Eventing in Information Systems Based on Command Query Responsibility Segregation Design Pattern

International audience

Eventual consistency is demanded nowadays in geo-replicated services that need to be highly scalable and available. According to the CAP constraints, when network partitions may arise, a distributed service should choose between being strongly consistent or being highly available. Since scalable services should be available, a relaxed consistency (while the network is partitioned) is the preferred choice. Eventual consistency is not a common data-centric consistency model, but only a state convergence condition to be added to a relaxed consistency model. There are still several aspects of eventual consistency that have not been analysed in depth in previous works: 1. which are the oldest replication proposals providing eventual consistency, 2. which replica consistency models provide the best basis for building eventually consistent services, 3. which mechanisms should be considered for implementing an eventually consistent service, and 4. which are the best combinations of those mechanisms for achieving different concrete goals. This paper provides some notes on these important topics.

Distributed financial systems must reconcile scalability with strict correctness guarantees. In payroll automation platforms, even minor consistency violations can produce cumulative monetary errors, regulatory exposure, and operational instability. Traditional consistency models—such as strong consistency or eventual consistency—are insufficient when applied uniformly across complex financial architectures. Instead, systems must define explicit consistency boundaries that align with financial invariants. This paper introduces the concept of consistency boundaries in distributed payroll backends and proposes architectural strategies for defining, enforcing, and validating these boundaries. By structuring identity-scoped mutation domains, separating read and write consistency zones, and coordinating cross-service financial workflows through controlled interfaces, backend systems can achieve deterministic payroll automation without sacrificing scalability. The study emphasizes that consistency is not a global property but a deliberately engineered boundary condition embedded within system design.

Eventual consistency is demanded nowadays in highly scalable and available geo-replicated services. According to the CAP theorem, when network partitions may arise a distributed service should choose between being strongly consistent or being highly available. Since scalable services must be available, relaxed consistency is the regular choice. Eventual consistency is not a regular data-centric consistency model, but only a state convergence property to be added to a relaxed consistency model. This paper discusses which data-centric consistency models are not implicitly convergent and, because of this, provide an adequate basis for building eventually consistent services.

Bitbox is an application that synchronizes distributed repositories of data. It can be used as a backup or sharing application similarly to popular cloud-based storage systems. Bitbox supports arbitrary and changing topologies, thus allowing residential gateways to be used as caches for synchronizing nomadic devices that connect only periodically. In this article, we describe the data-structure and algorithms powering Bitbox. We prove its correctness by showing that its synchronization scheme achieves strong eventual consistency.

• A new control logic for the SCMSHPD system under low meteorological conditions was proposed. • Performance of the SCMSHPD system operating under the new control logic were analyzed. • The effects of the waste heat recovery on the combined drying system under different meteorological parameters were obtained. • Drying process of the combined drying system was optimized. To solve the problem that the high drying temperature demand could not be met when combined drying system operated under low ambient temperature and weak solar irradiance, a new control logic of the solar combined multi-heat source heat pump drying (SCMSHPD) system was proposed and its simulation model was established. By modifying its operating strategy, the SCMSHPD system achieved a higher drying temperature under low environment temperature and weak irradiance, which ensured the implementation of the drying process. The simulation results was verified through experimental study. Additionally, to address the issue of significant heat loss of the exhaust air, waste heat recovery was implemented and its impact on the system’s operating characteristics was analyzed. At last, the drying process was optimized due to the significant improvement of the specific moisture extraction rate ( SMER ) and the system performance was further improved. The results showed that the errors in coefficient of performance ( COP ), energy consumption, and SMER between the experimental and simulation results were 4.04%, 1.84% and 1.53% respectively, which verified the reliability of the simulation model. In October, the COP of the SCMSHPD system without waste heat recovery was 3.66% higher than that of the ASHPD system, but with the decrease of ambient temperature and solar irradiance, the COP of the combined drying system increased by 5.86% in December, demonstrating the advantage of the SCMSHPD system with the new control logic under low meteorological parameters. The waste heat recovery could not improve the system performance of the SCMSHPD system operating with the new control logic proposed, which caused a decrease of 1.06% and 1.19% in October and December respectively. However, the SMER was significantly increased by 70.67% and 12.78% respectively, and the energy consumption was significantly decreased by 41.33% and 10.94%. The results indicated that although waste heat recovery resulted in a slight decrease in system COP , the significant reduction in energy consumption and notable increase in SMER demonstrated a marked improvement in the overall system performance. Due to the significant increase of the SMER , the drying time was shortened, which caused an increase of 1.77% in COP in October. With meteorological parameters became lower, the COP get a bigger increase of 3.34%. Therefore, it could be concluded that the combination of waste heat recovery and shortened drying time could effectively improve the system performance, and the lower the meteorological parameters, the greater the improvement in the system performance. This study can provide important guidance for the selection of control logic and the optimization of the drying process for the SCMSHPD system under low meteorological parameters.

