Modelling Contracts and Workflows for Verification and Enactment

The work presented in this thesis concerns some aspects related to the Modelling of Contracts and Workflows for Verification and Enactment. We have sought to gain some insight into the nature of contracts and workflows. in order that we may model them. primarily, for the purposes of verifying certain properties and for enacting them. Workflows help coordinate the enactment of business processes. A notable aspect of workflow technologies is the lack of formal semantics for workflow models. In this thesis, we consider the characterisation of workflow using a number of formal tools, viz. Milner's CCS, Cleaveland et ai's Prioritised CCS (which we abbreviate to PCCS) and the Situation Calculus (thanks mainly to Reiter), which is based on First-Order Logic. Using these, we provide formalisations of production workflows, which are somewhat rigid, inflexible structures, akin to production lines. We do so, in order that we may fiJo: their operational meaning for the purposes of verification and enactment. We define the Liesbet meta-model for production workflow to provide a reference ontology for the task of formalisation. We have also implemented a framework for the verification and enactment of Liesbet workflow models. Regarding verification, we are particularly interested in the key property of soundness, which is concerned with an absence of locking and redundant tasks in a workflow model. Our framework is capable of verifying this property of workflow models, as well as arbitrary temporally-extended constraints', which are constraints whose satisfaction is determined over successive states of enactment of a model. We also consider the definition of more flexible workflows, including collaborative workflows, using an approach that we have conceived called Institutional Workflow Modelling (IWM). The essence of IWM lies (in part) in the identification that the structure of a workflow model necessarily entails the existence of counts as relations. These relations prescribe how the occurrence of certain actions, in the context of a particular workflow model. count as the occurrence of other actions. We have also been interested in the modelling of contracts; and have found IWM to be useful as a foundational basis for contract modelling. ????????? Another fu.ndamental aspect of our IWM-based approach is a correspondence, which we have identified, between counts as relations and methods in Hierarchical Task Network (HTN)-based planning. Thus, we are able to advocate the use of an HTN-based planning framework for the verification of flexible workflows and contracts. We have implemented such a framework, whose planner is called Theodore. We define a sjmilar notion of soundness for flexible workflows and contracts, which the Theodore-based framework is able to verify, along with arbitrary temporallyextended constraints.Imperial Users onl

Adaptable processes

We propose the concept of adaptable processes as a way of overcoming the limitations that process calculi have for describing patterns of dynamic process evolution. Such patterns rely on direct ways of controlling the behavior and location of running processes, and so they are at the heart of the adaptation capabilities present in many modern concurrent systems. Adaptable processes have a location and are sensible to actions of dynamic update at runtime; this allows to express a wide range of evolvability patterns for concurrent processes. We introduce a core calculus of adaptable processes and propose two verification problems for them: bounded and eventual adaptation. While the former ensures that the number of consecutive erroneous states that can be traversed during a computation is bound by some given number k, the latter ensures that if the system enters into a state with errors then a state without errors will be eventually reached. We study the (un)decidability of these two problems in several variants of the calculus, which result from considering dynamic and static topologies of adaptable processes as well as different evolvability patterns. Rather than a specification language, our calculus intends to be a basis for investigating the fundamental properties of evolvable processes and for developing richer languages with evolvability capabilities

CaSPiS: A Calculus of Sessions, Pipelines and Services

Service-oriented computing is calling for novel computational models and languages with well disciplined primitives for client-server interaction, structured orchestration and unexpected events handling. We present CaSPiS, a process calculus where the conceptual abstractions of sessioning and pipelining play a central role for modelling service-oriented systems. CaSPiS sessions are two-sided, uniquely named and can be nested. CaSPiS pipelines permit orchestrating the flow of data produced by different sessions. The calculus is also equipped with operators for handling (unexpected) termination of the partner’s side of a session. Several examples are presented to provide evidence of the flexibility of the chosen set of primitives. One key contribution is a fully abstract encoding of Misra et al.’s orchestration language Orc. Another main result shows that in CaSPiS it is possible to program a “graceful termination” of nested sessions, which guarantees that no session is forced to hang forever after the loss of its partner

A Model Handbook of Hiring and Employment Practices and Procedures for Selected Private K-12 Schools

The purpose of the project was to develop a model handbook of hiring and employment practices and procedures for private K-12 schools. To accomplish this purpose a review of literature and current policies or procedures from public and private schools, agencies and organizations was conducted. Additional related information from selected sources was obtained and analyzed

Industry 5.0 Enabled Smart Logistics: Optimization of Distribution Network in Food Industry

The fourth industrial revolution, namely Industry 4.0, has substantially impacted the supply chain and logistics operations which led to the introduction of Logistics 4.0. The incorporation of novel technologies in this context developed smart logistics; however, scholars raised the concerns about socio-economic aspects of these improvements. Industry 5.0 as a value-driven paradigm, in this regard, initiated the trinary concept of sustainability, resilience, and human-centricity to put forward the technological and conceptual developments of industry according to this framework. Given the recency of this industrial revolution, not many research works have focused on the implication of Industry 5.0 for smart logistics. Therefore, this research aims at bridging this gap by investing effort into accomplishing a thorough systematic literature review to compare the topic of smart logistics in Industry 4.0 and Industry 5.0. The results define integration and intelligence among the key features, and spot simulation and digital twin among the enabling technologies of this concept. To realize these findings, a digital model of a company’s distribution network is created, and it facilitates the possibility of performing network optimization and simulation through an integrated platform. The results show that such approach has a remarkable contribution in performing the supply chain network optimization and determining the logistics performances of the redesigned network, e.g., optimal inventory level and capacity at each facility, shipping policy in individual transportation routes, etc. This approach enables the possibility of incorporating socio-economic aspects into logistics studies, e.g., CO2 emission, which are discussed as further research directions

Volume 4, Number 4, December 1984 OLAC Newsletter

Digitized December 1984 issue of the OLAC Newsletter

Integration of analysis techniques in security and fault-tolerance

This thesis focuses on the study of integration of formal methodologies in security protocol analysis and fault-tolerance analysis. The research is developed in two different directions: interdisciplinary and intra-disciplinary. In the former, we look for a beneficial interaction between strategies of analysis in security protocols and fault-tolerance; in the latter, we search for connections among different approaches of analysis within the security area. In the following we summarize the main results of the research

Mind the Gap: Trade-Offs between Distributed Ledger Technology Characteristics

When developing peer-to-peer applications on Distributed Ledger Technology (DLT), a crucial decision is the selection of a suitable DLT design (e.g., Ethereum) because it is hard to change the underlying DLT design post hoc. To facilitate the selection of suitable DLT designs, we review DLT characteristics and identify trade-offs between them. Furthermore, we assess how DLT designs account for these trade-offs and we develop archetypes for DLT designs that cater to specific quality requirements. The main purpose of our article is to introduce scientific and practical audiences to the intricacies of DLT designs and to support development of viable applications on DLT