Petru Nicolaescu

Yjs: A Framework for Near Real-Time P2P Shared Editing on Arbitrary Data Types

Near real-time shared editing of documents in the Web browser has become popular for many applications like text writing, drawing, sketching and others. These applications require protocols for exchanging messages among user agents and for resolving editing conflicts. The available frameworks mostly rely on operational transformation approaches and often expose drawbacks like failing to scale, restriction to linear data structures and client-server architectures. In this paper we present Yjs, a lightweight open-source JavaScript framework that can be used for collaborative editing of arbitrary data types in peer-to-peer settings. The framework is based on a new operational transformation-like approach and supports communication protocols like XMPP and WebRTC. From an engineering perspective Yjs is easy to integrate into Web applications. Evaluations show that it has a favorable runtime complexity.

A Microservice Approach for Near Real-Time Collaborative 3D Objects Annotation on the Web

Web-based collaborative learning environments enable groups of learners to negotiate meaning around shared digital artefacts, e.g. by annotating them collaboratively. This particularly applies for complex digital artefacts such as multimedia or 3D objects and is mostly achieved by using metadata description standards, understandable to both user and machines for queries, context detection and retrieving relevant details. However, current approaches lack the ability to rapidly prototype courses by using lightweight Web technologies on the server and the browser side. In this paper, we present a customizable and lightweight approach for designing and performing Web-based collaborative courses using 3D Objects in the medical domain. These artefacts and the annotations are shared using near real-time updates between learners and tutors. In principle, we solve the problem of different annotation standards that can be used in the same environment by providing an API for using simple contextualized annotations. The evaluations and collected user feedback show that our collaborative browser-based approach simplifies access to digital artefacts and enables more collaboration.

A Methodology and Tool Support for Widget-Based Web Application Development

Due to the rapid evolution of Web technologies and standards like WebRTC for the real-time Web, there is a reengineering pressure on many existing Web applications for not getting outdated and for reducing costs and maintainance efforts. In this paper, we propose a methodology designed to support developers through an application reengineering process for achieving modular and scalable Web applications, by bridging the old and the new: a RESTful microservice architecture with a presentation layer composed from widgets. The methodology is based on empirical studies conducted with the help of the widget developer community and proposes an agile development cycle and guidelines for the redesign activities. Based on its principles, we developed a tool that has been used in the methodology evaluation for modeling the widget-based Web applications. The obtained results show that the approach and the proposed architecture are suitable for enabling the future generation of widget-based applications.

Near Real-Time Peer-to-Peer Shared Editing on Extensible Data Types

Near real-time collaboration using Web browsers is becoming rapidly more and more popular for many applications such as text editing, coding, sketching and others. These applications require reliable algorithms to ensure consistency among the participating Web clients. Operational Transformation (OT) and more recently Commutative Replicated Data Types (CRDT) have become widely adopted solutions for this kind of problem. However, most existing approaches are non-trivial and require trade-offs between expressiveness, suitable infrastructure, performance and simplicity. The ever growing number of potential use cases, the new possibilities of cutting-edge messaging protocols that shaped the near real-time Web, and the use of N-way communication between clients (e.g. WebRTC), create a need for peer-to-peer algorithms that perform well and are not restricted to only a few supported data types. In this paper, we present YATA, an approach for peer-to-peer shared editing applications that ensures convergence, preserves user intentions, allows offline editing and can be utilized for arbitrary data types in the Web browser. Using Yjs, its open-source JavaScript library implementation, we have evaluated the performance and multiple usage of YATA in Web and mobile browsers, both on test and real-world data. The promising evaluation results as well as the uptake by many commercial vendors and open-source projects indicate a wide applicability of YATA.

SynC-LD: Synchronous Collaborative IMS Learning Design Authoring on the Web

The IMS Learning Design LD specification enables the formal definition of teaching and learning flows. Several IMS LD authoring tools have been developed, most of them desktop based. There are few authoring tools that are deployed in a browser based environment, and some have built-in support for asynchronous collaboration during authoring via shared repositories. However, there are currently no tools available that enable synchronous, collaborative authoring in real-time. This demonstration presents SynC-LD, a novel widget-based tool that closes this gap. It supports browser-based, collaborative visual modeling of activity flows and the definition of IMS LD elements and their attributes. Multiple users can collaborate synchronously on the same learning design, which is achieved through inter-widget communication technology. Initial end-user trials show that the SynC-LD tool is usable and that IMS LD authors see potential in real-time IMS LD authoring.

