Cloud computing is internet-based computing in which large groups of remote servers are networked to allow the centralized data storage, and online access to computer services or resources.
Cloud computing, or simply “the cloud”, also focuses on maximizing the effectiveness of the shared resources. Cloud resources are usually not only shared by multiple users but are also dynamically reallocated per demand.
The term “moving to cloud” also refers to an organization moving away from a traditional CAPEX model (buy the dedicated hardware and depreciate it over a period of time) to the OPEX model (use a shared cloud infrastructure and pay as one uses it).
Clouds can be classified as
◦ Public Cloud -Services are rendered over a network that is open for public use. Public cloud services may be free or offered on a pay-per-usage model
◦ Private Cloud is cloud infrastructure operated solely for a single organization, whether managed internally or by a third-party.
◦ Hybrid is a composition of two or more clouds (private, community or public) that remain distinct entities but are bound together, offering the benefits of multiple deployment models.
Cloud computing exhibits the following key characteristics:
◦ Agility improves with users’ ability to re-provision technological infrastructure resources.
◦ Application programming interface (API) accessibility to software that enables machines to interact with cloud software in the same way that a traditional user interface (e.g., a computer desktop) facilitates interaction between humans and computers.
◦ Cost reductions claimed by cloud providers.
◦ Device and location independence enable users to access systems using a web browser regardless of their location or what device they use (e.g., PC, mobile phone). As infrastructure is off-site (typically provided by a third-party) and accessed via the Internet, users can connect from anywhere.
◦ Maintenance of cloud computing applications is easier, because they do not need to be installed on each user’s computer and can be accessed from different places.
◦ Multitenancy enables sharing of resources and costs across a large pool of users thus allowing for:
◦ Performance is monitored, and consistent and loosely coupled architectures are constructed using web services as the system interface
◦ Productivity may be increased when multiple users can work on the same data simultaneously, rather than waiting for it to be saved and emailed.
◦ Reliability improves with the use of multiple redundant sites, which makes well-designed cloud computing suitable for business continuity and disaster recovery
◦ Scalability and elasticity via dynamic (“on-demand”) provisioning of resources on a fine-grained, self-service basis in near real-time
◦ Security can improve due to centralization of data, increased security-focused resources, etc., but concerns can persist about loss of control over certain sensitive data,the complexity of security is greatly increased when data is distributed over a wider area or over a greater number of devices, as well as in multi-tenant systems shared by unrelated users.
◦ Infrastructure as a service (IaaS)
◦ Platform as a service (PaaS)
◦ Software as a service (SaaS)
Cloud Computing Examples
◦ Amazon Web Services: The services offered are the Amazon EC2 , Amazon S3, Simple DB , Amazon SQS .
◦ Azure: Microsoft provides operating system services, hosting, systems development.
◦ Rack space, a popular hosting company, Mosso is behind a company which offers a basic hosting package and from this scaled as needed (and not migrate servers). Rack space recently acquired Jungle Disk, a popular client for Amazon S3 and that future will be integrated with Cloud Files another Mosso service.
◦ Google Apps
◦ Email, chat
◦ Google App Engine
◦ Create application
◦ Gmail, Google Talk, Google Calendar and Google Docs, etc.
Cloud Computing and Cloud solutions has become a reality and not just a buzz word anymore.