A programming system for process coordination in virtual organisations

PhD thesisDistributed business applications are increasingly being constructed by composing them from services provided by various online businesses. Typically, this leads to trading partners coming together to form virtual organizations (VOs). Each member of a VO maintains their autonomy, except with respect to their agreed goals. The structure of the Virtual Organisation may contain one dominant organisation who dictates the method of achieving the goals or the members may be considered peers of equal importance. The goals of VOs can be defined by the shared global business processes they contain. To be able to execute these business processes, VOs require a flexible enactment model as there may be no single ‘owner’ of the business process and therefore no natural place to enact the business processes. One solution is centralised enactment using a trusted third party, but in some cases this may not be acceptable (for instance because of security reasons). This thesis will present a programming system that allows centralised as well as distributed enactment where each organisation enacts part of the business process. To achieve distributed enactment we must address the problem of specifying the business process in a manner that is amenable to distribution. The first contribution of this thesis is the presentation of the Task Model, a set of languages and notations for describing workflows that can be enacted in a centralised or decentralised manner. The business processes that we specify will coordinate the services that each organisation owns. The second contribution of this thesis is the presentation of a method of describing the observable behaviour of these services. The language we present, SSDL, provides a flexible and extensible way of describing the messaging behaviour of Web Services. We present a method for checking that a set of services described in SSDL are compatible with each other and also that a workflow interacts with a service in the desired manner. The final contribution of this thesis is the presentation of an abstract architecture and prototype implementation of a decentralised workflow engine. The prototype is able to enact workflows described in the Task Model notation in either a centralised or decentralised scenario

Safe Class and Data Evolution in Large and Long-Lived Java Applications

There is a growing class of applications implemented in object-oriented languages that are large and complex, that exploit object persistence, and need to run uninterrupted for long periods of time. Development and maintenance of such applications can present challenges in the following interrelated areas: consistent and scalable evolution of persistent data and code, optimal build management, and runtime changes to applications. The research presented in this thesis addresses the above issues. Since Java is becoming increasingly popular platform for implementing large and long-lived applications, it was chosen for experiments. The first part of the research was undertaken in the context of the PJama system, an orthogonally persistent platform for Java. A technology that supports persistent class and object evolution for this platform was designed, built and evaluated. This technology integrates build management, persistent class evolution, and support for several forms of eager conversion of persistent objects. Research in build management for Java has resulted in the creation of a generally applicable, compiler-independent smart recompilation technology, which can be re-used in a Java IDE, or as a standalone Java-specific utility similar to make. The technology for eager object conversion that we developed allows the developers to perform arbitrarily complex changes to persistent objects and their collections. A high level of developer's control over the conversion process was achieved in part due to introduction of a mechanism for dynamic renaming of old class versions. This mechanism was implemented using minor non-standard extensions to the Java language. However, we also demonstrate how to achieve nearly the same results without modifying the language specification. In this form, we believe, our technology can be largely re-used with practically any persistent object solution for Java. The second part of this research was undertaken using as an implementation platform the HotSpot Java Virtual Machine (JVM), which is currently Sun's main production JVM. A technology was developed that allows the engineers to redefine classes on-the-fly in the running VM. Our main focus was on the runtime evolution of server-type applications, though we also address modification of applications running in the debugger. Unlike the only other similar system for Java known to us, our technology supports redefinition of classes that have methods currently active. Several policies for handling such methods have been proposed, one of them is currently operational, another one is in the experimental stage. We also propose to re-use the runtime evolution technology for dynamic fine-grain profiling of applications

Managing Smartphone Testbeds with SmartLab

The explosive number of smartphones with ever growing sensing and computing capabilities have brought a paradigm shift to many traditional domains of the computing field. Re-programming smartphones and instrumenting them for application testing and data gathering at scale is currently a tedious and time-consuming process that poses significant logistical challenges. In this paper, we make three major contributions: First, we propose a comprehensive architecture, coined SmartLab1, for managing a cluster of both real and virtual smartphones that are either wired to a private cloud or connected over a wireless link. Second, we propose and describe a number of Android management optimizations (e.g., command pipelining, screen-capturing, file management), which can be useful to the community for building similar functionality into their systems. Third, we conduct extensive experiments and microbenchmarks to support our design choices providing qualitative evidence on the expected performance of each module comprising our architecture. This paper also overviews experiences of using SmartLab in a research-oriented setting and also ongoing and future development efforts