A string-wise CRDT algorithm for smart and large-scale collaborative editing systems

Lv, Xiao; He, Fazhi; Cai, Weiwei; Cheng, Yuanfang

doi:10.1016/j.aei.2016.10.005

Cited by 36 publications

(11 citation statements)

References 25 publications

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“…(1) The qualitative evaluation of model similarity, such as similarity assessments for 3D CAD/ CAE model retrieval [10,17], focused on the qualitative aspects of the models, e.g., topological result and geometric profile. On the other hand, in the field of data exchange [29,37,42,51,57,58,67,69] and collaborative design [19,20,33,44,45,49], the quantitative comparison of the similarity between source and target of feature-based CAD models is the latest development [72]. So the proposed method can be adopted in this area to improve the computing efficiency of quantitative comparisons between large scale models in engineering applications of CAD/CAE/CAM in the future.…”

Section: Discussionmentioning

confidence: 99%

An efficient approach to directly compute the exact Hausdorff distance for 3D point sets

Zhang

Han

et al. 2017

ICA

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Hausdorff distance measure is very important in CAD/CAE/CAM related applications. This manuscript presents an efficient framework and two complementary subalgorithms to directly compute the exact Hausdorff distance for general 3D point sets. The first algorithm of Nonoverlap Hausdorff Distance (NOHD) combines branch-and-bound with early breaking to cut down the Octree traversal time in case of spatial nonoverlap. The second algorithm of Overlap Hausdorff Distance (OHD) integrates a point culling strategy and nearest neighbor search to reduce the number of points traversed in case of spatial overlap. The two complementary subalgorithms can achieve a highly efficient and balanced result. Both NOHD and OHD compute the exact Hausdorff distance directly for arbitrary 3D point sets. We conduct a number of experiments on benchmark models and CAD application models, and compare the proposed approach with other state-of-the-art algorithms. The results demonstrate the effectiveness of our method.

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Section: Discussionmentioning

confidence: 99%

An efficient approach to directly compute the exact Hausdorff distance for 3D point sets

Zhang

Han

et al. 2017

ICA

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“…What made WOOT and TTF special was not so much due to their alternative ways of dealing with the CP2 issue, but their unjustified claims and special roles in follow-up development: WOOT was late named as the first CRDT and further mystified to possess, among other superiorities over OT, a capability of making concurrent operations natively commutative [4,5,8,25,32,39,40,41,45,47,48,79,80,81] (which is to be demystified in Section 5.4 and [73]); TTF was claimed to be the first and cited as the sole correct OT capable of achieving CP2 correctness [4,5,8,21,40,42,45,81] (also reflected in footnote 4).…”

Section: Twin Solutions To Cp2-violation: Woot and Ttfmentioning

confidence: 99%

“…A variety of alternative techniques for consistency maintenance in co-editors had also been explored in the past decades [14,16,18,41,42,72]. One notable class of techniques is CRDT 3 (Commutative Replicated Data Type) for co-editors [4,5,8,25,32,37,39,40,41,45,47,48,79,80,81]. The first CRDT solution for plain-text co-editing appeared around 2006 [40,41], under the name of WOOT (WithOut Operational Transformation).…”

Section: Introductionmentioning

confidence: 99%

“…Recent years have seen OT being widely adopted in industry products as the core technique for consistency maintenance, ranging from battle-tested online collaborative richtext editors like Google Docs 1 [11], to emerging start-up products, such as Codox Apps 2 .A variety of alternative techniques for consistency maintenance in co-editors had also been explored in the past decades [14,16,18,41,42,72]. One notable class of techniques is CRDT 3 (Commutative Replicated Data Type) for co-editors [4,5,8,25,32,37,39,40,41,45,47,48,79,80,81]. The first CRDT solution for plain-text co-editing appeared around 2006 [40,41], under the name of WOOT (WithOut Operational Transformation).…”

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confidence: 99%

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Real Differences between OT and CRDT under a General Transformation Framework for Consistency Maintenance in Co-Editors

Sun

Sun²,

et al. 2020

Proc. ACM Hum.-Comput. Interact.

