Category: Master Students

William Ford Successfully Defends Master Thesis on Network Delay Models for dCPS

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On Wednesday, William Ford, a master student from VU/UvA defended his master thesis “Network Delay Model Creation and Validation for Design Space Exploration of Distributed Cyber-Physical Systems“. This thesis was executed in the context of the MasCot project DSE2.0 and was supervised by Benny and Faezeh Sadat Saadatmand, PhD student at Leiden University.

William’s thesis focuses on improving the development process of complex distributed cyber-physical systems (dCPS), such as the equipment developed by high-tech companies like ASML, Canon Production Printing, and Philips. Building physical prototypes for these systems is complex and costly, so the thesis explores automated and scalable model-based Design Space Exploration (DSE) as a solution. The research addresses the challenge of modeling network delays in dCPS, aiming to create models that balance speed and accuracy for DSE purposes. The methodology includes formalizing network topology and traffic concepts, resulting in an open-source framework for synthetic network generation called GeNSim. Three analytical network delay models—Constant Delay, Constant Bandwidth, and Latency-Rate, and a simulation-based approach using the INET framework—are proposed and evaluated synthetic networks and an industry case study at ASML. The findings reveal that each model has its strengths and weaknesses, with no single model meeting all requirements perfectly. Therefore, a multi-step modeling approach is suggested to leverage the strengths and mitigate the weaknesses of the different models.

William confidently presented his thesis. In particular, the committee was very happy with the Q&A session after the presentation, which resulted in a lively back and forth with interesting questions and answers. Having defended his thesis, William can now apply for his diploma and graduate. We thank William for his contributions to the DSE2.0 research and wish him all the best with his future career.

Master’s Thesis Explores User Behavior’s Impact on Digital Service Energy Consumption

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Just before the end of summer, Nsidibe Onoyom Bassey, master student at the Vrije Universiteit Amsterdam, has successfully defended her thesis “Impact of Users’ Behavior on Digital Service Energy Consumption“. Congratulations on the defense and completing your studies Nsidibe!

This work was supervised by Ana Lucia Varbanescu and myself in the context of our research project Energy Labels for Digital Services, which studies the energy consumption of applications distributed over the compute continuum. In particular, the research addresses the growing concerns over energy consumption in the ICT sector, which poses challenges to achieving net-zero emissions. While ICT solutions are often seen as efficient and low-cost, their energy impact is significant, particularly due to the high demand for digital services, such as online shopping. Energy consumption in the digital domain is largely driven by hardware, software, and infrastructure, but the role of user behavior in influencing this consumption is often overlooked. The thesis focuses on understanding how user behavior affects energy consumption in digital services, using a commonly used open-source online shop implemented as microservices as a case study. The energy consumption on both the client and server side is studied and experiments are conducted with different client browsers, user interactions, and number of users. Based on the experiments, an analytical model is proposed to estimate the energy impact of user behavior on the server side and recommendations are made to both users and developers for how to limit energy consumption.

Master Thesis Project Leads to Conference Publication on Microservice Architecture Anti-Patterns at SEAA 2024

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I am delighted to announce that our paper, “Graph-based Anti-Pattern Detection in Microservice Applications,” has been accepted for publication at the 50th Euromicro Conference Series on Software Engineering and Advanced Applications (SEAA). This paper stems from Amund Lunke Røhne’s master thesis project, which he conducted as an internship with TNO-ESI under the supervision of myself and Ben Pronk. This achievement showcases how exceptional work by master students can lead to publications in established conferences.

Our paper addresses a significant challenge in the evolution of microservice applications: as the microservice architecture evolves, architectural anti-patterns may emerge. These anti-patterns are challenging to detect and manage due to their informal natural language definitions and the lack of automated tools. To tackle this, we propose an automated methodology for detecting architectural anti-patterns related to microservice dependencies. A key component of this methodology is the novel Granular Hardware Utilization-Based Service Dependency Graph (GHUBS) model, which is automatically inferred from telemetry data. We have formalized three commonly known anti-patterns and developed algorithms to detect them within the GHUBS model. This methodology is supported by an open-source tool that automatically identifies and visualizes these anti-patterns. We validated our approach using both synthetic data and a case study of a popular microservice benchmarking suite, demonstrating successful detection of the formalized anti-patterns.

Congratulations to Amund on the acceptance of your paper! Your work has made both TNO-ESI and the Software Engineering program at the University of Amsterdam very proud!

Merrick Oost-Rosengren Successfully Defends Thesis on Early Component Verification using Colored Petri Nets

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Just before the summer holidays, another master student has finished his project. This time, it is Merrick Oost-Rosengren who successfully defended his thesis “Formal Verification of Components through Mirroring of Coloured Petri Nets“. Parts of this work was done as an internship with TNO-ESI in collaboration with Thales.

