Interests

My current focus is on cloud computing, rethinking the role of an Operating System (OS) now that you can rely on a hypervisor to do many of the things an OS kernel had to do before. I've been working on the MirageOS project to create a "programming framework" (really a set of nicely composable libraries) which makes it easy to write applications which run directly on top of hypervisors. For an overview of this work, check out the recent Communications of the ACM article or the ASPLOS 2013 paper or explore the MirageOS docs.

In the recent past I've had a lot of fun exploiting the capabilities of smartphones, in particular using

Earlier still, my PhD research focused on application-level security policies for mobile web-based systems. The work was supervised by Alan Mycroft in the CL. I'm grateful to Andy Hopper from the LCE (now the DTG) and the Schiff Foundation for support and funding respectively. I was also sponsored by the now defunct AT&T Laboratories Cambridge Ltd.

Papers which won prizes

Several of the papers we've written have won prizes:

Jitsu: Just-In-Time Summoning of Unikernels - A. Madhavapeddy, T. Leonard, M. Skjegstad, T. Gazagnaire, D. Sheets, D.Scott, R. Mortier, A. Chaudhry, B. Singh, J. Ludlam, J. Crowcroft, I. Leslie

won the Cambridge Computer Lab Ring Publication of the Year 2016 and was presented at 12th USENIX symposium on Networked Systems Design and Implementation (NSDI 2015)

We presented Jitsu: a system optimised for spinning up tiny Unikernels in response to network traffic. For example when the first TCP/IP SYN packet arrives for a webserver, we would buffer the packet while simultaneously starting the Unikernel which completes the handshake when it finishes booting in a few hundred milliseconds on an ARM A20.

Unikernels: Library Operating Systems for the Cloud - A. Madhavapeddy, R. Mortier, C. Rotsos, D. Scott, B. Singh, T. Gazagnaire, S. Smith, S. Hand, J Crowcroft

won a HIPEAC 2013 award presented at Eighteenth International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS 2013)

We present unikernels, a new approach to deploying cloud services via applications written in high-level source code. Unikernels are single-purpose appliances that are compile-time specialised into standalone kernels, and sealed against modification when deployed to a cloud platform. In return they offer significant reduction in image sizes, improved efficiency and security, and should reduce operational costs. Our Mirage prototype compiles OCaml code into unikernels that run on commodity clouds and offer an order of magnitude reduction in code size without significant performance penalty. The architecture combines static type-safety with a single address-space layout that can be made immutable via a hypervisor extension. Mirage contributes a suite of type-safe protocol libraries, and our results demonstrate that the hypervisor is a platform that overcomes the hardware compatibility issues that have made past library operating systems impractical to deploy in the real-world.

This describes the awesomeness of the MirageOS open-source library OS which hosts this website!

Melange: creating a functional internet - A. Madhavapeddy, A. Ho, T. Deegan, D. Scott, R. Sohan

Best student paper at EuroSys 2007

We present a framework based in OCaml called ``Melange'' which uses strong static typing and generative meta-programming to eliminate a serious class of bugs from Internet servers without paying a performance penalty. We report on fully-featured SSH and DNS servers and measure greater throughput, lower latency and increased flexibility all with source code which is more succinct than the C equivalents: OpenSSH and BIND.

Quite a fun piece of work which shows how well you can do by throwing away the old designs and starting again, with benefit of hindsight. Seems to evoke a love/hate response in readers.

Spatial Security Policies for Mobile Agents in a Sentient Computing Environment - D. Scott, A. Beresford, A. Mycroft

Won the European Association of Software Science and Technology (EASST) Best Software Science Paper award at FASE 2003 (part of ETAPS 2003) in Warsaw, Poland.

A Sentient Computing environment is one in which the system is able to perceive the state of the physical world and use this information to customise its behaviour. Mobile agents are a promising new programming methodology for building distributed applications. We presented: (i) a simple location-based mechanism for the creation of security policies to control mobile agents; (ii) a method of writing applications for a pervasive computing environment through the use of mobile agents and (iii) a demonstration of the applicability of recent theoretical work using ambients to model mobility.