The study of inclusive education has been regulated in Law Number 20 of 2023 concerning the National Education System. Based on data obtained from community partnership empowerment activities at Special Assistant Teachers (GPK) of Public Middle Schools in Magetan Regency, it shows that out of 43 GPKs, 86.04% of GPKs have difficulty using discussion and presentation methods in assisting slow learner students in learning mathematics. The problem occurs because there is no media specifically designed by GPK to attract the attention and interest of slow learner students. Following up on this problem, socialization and training activities for the E-IM3 information system were held for 43 GPKs. The activity method was carried out carefully, training in the use of E-IM3, and finally a system evaluation with a User Acceptance Test (UAT). The results of the UAT evaluation showed that the average score of the Software Engineering Test was 4.21, which means that E-IM3 is ready to use. The system functional test had a score of 3.87 and the User Interface (UI) test showed a score of 3.74, which means that there needs to be an improvement in system performance and a more attractive UI design.

A user interface (UI) is one of the most significant parts of an information system (IS). A user-friendly UI helps users to carry out their tasks with efficiency, effectiveness, and satisfaction. UI consists of five elements: metaphor, mental model, navigation, interaction, and appearance. Based on these, the designer must carefully select and design each element to be appropriate for the users. This research examines the influential process named user-centered design (UCD), a well-known process to raise product quality. Furthermore, the roles UI elements in IS development by observing it in a small family software services company in Thailand. The findings of this study show small family team is proper with UI design that concern in usability for user. Even though some UCD processes or UI elements are quite unclear, the clan culture helps team to design UI with flexibility, and unbiassed obtain comments from user.

The delay in networked control system can lead to a decrease in system performance. A sliding mode controller is designed to ensure the stability of the closed-loop system to compensate the delay. In the designed delay compensator, an integral sliding mode surface with delay compensation term is designed to eliminate the approach phase. The stability of the proposed delay compensation strategy based on sliding mode controller is also demonstrated using the Lyapunov stability method. The continuity of the control law not only ensures the existence of sliding modes and the existence of approach conditions but also weakens the impact of interference on the system to a certain extent. A numerical function, a networked inverted pendulum and networked electric heating furnace are used to verify that the designed delay compensation strategy can effectively compensate for the delay in networked control system, resulting in improved system performance.

