On Urgency in Asynchronous Timed Session Types

We study an urgent semantics of asynchronous timed session types, where input actions happen as soon as possible. We show that with this semantics we can recover to the timed setting an appealing property of untimed session types: namely, deadlock-freedom is preserved when passing from synchronous to asynchronous communication

Preserving Liveness Guarantees from Synchronous Communication to Asynchronous Unstructured Low-Level Languages

In the implementation of abstract synchronous communication in asynchronous unstructured low-level languages, e.g. using shared variables, the preservation of safety and especially liveness properties is a hitherto open problem due to inherently different abstraction levels. Our approach to overcome this problem is threefold: First, we present our notion of handshake refinement with which we formally prove the correctness of the implementation relation of a handshake protocol. Second, we verify the soundness of our handshake refinement, i.e., all safety and liveness properties are preserved to the lower level. Third, we apply our handshake refinement to show the correctness of all implementations that realize the abstract synchronous communication with the handshake protocol. To this end, we employ an exemplary language with asynchronous shared variable communication. Our approach is scalable and closes the verification gap between different abstraction levels of communication

Choreography and Orchestration Conformance for System Design

Abstract. In a previous work we have presented a formal framework devoted to show the relevance of choreography and orchestration in the design of service oriented applications. Even if useful to start a formal investigation of the relationship between choreography and orchestration, the proposed framework was not suitable to specify real case studies. In fact, it simply permitted to specify all possible computations abstracting away from the conditions driving the choice of the actual behaviour. In this paper we tackle this problem by introducing the notion of state variables. The addition of state requires a substantial modification of the entire framework because the same state variable, at the level of choreography, can be actually stored in distributed orchestrators that will need to synchronize in order to maintain consistent views. In order to faithfully investigate this problem we also need to modify the formal model at the orchestration level, moving from synchronous to asynchronous communication as the latter is the communication modality of the ordinary communication infrastructures.

Communication models for services

Abstract. Communication is an essential aspect of services. Services do not only realize simple request-response scenarios, but increasingly implement complex and stateful communication protocols. Such a protocol specifies the order in which messages are sent and received by a service and is an essential part of a service description. Services are usually not executed in isolation, but as a collaboration which is composed of several services. The behavior of such a collaboration is not only determined by the communication protocol of each participating service, but also by the way messages are exchanged. A communication model specifies the properties of the message channels between the services and defines the way how messages are sent and received. This paper studies and classifies several dimensions of communication models and describes their impact to the behavior of service compositions

3D Design Review Systems in Immersive Environments

Design reviews play a crucial role in the development process, ensuring the quality and effectiveness of designs in various industries. However, traditional design review methods face challenges in effectively understanding and communicating complex 3D models. Immersive technologies, particularly Head-Mounted Displays (HMDs), offer new opportunities to enhance the design review process. In this thesis, we investigate using immersive environments, specifically HMDs, for 3D design reviews. We begin with a systematic literature review to understand the current state of employing HMDs in industry for design reviews. As part of this review, we utilize a detailed taxonomy from the literature to categorize and analyze existing approaches. Additionally, we present four iterations of an immersive design review system developed during my industry experience. Two of these iterations are evaluated through case studies involving domain experts, including engineers, designers, and clients. A formal semi-structured focus group is conducted to gain further insights into traditional design review practices. The outcomes of these evaluations and the focus group discussions are thoroughly discussed. Based on the literature review and the focus group findings, we uncover a new challenge associated with using HMDs in immersive design reviews—asynchronous and remote collaboration. Unlike traditional design reviews, where participants view the same section on a shared screen, HMDs allow independent exploration of areas of interest, leading to a shift from synchronous to asynchronous communication. Consequently, important feedback may be missed as the lead designer disconnects from the users' perspectives. To address this challenge, we collaborate with a domain expert to develop a prototype that utilizes heatmap visualization to display 3D gaze data distribution. This prototype enables lead designers to quickly identify areas of review and missed regions. The study incorporates the Design Critique approach and provides valuable insights into different heatmap visualization variants (top view projection, object-based, and volume-based). Furthermore, a list of well-defined requirements is outlined for future spatio-temporal visualization applications aimed at integrating into existing workflows. Overall, this thesis contributes to the understanding and improvement of immersive design review systems, particularly in the context of utilizing HMDs. It offers insights into the current state of employing HMDs for design reviews, utilizes a taxonomy from the literature to analyze existing approaches, highlights challenges associated with asynchronous collaboration, and proposes a prototype solution with heatmap visualization to address the identified challenge

