The Effect of Thickness-Based Dynamic Matching Mechanism on a Hyperledger Fabric-Based TimeBank System

Round 1

Reviewer 1 Report

The work submitted by the authors, titled “The Effect of Thickness-based Dynamic Matching Mechanism on a Hyperledger Fabric-based TimeBank System”, proposes a “blockchain-based Time Bank system with a service-exchange and flexible matching mechanism”.
They claim that the dynamic tuning strategy they adopted is able to increase each node's neighbors without costing a much longer waiting time, then when the market structure changed, becoming thicker or thinner, the system adjusted the matching policy accordingly, dynamically.
The manuscript is written and organized quite well, although I suggest to the authors to fix some minor issues in order to improve its readability, such as, for instance, using the same characters size in the equations, placing the figures in the manuscript body, instead of in the tail, and correcting the alignment of some elements with respect to the margins of the manuscript (e.g., references from [6], equations numbering, and so on).
The references appear quite updated, but the authors should be extended them by citing and discussing in the introductory part of the manuscript (i.e., “Introduction” and “Related Work and Background” sections) additional literature works, which are close or directly related to the research domain taken into account, in order to offer an overview to the readers, works such as:

(-) Makridakis, Spyros, and Klitos Christodoulou. "Blockchain: Current challenges and future prospects/applications." Future Internet 11.12 (2019): 258.
(-) Joshi, Archana Prashanth, Meng Han, and Yan Wang. "A survey on security and privacy issues of blockchain technology." Mathematical foundations of computing 1.2 (2018): 121.
(-) Longo, Riccardo, et al. "Analysis of a Consensus Protocol for Extending Consistent Subchains on the Bitcoin Blockchain." Computation 8.3 (2020): 67.
(-) Lin, Xuheng, et al. "A blockchain-enabled decentralized time banking for a new social value system." 2019 IEEE Conference on Communications and Network Security (CNS). IEEE, 2019.

In addition, in my opinion, according to a logical scheme the “Related Work and Background” section should be renamed as “Background and Related Work", organizing its contents by following this sequence.

In the “Conclusion and Future Work” section the authors well summarize the idea behind the proposed work, but they should better underline the related advantages with regard to the real-world applications and the current literature.

The formal approach adopted by the authors and the related experimental results/information have not been presented in a quite clear form to the readers: I suggest to the authors to re-organize the information in a clearer form, especially with regard to sections 5 and 6.

Summarizing, apart from the minor issues I highlighted above, the main weakness I recognized in the proposed work is the absence of a “clear” and “strong” scientific contribution: for this reason, the authors should better highlight their scientific contribution, also in light of real use cases (with regard to the current literature).
This because from the reading of the manuscript this contribution does not appear clear and evident, also by considering that the authors have already published other very similar works, e.g.:

(-) Lee, Yu-Tse, et al. "A Time Bank System Design on the Basis of Hyperledger Fabric Blockchain." Future Internet 12.5 (2020): 84;
(-) Lee, Yu-Tse, et al. "A Time Bank System Design on the Basis of Hyperledger Fabric Framework." 2020 IEEE International Conference on Blockchain and Cryptocurrency (ICBC). IEEE, 220.

For this reason, they should better specify the new valuable scientific contribution related to this work.

Author Response

Point-to-point replies to the review-1 of the paper entitled:

 

 “The Effect of Thickness-based Dynamic Matching Mechanism on a Hyperledger Fabric-based TimeBank System,” co-authored by Jhan-Jia Lin, Yu-Tse Lewe, and Ja-Ling Wu.

 

Comment-1:

The manuscript is written and organized quite well, although I suggest to the authors to fix some minor issues in order to improve its readability, such as, for instance, using the same characters size in the equations, placing the figures in the manuscript body, instead of in the tail, and correcting the alignment of some elements with respect to the margins of the manuscript (e.g., references from [6], equations numbering, and so on).

Our Reply:

Thanks to the reviewer's encouragement, first of all. As suggested, we have:

1. Changed the characters in all equations to the same size as possible as we can.
2. Moved the figures and the tables to the most appropriate places in the manuscript's body instead of in the tail.
3. Corrected the alignment of some elements with respect to the margins of the manuscript.

