Information Technology Reference
In-Depth Information
20% of spending on enterprise applications and infrastructure software and 8% of
spending on custom software will be spent on Cloud computing. The worldwide
Cloud Computing market is expected to reach $95 billion by 2011. This represents
12% of the total worldwide software market.
One of the recurrent challenges for businesses in this area is how to manage
the deployment, distribution and configuration of the capabilities and resources
required for offering a service that is distributed over multiple hosts that may not be
under the control of the same enterprise. According to the analysis at (Dimitrakos et
al 2009a), the top four concerns in this area have to do with:
• How to define and enforce security policy
• How to measure and optimize resource usage
• How to monitor and evaluate the quality-of-service offered against an SLA
• How to manage configuration over a federation of hosting platforms
In response to this challenge we show how many of the common capabilities
mentioned in previous chapters can be integrated into, or enable, a capability that we
call “
(Enhanced) Application Virtualisation
”. This enables managing the deploy-
ment, distribution, coordination and configuration of the capabilities and resources
required for offering as a service applications distributed over a group of network
hosts. The latter can be nodes of a Grid or an aggregation of Cloud platforms offered
by a single or multiple platform providers. On such environments, this capability can
add an instrumentation layer configuring and coordinating different service execu-
tion environments for enabling the secure and manageable exposure to consumers
of remotely hosted (and potentially distributed) applications. Even if, in the shorter
term, an enterprise is not considering managing services that are distributed among
different Cloud environments, this collection of capabilities offers a means for
providing a unifying layer for managing security (i.e. identity, access management,
secure service integration, etc.), SLA fulfilment and performance monitoring across
multiple service delivery platforms.
An evolution of this bundle of capabilities could also be exploited to coordinate
the integration of, and manage, Software-as-a-Service (SaaS) offered on Cloud plat-
forms of different providers (e.g. Amazon, Microsoft Azure, etc.). It is reasonable,
in fact, to suppose that different Cloud providers could differentiate their offers
hence generating a market where different Cloud platforms are best fit for hosting
different kinds of services. Consequently offering a capability enabling the selection
of most suitable providers for hosting a SaaS solution as well as coordinating appli-
cation deployment and exposure on Cloud platforms offered by different providers
can be attractive and produce high return on investment. According to a 2009 survey
of European SMEs by ENISA (ENISA 2009) the majority of responders (32%)
consider a federation of Cloud platforms offered by various providers to be most
suitable Cloud for an SME. A close second (28%) is a Cloud platform offered by a
trusted partner for use by a business community.
A typical usage scenario of this capability is shown in the following figure 8.9,
where an Application Service Provider (ASP) provides an in-cloud SaaS to a client
on the basis of an agreed contract (SLA). In order to optimise capital expenditure