<p>Change is endemic in modern business competition. In an age of globalisation, with the rapid development of information technologies (IT), changes occur at a much faster pace, and are also more unpredictable. Being agile in a turbulent environment has been ranked highly by executives in surveys of business issues conducted in past five years. Today nearly all organisations rely on information systems (IS) to operate. IS Agility is critical in achieving overall agility and performance in business. However, despite the strong interest from the practitioner community, IS Agility in academia has often been perceived as an overly abstract concept that is difficult to study. Resultantly, despite its importance, little has been published on how to systematically solve IS Agility problems with theoretical rigour and practical relevance. This “how to” question is a challenging one to researchers and is the major motivation of the present study. A key difficulty to study IS Agility is the lack of a solid conceptualisation. In this thesis, based on a multidisciplinary literature review looking for a unified theory of IS Agility, we proposed the IS Agility Nomological Network (ISANN) as a holistic conceptualisation to be used for problem solving. Such a conceptualisation includes an IS Agility Cycle illustrating four stages (i.e. Sense, Diagnose, Select, and Execute) of the dynamic interactions between IS and its human agents (e.g. IS users and IS developers), a decision tree presenting four main IS Agility drivers (i.e. Change Frequency, Uncertainty, Information Intensity, and Time Criticality), and a pyramid incorporating four IS Agility Providers (i.e. Agile System-Development, Agile-System Architecture, Agile System-Operation, and Agile-System Configuration ). We classify IS Agility as having at least two sides, Dev Agility and Ops Agility. The former represents the agility of IS development function while the later refers to the IS operation function. We believe they are not the same, as agility in system development process doesn’t necessarily translate to agility in the resulting system operation. To be able to answer the “how to” question and design a systematic problem-solving approach, we then operationalised ISANN by developing data and task models in real-world settings. These models were used to investigate and analyse IS Agility problems faced by Software as a Service (SaaS) adopters. Such a SaaS environment, due to its multi-tenancy nature, provides a great opportunity to observe the interactions and trade-offs between Dev Agility (e.g. stories from engineers and developers) and Ops Agility (e.g. stories from operators and users), as well as an abundant source of IS Agility related business problems. Eventually, more elements and factors emerged from this SaaS practice and were merged into the final artefact created in this study: ISACAM (Information System Agility Causation Analysis Method). ISACAM incorporates all the dimensions and facts derived from the theoretical conceptualisation and the ongoing real-world problem-solving practice. The effectiveness of ISACAM in solving IS Agility problems has been observed through improved performance in real-life businesses. Furthermore, five technological rules have been synthesised to offer a prescription for designing solutions to improve IS Agility.</p>

Indonesia is known as a country with high disaster risk. Many disasters occur such as earthquakes, tsunami, landslides, and floods. Therefore an efficient and effective disaster management system becomes a priority among the government programs. One element of disaster management system is the humanitarian logistics, which is important in handling the logistics of the stuff needed by the victims of the disaster. There are red cross application from many countries, however only few application that relate donor, volunteer and logistics. By implementing this system, the victims of the disaster can receive any stuff needed on time and in sufficient quantity. Information system is an important factor in handling an efficient logistics. Therefore this paper is discussing a humanitarian information system that has been developed. The system is developed using deep interview process, on side visitation and modelling process. The information system is developed using an integrated web-based model under the coordination of Red Cross Indonesia (IRC), East Java province. In this research, the integration system involves many parties such as supermarkets, donors, volunteers, and disaster posts. The result of this research is a logistics information system design including Web-based User Interface for the administrator, donors, shelters, supermarkets and mobile device user interface designed for volunteers. The user interface will help Indonesia Red Cross to collect stuffs and distribute them to victims more efficient after the user interfaces have been approved the head of Indonesia Red Cross.

Strong consistency is widely used in systems such as relational databases. In a distributed system, strong consistency ensures that all clients observe consistent data updates atomically on all servers. However, such systems need to sacrifice availability when synchronization occurs.We propose a new consistency protocol, the observable atomic consistency protocol (OACP) to make write-dominant applications as fast as possible and as consistent as needed. OACP combines the advantages of (1) mergeable data types, specifically, convergent replicated data types, to reduce synchronization and (2) reliable total order broadcast to provide on-demand strong consistency. We also provide a high-level programming interface to improve the efficiency and correctness of distributed programming.We present a formal, mechanized model of OACP in rewriting logic and verify key correctness properties using the model checking tool Maude. Furthermore, we provide a prototype implementation of OACP based on Akka, a widely-used actor-based middleware. Our experimental evaluation shows that OACP can reduce coordination overhead compared to the state-of-the-art Raft consensus protocol. Our results also suggest that OACP increases availability through mergeable data types and provides acceptable latency for achieving strong consistency, enabling a principled relaxation of strong consistency to improve performance.

