What is Cloud Computing ?
The Internet is often represented as a cloud and the term “cloud computing” arises from that analogy. Accenture defines cloud computing as the dynamic provisioning of IT capabilities (hardware, software, or services) from third parties over a network. McKinsey says that clouds are hardware-based services offering compute, network and storage capacity where: hardware management is highly abstracted from the buyer; buyers incur infrastructure costs as variable OPEX [operating expenditures]; and infrastructure capacity is highly elastic . The cloud model differs from traditional outsourcing in that customers do not hand over their own IT resources to be managed. Instead they plug into the cloud, treating it as they would an internal data centre or computer providing the same functions.
The great advantage of cloud computing is “elasticity”: the ability to add capacity or applications almost at a moment’s notice. Companies buy exactly the amount of storage, computing power, security and other IT functions that they need from specialists in data-centre computing. They get sophisticated data centre services on demand, in only the amount they need and can pay for, at service levels set with the vendor, with capabilities that can be added or subtracted at will. The metered cost, pay-as-you-go approach appeals to small- and medium-sized enterprises; little or no capital investment and maintenance cost is needed. IT is remotely managed and maintained, typically for a monthly fee, and the company can let go of “plumbing concerns”. Since the vendor has many customers, it can lower the per-unit cost to each customer. Larger companies may find it easier to manage collaborations in the cloud, rather than having to make holes in their firewalls for contract research organizations. Now the second thing that comes to our mind is how big is cloud computing......
$42B
This is the estimated size of the cloud computing Infrastructure market in 2012, which was only $16B in 2008, IDC October 2008
 |
| What a cloud consists of |
TYPES OF CLOUDS
1.IaaS
Infrastructure as a Service (IaaS) also referred to as Resource Clouds, provide (managed and scalable) resources as services to the user – in other words, they basically provide enhanced virtualisation capabilities. Accordingly, different resources may be provided via a service interface: Data & Storage Clouds deal with reliable access to data of potentially dynamic size, weighing resource usage with access requirements and / or quality definition.
Examples: Amazon S3, SQL Azure.
2. PaaS
Platform as a Service (PaaS), provide computational resources via a platform upon which applications and services can be developed and hosted. PaaS typically makes use of dedicated APIs to control the behaviour of a server hosting engine which executes and replicates the execution according to user requests (e.g. access rate). As each provider exposes his / her own API according to the respective key capabilities, applications developed for one specific cloud provider cannot be moved to another cloud host – there are however attempts to extend generic programming models with cloud capabilities .
Examples: Force.com, Google App Engine, Windows Azure (Platform).
3. SaaS
Software as a Service (SaaS), also sometimes referred to as Service or Application Clouds are offering implementations of specific business functions and business processes that are provided with specific cloud capabilities, i.e. they provide applications / services using a cloud infrastructure or platform, rather than providing cloud features themselves. Often, kind of standard application software functionality is offered within a cloud.
Examples: Google Docs, Salesforce CRM, SAP Business by Design.
On the basis of the deployment modes of clouds, they can be categorized into 5 types:
1. Private Clouds are typically owned by the respective enterprise and / or leased. Functionalities are not directly exposed to the customer, though in some cases services with cloud enhanced features may be offered – this is similar to (Cloud) Software as a Service from the customer point of view.
Example: eBay.
2. Public Clouds . Enterprises may use cloud functionality from others, respectively offer their own services to users outside of the company. Providing the user with the actual capability to exploit the cloud features for his / her own purposes also allows other enterprises to outsource their services to such cloud providers, thus reducing costs and effort to build up their own infrastructure. As noted in the context of cloud types, the scope of functionalities thereby may differ.
Example: Amazon, Google Apps, Windows Azure.
3. Hybrid Clouds . Though public clouds allow enterprises to outsource parts of their infrastructure to cloud providers, they at the same time would lose control over the resources and the distribution / management of code and data. In some cases, this is not desired by the respective enterprise. Hybrid clouds consist of a mixed employment of private and public cloud infrastructures so as to achieve a maximum of cost reduction through outsourcing whilst maintaining the desired degree of control over e.g. sensitive data by employing local private clouds. There are not many hybrid clouds actually in use today, though initial initiatives such as the one by IBM and Juniper already introduce base technologies for their realization .
4. Community Clouds. Typically cloud systems are restricted to the local infrastructure, i.e. providers of public clouds offer their own infrastructure to customers. Though the provider could actually resell the infrastructure of another provider, clouds do not aggregate infrastructures to build up larger, cross-boundary structures. In particular smaller SMEs could profit from community clouds to which different entities contribute with their respective (smaller) infrastructure. Community clouds can either aggregate public clouds or dedicated resource infrastructures.
5.Special Purpose Clouds. In particular IaaS clouds originating from data centres have a “general purpose” appeal to them, as their according capabilities can be equally used for a wide scope of use cases and customer types. As opposed to this, PaaS clouds tend to provide functionalities more specialized to specific use cases, which should not be confused with “proprietary” of the platform: specialization implies providing additional, use case specific methods, whilst proprietary data implies that structure of data and interface are specific to the provider.
Cloud Computing Architecture
When talking about a cloud computing system, it's helpful to divide it into two sections: the front end and the back end. They connect to each other through a network, usually the Internet. The front end is the side the computer user, or client, sees. The back end is the "cloud" section of the system.
The front end includes the client's computer (or computer network) and the application required to access the cloud computing system. Not all cloud computing systems have the same user interface. Services like Web-based e-mail programs leverage existing Web browsers like Internet Explorer or Firefox. Other systems have unique applications that provide network access to clients.
On the back end of the system are the various computers, servers and data storage systems that create the "cloud" of computing services. In theory, a cloud computing system could include practically any computer program you can imagine, from data processing to video games. Usually, each application will have its own dedicated server.
A central server administers the system, monitoring traffic and client demands to ensure everything runs smoothly. It follows a set of rules called protocols and uses a special kind of software called middleware. Middleware allows networked computers to communicate with each other.
If a cloud computing company has a lot of clients, there's likely to be a high demand for a lot of storage space. Some companies require hundreds of digital storage devices. Cloud computing systems need at least twice the number of storage devices it requires to keep all its clients' information stored. That's because these devices, like all computers, occasionally break down. A cloud computing system must make a copy of all its clients' information and store it on other devices. The copies enable the central server to access backup machines to retrieve data that otherwise would be unreachable.
 |
| Layers in a cloud computing environment |
Visual Explanation of Cloud Computing and related concepts
No comments:
Post a Comment