Web-IDE for Low-Code Development in OutSystems

Due to the growing popularity of cloud computing and its numerous benefits, many desktop applications have been, and will continue to be, migrated into the cloud and made available through the web. These applications can then be accessed through any device that has access to a browser and internet connection, eliminating the need for installation or managing dependencies. Moreover, the process of introduction to the product is much simpler, faster and collaboration aspects are facilitated. OutSystems is a company that provides software that enables, through an Integrated Development Environment (IDE) and a specific Low-Code language, users to securely and rapidly build robust applications. However, there are only available desktop versions of this IDE. For this reason, the objective of the proposed thesis is to understand what would be the best path for developing a Web-based version of the IDE. To achieve this, it is important not only to understand the OutSystems Platform and, more specifically, the architecture of the Service Studio IDE, which is the component IDE provided by the product, but also to explore the state-of-the-art technologies that could prove to be beneficial for the development of the project. The goal of this work is to debate different architectural possibilities to implement the project in question and present a conclusion as to what the adequate course of action, given the context of the problem. After distinguishing what are the biggest uncertainties and relevant points, a proof of concept is to be presented accompanied with the respective implementation details. Finally, this work intends to determine what would be a viable technological architecture to build a Web-based IDE that is capable of maintaining an acceptable performance, similarly to Service Studio IDE, while also insuring that the this system is scalable, in order to be able to provide the service to a large amount of users. That is to say, to present a conclusion regarding the feasibility of the project proposed.Devido ao aumento de popularidade de tecnologias de computação cloud e as suas inúmeras vantagens, aplicações desktop estão e vão continuar a ser migradas para a cloud para que possam ser acedidas através da web. Estas aplicações podem ser acedidas através de qualquer dispositivo que tenha acesso à internet, eliminando a necessidade de instalação e gestão de dependências. Além disso, o processo de introdução ao produto é simplificado, mais rápido e a colaboração é facilitada. A OutSystems é uma empresa que disponibiliza um software que faz com que utilizadores, através de um IDE e uma linguagem de baixo nível, possam criar aplicações robustas de forma rápida e segura. No entanto, atualmente só existem versões deste IDE para desktop. Como tal, o objetivo da tese proposta é perceber qual será a melhor forma de desenvolver uma versão do IDE sobre a Web. Para alcançar isto, é importante não só compreender a Plataforma OutSystems e, mais especificamente, a arquitetura do Service Studio IDE, que é o principal componente disponibilizado pelo produto, mas também explorar as tecnologias estado de arte que podem ser benéficas para o desenvolvimento do projeto. O objetivo deste trabalho é debater diferentes arquiteturas possíveis para a implementação do projeto e concluir qual será o curso de ação adequado, dado o contexto do problema. Após distinguir quais são os maiores pontos de incerteza, uma prova de conceito é apresentada juntamente com os respetivos detalhes de implementação. Finalmente, este trabalho tem como intenção detalhar uma arquitetura tecnológica viável para construir um IDE na web capaz de manter uma performance aceitável, semelhante à do Service Studio IDE, e garantir a escalabilidade do sistema, de forma a conseguir oferecer o serviço a um número elevado de utilizadores. Por outras palavras, apresentar uma conclusão em relação à viabilidade do projeto proposto