Robert Krahn

Lively Wiki a development environment for creating and sharing active web content

Wikis are Web-based collaborative systems designed to help people share information. Wikis have become popular due to their openness which gives users complete control over the organization and the content of wiki pages. Unfortunately existing wiki engines restrict users to enter only passive content, such as text, graphics, and videos and do not allow users to customize wiki pages. Thus, wikis cannot be used to host or author rich dynamic and interactive content. In this paper we present Lively Wiki, a development and collaboration environment based on the Lively Kernel which enables users to create rich and interactive Web pages and applications - without leaving the Web. Lively Wiki combines the wiki metaphor with a direct-manipulation user interface and adds a concept for Web programming as well as programming tool support to create an easy to use, scalable, and extendable Web authoring tool. Moreover, Lively Wiki is self-supporting, i.e. the development tools were used for creating its own implementation thereby giving users the freedom to customize every aspect of the system.

Lively Fabrik A Web-based End-user Programming Environment

Lively Fabrik is a Web-based general-purpose end-user programming environment. Based on the Lively Kernel, Lively Fabrik extends the ideas of the original Fabrik system by empowering end-users to create interactive Web content entirely within their Web browsers. Web applications created with Lively Fabrik typically combine Web sources, data manipulation, and interactive user interface elements. The result can be a Mashup, but due to the powerful underlaying system, any general-purpose application. Connecting components with wires and scripting components is all that is needed to do so.

The SOM family: virtual machines for teaching and research

This paper introduces the SOM (Simple Object Machine) family of virtual machine (VM) implementations, a collection of VMs for the same Smalltalk dialect addressing students at different levels of expertise. Starting from a Java-based implementation, several ports of the VM to different programming languages have been developed and put to successful use in teaching at both undergraduate and graduate levels since 2006. Moreover, the VMs have been used in various research projects. The paper documents the rationale behind each of the SOM VMs and results that have been achieved in teaching and research.

Continuous Selective Testing

A manual and explicit activity, the frequent selection and execution of tests requires considerable discipline. Our approach automatically derives a subset of tests based on actual modifications to the code base at hand, then continuously executes them transparently in the background, and so supports developers in instantly assessing the effect of their coding activities with respect to the overall set of unit tests to be passed. We apply techniques of selective regression testing, mainly relying on dynamic analysis. By taking advantage of the internal program representation available in IDEs, we do not need to rely on expensive comparisons of different program versions to detect modified code entities.

Babelsberg/JS

�� � � � � � �� � ��� �� � � � � � � � � � � � � � � � � � � � � � � � � � � �� � � � � � � � � � � � � � � � � �� � � � � � � � � � � Constraints provide a useful technique for ensuring that desired properties hold in an application. As a result, they have been used in a wide range of applications, including graphical layout, simulation, scheduling, and problem-solving. We describe the design and implementation of an Object Constraint Programming language, an object-oriented language that cleanly integrates constraints with the underlying language in a way that respects encapsulation and standard object-oriented programming techniques, and that runs in browser-based applications. Prior work on Object Constraint Programming languages has relied on modifying the underlying Virtual Machine, but that is not an option for web-based applications, which have become increasingly prominent. In this paper, we present an approach to implementing Object Constraint Programming without Virtual Machine support, along with an implementation as a JavaScript extension. We demonstrate the resulting language, Babelsberg/JS, on a number of applications and provide performance measurements. Programs without constraints in Babelsberg/JS run at the same speed as pure JavaScript versions, while programs that do have constraints can still be run efficiently. Our design and implementation also incorporate incremental re-solving to support interaction, as well as a cooperating solvers architecture that allows multiple solvers to work together to solve more difficult problems.

Efficient Layer Activation in Context JS

Context-oriented programming (COP) describes language extensions for modularizing behavioral or structural variations that are to be composed at run-time. Different COP infrastructures and implementations offer several strategies for scoping, activation, and deactivation of such compositional units. Often, the mechanisms employed cause substantial execution overhead. In this paper we present an optimization technique for ContextJS -- our COP extension to JavaScript -- that can significantly reduce this overhead to run context-aware code efficiently.

The Ignite Distributed Collaborative Scientific Visualization System

We describe the Ignite Distributed Collaborative Scientific Visualization System (IDCVS), a system which permits real-time interaction and visual collaboration around large data sets, with an initial emphasis on scientific data. The IDCVS offers such a collaborative environment, with real-time interaction on any device between users separated across the wide area. It provides seamless interaction and immediate updates even under heavy load and when users are widely separated: the design goal was to fetch a data set consisting of 30,000 points from a server and render it within 150ms, for a user anywhere in the world, and reflect changes made by a user in one location to all other users within a bound provided by network latency. The system was demonstrated successfully on a significant worldwide air pollution data set, with values on 10, 25, 50, and 100km worldwide grids, monthly over an 18-year period. It was demonstrated on a wide variety of clients, including laptop, tablet, and smartphone.

The Ignite Distributed Collaborative Visualization System

Sushil Bhojwani Matt Hemmings Dan Ingalls Jens Lincke University of Victoria University of Victoria CDG, SAP Hasso Plattner Institute sushilsrk@gmail.com mhemming@uvic.ca danhhingalls@gmail.com Jens.Lincke@hpi.de Robert Krahn David Lary Rick McGeer Glenn Ricart CDG, SAP UT Dallas CDG/US Ignite US Ignite robertkrahn@gmail.com dlary@utdallas.edu rick@mcgeer.com glenn.ricart@us-ignite.org Marko Roder Yvonne Coady Ulrike Stege CDG, SAP University of Victoria University of Victoria markoroeder@cdglabs.org ycoady@uvic.ca ustege@uvic.ca

Implementing scoped method tracing with ContextJS

Customized method tracers can be a valuable tool for debugging and program comprehension. They allow to declaratively specify what parts of the call graph should be captured and are an alternative to tedious manual debugging techniques. Method tracers are easy to implement in dynamic languages but avoiding multiple method instrumentation and recursion in the client code can become complex. In this paper we show how Context-oriented Programming (COP) can be leveraged to address such issues. Our approach is based on ContextJS, a COP implementation for JavaScript, which provides scoping mechanisms and an infrastructure for method instrumentation. These abstractions allow to separate target and tracer logic so that self-referentiality is avoided.

LiveTalk: A Framework for Collaborative Browser-Based Replicated-Computation Applications

In this paper we describe LiveTalk, a framework for Collaborative Browser-based Replicated-Computation applications. LiveTalk permits multiple users separated across the wide area to interact with separate copies of a single application, sharing a single virtual workspace, using very little network bandwidth. LiveTalk features an integrated, browser-based programming environment with native graphics and live evaluation, an integrated, pluggable web server, and a simple messaging service that serves to coordinate activity on shared application sessions, and provides for multiple, mutually-isolated sessions. The first use case for LiveTalk are collaborative big-data visualizations running on thin-client devices such as cellular phones, tablets, and netbooks. These applications form part of a new class of application where the distributed Cloud is leveraged to provide low latency, and high-bandwidth access to geographically disparate users while maintaining the feel of immediacy associated with local computation. The primary motivation of this work is to permit low latency, collaborative applications to be built quickly and easily, while requiring no setup for use by the end-user.