An Approach to Designing Critical Railway Voice Communication
Round 1
Reviewer 1 Report
I think the authors did a good job of describing their work in detail. I have only one major concern with the paper. I felt that their contribution relative to existing literature was lost in the details. I struggled to understand what was the goal of the paper and how compare to existing research.
Author Response
Authors’ answer: Thank you for the valuable recommendations.
Reviewer’s comment: I struggled to understand what was the goal of the paper and how compare to existing research.
Authors’ answer: In order to make the goal of the paper clearer, the following paragraph is included in the Introduction at the end of introduction
“As far as the FRMCS user requirements case just specify the needs to provide secure and reliable communication applications, the technical details of FRMCS applications are not considered and are implementation dependent. The main goal of the paper is to formulate an approach which is a more technologically acceptable option and is independent of a specific implementation of proprietary solutions. In line with this goal, there are various platform-dependent, proprietary solutions that are not open sourced in a way to become available to the wider application developer community. As far as our knowledge, there is no published research on railway-specific and especially FRMCS specific services, because this is a highly competitive market. The proposed approach facilitates the sharing and modification of APIs, which enables it to improve over time and to be tailored to the specific needs.”
Reviewer 2 Report
The authors applied principles of service-oriented architecture to design critical railway voice communication applications.The manuscript is structured correctly and the content is presented in a logically consistent order. However, the manuscript lacks "Related work" and "Discussion and limitations" sections.
In the "Introduction" section, the authors state the contributions of the paper. But, the authors must underline what is the difference in comparison to existing works and point out the main advantages of their approach. They should emphasize novelty here.
Besides, in the content of the article, the authors often refer not to individual articles, but to a range of even 3-4 articles (pages 1, 2, 3, and 5). It is not recommended. Please write something significant about each paper you cite.
In the "Related work" section, authors should refer to a broader issue. In my view, the subject is considered in the literature in the context of business process execution optimization. There are various methods that can be grouped into three stages of business process optimization: Resource Allocation, Service Composition, and Service Scheduling. I recommend using the paper: "Optimization of Business Process Execution in Services Architecture: A Systematic Literature Review" (https://doi.org/10.1109/ACCESS.2021.3102668). It is worth underlining that Resource Allocation can be done dynamically. Besides, there is a need to augment the literature on the design topic of voice communication systems. Please use in the "Related work" section the following papers: - "A Framework for Smart Home System with Voice Control Using NLP Methods" (https://doi.org/10.3390/electronics12010116) - "A Multilayered Audio Signal Encryption Approach for Secure Voice Communication" (https://doi.org/10.3390/electronics12010002).
Moreover, in the "Discussion and limitations" section the authors should discuss the pros and cons of the approach. That is the place for a wider analysis of the results and drawing general findings. I am asking the authors to clarify whether the proposed approach takes into account dynamic resource allocation to services. Also, please comment on the potential impact of component failures on architecture robustness.
An architectural description of the use cases and the configuration for performance evaluation is not the best side of the manuscript. The authors should look for papers with relevant architectural views: Use cases, Integrated services, and Deployment. As a result, the "References" section should be enriched. It is worth using Unified Modeling Language diagrams. For example, Figure 9 can be represented in a more standardized way in a UML Component diagram with services explicitly shown. Besides, section 7 lacks a diagram presenting the configuration of the performance evaluation environment. I suggest using the UML Deployment diagram
The "Conclusions" section should be more supported by the results and it is worth adding the planned further work.
Please add DOIs for papers in the "References" section. Please also remove preprint [13] from 2021. If needed, I would like the authors to look for up-to-date published papers.
The English used in the manuscript requires additional effort to correct as far as punctuation and style are concerned. Please avoid sentences with "etc." (pages 2, 4, 5). Generally, minor stylistic or punctuation errors should be corrected but they do not diminish the value of the manuscript.
Author Response
Authors’ answer: Thank you for the valuable recommendations.
Reviewer’s comment: The manuscript lacks "Related work" and "Discussion and limitations" sections.
Authors answer: two new sections are included, namely Related work” and “Discussion and limitation”. Please, refer to the manuscript.