Comment 2:
The references appear quite updated, but the authors should be extended them by citing and discussing in the introductory part of the manuscript (i.e., “Introduction” and “Related Work and Background” sections) additional literature works, which are close or directly related to the research domain taken into account, in order to offer an overview to the readers, works such as:

(1A) Makridakis, Spyros, and Klitos Christodoulou. "Blockchain: Current challenges and future prospects/applications." Future Internet 11.12 (2019): 258.
(1B) Joshi, Archana Prashanth, Meng Han, and Yan Wang. "A survey on security and privacy issues of blockchain technology." Mathematical foundations of computing 1.2 (2018): 121.
(1C) Longo, Riccardo, et al. "Analysis of a Consensus Protocol for Extending Consistent Subchains on the Bitcoin Blockchain." Computation 8.3 (2020): 67.
(1D) Lin, Xuheng, et al. "A blockchain-enabled decentralized time banking for a new social value system." 2019 IEEE Conference on Communications and Network Security (CNS). IEEE, 2019.

Our Reply:

1. First of all, we want to thank the anonymous reviewer for bringing these references to our attention, especially the fourth one, which focused on a very similar subject to our work.
2. After carefully reading the suggested references, we find that three of them do have a close relationship with our work. As suggested, all the three related references have been cited in appropriate sections and included as new references in the revision. 
3. Ref. [1C] considered the inconsistency of Bitcoin Blockchain’s subchains, which is loosely related to our work, we decided not to include it in our current revision.
4. For ease of referencing, we listed all our responses in the following:

• Responses to Ref. [1A]

Makridakis Spyros and Klitos Christodoulou [1A] gave a survey of the blockchain, discussing its advantages and possible drawbacks and their implications for the future of the Internet and human lives and societies. Besides some general introduction and discussion about the disruptive changes and unique values of blockchain, the authors also described several major blockchain applications with the highest prospective advantages. For example, they discussed the most notable subset of innovative blockchain applications—Smart Contracts, DAOs (Decentralized Autonomous Organizations), and super secure networks—at the end of their work. (This paragraph has been included at the end of line 50 of the original manuscript.)

 

• Responses to Ref. [1B]

Joshi, Archana Prashanth, Meng Han, and Yan Wang [1B] tried to conduct a comprehensive survey on the blockchain technology by discussing its structure to different consensus algorithms as well as the challenges and opportunities from the prospective of data security and privacy. (This paragraph has been inserted into line 53 of the original manuscript.)

• Responses to Ref. [1D]

Moreover, as pointed out by one of the anonymous reviewers, Xuheng Lin et al. in their position paper [1D], proposed a BLockchain-ENabled Decentralized Time Banking System (BlendTBS) for encouraging people in the community to be engaged in mutual serving relationships. For achieving the goal, BlendTBS rewards the residents who commit to socially beneficial activities. In the practical matching algorithm design, we believe that an incentive mechanism [23] or a rewarding mechanism [1D] for dealing with unbalanced supply and demand must also be considered carefully. (This paragraph has been included in line 551 of the original manuscript.)

 

Finally, as mentioned in [1D], a small-scale study was planned to examine the utility of BlendTBS to a traditional community on the island of Aneityum, Republic of Vanuatu. We believe that our dynamic matching algorithm might help enhance the applicability of BlendTBS, especially when the community scale is enlarged. (This paragraph has been included at the end of the original manuscript.)

 

Comment 3:

In addition, in my opinion, according to a logical scheme the “Related Work and Background” section should be renamed as “Background and Related Work", organizing its contents by following this sequence.

Our Reply:

As suggested, we change the title of Section 2 to "Background and Related Work".

Comment 4:

In the “Conclusion and Future Work” section the authors well summarize the idea behind the proposed work, but they should better underline the related advantages with regard to the real-world applications and the current literature.

Our Reply:

To emphasize the possible contributions of work, we add the following paragraph to the beginning of the “Conclusion and Future Work” section, where one more reference is added.