Continuous evaluation of information systems (IS) is critical for their improvement. The context in which a system is embedded is a critical determinant for evaluation of its success. The paper explores the role of contextual factors in impacting the user evaluation of IS with regards to two key dimensions: information quality (IQ) and interface usability (IU), using a multi criteria decision making (MCDM) technique, analytic hierarchical process. The contextual factors include organisation size, industry of operation, type of IS, functional area and managerial level of user. The results show that excluding industry, all contextual factors significantly influence the user perception of IS evaluation. Additionally, IQ attributes of accuracy and reliability and IU attributes of efficiency and guidance are perceived as most significant by the users for IS evaluation.

A mobile nursing station is an innovative cart that integrates a wireless network, information technology devices, and online charts. In addition to improving clinical work and workflow efficiencies, data is integrated among different information systems and hardware devices to promote patient safety. This study investigated the effectiveness of mobile nursing cart use. We compared different distributions of nursing activity working samples to evaluate the nursing information systems in terms of interface usability and usage outcomes. There were two parts of this study. Part one used work sampling to collect nursing activity data necessary to compare a unit that used a mobile nursing cart (mobile group, n = 18) with another that did not (traditional group, n = 14). Part two applied a nursing information system interface usability questionnaire to survey the mobile unit with nurses who had used a mobile nursing station (including those who had worked in this unit as floating nurses) (n = 30) in order to explore interface usability and effectiveness. We found that using the mobile nursing station information system increased time spent on direct patient care and decreased time spent on indirect patient care and documentation. Results further indicated that participants rated interface usability as high and evaluated usage effectiveness positively. Comments made in the open-ended question section raised several points of concern, including problems / inadequacies related to hardware devices, Internet speed, and printing. This study indicates that using mobile nursing station can improve nursing activity distributions and that nurses hold generally positive attitudes toward mobile nursing station interface usability and usage effectiveness. The authors thus encourage the continued implementation of mobile nursing stations and related studies to further enhance clinical nursing care.

Human supervisory control and monitoring of automated systems, as well as, passive system(s) information processing can all be classified as forms of out‐of‐the‐loop (OOTL) performance. Whether the operator's task is to decide if process control intervention is necessary, detect a critical system event, or accept or reject the actions of a computer controller, he or she is removed from direct, real‐time control of the system. OOTL performance is a critical issue in overall automated systems functioning because it is associated with numerous negative consequences including: (a) operator failure to observe system parameter changes and intervene when necessary (vigilance decrements); (b) human over‐trust in computer controllers (complacency); (c) operator loss of system or situation awareness; and (d) operator direct/manual control skill decay. These consequences have been found to impact human performance under both normal operating conditions and system failure modes, with a greater effect on the latter [15] leading to serious problems in operator ability to perform their assigned tasks when working with automated systems.Level of automation (LOA) has been put forth as an approach to ameliorating OOTL performance problems. It is intended to determine the optimal assignment of control between a human operator and computer in order to keep both involved in system operations. LOA considers the capabilities and capacities of both the human and computer controller in determining their optimal coupling. It constitutes a systems approach to resolving OOTL performance problems by minimizing the negative consequences associated with the removal of the operator from active system control, and allows for the strengths of both human decision making and computer processing to be realized. When compared to a technological approach that assesses only the capabilities of the computer in allocating as much responsibility to the machine as possible, and assigning the remaining tasks to the human operator, the advantages can be considerable.A LOA taxonomy will be presented along with research examining its utility in a dynamic control task. Using LOA to identify optimal combinations of human and computer control was found to produce improvements in system performance under intermediate levels. These levels involve joint human and computer control of various system functions, such as monitoring, planning, and option selection and implementation. Results indicated decreases in the number of system processes/tasks overlooked by operators. These improvements may translate into cost reductions due to improved operational safety and are anticipated to be applicable to process control operations.