Preserving Access to Previous System States in the Lively Kernel

In programming systems such as the Lively Kernel, programmers construct applications from objects. Dedicated tools make it possible to manipulate the state and behavior of objects at runtime. Programmers are encouraged to make changes directly and receive immediate feedback on their actions. However, when programmers make mistakes in such programming systems, they need to undo the effects of their actions. Programmers either have to edit objects manually or reload parts of their applications. Moreover, changes can spread across many objects. As a result, recovering previous states is often error-prone and time-consuming. This report presents an approach to object versioning for systems like the Lively Kernel. Access to previous versions of objects is preserved using version-aware references. These references can be resolved to multiple versions of objects and, thereby, allow reestablishing preserved states of the system. We present a design based on proxies and an implementation in JavaScript

Naming Anonymous JavaScript Functions

JavaScript developers create programs by calling functions and they use functions to construct objects. JavaScript development tools need to report to developers about those functions and constructors, for example in debugger call-stacks and in object representations. However, most functions are anonymous: developers need not to specify names for functions. Based on our analysis of ten large, widely used JavaScript projects, less than 7\% of JavaScript functions are named by developers. After studying examples from these JavaScript projects, we propose \textit{Static Function-Object Consumption}, a principled, automated approach based on local source code analysis for providing names to nameless JavaScript functions. We applied our approach to 90000 anonymous functions that appeared in the analyzed JavaScript project. The approach is successful in naming more than 99\% (91\% are unique within their file) of anonymous functions while the average length of function names is kept less than 37 characters

Querypoint Debugging (Semi-Automated Inspection of Buggy Execution)

Debugging is a hard and time-consuming programming task that appears in the most stages of software development and maintenance. Therefore, any improvement in the debugging practice can significantly reduce the time and costs of software production. In this dissertation, our focus is on locating defects, a major debugging task. We first analyze the widely-used and new approaches to locating-defects. From this analysis we identify several main problems in these approaches that cause accidental difficulty. In order to better understand the locating-defects process, we systematically analyze this process based on modeling the developer’s mental model. From this analysis, we develop a model that explains how a developer progresses in this stage : a developer’s general strategy is to reduce the suspicious interval on the buggy execution until locating a fault. There are three basic types of movement : controlled forward navigation, search, and causality backward navigation. We propose Querypoint Debugging as a new approach to debugging that attempts to abstract away a developer’s inspection from one particular execution. We show how querypoints are defined for various types of movement, how they are processed, and how they solve most issues existing in the available debugging approaches. We have built two prototypes of the querypoint idea. The first prototype is a general querypoint debugger for Java which is supposed to support various types of querypoints. We demonstrate how a buggy painting application can be debugged using this debugger. The second prototype is one querypoint, lastChange, that is integrated to a famous JavaScript debugger, Firebug. With this prototype, we show that querypoints can be smoothly integrated with traditional debuggers. Moreover, the idea can be implemented even for weakly-typed languages such as JavaScript. We end this dissertation with providing a solution to a special but an important problem which particularly appears in JavaScript debuggers. Anonymous JavaScript functions are a major challenge for tool developers. After analyzing and classifying anonymous JavaScript functions in 10 large projects, we proposed an efficient algorithm that can successfully name 99 percent of anonymous functions

