Cloud computing is using information technology as a service over the network. These services are encapsulated, have an API, and are available over the network. Cloud computing is based on the principle of efficiency. It can be provided using enterprise resources, or it can be provided by a cloud provider that takes all of the capital risk of owning the infrastructure. The model for cloud computing is called infrastructure as a service - IaaS. The combination of virtual machines and appliances as standard deployment objects is one of the key features of cloud computing. Virtual machines have become a standard deployment object. They enhance flexibility because they abstract the hardware to the point where software stacks can be deployed and redeployed without being tied to a specific physical server. The combination of virtual machines and appliances as standard deployment objects is one of the key features of cloud computing. Compute clouds are usually complemented by storage clouds that provide virtualized storage.
- A developer chooses a Load Balancer, Web Server, and Database Server appliances from a library of preconfigured virtual machine images;
- The developer configures each component to make a custom image;
- The developer creates the new architecture, making the components meet specific application requirements;
- The developer chooses patterns for each layer and deploys them, handling networking, security, and scalability issues.
Public Cloud Model
- Public Clouds;
- Private Clouds;
- Hybrid Clouds.
A public cloud provides services to multiple customers, and is typically deployed at a colocation facility. Public clouds are run by third parties, and applications from different customers are likely to be mixed together on the cloud’s servers, storage systems, and networks.
Private Cloud Model
Private clouds may be supported by a company, by a cloud provider, or by a third party such as an outsourcing firm. They are built for the exclusive use of one client, providing the utmost control over data, security, and quality of service. The enterprise owns the infrastructure and has control over how applications are deployed.
Hybrid Cloud Model
Hybrid clouds combine both public and private cloud models, and they can be particularly effective when both types of cloud are located in the same facility.