Computer Laboratory


The focus of Opera group research is the design and deployment of open, large-scale, widely distributed systems. Two major thrusts are in the areas of asynchronous middleware - the Cambridge Event Architecture (CEA) and, more recently, Hermes and SBUS - and an open, role-based, access control architecture for secure interworking services: OASIS. These areas are interrelated in that access control is needed on event registration and notification and events are needed for timely revocation of access rights. A third area, policy management, originated from our work on access control but has wide application which we are exploring in a number of projects. Also growing out of access control and policy is work on wide area and ubiquitous computation based on trust. Recent work under the SmartFlow grant has focussed on distributed information flow control (IFC). Here, policy is enforced not only at the boundaries of system components but end-to-end. The CloudSafetyNet grant will explore how IFC can make cloud computing more secure.


CloudSafetyNet - CamFlow

CloudSafetyNet: End-to-end application security in the cloud, see the project page CloudSafetyNet
The project explores the use of Information Flow Control to achieve greater security in cloud computing.

EPSRC grant EP/K011510/1: January 2013 - June 2016
with Imperial College EP/K008129/1 and collaborators, University of Otago New Zealand and the English Cancer Registry, Public Health England.

Work on CamFlow continues after the end of the grant, see the project page: CloudSafetyNet

MCCRC (Microsoft Cloud Computing Research Centre)

This project is a Microsoft-funded collaboration between Cambridge (PIs Jon Crowcroft and Jatinder Singh) and QMUL's Law Department (PI Christopher Millard). The Opera group is contributing research on Information Flow Control for Cloud Computing.

MCCRC has run an annual workshop CLaw (Cloud Law) at IEEE IC2E in 2015, 2016 and 2017 see
CLaw: IEEE International Workshop on Legal and Technical Issues in Cloud Computing as part of IC2E: IEEE International Conference on Cloud Engineering



Personal and Social Communication Services for Health and Lifestyle Monitoring, EPSRC/TSB, July 2009 - December 2012, with Essex University, initially with project partners BT and Ericsson both of whom had to withdraw early in the project. From 2011 the project partners are HW Communications, Thales (UK), and MAC Ltd.

For more information:


This project investigates and addresses the shortcomings of existing middleware systems for deployment within the healthcare domain. An extendable, event-based middleware architecture, SmartFlow, will be developed that can integrate heterogeneous systems and provide a framework for dynamically managing middleware extensions. SmartFlow is in collaboration with Imperial College London's Large-Scale Distributed Systems Group and CBCU Research (Clinical and Biomedical Computing Unit) and ECRIC (Eastern Cancer Registry and Information Centre), in Cambridge, both part of the UK National Health Service.

More information on the project can be found at:


TIME-EACM (Transport Information Monitoring Environment-Event Architecture and Context Management) used the City of Cambridge as a testbed for developing software to monitor and analyse traffic. The project designed and developed an event-based middleware SBUS to provide a convenient basis for applications to acquire the information of interest to them. Statistical analysis and visualisation of the data followed in the second half of the grant.

EPSRC grant EP/C547632/1: October 2005 - March 2011.
A small impact grant will continue the work in 2012.


The aim of CareGrid is to develop software to realise trust domains, scalable from body-area networks through to grid applications, in which decisions are based on evidence, mitigated by trust and privacy requirements.


EDSAC21 - Event-Driven, Secure Application Control for the 21st century

The goal of the EDSAC21 project is to add role-based access control to a large-scale and collaborative publish/subscribe communication system.


Access Control Policy Management

We are working on policy-driven applications. We have extended the PostgreSQL Object-Relational Database Management System with active database triggers. This functionality supports both an active security platform (where the security properties of an application are monitored and any violations are notified) and active policy management.


CEA - Cambridge Event Architecture

Our early work on the Cambridge Event Architecture (CEA) extended the then-predominant, object-oriented middleware (CORBA and Java) with a publish, register, notify paradigm.

CEA events were typed to support the programming of distributed, event-based applications.


COBRA - Content-Based Retrieval Architecture

COBRA - Content-Based Retrieval Architecture - is an attempt to build a framework to construct multimedia information retrieval systems.


Earls Colne

This project presents 500 years of searchable historical records from an Essex town. The contribution of the Computer Laboratory is described in the introduction, under Brief History of the Project .



ECCO aims to be an event-based distributed system over peer-to-peer networks in a multi-event broker model that adapts to mobile computing environments and web services.



Hermes is a publish/subscribe system where a network of event brokers decouples publishers and subscribers.

This is in contrast with CEA's extensions to middleware for closely coupled components. Hermes uses XML for event transport while allowing standard programming languages such as Java for typed-event programming in end systems.

We have also worked on event composition, provided as a service placed optimally above the broker network.

IMP - Interactive Multimedia Presentation

The IMP - Interactive Multimedia Presentation - project is investigating how to provide support for the process of constructing interactive applications within distributed multimedia environments.


MSSA - Multi-Service Storage Architecture

The multi-service storage architecture (MSSA) was designed to meet the needs of existing and emerging applications such as those with multimedia presentation support requirements and those which wish to use multi-file structured documents. The MSSA allows evolution from, and compatibility with, traditional applications.


Nomadic Pict

More information on the Nomadic Pict web page.

OASIS - An Open Architecture for Secure, Interworking Services

An emerging requirement is for applications and distributed services to cooperate or inter-operate. Existing mechanisms are able to hide the heterogeneity of host operating systems and abstract the issues of distribution and object location.

However, in order for systems to inter-operate securely there must also be mechanisms to hide differences in security policies, or at least to support negotiation between them.


Operating Systems

The Opera group has been working on improving general-purpose operating systems.


PEPITO - Peer-to-Peer Implementation and Theory

More information on the PEPITO web site.


SECURE is an IST Global Computing project to create security mechanisms for the Internet, based on explicit models of trust and risk. SECURE itself is an acronym which stands for Secure Environments for Collaboration among Ubiquitous Roaming Entities (and is in no way contrived...)

The project is a distributed, collaborative one and includes a number of researchers from the Cambridge University Computer Lab. To the right you can see several members of the SECURE team captured in their natural habitat, sightseeing around Europe.