Michael F. Plass

VoCCN: voice-over content-centric networks

A variety of proposals call for a new Internet architecture focused on retrieving content by name, but it has not been clear that any of these approaches are general enough to support Internet applications like real-time streaming or email. We present a detailed description of a prototype implementation of one such application -- Voice over IP (VoIP) -- in a content-based paradigm. This serves as a good example to show how content-based networking can offer advantages for the full range of Internet applications, if the architecture has certain key properties.

Networking named content

Current network use is dominated by content distribution and retrieval yet current networking protocols are designed for conversations between hosts. Accessing content and services requires mapping from the what that users care about to the networks where. We present Content-Centric Networking (CCN) which uses content chunks as a primitive---decoupling location from identity, security and access, and retrieving chunks of content by name. Using new approaches to routing named content, derived from IP, CCN simultaneously achieves scalability, security, and performance. We describe our implementation of the architectures basic features and demonstrate its performance and resilience with secure file downloads and VoIP calls.

Curve-fitting with piecewise parametric cubics

Parametric piecewise-cubic functions are used throughout the computer graphics industry to represent curved shapes. For many applications, it would be useful to be able to reliably derive this representation from a closely spaced set of points that approximate the desired curve, such as the input from a digitizing tablet or a scanner. This paper presents a solution to the problem of automatically generating efficient piecewise parametric cubic polynomial approximations to shapes from sampled data. We have developed an algorithm that takes a set of sample points, plus optional endpoint and tangent vector specifications, and iteratively derives a single parametric cubic polynomial that lies close to the data points as defined by an error metric based on least-squares. Combining this algorithm with dynamic programming techniques to determine the knot placement gives good results over a range of shapes and applications.

Custodian-based information sharing

Information sharing systems such as iCloud, Dropbox, Facebook, and Twitter are ubiquitous today, but all of them depend on massive server infrastructure and always-on Internet connectivity. We have designed and implemented a sharing system that does not require infrastructure yet supports robust, distributed, secure sharing by opportunistically using any and all connectivity, local or global, permanent or transient, to communicate. One key element of this system is a new information routing model that so far has proven to be as scalable and efficient as the best of the current Internet routing protocols, while operating in an environment more complex and dynamic than they can tolerate. The new routing model is made possible by new affordances offered by information-centric networking, in particular, the open source CCN [1] release. This article describes the new system and its routing model, and provides some performance measurements.

Ropes: an alternative to strings

Programming languages generally provide a ‘string’ or ‘text’ type to allow manipulation of sequences of characters. This type is usually of crucial importance, since it is normally mentioned in most interfaces between system components. We claim that the traditional implementations of strings, and often the supported functionality, are not well suited to such general‐purpose use. They should be confined to applications with specific, and unusual, performance requirements. We present ‘ropes’ or ‘heavyweight’ strings as an alternative that, in our experience leads to systems that are more robust, both in functionality and in performance.