Exploiting Smalltalk Modules In A Customizable Programming Environment

This paper describes how we have extended a module structure of the Smalltalk LearningWorks to provide a programming environment deigned for very large scale technology transfer. The ‘module’ is what we have termed the LearningBook, a set of classes and persistent objects, including an HTML browser, programming and visualization tools, and microworlds. The context for this development is a distance learning university course in object technology which has enrolled over 5,100 mature students in its first year – making it the largest such course in the world. While promoting a systems building approach, we have successfully added support for programming in the small and the needs of the isolated novice. Two principles have applied: (i) the programming environment and its modules fit into a consistent framework for personal management of study and (ii) details of complex facilities, such as the class library, are progressively disclosed as knowledge and sophistication grow. The paper shows how these principles have guided the exploitation of LearningBook modules. To provide context, relevant academic background is given. Early informal feedback is reported and a project currently underway to observe in detail how thousands of learners use the Smalltalk programming environment is sketched

Waterfall: Primitives Generation on the Fly

Modern languages are typically supported by managed runtimes (Virtual Machines). Since VMs have to deal with many concepts such as memory management, abstract execution model and scheduling, they tend to be very complex. Additionally, VMs have to meet strong performance requirements. This demand of performance is one of the main reasons why many VMs are built statically. Thus, design decisions are frozen at compile time preventing changes at runtime. One clear example is the impossibility to dynamically adapt or change primitives of the VM once it has been compiled. In this work we present a toolchain that allows for altering and configuring components such as primitives and plug-ins at runtime. The main contribution is Waterfall, a dynamic and reflective translator from Slang, a restricted subset of Smalltalk, to native code. Waterfall generates primitives on demand and executes them on the fly. We validate our approach by implementing dynamic primitive modification and runtime customization of VM plug-ins

Separable User Interface Architectures in Teaching Object Technology

This paper concerns the critical role of separable user interface design in teaching object-oriented systems. M206 "Computing: An Object-oriented Approach" is a large-scale university-level introduction to software development designed from scratch for distance learning, using an objects-first approach with Smalltalk. The course is degree-level, counting as one sixth, and is being offered in the UK, Western Europe and Singapore. To address the needs of industry we have developed a radical syllabus that adheres to the principle of designing complex systems by separating view and model, and have developed a programming and learning environment to support these ideas. In the paper we examine how separable user interface architectures have guided our teaching of object technology and the design of powerful microworlds that are both usable and extendible by neophytes. The course and relevant teaching with software is outlined and the technical design and pedagogic use of the microworlds and GUI builder tool are described

Employing Object Technology to Expose Fundamental Object Concepts

We explore technical issues in the design of programming tools, development environments, simulations, code examples, user interface frameworks and pedagogies for a university-level course on object-oriented software development. The course, M206 Computing: An Object-Oriented Approach has been specifically developed for distance learning, and is enrolling over 5,000 students per year (average age 37) in the UK, Europe and Singapore. The course introduces computing via an object-oriented approach. M206 is substantial in extent representing one sixth of a degree. It embodies a practical, industry oriented view of computing and includes programming, analysis, design and group working. Considerable effort has been invested in making the simplicity, consistency and power of object technology accessible to and capable of being applied by beginners. A diverse set of educational media, such as CD-ROMs, TV and the Web, have been deployed as learning resources. We describe the agenda for the course; its object-oriented pedagogy and our strategy for delivery. We explain measures taken to avoid misconceptions about objects, our analysis and design method, and the Smalltalk programming environment we have developed specifically for learners and which is crucial to our approach. We outline how our adherence to the separation of view and domain model leads to technical innovations. Concluding remarks reflect on the benefits a reflexive strategy, both in education and training

A comparative analysis of adaptive middleware architectures based on computational reflection and aspect oriented programming to support mobile computing applications

Mobile computing applications are required to operate in environments in which the availability for resources and services may change significantly during system operation. As a result, mobile computing applications need to be capable of adapting to these changes to offer the best possible level of service to their users. However, traditional middleware is limited in its capability of adapting to environment changes and different users requirements. Computational Reflection and Aspect Oriented Programming paradigms have been used in the design and implementation of adaptive middleware architectures. In this paper, we propose two adaptive middleware architectures, one based on reflection and other based on aspects, which can be used to develop adaptive mobile applications. The reflection based architecture is compared to an aspect oriented based architecture from a quantitative perspective. The results suggest that middleware based on Aspect Oriented Programming can be used to build mobile adaptive applications that require less processor running time and more memory space than Computational Reflection while producing code that is easier to comprehend and modify.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Modules as values in a persistent object store

