Transparent adaptation of single-user applications for multi-user real-time collaboration

Abstract

Single-user interactive computer applications are pervasive in our daily lives and work. Leveraging single-user applications for supporting multi-user collaboration has the potential to significantly increase the availability and improve the usability of collaborative applications. In this article, we report an innovative Transparent Adaptation (TA) approach and associated supporting techniques that can be used to convert existing and new single-user applications into collaborative ones, without changing the source code of the original application. The cornerstone of the TA approach is the operational transformation (OT) technique and the method of adapting the single-user application programming interface to the data and operation models of OT. This approach and supporting techniques were developed and tested in the process of transparently converting two commercial off-the-shelf single-user applications (Microsoft Word and PowerPoint) into real-time collaborative applications, called CoWord and CoPowerPoint, respectively. CoWord and CoPowerPoint not only retain the functionalities and “look-and-feel” of their single-user counterparts, but also provide advanced multi-user collaboration capabilities for supporting multiple interaction paradigms, ranging from concurrent and free interaction to sequential and synchronized interaction, and for supporting detailed workspace awareness, including multi-user telepointers and radar views. The TA approach and generic collaboration engine software component developed from this work are potentially applicable and reusable in adapting a wide range of single-user applications.

Supporting Customized Views for Enforcing Access Control Constraints in Real-Time Collaborative Web Applications

“…The seminal work of Sun et al [19] proposes the transparent adaptation (TA) approach to convert single-user applications into collaborative multi-user applications. The cornerstone of TA is operational transformation (OT) [4].…”

A Flexible Access Control Model for Distributed Collaborative Editors

“…It is known that collaborative editors manipulate share objects that admit a linear structure [3,13,15]. This structure can be modelled by the list abstract data type.…”

“…For instance, an element may be regarded as a character, a paragraph, a page, an XML node, etc. In [15], it has been shown that this linear structure can be easily extended to a range of multimedia documents, such as MicroSoft Word c and PowerPoint c documents. It is clear that combinations of these operations enable us to define more complex ones, such as cut/copy and paste, that are intensively used in professional text editors.…”

“…DCE are distributed systems that have to consider human interactions. So, they are characterised by the following requirements: (i) High local responsiveness: the system has to be as responsive as its single-user editors [3,14,15]; (ii) High concurrency: the users must be able to concurrently and freely modify any part of the shared document at any time [3,14]; (iii) Consistency: the users must eventually see a converged view of all copies [3,14] must be synchronized in decentralized fashion in order to avoid a single point of failure; (v) Scalability: a group must be dynamic in the sense that users may join or leave the group at any time.…”

Symbolic Model-Checking of Optimistic Replication Algorithms

“…This technique consists of an algorithm which transforms an update (previously executed by some other user) according to local concurrent updates in order to achieve convergence. It is used in many collaborative editors including Joint Emacs [8] (an Emacs collaborative editor), CoWord [13] (a collaborative version of Microsoft Word), CoPowerPoint [13] (a collaborative version of Microsoft PowerPoint) and, more recently, the Google Wave (a new google platform 3 ).…”