Reviewer’s comment: In the "Introduction" section, the authors state the contributions of the paper. But, the authors must underline what is the difference in comparison to existing works and point out the main advantages of their approach. They should emphasize novelty here.
Authors answer: The following paragraph is included in the Introduction at the end of “Introduction”.
“As far as the FRMCS user requirements case just specify the needs to provide secure and reliable communication applications, the technical details of FRMCS applications are not considered and are implementation dependent. The main goal of the paper is to formulate an approach which is a more technologically acceptable option and is independent of a specific implementation of proprietary solutions. In line with this goal, there are various platform-dependent, proprietary solutions that are not open sourced in a way to become available to the wider application developer community. As far as our knowledge, there is no published research on railway-specific and especially FRMCS specific services, because this is a highly competitive market. The proposed approach facilitates the sharing and modification of APIs, which enables it to improve over time and to be tailored to the specific needs.”
The following paragraph is included at the end of “Related work”:
“The novelty of the current research can be summarized as follows:
- Based on the specified FRMCS user requirements, security related functions that are not explicitly specified, but are used in different FMCS applications, are identified and synthesized as reusable microservices.
- Common features such as role management and presence, location, inviting-a-user messaging, assured voice communications, and multiuser talker control are also designed as services. The RESTful APIs are defined, and the service use is illustrated by message flows.
- The service feasibility is illustrated by modeling the communication state from application and FRMCS system points of view, and the models are formally verified.
- The API performance is evaluated in terms of injected latency.”
Reviewer’s comment: Besides, in the content of the article, the authors often refer not to individual articles, but to a range of even 3-4 articles (pages 1, 2, 3, and 5). It is not recommended. Please write something significant about each paper you cite.
Authors’ answer: Each cited article, that is aggregated within a range in the original manuscript, is commented separately in the revised version..
Reviewer’s comment: In the "Related work" section, authors should refer to a broader issue. In my view, the subject is considered in the literature in the context of business process execution optimization. There are various methods that can be grouped into three stages of business process optimization: Resource Allocation, Service Composition, and Service Scheduling. I recommend using the paper: "Optimization of Business Process Execution in Services Architecture: A Systematic Literature Review" (https://doi.org/10.1109/ACCESS.2021.3102668). It is worth underlining that Resource Allocation can be done dynamically. Besides, there is a need to augment the literature on the design topic of voice communication systems. Please use in the "Related work" section the following papers: - "A Framework for Smart Home System with Voice Control Using NLP Methods" (https://doi.org/10.3390/electronics12010116) - "A Multilayered Audio Signal Encryption Approach for Secure Voice Communication" (https://doi.org/10.3390/electronics12010002).
Authors answer: Both recommended articles doi:10.1109/ACCESS.2021.3102668 and doi:10.3390/electronics12010002 are valuable and therefor included appropriately into the revised manuscript.
Reviewer’s comment: Moreover, in the "Discussion and limitations" section the authors should discuss the pros and cons of the approach. That is the place for a wider analysis of the results and drawing general findings. I am asking the authors to clarify whether the proposed approach takes into account dynamic resource allocation to services. Also, please comment on the potential impact of component failures on architecture robustness.
Authors’ answer: A new section “Discussion and limitation” is included. Please, refer to the manuscript.
Reviewer’s comment: An architectural description of the use cases and the configuration for performance evaluation is not the best side of the manuscript. The authors should look for papers with relevant architectural views: Use cases, Integrated services, and Deployment. As a result, the "References" section should be enriched. It is worth using Unified Modeling Language diagrams. For example, Figure 9 can be represented in a more standardized way in a UML Component diagram with services explicitly shown. Besides, section 7 lacks a diagram presenting the configuration of the performance evaluation environment. I suggest using the UML Deployment diagram
Authors’ answer: References are extended by including paper doi:10.1109/ACCESS.2021.3102668 and Fig. 9 is improved using an UML collaboration diagram. In the section that describes the experiment set up, an UML deployment diagram is added to elaborate the description.
