as the remote allocation of resources on the cloud. According to NIST (National Institute of Standard and Technology), the formal deﬁnition of cloud computing is the following: “Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g. networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction”
on top of basic provisioning and releasing of resources. Most of these service models fall into one of the following categories: Infrastructure as a Service Platform as a Service Software as a Service IaaS PaaS SaaS
following features of cloud computing: • Speed and Agility: ◦ Provisioned with a few clicks. ◦ Scale up or down with ease. ◦ Elasticity and demand-driven. • Cost: ◦ Reducing the up-front cost. ◦ Cost estimator, which assists users in better resource planning. • Easy access to resources: ◦ Access from any place and device. • Maintenance: ◦ Providers in charge of keeping resources up, running, and up-to-date. • Multi-tenancy: ◦ Multiple users sharing the same pool of resources, which helps to drive down the costs incurred by each user. • Reliability: ◦ Resources can be hosted in different data center locations, to provide increased reliability, resiliency, and high-availability.
Cloud: It is designated and operated solely for one organization. It can be hosted internally or externally and managed by internal teams or a third party. I.e., using OpenStack. • Public Cloud: It is open to the public and anybody can use it for a prize. I.e., Amazon Web Services, Google Cloud Platform, and Microsoft Azure. • Hybrid Cloud: Public and private clouds bounded together. Beneﬁcial for: ◦ Storage of sensitive information on the private cloud, while offering public services based on that information from a public cloud. ◦ Meeting temporary resources during peak or times of high demand by scaling to the cloud, when such temporary resources cannot be met on the private cloud.
Formed by multiple organizations sharing a common cloud infrastructure. • Distributed Cloud: Formed by distributed systems connected to a single network. • Multi Cloud: Use of multiple public cloud providers by one organisation to avoid vendor lock-in (running the same workloads). • Poly Cloud: Use of multiple public cloud providers by one organisation to leverage speciﬁc services from each provider (running different workloads).