In the outbreaking era of influenza and viruses, especially the COVID-19 these days, the necessity and importance of building mutual assistance within communities has increased significantly. As shown in this work, with the aid of modern technology such as Blockchain, TimeBank systems [4, 1D] could manifest their value in building community, inclusion, volunteerism, and social assistance. As stated in [24], the theory of matching algorithms has focused mostly on static environments until recently. In other words, little is known in the case where all participants arrive and depart dynamically, like the one we faced in a Timebank system. Our work helps bridge this gap by introducing and realizing a simpler dynamic matching algorithm that worked when any one of the SPs or the SRs can arrive or depart online.

Comment 5:

The formal approach adopted by the authors and the related experimental results/information have not been presented in a quite clear form to the readers: I suggest to the authors to re-organize the information in a clearer form, especially with regard to sections 5 and 6.

Our Reply:

As suggested, we have tried our best to make the presentations, including all equations, figures, and tables, in Sections 5 and 6 as clear as possible.

Comment 6:

Summarizing, apart from the minor issues I highlighted above, the main weakness I recognized in the proposed work is the absence of a “clear” and “strong” scientific contribution: for this reason, the authors should better highlight their scientific contribution, also in light of real use cases (with regard to the current literature).
This because from the reading of the manuscript this contribution does not appear clear and evident, also by considering that the authors have already published other very similar works, e.g.:

[1E] Lee, Yu-Tse, et al. "A Time Bank System Design on the Basis of Hyperledger Fabric Blockchain." Future Internet 12.5 (2020): 84;
[1F] Lee, Yu-Tse, et al. "A Time Bank System Design on the Basis of Hyperledger Fabric Framework." 2020 IEEE International Conference on Blockchain and Cryptocurrency (ICBC). IEEE, 220.

For this reason, they should better specify the new valuable scientific contribution related to this work.

Our Reply:

1. The work [1F] presented in the ICBC conference is an abstract version of the paper published in Future Internet [1E]. We have indicated this fact in Reference [4] of the revision.
2. To show the three mentioned TimeBank systems' contributions, the following comparison table is included in the final section of the revision.

Table 3. The Similarities and Differences of the three mentioned TimeBank Systems.

Works for TimeBank	Blockchain Types	Market Characteristics	Specific Contributions
Xuheng Lin’s work [1D]	Permissioned	Static	l   Rewarding Mechanism l   Plan for field trial
Lee’s Work [4]	Permissioned (Hyper-ledger Fabric)	Static	Privacy-preserving Grading Mechanism for measuring users’ degree of satisfaction
The Proposed Work	Permissioned (Hyper-ledger Fabric)	Dynamic	Dynamic Matching Mechanism for fitting the Dynamic Changing of markets

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

The paper is well-written but is still has to be proof-read. Typos such as in line 138 and other lines should be fixed.

Some references are missing to support the statements, in particular the general knowledge about blockchain such as 
M. Raikwar et al., "SoK of Used Cryptography in Blockchain," IEEE Access, vol. 7, pp. 148 550–148 575, 2019

What is the contribution of this manuscript compared to ref [4] written by the authors?

Section 3 provides a good overview of the system, the steps and its structure.
Section 5 explains the model, but what happens when several receivers ask for the same service?

As a future work, the authors consider adding feedback for the service providers. Using blockchain for transparent trust by using proof of a service has been done for other domains. 
Rensaa, Jens-Andreas Hanssen, et al. "VerifyMed-A blockchain platform for transparent trust in virtualized healthcare: Proof-of-concept." Proceedings of the 2020 2nd International Electronics Communication Conference. 2020.

What about the privacy issues? The paper 
Hasselgren, Anton, et al. "GDPR Compliance for Blockchain Applications in Healthcare." arXiv preprint arXiv:2009.12913(2020)
covers well GDPR issues.

The outlook of table 1 should be edited. It shows the cursor and other suggestions.

References should be edited and all should follow the same style. Delete the space between lines 599 and 601.

Author Response

Point-to-point replies to the review-2 of the paper entitled:

 

 “The Effect of Thickness-based Dynamic Matching Mechanism on a Hyperledger Fabric-based TimeBank System,” co-authored by Jhan-Jia Lin, Yu-Tse Lewe, and Ja-Ling Wu.

