1. A data structure embodied on one or more computer-readable media, the data structure comprising: an abstract content model that represents content that can be requested from a content requester, the abstract model comprising a directional graph that features a top-down hierarchical structure having nodes that represent components of the content and edges that represent relationships between the nodes, the nodes being configured to have a node status that defines dynamic statuses of the nodes during content delivery; the abstract content model being configured for processing so that an optimal delivery plan for delivering the content can be selected.