19. A system comprising: a content requester configured to request a content; a content source configured to supply the content; and a server computer configured to: process the content to provide an abstract content model providing at least one directional graph comprising nodes that represent components of the content and edges that represent relationships between the nodes, wherein the directional graph G=(N, E) that satisfies the following condition, where N stands for “node” of G and E stands for “edge” sets of G: a node set N can be divided into several subsets as N j, i=1 . . . m where N = ⋃ i = 1 m ⁢ N i and N i ∩N j =Φ, ∀i,j=1 . . . m,i≠j; ∀a=(n s ,n e )εE, there exists a pair of 1≦i<j≦m such that n s εN i and n e εN j ; and ∀a=(n s n e )εE,s≠e; process the abstract content model to select an optimal delivery plan the use of which will permit requested content to be delivered to the content requester; and process the abstract content model to provide deliverable content in accordance with the selected delivery plan.
19. A system comprising: a content requester configured to request a content; a content source configured to supply the content; and a server computer configured to: process the content to provide an abstract content model providing at least one directional graph comprising nodes that represent components of the content and edges that represent relationships between the nodes, wherein the directional graph G=(N, E) that satisfies the following condition, where N stands for “node” of G and E stands for “edge” sets of G: a node set N can be divided into several subsets as N j, i=1 . . . m where N = ⋃ i = 1 m ⁢ N i and N i ∩N j =Φ, ∀i,j=1 . . . m,i≠j; ∀a=(n s ,n e )εE, there exists a pair of 1≦i<j≦m such that n s εN i and n e εN j ; and ∀a=(n s n e )εE,s≠e; process the abstract content model to select an optimal delivery plan the use of which will permit requested content to be delivered to the content requester; and process the abstract content model to provide deliverable content in accordance with the selected delivery plan. 21. The system of claim 19 , wherein there are multiple different types of edges.