer tools to help developers use software languages such
as Ruby, Java and PHP, as well as ways for users to provision
and manage workloads remotely.
Combining two layers (or even three) of cloud services is
a trend that may grow over time. By adopting some cloud
infrastructure earlier rather than later, organizations will
be better prepared to move more services to the cloud — in
whatever form they happen to take.