When people hear the word “cloud”, they imagine rain and water and all these meteorological things. Cloud in IT is the buzz word for something that is well known and used – Internet. It is based on utility and consumption of computing resources. In fact, it is a broader concept of converged infrastructure and shared services.
Why should we use a cloud-based solution?
Simply because the cloud helps us to focus on our core business (developing applications, creating products, organizing our daily arrangements). Cloud computing allows the user to benefit from existing technologies without a deep knowledge and wherever and whenever the user decides.
Cloud model is composed of five essential characteristics:
- On-demand self-service – It means that the user can provision computer capabilities (server time and network storage for example) without requiring human interaction with each service provider.
- Resource pooling – Provider’s resource are pooled to serve multiple clients. One important thing to mention is that the customer has no idea of the exact location of the provided resource (and he does not care in most of the cases).
- Rapid elasticity – Capabilities can be scaled rapidly outward and inward depending on the consumer needs.
- Measured service – Resource usage can be monitored, controlled and reported, providing transparency for both the provider and consumer.
As there is a service provided, it is necessary to codify the specific parameters and minimum levels required for each element of the service, as well as the remedies for failure to meet those requirements. It is important for the consumer to specify his rights and cost to continue and discontinue using the service.
This special agreement is called Service Level Agreement (SLA) and it is a part of a service contract where the service is formally defined. Particular aspects of the service – scope, quality, responsibilities – are between the service provider and the service user. There are many providers that do not use this kind of agreement when they are signing a contract. They assure their clients that the service will have 24/7 support for example.
There are three different service models according to IETF (Internet Engineering Task Force): Infrastructure-as-a-service, Platform-as-a-service, Software-as-a-service. Each of them represents a different level of abstraction (as it`s seen in the picture).
The provided capability is to provision processing, storage, networks and other fundamental computing resources, where the customer can deploy software (operating systems, applications). The consumer is able to control operating systems, storage and deployed application. Famous IaaS providers are Amazon Web Services, the communications giant AT&T, BlueLock.
The provided capability is to deploy onto the cloud infrastructure consumer-created and acquired applications created using programming languages, libraries, services and tools supported by a provider. The customer can control the deployed applications and possibly configuration settings for the application-hosting environment.
A list of top PaaS providers contains names Amazon (again), Appistry and Salesforce.
The provided capability is to use the provider’s applications running on cloud infrastructure (collection of hardware and software that enables five essential characteristics of cloud computing). In this model, the customer isn`t allowed to control or manage underlying cloud infrastructure with a possible exception of limited user-specific application configuration settings.
SaaS Providers can be divided into several product categories: Customer Service, Office Suite, Project Management and etc. Many companies like Oracle, Google, Microsoft, Adobe, Cisco, Intuit, Symantec, SAP, and DATEV though not SaaS providers primarily do have portfolios of products that far outstrip many on this list in revenue. Others are companies that do SaaS as their primary business (Salesforce, Linkedin, Concur Technologies, Ultimate Software Group).
It is understandable that many organizations invent their own “as a service” in order to present unique service as a cloud solution. In most cases their definition of “something-as-a-service” sounds amusing: Globalization-as-a-Service, Metal-as-a-Service, Registration-as-a-Service, Vehicle-as-a-Service ... all of them are true stories.
Clouds can be divided by their deployment model too. So, here are the four deployment models:
- The Private cloud infrastructure is provisioned for exclusive use by a single organization comprising multiple customers. It may be owned and managed by the organization, a third party, or some combination of them.
- The Community cloud infrastructure is provisioned for exclusive use by a specific community of customers from organization that shares concerns.
- A Public cloud is when the services are rendered over a network that is open for public use. It may be owned and managed by a business, academic or government organization. It exists on the premises of the cloud provider.
- A Hybrid cloud is a composition of two or more distinct cloud infrastructures (private, community or public) that remain unique entities but are bound together.
Customers use (or create) that type of model that fits their own needs. It depends on many factors, such as:
- Hosting of services
- Security requirements
- If cloud should be shared or not
- How many of the services should be manageable
- Customization capabilities