Main ICN Architectures
This chapter presents some of the main ICN architecture proposals, focusing on how the basic content-oriented concepts are applied. Research projects developing and extending these concepts are briefly presented as well.
3.1. Content-based networking/combined broadcast and content-based
Content-based networking (CBN) architecture [CAR 00] is one of the first ICN proposals, heavily based on event-notification publish/subscribe systems. CBN is an architecture in which content is published without explicit receiver addresses, delivering it to all nodes that have declared an interest in receiving that content.
Each CBN node advertises a predicate that defines its interest in receiving messages called the receiver predicate, or r-predicate. Messages are identified by AVPs, as described in section 2.1.3, identified by attribute type, name and value. For example, a set of valid AVPs would be [string company = PET, int price = 30]. Predicates are usually represented by a set of restrictions, or Boolean filters, applied over these AVPs. The predicate [string company = PET ∧ int price <40], for example, covers the message just shown. Besides the r-predicate, nodes can issue a sender predicate, or s-predicate, defining content they intend to serve. An r-predicate, while setting interest for messages, can be interpreted as a content-based network address once it sets the necessary forwarding state in the network, allowing nodes to receive content. Thus, predicate issuing ...