Browsing by Author "Zorn, Christoph"

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Open Access
Concern-driven reporting of declarative performance analysis results using natural language and visualization
(2018) Zorn, Christoph
Recent trends in the development of software architectures show that an increasing interest in the quality assurance of software solutions exists. To sustain the value of these programs, continuous testing and performance analysis has to be performed in every layer of the application. This process is usually performed by performance analysts, which are aware of pitfalls and unsuspected problems. Moreover is the development of software shifting into the culture of DevOps, the practice of managing all steps of the software construction in one department. This requires developers to be flexible and perform a diverse amount of tasks. In the case of performance analysis, a developer has to take the place of a software analyst. It requires profound expertise in the field of software performance evaluation. With an exceeding amount of analysis technologies, it is impossible to be an expert in every analysis solution. This suggests that the process of performance analysis has to be altered and simplified. On the one hand, people outside the performance analysis community have to be provided with tools for easier access. On the other hand, the complexity of such tools should support advanced expert configurations as well. Declarative Performance Engineering (DPE) tries to abstract the definition of performance relevant questions and the execution of the performance evaluation. The idea behind DPE is to hide complex configuration from inexperienced users and provide existing use cases to perform simple and advanced performance analysis. This thesis aims to provide users of performance evaluation with such a declarative approach. Users can formulate questions in human language and receive a range of evaluation options through the format of the question. The results of those evaluation methodologies are independently processed and presented to the user based on the asked question. This is done with declarative methods and advanced visualization technologies. To get a prospect on the possibilities in declarative performance reporting, a prototype is created that will be evaluated by two user groups in a user study. Experts in performance analysis will show what level of detail is necessary to make accurate predictions. Inexperienced users with no background in performance analysis will report which level of support is needed to perform basic evaluations. The outcome of the study will be examined on the differences in user behavior between the two user groups and reflects on the possible use of the prototype in the future. Collected data will be discussed and set into context with existing projects in the area of declarative performance analysis.
Open Access
Interactive elicitation of resilience scenarios in microservice architectures
(2021) Zorn, Christoph
Context. Elicitation of requirements in software systems is a complex task. Hence, it requires knowledgeable software architects and other domain experts. Especially in distributed environments such as microservice-based systems, this is the case. Components of the system are developed in isolation and commonly share no prerequisites. Therefore, a precise specification is necessary to ensure the availability and performance of the individual components. Problem. In practice, requirements elicitation of non-functional attributes is often neglected or does not follow a systematic approach. If the elicitation process is performed at all, stakeholders meet in physical group meetings. Here, the presence of domain experts with profound knowledge of the inspected system is required. Such an approach is very time-consuming and can result in high costs. Furthermore, participants are required to cover all essential use cases in a limited number of meetings. Objective. This work proposes Resirio, a requirements chatbot supporting resilience engineers in the elicitation process of resilience-related attributes. Previous works have introduced interactive solutions for requirements elicitation. However, they lack formalization and precise elicitation methodologies. The proposed approach should make the elicitation process more effective for software architects and more accessible to inexperienced requirements engineers. Method. Resirio ensures that requirements are elicited in a systematic approach and stored in template-based ATAM scenarios. We use a CHAZOP-based hazard analysis technique to inspect metrics in traces from Zipkin and Jaeger. Hazards identified by the analysis help to examine stimuli that may lead to deviations from the optimal behavior of the system. With the stimulus as an input, users create ATAM scenarios in a conversation with Resirio. Response and response measure, which are parameters of the scenario, are formalized based on MTL. Result. In a user study with software architects, engineers, and researchers from industry and academia, we evaluated Resirio's usability, effectiveness, and support. We compared the user's interaction with the prototype and examined elicited scenarios during the study. The developed prototype gives novice requirements engineers a foundation for fast requirements elicitation but requires advanced features for expert users to define more precise scenarios. Conclusion. We showcase an interactive solution that enables quick and easy elicitation of resilience-related requirement attributes. Following the systematic CHAZOP-based approach, hazard are identified in traces from Zipkin and Jaeger. In a conversation with Resirio, stakeholders of a microservice-based software system are assisted in refining ATAM scenarios. Results from the user study show that resilience engineers prefer the fast and direct input of Quick Replies to written text.