Paper five Cloud Definitions, Deployment Considerations & Diversity
1.2.1 Cloud Service Delivery Models: There are three primary business or commercial models (Genus) for the delivery of Cloud services: SaaS (software-as-a-service) refers to software or applications that are accessed over the internet (typically from a public Cloud, multi-tenancy (or shared) environment as a fully managed service). Unlike desktop applications, SaaS apps require no installation as they connect via the internet. Salesforce.com, Microsoft Office365 are popular examples of a service based in the Cloud. Typically solutions are priced per user accessing them and licensing is the responsibility of the service provider. IaaS (infrastructure-as-a-service) delivers computing infrastructure on-demand – such as RAM, storage and processors typically as virtual servers along with networking capabilities to effectively provide a hosted data centre or server on demand upon which business can run their applications. This is computing as a service, rather than businesses having to purchase and manage their own expensive infrastructure. As with most Cloud services it can be scaled up and down and customers usually only pay for what they consume. Applications may be licensed via some service providers but the accountability for licensing and management of the solution remains with the end user unless subcontracted to a partner. PaaS (platfrom-as-a-service) offers a level of abstraction above IaaS where by the management of infrastructure is automated and effectively hidden from the user. It often refers to the environment within which developers can build and launch new applications as it simplifies this activity. Well known Cloud platforms include Microsoft Azure, Amazon EC2, and Force.com Whilst the above relate to the standard Service Delivery models, returning to the notion of ‘evolution’, a lot of marketing activity has led to the context of there being an accepted wisdom of XaaS (whereby X may relate to IT elements or solutions such as Database, Storage, etc). Whilst this is not truly an introduction of new ‘Genus’, the notion of a Database being a type or ‘species’ of SaaS or IaaS is viable and has become accepted language in many circles.
1.2.2 Cloud Deployment Models: Typically organisations will not move their business wholly away from an on-premise capability, especially where they have legacy IT solutions to manage, complex integrations and regulatory environments where data sovereignty may be an issue. As such many organisations select multiple deployment models depending on the application, size and complexity of business etc. Organisations will combine the following as needed: Public Cloud: Public Clouds are intended to be used by multiple parties at once and are designed to provide maximum value for money through a standardised and hi-scale approach on shared infrastructure. Public Cloud is the most logical deployment model for delivering SaaS. Many public Clouds operate internationally for scale or geographic resilience, but this gives rise to some concerns for some businesses over where their data is being stored at any particular point in time which may prefer a Private or Hybrid Cloud approach. Private Cloud: Private Clouds are intended to be restricted to a single customer or trusted community. However, dedicated components can vary between providers beyond storage, processing and RAM to include the network security and hypervisor elements. These are popular among organisations looking to access the benefits of Cloud Computing but retain higher control and flexibility of configuration compared to a public Cloud. Private Clouds can be run inside a company data centre or be hosted by a third party. IaaS is a delivery model best associated with Private Clouds where data sovereignty is a key issue. Hybrid Cloud: A Hybrid Cloud as the name infers is a Cloud capability that joins either private and/or public Clouds, or on-premise infrastructure to private/public Clouds in order to provide a customer or community with an appropriate or even bespoke environment to meet their specific operational needs. Again there have been a number of market evolutions and naming conventions introduced to further segment these deployment models such as the UK Government approach to GCloud (the Government Cloud which is still in definition) or Community Clouds that could arguably both be types or ‘species’ of a Hybrid Cloud genus.
© Cloud Forum IP Ltd 2012
five
Organisations will not move their business wholly away from an onpremise capability, especially where they have legacy IT solutions to manage