Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaf 87). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaf 87). Also available on the Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 105-107). Also available via the Internet.

Modern telecommunication applications must provide high availability and performance. They must also be maintainable in order to reduce the maintenance cost and time-to-market for new versions. Previous studies have shown that the ambition to build maintainable systems may result in very poor performance. Here we evaluate an application called SDP pre-paid and show that the ambition to build systems with high performance and availability can lead to a complex software design with poor maintainability. We show that more than 85% of the SDP code is due to performance and availability optimizations. By implementing a SDP prototype with an alternative architecture we show that the code size can be reduced with an order of magnitude by removing the performance and availability optimizations from the source code and instead using modern fault tolerant hardware and third party software. The performance and availability of the prototype is as least as good as the old SDP. The hardware and third party software cost is only 20-30% higher for the prototype. We also define three guidelines that help us to focus the additional hardware investments to the parts where it is really needed.

Today's technological systems are expected to perform at very high standards throughout their operational phase. The cost associated with unavailability of these systems is very high and especially with the defense systems or medical equipment which can directly affect human lives. The maintenance system plays an important role in achieving higher performance targets. In order to manage maintenance activities in more informed and rational manner, it is very important to understand the inherently complex and dynamic structure of the system. Traditionally maintenance policies are derived from reliability characteristics of individual components or sub-systems. This research makes an attempt to understand the system from the forest level and suggest better maintenance policies for achieving higher availability and lower system degradation. The leverage is gained from System Dynamics framework's ability to model complex systems and capture various feedback loops. The simulation results reveal that with the limited preventive maintenance capacity and within the given assumptions of the model, there exists and optimal preventive maintenance interval which is not the minimum. The simulation results also reflect that frequent preventive maintenance is required at higher load factors. / Master of Science

Context: Node.js is an established web framework built using JavaScript. As a result, there are a wide variety of frameworks that have emerged that specialize in different quality attributes and functionalities. Some of which are heavily geared to performance and benchmarking while others might focus on security, availability, robustness, etc. Objectives: The project aims to explore different Node.js server-side frameworks and determine their maintainability using metrics such as Halstead metrics, Maintainability index, source line of code as well as Logical source lines of code. This thesis also explores if there is a correlation between the quality attributes maintainability and performance. Realization: In order to explore the different quality attributes, the thesis relied upon experiments and a literature review. The hierarchical method in this thesis was first to examine their performance, later examine their overall maintainability. Examined is also the impact of comments and how they can affect the results of the maintainability index Results: The results indicate all the selected frameworks have a low-to borderline medium cyclomatic complexity, also a high degree of maintainability using two different 3 metric maintainability index formulas. The latency tests indicate the different frameworks produce similar performance results. Conclusion: Concluded in this thesis is, there seems to be no relationship between both lines of code, logical lines of code, and cyclomatic complexity. There also seems to be no correlation between Halstead volume and the overall maintainability index for both the 3 metric formulas used. There is a slight indication of a relationship between Halstead Effort and Cyclomatic Complexity using one of the 3 metric formulas i.e., as the cyclomatic complexity decreases the overall maintainability (using Halsted’s effort instead of Halstead’s volume) increases.

Innovation and new technologies are daily changing the characteristics of facilities as building owners are requiring more automated services, increased security is becoming more prevalent, and budget constraints are affecting facility operations. Therefore, additional avenues should be evaluated to reduce long-term costs by improving facility maintainability. The conclusions of these quarries should be incorporated into the design and preplanning phases as early as possible, as this is when the most impact can be made at the least expense. As it relates to this effort, preplanning refers to the project concept development and includes some initial aspects of the design. Preplanning for maintainability is one aspect that has historically not received much industry attention. This study considered the preplanning process as it pertains to maintainability, particularly for intelligent buildings, as this is the current trend in which building construction is heading. It limitedly considered the historic aspects of construction and automation, assessed the current situation and considered the projected future needs. Based on the expectations as to where future building intelligence will lead, it was ascertained that better preplanning should be incorporated into the construction process, especially as it pertains to maintainability.

Call number: LD2668 .T4 1979 K37 / Master of Science

Inter-process communications (IPC) are ubiquitous in today’s software systems, yet they are rarely treated as first-class programming concepts. Implementing crosscutting concerns for message-based IPC are difficult, even using aspect-oriented programming languages (AOPL) such as AspectJ. Many of these challenges are because the context of a communication-related crosscutting concern is often a conversation consisting of message sends and receives. Hence, developers typically have to implement communication protocols manually using primitive operations, such as connect, send, receive, and close. This dissertation describes an extension to AspectJ, called CommJ, with which developers can implement communication-related concerns in cohesive and loosely coupled aspects. It then presents preliminary, but encouraging results from a subsequent study that begin by defining a reuse and maintenance quality model. Subsequently the results show seven different ways in which CommJ can improve the reusability and maintainability of applications requiring network communications.

As the pace of business change increases, service-oriented (SO) solutions should facilitate easier maintainability as underlying business logic and rules change. To date, little effort has been dedicated to considering how the structural properties of coupling and cohesion may impact on the maintainability of SO software products. Moreover, due to the unique design characteristics of Service-Oriented Computing (SOC), existing Procedural and Object-Oriented (OO) software metrics are not sufficient for the accurate measurement of service-oriented design structures. This thesis makes a contribution to the field of SOC, and Software Engineering in general, by proposing and evaluating a suite of design-level coupling and cohesion metrics for predicting the maintainability of service-oriented software products early in the Software Development LifeCycle (SDLC). The proposed metrics can provide the following benefits: i) facilitate design decisions that could lead to the specification of quality SO designs that can be maintained more easily; ii) identify design problems that can potentially have a negative effect on the maintainability of existing service-oriented design structures; and iii) support more effective control of maintainability in the earlier stages of SDLC. More specifically, the following research was conducted as part of this thesis: - A formal mathematical model covering the structural and behavioural properties of service-oriented system design was specified. - Software metrics were defined in a precise, unambiguous, and formal manner using the above model. - The metrics were theoretically validated and empirically evaluated in order to determine the success of this thesis as follows: a. Theoretical validation was based on the property-based software engineering measurement framework. All the proposed metrics were deemed as theoretically valid. b. Empirical evaluation employed a controlled experimental study involving ten participants who performed a range of maintenance tasks on two SO systems developed (and measured using the proposed metrics) specifically for this study. The majority of the experimental outcomes compared favourably with our expectations and hypotheses. More specifically, the results indicated that most of the proposed metrics can be used to predict the maintainability of service-oriented software products early in the SDLC, thereby providing evidence for the validity and potential usefulness of the derived metrics. Nevertheless, a broader range of industrial scale experiments and analyses are required to fully demonstrate the practical applicability of the metrics. This has been left to future work.