A fun project which combined ceiling-mounted ultrasonic location sensors and a very small amount of theory

Abstracting Application-Level Web Security - D. Scott, R. Sharp

Best Paper at the 11th International World-Wide Web conference (WWW2002)

Application-level web security refers to vulnerabilities inherent in the code of a web-application (irrespective of the technologies in which it is implemented or the security of the systems on which it is build). Many application-level vulnerabilities have been exploited with serious consequences: hackers have tricked e-commerce sites into shipping goods for no charge, accounts have been hijacked and confidential information leaked. We present new tools and techniques which allow the abstraction of security policy from large web-applications in heterogeneous multi-platform environments and analyse their usefulness.

I think people liked this paper because of its practical focus and good timing. It's worth reading if only for the jokes!

Refereed Reports

2015  

A. Madhavapeddy, T. Leonard, M. Skjegstad, T. Gazagnaire, D. Sheets, D.Scott, R. Mortier, A. Chaudhry, B. Singh, J. Ludlam, J. Crowcroft, I. Leslie

Jitsu: Just-In-Time Summoning of Unikernels

Presented at 12th USENIX symposium on Networked Systems Design and Implementation (NSDI 2015), May 2015

[pdf: 352KiB]

2014  

A. Madhavapeddy, D. Scott

Unikernels: The Rise of the Virtual Library Operating System

Appeared in Communications of the ACM, January 2014

[CACM]

2013  

A. Madhavapeddy, R. Mortier, C. Rotsos, D. Scott, B. Singh, T. Gazagnaire, S. Smith, S. Hand, J. Crowcroft

Unikernels: Library Operating Systems for the Cloud

Appeared in Eighteenth International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS 2013), March 2013

[pdf: 700KiB]

2010  

D. Scott, R. Sharp, T. Gazagnaire, A. Madhavapeddy

Using Functional Programming within an Industrial Product Group: Perspectives and Perceptions

Appeared in The 15th ACM SIGPLAN International Conference on Functional Programming (ICFP '10), September 2010

[pdf: 150KiB] [slides]

2007  

A. Madhavapeddy, A. Ho, T. Deegan, D. Scott, R. Sohan

Melange: Towards a "functional" Internet

Appeared in EuroSys 2007, March 2007

[pdf: 740KiB]

2006  

E. Toye, R. Sharp, A. Madhavapeddy, D. Scott, E. Upton, A. Blackwell

Interacting with Mobile Services: An Evaluation of Camera-Phones and Visual Tags

In Personal and Ubiquitous Computing Journal, February 2006

[pdf: 330 kB]

2005  

A. Madhavapeddy, R. Sharp, D. Scott, A. Tse

Audio Networking: The Forgotten Wireless Technology

In IEEE Pervasive Computing (volume 4, number 3), July-September 2005

[pdf: 1 MiB]

2005  

A. Madhavapeddy, D. Scott, R. Sharp

SPLAT: A Tool for Model-Checking and Dynamically Enforcing Abstractions

In the proceedings of the 12th Internation SPIN Workshop on Model Checking of Software (SPIN 2005)

[pdf: 120 kB]

2005  

E. Toye, R. Sharp, A. Madhavapeddy, D.Scott

Using Smart Phones to Access Site-Specific Mobile Services

In the special issue of IEEE Pervasive Computing on the Smart Phone: A First Platform for Pervasive Computing, April-June 2005

[pdf: 2.4 MiB]

2005  

A. Madhavapeddy, D. Scott

On the Challenge of Delivering High-Performance, Dependable, Model-Checked Internet Servers

In the proceedings of the First Workshop on Hot Topics in System Dependability (HotDep-05), June 2005.

[pdf: 80 kB]

2005  

D. Scott, R. Sharp, A. Madhavapeddy, E. Upton

Using Visual Tags to Bypass Bluetooth Device Discovery

ACM Mobile Computing and Communications Review (MC2R), January 2005, Volume 9, Number 1, Pages 41-53.