This research addresses a challenge in distributed component-based systems, where different components are developed by different teams, perhaps even different organizations, over time. The problem is that when components are ultimately integrated, their interactions may cause deadlocks, livelock, or unbounded memory behavior. Fixing such problems late in the development process is very costly. An alternative approach is to model components, or component interfaces, early in the design process and use model checking to verify the behavior of the component and its interactions. However, we may not know which components it will interact with yet. Perhaps they have not yet been developed?

The thesis addresses this challenge by proposing a methodology and corresponding tool chain, where components as modelled as Colored Petri Nets from which a verification model, a mirror of the component that captures relevant possible behaviors of interacting components, is automatically generated. As a part of the methodology, the thesis proposes a new class of Colored Petri Nets called Mirrorable Open Colored Petri Nets. This class combines features of existing Colored Petri Nets and Open Petri Nets, and also adds extra semantics to allow the component to be mirrored. It also describes methods for mirroring such a net and fusing the mirror with the original component, such that the components and its interactions can be verified using reachability analysis.

We congratulate Merrick on his successful defense and wish him a lovely summer!

The Journey from Offline to Online Conformance Checking for Microservice Applications

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Ricardo Andrade has successfully defended his master thesis “Real-Time Conformance Checking for Microservice Applications“. This thesis was done in the context of the ArchViews project together with Thales. The academic supervisor was ESI colleague and TU/e professor Johan Lukkien and the daily supervision at ESI was done by myself and Ben Pronk.

The thesis addresses the shift from monolithic architectures to microservice architectures in order to manage the complexities and dependencies that emerge as systems grow and incorporate new features. A significant gap identified in the management of microservice applications is the lack of effective conformance checking techniques that can verify whether the execution of microservices aligns with their specification. To address this, the thesis proposes an innovative solution by developing an online conformance checker specifically designed for microservice applications. The project begins with the creation of an offline conformance checker that evaluates conformance using execution traces and sequence diagrams. The work then progresses to an online conformance checker, significantly improving performance and delivering conformance results within approximately 30 seconds per trace. This rapid response time meets the requirement for swift identification and correction of non-conforming sequences, thereby offering a practical and effective tool for managing microservice applications.

Ricardo presented his work very well using beautifully prepared slides. He confidently answered questions from the audience and the examination committee and left the session with a good grade. Ricardo is now moving on from his studies to start his career at CGI. We wish him the best of luck in his future career.

Jesse Liauw-A-Fong Defends Master’s Thesis on Local Anomaly Detection in Smart Public Transport Vehicles

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Yesterday, Jesse Liauw-A-Fong, a student of the Master of Software Engineering program at UvA, defended his thesis Local Anomaly Detection in Smart Public Transport Vehicles. This research was conducted externally at a company called Ximedes. Jessie’s research is addressing the problem of detecting anomalies, such as a loss of cloud connection, in Smart Public Transport Vehicles (SPTV), such as buses, trams, and metros, comprising many complex heterogeneous systems. It emphasizes the importance of local, context-aware anomaly detection due to the dynamic nature of SPTVs and explores the generalization of anomaly detection, particularly addressing performance, normal region, and quality challenges. The research proposes a unified data collection framework comparing agent-based and agent-less methods, advocating for an agent-based approach for its adaptability and integration ease. It also quantitatively evaluates three local anomaly detection algorithms on real data from a specific bus line. We thank Jessie for his contributions to our research and wish him the best of luck in his future career.

Master Thesis Shines Light on Hardware Dimensioning for Cyber-Physical Systems

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On Wednesday, Marijn Vollaard defended his master thesis “Hardware Dimensioning for Microservice-based Cyber-Physical Systems: A Profiling and Performance Prediction Method” at the University of Amsterdam. This research has been supervised by Ben Pronk and myself as a part of a project with TNO-ESI.

The thesis addresses the problem of determining the number of homogeneous compute nodes needed for a particular variant of a cyber-physical system to meet its timing requirements. This is important in early discussions with customers and bidding processes, since it affects the size and cost of the resulting system. To this end, the thesis proposes a structured hardware dimensioning methodology comprising a profiling method and a performance prediction method. The four novel contributions of the thesis are: 1) A component-based profiling method, 2) a performance prediction method, 3) a structured hardware dimensioning methodology, and 4) validation of the approach, using a case study that represents a prototype of a CPS. Experimental evaluations on the case study show that the predicted performance differs from measurements on the application by at most 20%, which is satisfactory for hardware dimensioning decisions for new product variants.

