by the individual content. Content policies can be changed dynamically and can include actions that should be performed when a policy itself is changed – enabling a highly dynamic environment to be created.

Thus, the relationship between a broadcaster and a content provider is an action within a content policy – for example, when content is made available, an action with a content policy might define that it is automatically shared with particular content providers, or simply define that it is available to share. The means of sharing, the format and the timing of sharing are also defined by policies within the cloud store. This policy-driven approach also manages content sharing and processing by external service partners. For example, when content is to be transcoded, a content policy may define that it is done by a third-party company and define how the transfer to the service company is to be performed. This might mean that a physical copy of the content is created and dispatch by courier requested, or more generally within the infrastructure that the Media Dispatch Protocol [12] is used to auto-negotiate and initiate the transfer of content directly to the chosen content service provider.

19.4  PRISM Cloud Implementation

An implementation of a broadcasting infrastructure presents a significant challenge in that it includes activities that are scheduled and predictable, and activities that are demand-driven and unpredictable. In delivering content to users, a minimum QoS is expected; otherwise, users will not use the content services. And, yet, the predictable and scheduled activities required by a broadcaster within the infrastructures must be maintained.

In addition, a broadcast infrastructure includes fixed assets, potentially mobile assets and an increasing need to scale the infrastructure dynamically to meet user demand. Thus, large-scale content stores will be in fixed and defined locations within broadcast locations – for example, the BBC may implement a single, centralised large-scale content store with smaller stores available within affiliate broadcasters or even at the premises of its production partners. This situation is further complicated by specialist service equipment being clustered around these content stores to support content processing – where the locality to the content reduces the need to move large-scale content across congested networks. A solution must live with this reality and permit these fixed assets to be supplemented to support predicted and unpredicted spikes in demand – for example, the rush of users requesting content for a new programme shortly after it is released.

19.4.1  Cloud Resources

The PRISM infrastructure is defined as a collection of resource clouds that can be used to support services within the media infrastructure. The cloud is composed of fixed