Comment 1;

The paper is well-written but is still has to be proof-read. Typos such as in line 138 and other lines should be fixed.

Our Reply:

Thanks to the reviewer's encouragement, first of all. As suggested, we have corrected all the typos as possible as we can.

Comment 2:

Some references are missing to support the statements, in particular the general knowledge about blockchain such as 
[2A] M. Raikwar et al., "SoK of Used Cryptography in Blockchain," IEEE Access, vol. 7, pp. 148 550–148 575, 2019

Our Reply:

1. First of all, we want to thank the anonymous reviewer for bringing the reference to our attention.
2. As suggested, the reference has been cited in the “Introduction” section and included as a new reference in the revision. 
3. For ease of referencing, we listed our response to [2A] in the following:

Reference [2A] gives a thorough review and systematizes all cryptographic concepts already used in blockchain. Moreover, the authors present a list of cryptographic skills which have not yet been applied but have immense potentials to improve the current blockchain solutions.

Comment 3:

What is the contribution of this manuscript compared to ref [4] written by the authors?

Our reply:

To show our work's possible contributions compared with existing TimeBank systems, we include the following comparison table in the final section of the revision.

Table 3. The Similarities and Differences of the three mentioned TimeBank Systems.

Works for TimeBank	Blockchain Types	Market Characteristics	Specific Contributions
Xuheng Lin’s work [1D]	Permissioned	Static	l   Rewarding Mechanism l   Plan for field trial
Lee’s Work [4]	Permissioned (Hyper-ledger Fabric)	Static	Privacy-preserving Grading Mechanism for measuring users’ degree of satisfaction
The Proposed Work	Permissioned (Hyper-ledger Fabric)	Dynamic	Dynamic Matching Mechanism for fitting the Dynamic Changing of markets

Comment 4:
Section 5 explains the model, but what happens when several receivers ask for the same service?

Our Reply:

If there are no other referencing factors, such as Satisfaction Scores [4], our system prefers the SR with higher node degrees when more than one SRs arrive at the market simultaneously. Otherwise, the higher the Satisfaction Score, the higher the priority the SR.  

Comment 5:

1. As a future work, the authors consider adding feedback for the service providers. Using blockchain for transparent trust by using proof of a service has been done for other domains. 
   Rensaa, Jens-Andreas Hanssen, et al. "VerifyMed-A blockchain platform for transparent trust in virtualized healthcare: Proof-of-concept." Proceedings of the 2020 2nd International Electronics Communication Conference. 2020.
2. What about the privacy issues? The paper 
   Hasselgren, Anton, et al. "GDPR Compliance for Blockchain Applications in Healthcare." arXiv preprint arXiv:2009.12913(2020)
   covers well GDPR issues.

Our Reply:

1. In our previous work about TimeBank [4], we presented a grading system that allows the TimeBank's members to give each other a grade for reflecting their degrees of satisfaction with the system's results. The grading results can be viewed as a kind of feedback for the service providers and service receivers.
2. As stated in line 184 of the original manuscript, the TimeBank involved members' safety is the top priority. In practical applications, "Real Name Registration" is always a must. This situation is quite different from that of the virtual healthcare mentioned by the reviewer. This is the reason why we didn't discuss GDPR related issues in this work. On the other hand, there does a privacy issue in our designed TimeBank system. Please refer to our previous work [4], since most of the participants in a TimeBank may be neighbors in the same community or live in geometric close-by regions; therefore, direct revealing of every individual's grade will cause disharmony. So, the design of the grading system mentioned above follows the privacy-preserving principle. That is, the system will hide every single grade, and only the average will be released.
3. Based on the replies addressed above, we didn’t respond to these comments in this revision.

 

Comment 6:

The outlook of table 1 should be edited. It shows the cursor and other suggestions.

References should be edited and all should follow the same style. Delete the space between lines 599 and 601.

Our Reply:

1. Table I has been edited in the revision as suggested.
2. The Spacing between Lines 599 and 601 has been deleted as suggested.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors address all the concerns. The paper can be accepted.