Journal ArticleWe report on an object manager (OM) providing persistent implementations for C ++ classes. Our OM generalizes this problem to that of managing persistent modules, where the module concept is an abstract data type (ADT). This approach permits a powerful suite of module manipulation operations to be applied uniformly to modules of many provenances, including non-class based entities such as conventional object files, application libraries, and shared system libraries. OMOS, a generalized linker and loader, plays a central role in our OM. Class implementations are represented by OMOS modules, which in turn are constructed from OMOS meta-objects encapsulating linkage blueprints. We cleanly solve the problems of (i) logically (but not physically) including executable object files in our OM, (ii) reconciling class inheritance history and linkage history, and (iii) supporting alternative implementations of a class, for client interoperability or version control

A comparative analysis of adaptive middleware architectures based on computational reflection and aspect oriented programming to support mobile computing applications

Mobile computing applications are required to operate in environments in which the availability for resources and services may change significantly during system operation. As a result, mobile computing applications need to be capable of adapting to these changes to offer the best possible level of service to their users. However, traditional middleware is limited in its capability of adapting to environment changes and different users requirements. Computational Reflection and Aspect Oriented Programming paradigms have been used in the design and implementation of adaptive middleware architectures. In this paper, we propose two adaptive middleware architectures, one based on reflection and other based on aspects, which can be used to develop adaptive mobile applications. The reflection based architecture is compared to an aspect oriented based architecture from a quantitative perspective. The results suggest that middleware based on Aspect Oriented Programming can be used to build mobile adaptive applications that require less processor running time and more memory space than Computational Reflection while producing code that is easier to comprehend and modify.8th IFIP/IEEE International conference on Mobile and Wireless CommunicationRed de Universidades con Carreras en Informática (RedUNCI

Proceedings of the ECSCW'95 Workshop on the Role of Version Control in CSCW Applications

The workshop entitled "The Role of Version Control in Computer Supported Cooperative Work Applications" was held on September 10, 1995 in Stockholm, Sweden in conjunction with the ECSCW'95 conference. Version control, the ability to manage relationships between successive instances of artifacts, organize those instances into meaningful structures, and support navigation and other operations on those structures, is an important problem in CSCW applications. It has long been recognized as a critical issue for inherently cooperative tasks such as software engineering, technical documentation, and authoring. The primary challenge for versioning in these areas is to support opportunistic, open-ended design processes requiring the preservation of historical perspectives in the design process, the reuse of previous designs, and the exploitation of alternative designs. The primary goal of this workshop was to bring together a diverse group of individuals interested in examining the role of versioning in Computer Supported Cooperative Work. Participation was encouraged from members of the research community currently investigating the versioning process in CSCW as well as application designers and developers who are familiar with the real-world requirements for versioning in CSCW. Both groups were represented at the workshop resulting in an exchange of ideas and information that helped to familiarize developers with the most recent research results in the area, and to provide researchers with an updated view of the needs and challenges faced by application developers. In preparing for this workshop, the organizers were able to build upon the results of their previous one entitled "The Workshop on Versioning in Hypertext" held in conjunction with the ECHT'94 conference. The following section of this report contains a summary in which the workshop organizers report the major results of the workshop. The summary is followed by a section that contains the position papers that were accepted to the workshop. The position papers provide more detailed information describing recent research efforts of the workshop participants as well as current challenges that are being encountered in the development of CSCW applications. A list of workshop participants is provided at the end of the report. The organizers would like to thank all of the participants for their contributions which were, of course, vital to the success of the workshop. We would also like to thank the ECSCW'95 conference organizers for providing a forum in which this workshop was possible

Building Programmable Wireless Networks: An Architectural Survey

In recent times, there have been a lot of efforts for improving the ossified Internet architecture in a bid to sustain unstinted growth and innovation. A major reason for the perceived architectural ossification is the lack of ability to program the network as a system. This situation has resulted partly from historical decisions in the original Internet design which emphasized decentralized network operations through co-located data and control planes on each network device. The situation for wireless networks is no different resulting in a lot of complexity and a plethora of largely incompatible wireless technologies. The emergence of "programmable wireless networks", that allow greater flexibility, ease of management and configurability, is a step in the right direction to overcome the aforementioned shortcomings of the wireless networks. In this paper, we provide a broad overview of the architectures proposed in literature for building programmable wireless networks focusing primarily on three popular techniques, i.e., software defined networks, cognitive radio networks, and virtualized networks. This survey is a self-contained tutorial on these techniques and its applications. We also discuss the opportunities and challenges in building next-generation programmable wireless networks and identify open research issues and future research directions.Comment: 19 page