A Constraint-based Approach for Generating Transformation Patterns

TL;DR

This paper introduces a constraint-based method using CSP theory to generate correct transformation patterns for undo operations in collaborative editing, improving the reliability of undo functionalities in OT-based systems.

Contribution

It presents a novel CSP-based framework for designing undo transformation patterns that ensure correctness and consistency in collaborative applications.

Findings

Developed a CSP model for undo transformation patterns

Ensured correctness and undoability of patterns

Simplified design of collaborative objects

Abstract

Undoing operations is an indispensable feature for many collaborative applications, mainly collaborative editors. It provides the ability to restore a correct state of shared data after erroneous operations. In particular, selective undo allows to undo any operation and is based on rearranging operations in the history thanks to the Operational Transformation (OT) approach. OT is an optimistic replication technique allowing for updating the shared data concurrently while maintaining convergence. It is a challenging task how to meaningfully combine OT and undo approaches. Indeed, undoing operations that are received and executed out-of-order at different sites leads to divergence cases. Even though various undo solutions have been proposed over the recent years, they are either limited or erroneous. In this paper, we propose a constraint-based approach to address the undo problem. We use Constraint Satisfaction Problem (CSP) theory to devise correct and undoable transformation patterns (w.r.t OT and undo properties) which considerably simplifies the design of collaborative objects.