Context-dependent applications are relatively complex due to their multiple variations caused by context activation, especially in the presence of unanticipated adaptation. Testing these systems is challenging, as it is hard to reproduce the same execution environments. Therefore, a software failure caused by bugs is no exception. This paper presents a rollback mechanism to recover from software failures as part of a role-based runtime with support for unanticipated adaptation. The mechanism performs checkpoints before each adaptation and employs specialized sensors to detect bugs resulting from recent configuration changes. When the runtime detects a bug, it assumes that the bug belongs to the latest configuration. The runtime rolls back to the recent checkpoint to recover and subsequently notifes the developer to fix the bug and re-applying the adaptation through unanticipated adaptation. We prototype the concept as part of our role-based runtime engine LyRT and demonstrate the applicability of the rollback recovery mechanism for unanticipated adaptation in erroneous situations.

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Adaptability is an intrinsic property of software systems that require adaptation to cope with dynamically changing environments. Achieving adaptability is challenging. Variability is a key solution as it enables a software system to change its behavior which corresponds to a specific need. The abstraction of variability is to manage variants, which are dynamic parts to be composed to the base system. Run-time variability realizes these variant compositions dynamically at run time to enable adaptation. Adaptation, relying on variants specified at build time, is called anticipated adaptation, which allows the system behavior to change with respect to a set of predefined execution environments. This implies the inability to solve practical problems in which the execution environment is not completely fixed and often unknown until run time. Enabling unanticipated adaptation, which allows variants to be dynamically added at run time, alleviates this inability, but it holds several implications yielding system instability such as inconsistency and run-time failures. Adaptation should be performed only when a system reaches a consistent state to avoid inconsistency. Inconsistency is an effect of adaptation happening when the system changes the state and behavior while a series of methods is still invoking. A software bug is another source of system instability. It often appears in a variant composition and is brought to the system during adaptation. The problem is even more critical for unanticipated adaptation as the system has no prior knowledge of the new variants. This dissertation aims to achieve anticipated and unanticipated adaptation. In achieving adaptation, the issues of inconsistency and software failures, which may happen as a consequence of run-time adaptation, are evidently addressed as well. Roles encapsulate dynamic behavior used to adapt players representing the base system, which is the rationale to select roles as the software system's variants. Based on the role concept, this dissertation presents three mechanisms to comprehensively address adaptation. First, a dynamic instance binding mechanism is proposed to loosely bind players and roles. Dynamic binding of roles enables anticipated and unanticipated adaptation. Second, an object-level tranquility mechanism is proposed to avoid inconsistency by allowing a player object to adapt only when its consistent state is reached. Last, a rollback recovery mechanism is proposed as a proactive mechanism to embrace and handle failures resulting from a defective composition of variants. A checkpoint of a system configuration is created before adaptation. If a specialized bug sensor detects a failure, the system rolls back to the most recent checkpoint. These mechanisms are integrated into a role-based runtime, called LyRT. LyRT was validated with three case studies to demonstrate the practical feasibility. This validation showed that LyRT is more advanced than the existing variability approaches with respect to adaptation due to its consistency control and failure handling. Besides, several benchmarks were set up to quantify the overhead of LyRT concerning the execution time of adaptation. The results revealed that the overhead introduced to achieve anticipated and unanticipated adaptation to be small enough for practical use in adaptive software systems. Thus, LyRT is suitable for adaptive software systems that frequently require the adaptation of large sets of objects.

The thesis analyses in detail the relationship between the money stock defined by money aggregates M1 and M2 and the real GDP in the Czech Republic for period between 1996 and 2015. A long-term relationship between the real GDP and the money aggregate is not found using quarterly time series data. These conclusions are in accordance with the economic theory which does not confirm that money affects level of the real GDP in the long run. Short-term relationship between given variables is also analysed. Results indicate that the growth rate of the money aggregate M1 statistically significantly affects the growth rate of the real GDP in the same direction which is in line with monetary theories of business cycle. On the other hand, any statistically significant relationship for the money aggregate M2 is not found which speaks in favour of the Real Business Cycle theory. The Policy Ineffectiveness Proposition accepted by New Classical Macroeconomists is also tested in the thesis. The issue is investigated for the whole period and subsequently for shorter time from 2000 to 2015 where the uniform monetary policy is applied. Results for the money aggregate M1 imply that expected changes in the growth rate of M1 play important role in the money-output relationship which is consistent with the New Keynesian Macroeconomic theory. Considering the shorter period of time, Lucas' theory seems to be more appropriate explanation. Outcomes for the aggregate M2 provide mixed conclusions which support rather the Real Business Cycle theory. At the end of the thesis, there is a section devoted to the quasi money (one of M2 aggregate components) as a possible source of mixed results.

