Thèse de doctorat: Algorithmes de classification répartis sur le cloud

tel-00744768, version 1 - 23 Oct 2012
16 CHAPTER 2. PRESENTATION OF CLOUD COMPUTING
to outsource their computing solution, making computation and storage a facility
as electricity already is. These new commercial services are referred to as Cloud
Computing.
The fast-growing interest in Cloud Computing over the past few years has led to a
fuzzy and continuously evolving situation: many have heard of it, but few people
actually agree on a specific definition. More importantly, even fewer understand
how it can benefit them. From our point of view, the best definition of Cloud
Computing has been provided by Armbrust et al. in [25]: Cloud Computing
"refers to both the applications delivered as services over the Internet and the
hardware and systems software in the data centers that provide those services".
From a consumer’s point of view, Cloud Computing allows any user to rent a
large number of computing instances in several minutes to perform data/compute
intensive jobs or build web applications. Since such instances can be dynamically
provisioned up or down, it allows users to meet specific scale-up constraints, i.e.
to be able to be enlarged to accommodate growing amount of work. For example,
this scaling elasticity lets consumers face weekly data consumption peaks. The
storage and computing capacities are provided as a service in a pay-as-you-go
way. Cloud Computing therefore disburdens users from the hardware investment.
Many Cloud Computing solutions have already been developed. There are two
categories of cloud solutions. The first category includes all the big Cloud Computing
providers, such as Google, Microsoft or Amazon. They often provide
the cheapest prices of Cloud Computing solutions, through well-designed but
fixed frameworks. The second category gathers all the small Cloud Computing
offers. Contrary to the former ones, the small actors provide their customers with
custom Cloud Computing solutions. While the storage or CPU costs of these
companies usually cannot compete with the big providers’ prices, their economic
advantage lies in all the specific services provided to their customers with. In
particular, the small Cloud Computing providers sometimes embody the ability
for companies’ top management to challenge or replace some tasks previously
reserved to their Information Technology (IT) department, for example in the case
of a conflict between the top management and the IT. As a consequence, the Cloud
Computing adoption may sometimes be the subject of internal political dealings.
The small and custom Cloud Computing offers are therefore of prime interest
for many potential customers as they can adapt to specific needs. However, the
present chapter does not further detail these offers, as it aims to focus on the most
appropriate cloud solutions for intensive computations.
A survey of Cloud Computing realized in 2011 by TNS ([8]) provides first feed