View-Based Near Real-Time Collaborative Modeling for Information Systems Engineering

Conceptual modeling is a creative, social process that is driven by the views of involved stakeholders. However, few systems offer view-based conceptual modeling on the Web using lock-free synchronous collaborative editing mechanisms. Based on a (meta-)modeling framework that supports near real-time collaborative modeling and metamodeling in the Web browser, this paper proposes an exploratory approach for collaboratively defining views and viewpoints on conceptual models. Viewpoints are defined on the metamodeling layer and instantiated as views within a model editor instance. The approach was successfully used for various conceptual modeling languages and it is based on user requirements for model-based creation and generation of next-generation community applications. An end-user evaluation showed the usefulness, usability and limitations of view-based collaborative modeling. We expect that Web-based collaborative modeling powered by view extensions will pave the way for a new generation of collaboratively and socially engineered information systems.

Adaptive Video Techniques for Informal Learning Support in Workplace Environments

Learning at the workplace is largely informal and there is a high potential to make it more effective and efficient by means of technology, especially by using the power of multimedia. The main challenge is to find relevant information segments in a vast amount of multimedia resources for a particular objective, context and user. In this paper, we aim to bridge this gap using a personalized and adaptive video consumption strategy for professional communities. Our solution highlights relevant concepts within segments of video resources by means of collaborative semantic annotations, analyzes them based on the user’s learning objectives and recomposes them anew in a personalized way. As the preferred adaptation may be context dependent, the user has the opportunity to select a predefined adaptation strategy or to specify a new one easily. The approach uses a Web-based system that outputs a relevant mix of information from multiple videos, based on the user preferences and existing video annotations. The system is open source and uses an extendable approach based on micro-services. The performed evaluation investigated the usability and usefulness of the approach. It showed that effectiveness and especially efficiency of such informal learning could be indeed better with adaptive video techniques applied. On the other hand, collected ideas on how to improve the usability of the system show opportunities for its further improvements. These results suggest that personalization and adaptive techniques applied on video data are a good direction to proceed in facilitating informal learning in workplace environments.

Collaborative Drawing Annotations on Web Videos

Collaborative Drawing over a computer network, in particular on videos, usually requires some complex client-server architecture. In this paper, we want to demo an approach with the following distinctive features. On the client side we enable peer-to-peer collaborative video drawing in recent Web browsers supporting WebRTC. Developers can therefore embed it in arbitrary Web pages and users do not need to install any additional software. For persistence we use a microservice driven cloud approach which can be set up easily. All components are open source to facilitate wide use and further development. A use case evaluation showed promising results and will be presented in the demo.

Near Real-Time Collaborative Conceptual Modeling on the Web

Collaboration during the creation of conceptual models is an integral pillar of design processes in many disciplines. Synchronous collaboration, in particular, has received little attention in the conceptual modeling literature so far. There are many modeling and meta-modeling tools available, however most of these do not support synchronous collaboration, are offered under restrictive licenses, or build on proprietary libraries and technologies. To close this gap, this paper introduces the lightweight meta-modeling framework SyncMeta, which supports near real-time collaborative modeling, meta-modeling and generation of model editors in the Web browser. It employs well-proven Operational Transformation algorithms in a peer-to-peer architecture to resolve conflicts occurring during concurrent user edits. SyncMeta was successfully used to create meta-models of various conceptual modeling languages. An end-user evaluation showed that the editing tools of SyncMeta are considered usable and useful by collaborative modelers.

SeViAnno 2.0: Web-enabled collaborative semantic video annotation beyond the obvious

A lot of tool support for semantic video annotation is already available, supporting users or even automating tasks on different granularity levels in different metadata formats. In some domains like soccer or medicine, highly specialized solutions are even more advanced and create many new business opportunities. Still, support for mobile Web-enabled and collaborative general semantic video annotation is limited, mostly due to the high costs of developing and running such services. SeViAnno is a long-term development addressing in particular such engineering tasks. The current release is based on RESTful Web services enabling much easier integration of new input and output formats on the metadata management level as well as an easier development process of mobile and Web-based clients. This will be demonstrated by different existing prototypes. Together with a cloud computing-oriented open-source strategy this engineering solution is more sustainable and can be exploited with lower costs.