Large scale IoT service deployments run on a high number of distributed, interconnected computing nodes comprising sensors, actuators, gateways and cloud infrastructure. Since IoT is a fast growing, dynamic domain, the implementation of software components are subject to frequent changes addressing bug fixes, quality insurance or changed requirements. To ensure the continuous monitoring and control of processes, software updates have to be conducted while the nodes are operating without losing any sensed data or actuator instructions. Current IoT solutions usually support the centralized management and automated deployment of updates but are restricted to broadcasting the updates and local update processes at all nodes. In this paper we propose an update mechanism for IoT deployments that considers dependencies between services across multiple nodes involved in a common service and supports a coordinated update of component instances on distributed nodes. We rely on LyRT on all IoT nodes as the runtime supporting local disruption-minimal software updates. Our proposed middleware layer coordinates updates on a set of distributed nodes. We evaluated our approach using a demand response scenario from the smart grid domain.

This dissertation in practice focuses on a review of literature to answer the guiding question, what can teachers and other educational stakeholders do to help address their sources of dissatisfaction in order to build a positive school climate? The author used a modified frame analysis from Bolman and Deal, other published literature, and personal experience to identify seven different, but sometimes related, domains that affect teachers and school climate. These seven domains include operations/management, contract application, professional development, classroom management, interpersonal, financial, and unanticipated events. The modified frame analysis was used to help empower teachers to solve problems that affect their performance and motivation, to prevent burnout, attrition, as well as help build and maintain a positive school climate. This dissertation promotes the notion that school climate is composed of and constructed from these seven domains as constituent parts that combine to create the school climate. The author-created tool, Tools for Teachers to Address Domains of Dissatisfaction, enables teachers to quickly reference potential solutions to problems faced. The tool is a prototype, created based on professional literature sources focusing on research-based strategies to identify problems and methods a teacher can use to solve a problem, thus preventing a negative school environment for the students, staff as well as other stakeholders. The domains of dissatisfaction were tested against real-life issues submitted to a Faculty Advisory Committee in order to provide veracity and justification of the domains.

Business organisations today are faced with the complex problem of dealing with evolution in their software information systems. This effectively concerns the accommodation and facilitation of change, in terms of both changing user requirements and changing technological requirements. An approach that uses the software development life-cycle as a vehicle to study the problem of evolution is adopted. This involves the stages of requirements analysis, system specification, design, implementation, and finally operation and maintenance. The problem of evolution is one requiring proactive as well as reactive solutions for any given application domain. Measuring evolvability in conceptual models and the specification of changing requirements are considered. However, even "best designs" are limited in dealing with unanticipated evolution, and require implementation phase paradigms that can facilitate an evolution correctly (semantic integrity), efficiently (minimal disruption of services) and consistently (all affected parts are consistent following the change). These are also discussed / Computing / M. Sc. (Information Systems)

Business organisations today are faced with the complex problem of dealing with evolution in their software information systems. This effectively concerns the accommodation and facilitation of change, in terms of both changing user requirements and changing technological requirements. An approach that uses the software development life-cycle as a vehicle to study the problem of evolution is adopted. This involves the stages of requirements analysis, system specification, design, implementation, and finally operation and maintenance. The problem of evolution is one requiring proactive as well as reactive solutions for any given application domain. Measuring evolvability in conceptual models and the specification of changing requirements are considered. However, even "best designs" are limited in dealing with unanticipated evolution, and require implementation phase paradigms that can facilitate an evolution correctly (semantic integrity), efficiently (minimal disruption of services) and consistently (all affected parts are consistent following the change). These are also discussed / Computing / M. Sc. (Information Systems)