On the Development of Real-Time Multi-User Web Applications

With the increasing popularity of the World Wide Web (WWW), end-user applications are moving from desktop to the browser. Web applications have several benefits over native applications: web applications have worldwide availability for any browsing capable device without prior installations. In addition, web applications are easy to distribute and update – once deployed, a web application is instantly available worldwide and further modifications to the system are propagated automatically. The current trend seems to be that web applications are offering collaboration, social connections, and user to user interactions as key features. This can be seen, for example, in the popularity of Facebook, Flickr, and Twitter. Despite all the benefits of the Web, web applications are suffering from the shortcomings in underlying technologies. The Web is strongly rooted in information sharing, and the current technical solutions isolate users rather than make them aware of each other. Since the data cannot be pushed from server to a client, the client must always initiate the communication, which causes a considerable impediment for real-time multi-user web applications, like online chats that have several concurrent users continuously interacting with each other. For such systems, it would be practical if the server could push messages to clients. As a further obstacle, most web application frameworks isolate users in their private sessions that only interact indirectly via the database. This main contribution of this thesis is to make the development of real-time multi-user web applications easier. We elaborate on the difficulties in implementation and design and introduce methods of circumventing them. The main argument is that the Web, the available technology stack, and the frameworks are difficult to use for developing real-time multi-user web applications. However, by selecting the proper approach, the problems can be solved. In this thesis, we have divided the frameworks in groups based on how they make separation of concerns between the client and the server. The separation is important as it determines the thickness of the client and thus where to locate the business logic and the application state. In addition, it has effect on the synchronization of the state between the clients. To collect experiences and for backing up our assumptions, we have implemented real-time multi-user web applications for several frameworks and studied how the frameworks should be used for enabling real-time multi-user application development

HIVE-MIND SPACE: A META-DESIGN APPROACH FOR CULTIVATING AND SUPPORTING COLLABORATIVE DESIGN.

The ever-growing complexity of design projects requires more knowledge than any individual can have and, therefore, needs the active engagement of all stakeholders in the design process. Collaborative design exploits synergies from multidisciplinary communities, encourages divergent thinking, and enhances social creativity. The research documented in this thesis supports and deepens the understanding of collaborative design in two dimensions: (1) It developed and evaluated socio-technical systems to support collaborative design projects; and (2) It defined and explored a meta- design framework focused on how these systems enable users, as active contributors, to modify and further develop them. The research is grounded in and simultaneously extends the following major dimensions of meta-design: (1) It exploits the contributions of social media and web 2.0 as innovative information technologies; (2) It facilitates the shift from consumer cultures to cultures of participation; (3) It fosters social creativity by harnessing contributions that occur in cultures of participation; (4) It empowers end-users to be active designers involved in creating situated solutions. In a world where change is the norm, meta-design is a necessity rather than a luxury because it is impossible to design software systems at design time for problems that occur only at use time. The co-evolution of systems and users\u2bc social practices pursued in this thesis requires a software environment that can evolve and be tailored continuously. End-user development explores tools and methods to support end users who tailor software artifacts. However, it addresses this objective primarily from a technical perspective and focuses mainly on tailorability. This thesis, centered on meta-design, extends end-user development by creating social conditions and design processes for broad participation in design activities both at design time and at use time. It builds on previous research into meta- design that has provided a strategic overview of design opportunities and principles. And it addresses some shortcomings of meta-design, such as the lack of guidelines for building concrete meta-design environments that can be assessed by empirical evaluation. Given the goal of this research, to explore meta-design approaches for cultivating and supporting collaborative design, the overarching research question guiding this work is: How do we provide a socio-technical environment to bring multidisciplinary design communities together to foster creativity, collaboration, and design evolution? 8 To answer this question, my research was carried out through four different phases: (1) synthesizing concepts, models, and theories; (2) framing conceptual models; (3) developing several systems in specific application areas; and (4) conducting empirical evaluation studies. The main contributions of this research are: \uf0a7 The Hive-Mind Space model, a meta-design framework derived from the \u201csoftware shaping workshop\u201d methodology and that integrates the \u201cseeding, evolutionary growth, reseeding\u201d model. The bottom-up approach inherent in this framework breaks down static social structures so as to support richer ecologies of participation. It provides the means for structuring communication and appropriation. The model\u2bcs open mediation mechanism tackles unanticipated communication gaps among different design communities. \uf0a7 MikiWiki, a structured programmable wiki I developed to demonstrate how the hive-mind space model can be implemented as a practical platform that benefits users and how its features and values can be specified so as to be empirically observable and assessable; \uf0a7 Empirical insights, such as those based on applying MikiWiki to different collaborative design studies, provide evidence that different phases of meta-design represent different modes rather than discrete levels