[pdf: 200KiB]

2004  

D. Scott

Abstracting Application-Level Security Policy for Ubiquitous Computing

PhD thesis, University of Cambridge

[pdf: 2MiB] [UCAM-CL-TR-613]

2004  

K. Mansley, A. Beresford, D. Scott

The Carrot Approach: Encouraging use of location systems

This paper describes techniques to encourage (rather than force) the use of location-aware apps in the face of declining participation. Presented at The Sixth International Conference on Ubiquitous Computing (UBICOMP 2004) in Nottingham, UK in Septempter 2004

[pdf: 400kB]

2004  

K. Mansley, D. Scott, A. Tse, A. Madhavapeddy

Feedback, Latency, Accuracy: Exploring Tradeoffs in Location-Aware Gaming

Presented at NetGames 2004, in conjunction with ACM SIGCOMM 2004, August 2004

[pdf: 1.3MB]

2003  

A. Madhavapeddy, D. Scott, R. Sharp

Context-Aware Computing with Sound

This paper describes simple techniques for audible data communication and shows how these channels, although low bandwidth, may be used to create cheap context-aware applications. Presented at The Fifth International Conference on Ubiquitous Computing (UBICOMP) 2003 in Seattle, Washington.

[pdf: 237kB]

2003  

D. Scott, R. Sharp

Specifying and Enforcing Application-Level Web Security Policies

Invited contribution to Jul/Aug 2003 IEEE Transactions in Knowledge and Data Engineering (TKDE)

[IEEE]

2003  

A. Madhavapeddy, A. Mycroft, D. Scott, R. Sharp

The Case For Abstracting Security Policies

This paper describes an infrastructure for imposing Stateful Syscall Policies on existing programs. Presented at The 2003 International Conference on Security and Management

[pdf: 68kB] 

2003  

D. Scott, A. Beresford, A. Mycroft

Spatial Policies for Sentient Mobile Applications

This paper describes a runtime for implementing a Spatial Policy system for sentient applications built from Mobile Agents Presented at IEEE Policy 2003.

[pdf: 132kB]

2003  

D. Scott, A. Beresford, A. Mycroft

Spatial Security Policies for Mobile Agents in a Sentient Computing environment

Presented at FASE 2003 (part of ETAPS 2003) in Warsaw, Poland. Won the European Association of Software Science and Technology (EASST) Best Software Science Paper award. © Springer-Verlag

[gzipped ps: 164kB] [pdf: 170Kb]

2002  

D. Scott, R. Sharp

Developing Secure Web Applications

(C)2002 IEEE Internet Computing

IEEE Internet Computing Magazine in the Nov/Dec 2002 special issue on The Technology of Trust

[pdf: 560kb]

2002  

D. Scott, R. Sharp

Abstracting Application-Level Web Security

Please read the errata

Proceedings of the 11th International World-Wide Web conference (WWW2002) where it also received the "Best Paper" award.

[pdf: 180Kb] [slides]

2001  

J. Weatherall, D. Scott

Mobile Computing with Python

Proceedings of the 9th International Python Conference Python9), March 2001

[pdf: 800KiB]

Unrefereed Reports

2005

D. Scott

Abstracting application-level security policy for ubiquitous computing

Technical Report UCAM-CL-TR-613, University of Cambridge

[pdf: 2.2 MB]

2004

E. Toye, A. Madhavapeddy, R. Sharp, D. Scott, A. Blackwell, E. Upton

Using camera-phones to interact with context-aware mobile services

Technical report UCAM-CL-TR-609, University of Cambridge

[pdf: 0.4MiB] [UCAM-CL-TR-609]

2002

D. Scott, R. Sharp

SPECTRE: A Tool for Inferring, Specifying and Enforcing Web-Security Policies

This paper describes the implementation of the dynamic policy enforcement tool called "SPECTRE"

[pdf: 145Kb]

2002

D. Scott, R. Sharp

The SWAP Project

This poster describes the overall aim of the SWAP Project

[pdf: 125Kb]


Videos

2003

A. Madhavapeddy, D. Scott, R. Sharp

Audio Notes

This video demonstrates how audionotes (special sequences of DTMF tones) may be used to store and retrieve documents via standard audio recording equipment.

[MPEG: 20MiB]

2003

A. Madhavapeddy, D. Scott, R. Sharp

Audio Authentication

This video demonstrates how a capability to access a resource may be sent as a melodic ring tone via SMS to a mobile phone handset.

[MPEG: 14MiB]

2003

A. Madhavapeddy, D. Scott, R. Sharp

Room-grained Location

This video demonstrates how audio beacons operating at approximately 21kHz (imperceptible to humans) may be used to easily infer room-grained location.

[MPEG: 4.6MiB]

2003

A. Madhavapeddy, D. Scott, R. Sharp

Telephone Attachments

This video demonstrates how document references may be easily transmitted across telephone networks as sequences of DTMF tones.

[MPEG: 13MiB]