A Generic Undo Support for State-Based CRDTs

CRDTs (Conflict-free Replicated Data Types) have properties desirable for large-scale distributed systems with variable network latency or transient partitions. With CRDT, data are always available for local updates and data states converge when the replicas have incorporated the same updates. Undo is useful for correcting human mistakes and for restoring system-wide invariant violated due to long delays or network partitions. There is currently no generally applicable undo support for CRDTs. There are at least two reasons for this. First, there is currently no abstraction that we can practically use to capture the relations between undo and normal operations with respect to concurrency and causality. Second, using inverse operations as the existing partial solutions, the CRDT designer has to hard-code certain rules and design a new CRDT for almost every operation that needs undo support. In this paper, we present an approach to generic support of undo for CRDTs. The approach consists of two major parts. We first work out an abstraction that captures the semantics of concurrent undo and redo operations through equivalence classes. The abstraction is a natural extension of undo and redo in sequential applications and is straightforward to implement in practice. By using this abstraction, we then device a mechanism to augment existing CRDTs. The mechanism provides an "out of the box" support for undo without the involvement of the CRDT designers. We also present a practical application of the approach in collaborative editing

Introducing Selective Undo Features in a Collaborative Editor

Undo is an important functionality of editors. Selective undo is widely regarded as an important feature for collaborative editing. However, even after nearly three decades of active research and development, there is still no practical support of selective undo for collaborative editing. This paper introduces the selective undo features that we have implemented as part of a collaborative editing subsystem in the GNU Emacs text editor

Software as a service: Undo

This paper proposes a highly automated mechanism to build an undo facility into a new or existing system easily. Our proposal is based on the observation that for a large set of operators it is not necessary to store in-memory object states or executed system commands to undo an action; the storage of input data is instead enough. This strategy simplifies greatly the design of the undo process and encapsulates most of the functionalities required in a framework structure similar to the many object-oriented programming frameworks

Service Oriented Architecture for Undo Functionality

This paper proposes a highly automated mechanism to build an undo facility into a new or existing system easily encapsulated into a service. Our proposal is based on the observation that for a large set of operators it is not necessary to store in-memory object states or executed system commands to undo an action; the storage of input data is instead enough. The use of services strategy simplifies greatly the design of the undo process and encapsulates most of the functionalities required in a framework structure similar to the many object-oriented programming frameworks. We present a proof of concept illustrating the simplicity and reusability of the proposed framework under alignments of Software as a Service.Trabajo presentado en el VI International Conference on Research and Practical Issues of Enterprise Information Systems, realizado del 19 al 21 de septiembre en Bélgica

Service Oriented Architecture for Undo Functionality

This paper proposes a highly automated mechanism to build an undo facility into a new or existing system easily encapsulated into a service. Our proposal is based on the observation that for a large set of operators it is not necessary to store in-memory object states or executed system commands to undo an action; the storage of input data is instead enough. The use of services strategy simplifies greatly the design of the undo process and encapsulates most of the functionalities required in a framework structure similar to the many object-oriented programming frameworks. We present a proof of concept illustrating the simplicity and reusability of the proposed framework under alignments of Software as a Service.Facultad de Informátic

Interactive Visual Histories for Vector Graphics

Presentation and graphics software enables users to experiment with variations of illustrations. They can revisit recent editing operations using the ubiquitous undo command, but they are limited to sequential exploration. We propose a new interaction metaphor and visualization for operation history. While editing, a user can access a history mode in which actions are denoted by graphical depictions appearing on top of the document. Our work is inspired by the visual language of film storyboards and assembly instructions. Our storyboard provides an interactive visual history, summarizing the editing of a document or a selected object. Each view is composed of action depictions representing the userâ s editing actions and enables the user to consider the operation history in context rather than in a disconnected list view. This metaphor provides instant access to any past action and we demonstrate that this is an intuitive interface to a selective undo mechanism

ChangeBeadsThreader: An Interactive Environment for Tailoring Automatically Untangled Changes

To improve the usability of a revision history, change untangling, which reconstructs the history to ensure that changes in each commit belong to one intentional task, is important. Although there are several untangling approaches based on the clustering of fine-grained editing operations of source code, they often produce unsuitable result for a developer, and manual tailoring of the result is necessary. In this paper, we propose ChangeBeadsThreader (CBT), an interactive environment for splitting and merging change clusters to support the manual tailoring of untangled changes. CBT provides two features: 1) a two-dimensional space where fine-grained change history is visualized to help users find the clusters to be merged and 2) an augmented diff view that enables users to confirm the consistency of the changes in a specific cluster for finding those to be split. These features allow users to easily tailor automatically untangled changes.Comment: 5 pages, SANER 202

Human-Centric Tools for Navigating Code

All software failures are fundamentally the fault of humansthe software\u27s design was flawed. The high cost of such failures ultimately results in developers having to design, implement, and test fixes, which all take considerable time and effort, and may result in more failures. As developers work on software maintenance tasks, they must navigate enormous codebases that may comprise millions of lines of code organized across thousands of modules. However, navigating code carries with it a plethora of problems for developers. In the hopes of addressing these navigation barriers, modern code editor and development environments provide a variety of features to aid in navigation; however, they are not without their limitations. Code navigations take many forms, and in this work I focus on three key types of code navigation in modern software development: navigating the working set, navigating among versions of code, and navigating the code structure. To address the challenges of navigating code, I designed three novel software development tools, one to enhance each type of navigation. First, I designed and implemented Patchworks, a code editor interface to support developers in navigating the working set. Patchworks aims to make these more efficient by providing a fixed grid of open code fragments that developers can quickly navigate. Second, I designed and implemented Yestercode, a code editor extension to support navigating among versions of code. Yestercode does so by providing a comparison view of the current code and a previous version of the same code. Third, I designed and implemented Wandercode, a code editor extension to enable developers to efficiently navigate the structure of their code. Wandercode aims to do so by providing a visualization of the code\u27s call graph overlayed on the code editor. My approach to designing these tools for more efficient code navigation was a human-centric onethat is, based on the needs of actual developers performing real software development tasks. Through user study evaluations, I found that these tools significantly improved developer productivity by reducing developers\u27 time spent navigating and mental effort during software maintenance tasks