The defense went well and Marijn confidently presented his story and convincingly answered the questions of the audience. The examination committee, impressed by his work, awarded his thesis a well-deserved grade of 8. As we bid farewell to Marijn, embarking on his next career adventure, we also extend our heartfelt congratulations. He certainly has much to be proud of. We wish him all the best on his travels and in his future pursuits.

Master’s Student Marijn Vollaard Shines with Study on Hardware Dimensioning for Microservice Applications in Cyber-Physical Systems

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Our master’s student, Marijn Vollaard, has achieved a significant milestone by completing and presenting his literature study titled “Hardware Dimensioning for Microservice Applications in Cyber-Physical Systems: Current Directions and Challenges” The study addresses the challenge of dimensioning the number of compute nodes required to meet the performance demands of microservice-based applications in cyber-physical systems. It thoroughly reviews an extensive body of literature on application and system profiling, performance prediction, and design-space exploration to establish the current state of knowledge in this field. The survey culminates in a discussion about how the surveyed literature applies to microservice applications, the cyber-physical systems context, and the problem of hardware dimensioning. Overall, this is a nice piece of work with a lot of references presented in a systematic way. Congratulations to Marijn for his great effort!”

Master Thesis Tackles Architectural Anti-patterns in Microservice Applications

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Today, we are delighted to announce the successful defense of the outstanding master’s thesis titled “Architectural Anti-Pattern Identification and Mitigation in Microservice Applications Based on Telemetry” by our master student, Amund Lunke Rohne from the University of Amsterdam. This master’s project was a collaborative effort involving TNO-ESI and Thales.

The thesis addresses the problem that microservices offer benefits like scalability and separation of concerns, but also introduce many complex service dependencies. The decomposition of microservice applications can impact system performance and maintainability and can lead to architectural anti-patterns over time. While simple anti-patterns can be detected using analysis of service dependencies, there is a lack of formal mathematical definitions which prevents more complex anti-patterns from being automatically detected by tools. The thesis introduces a novel model called Granular Hardware Utilization-Based Service Dependency Graph (GHUBS), a fine-grained model that captures the interactions dependencies between services at the level of individual requests. The GHUBS model can be manually specified in early design phases to validate a microservice decomposition, or automatically created using telemetry data from a running application. Mathematical formalizations are introduced for four common architectural anti-patterns and methods for automatically detecting them using the GHUBS model is presented. A method for recommending how to mitigate the identified anti-patterns based on the service dependencies in the GHUBS model, as well as resource utilization metrics for the services, is also presented. The approach is implemented in a tool called Televisor and validated through case studies on open-source microservice benchmarking applications, revealing instances of these anti-patterns.

We thank Amund for his work and a fruitful collaboration, and wish him the best of luck in his future career.

Scaling the Future: Master Thesis Defense on Scalability in Simulation Environments for Distributed Cyber-Physical Systems

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Today, we celebrate that Herman Kelder successfully defended his master thesis “Scalability in System-Level Simulation Environments for Distributed Cyber-Physical Systems“. This work was carried out in the context of the DSE2.0 project, where we address the complex scientific challenges involved in performing design-space exploration (DSE) for complex distributed cyber-physical systems (dCPS), such as lithography machines. Three key challenges in this context are: 1) automatically modelling the application and platform based on data from the running system, 2) scalable search and pruning algorithms that help navigate large design spaces efficiently, and 3) scalable simulation environments that allow many design points to be efficiently evaluated concurrently.

Herman’s thesis addresses the last of these three challenges. To facilitate scalable and efficient DSE for dCPS, an evaluation environment is proposed, implemented, and evaluated. The research considers key design considerations for developing a distributed evaluation workflow that can dynamically be adapted to enable efficient and scalable exploration of the vast design space of complex, distributed cyber-physical systems. Evaluation of the proposed environment employs a set of system models, representing design points within a DSE process, to assess the solution and its behavior, performance, capability, and applicability in addressing the scalability challenge in the context of DSE for dCPS. During the evaluation, the performance and behavior are investigated in three areas: (i) Simulation Campaign, (ii) Task Management Configuration, and (iii) Parallel Discrete-Event Simulation (PDES). Throughout the evaluation, it is demonstrated that the proposed environment is capable of providing scalable and efficient evaluation of design points in the context of DSE for dCPS. Furthermore, the proposed solution enables designers and researchers to tailor it to their environment through dynamic complex workflows and interactions, workload-level and task-level parallelism, and simulator and compute environment agnosticism.

Herman executed his project meticulously and delivered excellent research results, both in terms of concepts and implementation. Thank you very much for your contributions Herman and we hope to work with you again at some point.