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OT (Operational Transformation) was invented for supporting real-time co-editors in the late 1980s and has evolved to become a core technique used in today's working co-editors and adopted in major industrial products. CRDT (Commutative Replicated Data Type) for co-editors was first proposed around 2006, under the name of WOOT (WithOut Operational Transformation). Follow-up CRDT variations are commonly labeled as "post-OT" techniques and have made broad claims of superiority over OT solutions, in terms of correctness, time and space complexity, simplicity, etc. Over one decade later, however, OT remains the choice for building the vast majority of co-editors, whereas CRDT is rarely found in working co-editors. Why? Based on comprehensive review and comparison on representative OT and CRDT solutions and co-editors based on them, we present our discoveries in relation to this question and beyond in a series of three articles.In prior work, we have revealed that CRDT is like OT in following the same general transformation approach and CRDT is not natively commutative for concurrent operations in co-editors, which helps to clarify what CRDT really is and is not for co-editors. In this article, we reveal OT and CRDT differences in correctness and complexity by dissecting and examining representative OT and CRDT solutions. We explore how different basic approaches ̶ the concurrency-centric approach taken by OT and the content-centric approach taken by CRDT ̶ had resulted in different technical challenges, correctness and complexity issues, and solutions. Moreover, we reveal hidden algorithmic flaws with representative CRDT solutions, and discuss common myths and facts related to correctness, time and space complexity, and simplicity of OT and CRDT. We present facts and evidences that refute CRDT claimed advantages over OT. We hope the discoveries from this work help clear up common myths and confusions surrounding OT and CRDT, and accelerate progress in co-editing technology for real world applications. ; URL: https://www.ntu.edu.sg/home/CZSun 20,38,43,54,55,58,61,70,71,77], and support real-time collaboration in rich-text co-editing in word processors [60,65,68,82], HTML/XML Web document co-editing [10], spreadsheet co-editing [69], 3D model co-editing in digital media design tools [1,2], and file synchronization in cloud storage systems [3]. Recent years have seen OT being widely adopted in industry products as the core technique for consistency maintenance, ranging from battle-tested online collaborative richtext editors like Google Docs 1 [11], to emerging start-up products, such as Codox Apps 2 .A variety of alternative techniques for consistency maintenance in co-editors had also been explored in the past decades [14,16,18,41,42,72]. One notable class of techniques is CRDT 3 (Commutative Replicated Data Type) for co-editors [4,5,8,25,32,37,39,40,41,45,47,48,79,80,81]. The first CRDT solution for plain-text co-editing appeared around 2006 [40,41], under the name of WOOT (WithOut Operational Transformation). One mo...

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“…Typical studies of Co-CAD systems of replicated architecture assume that the execution orders are different among the cooperative sites and then try to maintain a consistent result after the operations are received and executed on different sites with divergent orders [10][11][12]. This assumption comes from co-editing systems of replicated architecture, in which a lot of tricky algorithms are proposed to address the challenge of how to achieve consistent results in a non-consistent (dis-ordered) operations sequence.…”

Section: Introductionmentioning

confidence: 99%

Collaborative CAD Synchronization Based on a Symmetric and Consistent Modeling Procedure

Han

2017

Symmetry

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Abstract:One basic issue with collaborative computer aided design (Co-CAD) is how to maintain valid and consistent modeling results across all design sites. Moreover, modeling history is important in parametric CAD modeling. Therefore, different from a typical co-editing approach, this paper proposes a novel method for Co-CAD synchronization, in which all Co-CAD sites maintain symmetric and consistent operating procedures. Consequently, the consistency of both modeling results and history can be achieved. In order to generate a valid, unique, and symmetric queue among collaborative sites, a set of correlated mechanisms is presented in this paper. Firstly, the causal relationship of operations is maintained. Secondly, the operation queue is reconstructed for partial concurrency operation, and the concurrent operation can be retrieved. Thirdly, a symmetric, concurrent operation control strategy is proposed to determine the order of operations and resolve possible conflicts. Compared with existing Co-CAD consistency methods, the proposed method is convenient and flexible in supporting collaborative design. The experiment performed based on the collaborative modeling procedure demonstrates the correctness and applicability of this work.

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A string-wise CRDT algorithm for smart and large-scale collaborative editing systems

Cited by 36 publications

References 25 publications

An efficient approach to directly compute the exact Hausdorff distance for 3D point sets

An efficient approach to directly compute the exact Hausdorff distance for 3D point sets

Real Differences between OT and CRDT under a General Transformation Framework for Consistency Maintenance in Co-Editors

Collaborative CAD Synchronization Based on a Symmetric and Consistent Modeling Procedure

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