Edel Sherratt

SDL - The IoT Language

Interconnected smart devices constitute a large and rapidly growing element of the contemporary Internet. A smart thing can be as simple as a web-enabled device that collects and transmits sensor data to a repository for analysis, or as complex as a web-enabled system to monitor and manage a smart home. Smart things present marvellous opportunities, but when they participate in complex systems, they challenge our ability to manage risk and ensure reliability. SDL, the ITU Standard Specification and Description Language, provides many advantages for modelling and simulating communicating agents --- such as smart things --- before they are deployed. The potential for SDL to enhance reliability and safety is explored with respect to existing smart things below. But SDL must advance if it is to become the language of choice for developing the next generation of smart things. In particular, it must target emerging IoT platforms, it must support simulation of interactions between pre-existing smart things and new smart things, and it must facilitate deployment of large numbers of similar things. Moreover, awareness of the potential benefits of SDL must be raised if those benefits are to be realized in the current and future Internet of Things.

Gravimagnetic field tensor gradiometry formulas for uniform polyhedra

Full field gradient data in gravity and magnetic surveys are becoming routinely available. Such data offer interpretational advantages over direct field measurement by de-emphasising regional trends during differential measurement, thereby highlighting the contribution of local targets (Nelson (1988); Pedersen and Rasmussen (1990); Zhang et al. (2000)). Polyhedra have provided a powerful forward modeling tool for the field anomalies of targets of uniform density or magnetization, and it is natural to extend their modeling capabilities to the computation of field gradients. This work provides closed formulas for polyhedral field gradient computation. Validation checks confirm correct derivation.

Designing distributed services with SDL

In this approach, distributed services are developed by automatically generating Java implementations from designs expressed in SDL (Specification and Description Language). The authors discuss SDLs characteristics, limitations and expected future improvements in the next release.

Tool integration: experiences from the BOOST project

The BOOST project aims to support the development of telecommunications services by establishing effective ways of creating object-oriented service creation environments (SCEs). A major part of the project has entailed the constructing SCEs by integrating existing software tools. This paper evaluates different approaches to tool integration, covering both integration by encapsulation within an existing environment, and direct tool-to-tool integration. The use of Tcl, a language to increase tool programmability, is discussed, and examples illustrating its application in BOOST are provided. Finally, a general mechanism for direct tool-to-tool integration, and an approach towards fully open, active environments and services are presented.<<ETX>>

Distributed ASM - Pitfalls and Solutions

While sequential Abstract State Machines ASM capture the essence of sequential computation, it is not clear that this is true of distributed ASM. This paper looks at two kinds of distributed process, one based on a global state and one based on variable access. Their commonalities are extracted and conclusions for the general understanding of distributed computation are drawn, providing integration between global state and variable access.

SDL in a changing world

SDL has provided robust and adaptable modelling capabilities through many developments in the world of telecommunications. In recent years, however, that world has undergone deeper and more frequent paradigm shifts than hitherto. This paper briefly summarises the emergence of grid computing, pervasive computing and mobile and ad-hoc communications. It explores developments in modelling, as reflected by the emergence of SDL-2000 as an ITU standard, and the subsequent publication of UML 2.0. It considers the relationship between SDL and UML, including establishment of SDL as a UML profile, work by the MODA-TEL project and the formation of the ETSI specialist task force 250. It concludes with suggestions for specific tasks in the development of the next revision of SDL. This does not represent any new development for SDL, nor does it present any new applications of SDL. Rather it focuses on the forces affecting the evolution of SDL, and the opportunities to be grasped and challenges to be faced.

Arise: operating PCTE over a wide-area network

A case study in which the feasibility of operating the Portable Common Tools Environment (PCTE) across a wide-area network was determined as part of the Arise project is discussed. Simple benchmarks and experiments with a configuration-management application indicate that a wide-area PCTE is feasible, provided there is a suitable data-distribution strategy.<<ETX>>

Intelligent Resilience in the IoT

Failing or hostile elements are normal in the public Internet of Things (IoT). Resilient IoT systems are engineered to fail safely and recover gracefully in the face of challenges presented by their environment. Approaches to ensuring resilient behaviour include intrusion detection, redundancy and self-healing. Adaptive, anomaly-based defence mechanisms are particularly well-suited to systems that are deployed in the public internet. This paper discusses the use of SDL+ (SDL with MSC and ASN.1) to generate simulation results for training anomaly-based defence mechanisms for smart systems. It outlines an approach based on the SDL+ methodology to create resilient IoT systems.

SDL: Meeting the IoT Challenge

SDL 2010 offers excellent support for modelling, simulating and testing systems of communicating agents. However, it is not perfectly adapted to meeting the specific challenges presented by the Internet of Things (IoT). Three areas that pose a challenge are considered, and language adaptations that aim to address the specific needs of IoT systems developers are explored.

Relativity and abstract state machines

The Abstract State Machine (ASM) formalism has proved an effective and durable foundation for the formal semantics of SDL. The distributed ASMs that underpin the SDL semantics are defined in terms of agents that execute ASM programs concurrently, acting on partial views of a global state. The discrete identities of successive global states are ensured by allowing input from the external world only between steps, and by having all agents refer to an external global time. But distributed systems comprising independent agents do not have a natural global time. Nor do they have natural global states. This paper takes well-known concepts from relativity and applies them to ASMs. The spacetime in which an ASM exists and moves is defined, and some properties that must be preserved by transformations of the frame of reference of an ASM are identified. Practical implications of this approach are explored through reservation and web service examples.