Reviewer’s comment: Please add DOIs for papers in the "References" section. Please also remove preprint [13] from 2021. If needed, I would like the authors to look for up-to-date published papers.
Authors’ answer: The respective DOIs have been added to the references and corrections been made accordingly.
Reviewer’s comment: The English used in the manuscript requires additional effort to correct as far as punctuation and style are concerned. Please avoid sentences with "etc." (pages 2, 4, 5). Generally, minor stylistic or punctuation errors should be corrected but they do not diminish the value of the manuscript.
Authors’ answer: Done.
Reviewer 3 Report
This paper proposes an approach to design critical railway voice communication applications based on the principles of service-oriented architecture (such as role management and presence, location, inviting-a-user messaging, assured voice communications, and multiuser talker control). The use of services’ Application Programming Interfaces (APIs) are illustrated through the use cases. A mathematical analysis was also conducted. The paper is quite informative and well-written. There are some minor suggestions to strengthen the manuscript quality:
1. The literature survey should be elaborated in Tablular form for a quick overview of the existing work and its limitations.
2. Figure 1 should be described explicitly. It will further help the readers to understand the rest of the related Figures.
3. How are Figures 19 and 20 informative? Please elaborate.
4. The relevancy of the Proposition is unclear. Please incorporate proper justification.
Author Response
Authors’ answer: Thank you for the valuable recommendations.
Reviewer’s comment: The literature survey should be elaborated in Tablular form for a quick overview of the existing work and its limitations
Authors’ answer: The literature survey is elaborated in a tabular form and textually extended. The paper novelty is highlighted. Please, refer to the end of the “Introduction”, the new section “Related Work”, and the new section “Discussions and limitations”.
Reviewer’s comment: Figure 1 should be described explicitly. It will further help the readers to understand the rest of the related Figures
Authors’ answer: The explanation of Fig.1 is extended.
Reviewer’s comment: How are Figures 19 and 20 informative? Please elaborate.
Authors’ answer: A short reasoning is added to the explanatory text in order to make the Figures' being justified.
Reviewer’s comment: The relevancy of the Proposition is unclear. Please incorporate proper justification.
Authors’ answer: The models of the voice call communication state are used to illustrate the approach feasibility. The proposition and the proof are used to validate the models. The following is included in the Section “Verification of the Critical Voice Application Design”
“Both models have to run as parallel processes and the communication between them need to be synchronized, i. e. the processes have to expose equivalent behavior. Bisimilarity is usually referred as a behavioral equivalency for processes and is known as a well-established and powerful proof technique. It is defined as a union of all bisimulation relations on terms as pairs [37]. The most common notation, on which the bisimulation is studied, is Labelled Transition System (LTS) which is essentially a labeled directed graph”
Round 2
Reviewer 2 Report
The authors applied principles of service-oriented architecture to design critical railway voice communication applications.
Generally, the manuscript has been improved and the authors have highlighted changed parts of the text.
I confirm that the authors have addressed virtually all of my concerns. However, there are a few changes that the authors must incorporate prior to publication.
I appreciate that the authors have refined an architectural description. They have added the Unified Modeling Language Deployment diagram presenting the execution environment.
But, the authors claim that in Figure 9 they applied the UML Collaboration diagram. Please, be advised that from version 2.0 in UML there is a UML Communication diagram instead of a UML Collaboration diagram. Please correct the name of the used diagram.
I confirm that the authors significantly improved the "References" section. I appreciate that the authors augmented that section with relevant papers and provided DOIs.
However, it is required to check again the names of the authors, years of publication, numbers of volumes, and ranges of pages. Please be as precise as with the bibliographic item [31].
The manuscript is structured correctly and the content is presented in a logically consistent order. The authors added the "Discussion and limitations" section and discussed the pros and cons of the approach. I would be content to see more discussion on dynamic resource allocation to services. But, the content of the section is satisfactory.
Author Response
Dear Reviewer,
Speaking on behalf of all authors, I'd wish to thank You for the valuable remarks, suggestions, and support, especially regarding the UML diagram kind and the References, that are improved in the manuscript.
Author Response File: 
Author Response.pdf
