Accounting and Accountability in Content Distribution Architectures: A Survey

Many content distribution architectures offer desirable elements that lead to less bandwidth usage, reduced network congestion, higher content availability, and reduced costs. However, their level of adoption and utilization in commercial environments depends on the level of content accounting and accountability they offer. Content accounting refers to any information that a content distributor needs to track relating to the delivery of content to its intended consumers. In contrast, content accountability refers to the willingness of the communicating infrastructure to produce accurate and verifiable information about the content distribution process. This article surveys existing and proposed future content delivery architectures detailing their methodologies for providing efficient low-cost content distribution, content accounting, and accountability across trustworthy and untrustworthy infrastructures. We use two methods to help identify the drawbacks and merits of these architectures. The first is a taxonomy for accounting information based on our analysis of logging information gathered from the surveyed systems. The second is a generic model for content distribution based on a synthesis of desirable elements from the surveyed architectures. These methods help highlight key architectural elements required for efficient low-cost content distribution. Finally, we identify outstanding challenges related to establishing accountability in accounting information produced for content distributed across trusted and untrusted infrastructures.