For the purposes of this guidance, cloud computing is defined as networked IT infrastructure, platforms or software that is provided on-demand by one or more cloud service providers. By definition cloud computing can be vague and nebulous. This guidance particularly concerns itself with cloud computing which, in effect, is running software applications or infrastructure on (and therefore transferring data to and from) some else's computing service (sometimes known as the “public cloud”). Cloud computing services on another organisation's IT may also be referred to as “hosted services”.
Note: For completion, cloud computing may also be provided via a private cloud service, installed and controlled locally (also referred to as “on premise”). The University offers a private cloud service through IT Services. A combination of public and private cloud services, where data may move between services, is generally known as a hybrid cloud.
There are three recognised models for the delivery of cloud IT services:
- Infrastructure-as-a-service – the delivery of basic or raw computing facilities such as servers, storage, and networking. These facilities would be used in preference to installing hardware, for example, in your own department or data centre and are generally used to support software applications that you or someone else may have developed separately.
- Platform-as-a-service – delivery of a specific platform (running on top of infrastructure) that enables the development or deployment of applications (e.g. Microsoft Azure advertises itself as a cloud computing platform that includes database and web hosting services as well as storage and servers);
- Software-as-a-service – delivery of applications for specific purposes that can be used with little additional effort (or expense in many cases) by individuals as well as organisations. “File sync & share” applications such as Dropbox are an example of software-as-a-service; as is Office365 or Google Apps. Software-as-a-service will likely be delivered from a cloud computing platform that, in turn, is built on infrastructure-as-a-service (e.g. the University of Manchester provides courses to the general public via the Coursera education platform which in turn is hosted on the Amazon cloud computing platform (via Amazon CloudFront)).
For clarity this guidance recognises three distinct roles in the provision and use of cloud computing services:
- The cloud service provider – the organisation providing one or more cloud It services, whether infrastructure, platform or software (or a combination);
- The cloud customer – the organisation or individual selecting and agreeing to terms and conditions for the use of cloud IT services;
- The cloud end-user – those who actually use the cloud IT service.
In some circumstances the cloud customer will be the University of Oxford, a department or college and the cloud end-users will be staff or students. In other circumstances, an individual may be both customer and end-user (e.g. in registering for a Dropbox account, or using a personal credit card to pay for Amazon Web Services).
- The definition of cloud computing may be simplified to 'outsourcing the provision of IT facilities to another organisation'.
- A software application provided by a cloud service provider may involve a 'stack' of organisations involved in its delivery and support.