Basic prerequisites for the use of cloud services

• Broadband network access. Cloud functions are available through the network (usually the Internet) and accessible through standardized mechanisms that support the use of heterogeneous platforms – thin or thick client (such as mobile phones, tablets, laptops, workstations …).
• Flexibility (elasticity). The cloud capacity can be secured elastically and in some cases released automatically, at the increased or decreased rate according to the demand. Secured cloud capacity available for the consumer may seem limitless, and it may be provided at any time in any quantity.
• Measurable services. Cloud systems control and optimize the use of available resources automatically using the EMF (xxxxx) at some level of abstraction corresponding to the type of service (such as storage, processing, bandwidth, and active user accounts). The use of  resources can be monitored, controlled and communicated  so that it can  ensure transparency for both the provider and the consumer of the utilized service.
• Self-service as required. The consumer may s order processing power required (e.g. time and power of a server and network storage with the appropriate capacity) as needed automatically without the need for human interaction with each service provider.
• Pooling resources. Provider’s computing resources are pooled to serve more consumers by means of multi-tenant model, with different physical and virtual resources dynamically distributed according to the consumer request . When allocating resources, there is the principle of independence in the location. This means that the customer, generally, has no control or knowledge of the exact location of the provided resources but he may be able to determine the location at the higher level of abstraction (e.g. country or data centre). Examples of resources include data storage, processing power, size of memory and network bandwidth.