Bringing Federated Semantic Queries to the GIS-Based Scenario
Round 1
Reviewer 1 Report
Dear authors,
This article promises to outline an approach to request, retrieve and consume (geospatial) knowledge graphs which are available through distributed platforms based on the use of SPARQL 1.1 and GeoSPARQL standards. In addition to this, the authors aim to highlight the fact that this enables the consumption of geospatial knowledge graphs by lightweight applications and QGIS. In order to outline this approach, the authors perform federated queries using the mentioned standards and store the results using a local deployment of the Apache Marmotta triple store.
Overall, the article highlights an important step in identifying, combining and enriching existing geospatial resources available on the web in the form of knowledge graphs and making them consumable for GIS applications through plugins and other web-based applications. The article is well written and outlines the importance of the results clearly through the use of the example chapter.
There are, however, some issues that need to be clarified and/or addressed in the article before publication. Please see as follows:
1. The article makes the assertion that 'In this sense, to the best of our knowledge, there are no existing triple stores that support the combined implementation of GeoSPARQL and SPARQL 1.1 in order to allow performing federated geospatial queries on the Web of Data.' This is, of course, a very broad statement and more research into this needs to be done. Whilst an agreement on this could be reached that this assertion is true if an statement such as 'with good performance over large datasets', this does not seem to be what the authors are testing with their approach and if this were to be tested a similar conclusion would be found for SQL too. At Kadaster (Dutch Land Registry), a TriplyDB triple store instance is being used which makes use of Virtuoso and/or Jena Fuseki and federated queries across (large) knowledge graphs are being done here. Another example is Communica where complex federated queries are also being performed.
2. The article highlights an approach to perform federated queries (which is claimed as previously not possible), enrich knowledge graphs with geographic information and offer a single source for a QGIS or web-based GIS application. Based on the previous comment, the novelty of this approach in the article needs to be clarified before acceptance of this paper.
3. It is not, however, clear whether this federated querying is the central element to this article so, in addition to clarifying the novelty, the approach demonstrated in this paper as novel should also be defined more concretely.
4. In various parts of the article there are some clumsy English formulations. A detailed review of this should sort out most of these issues and would improve the English quality of the paper.
The approach offered in this paper provides some valuable insight into the importance of federated querying and the consumption of existing knowledge graphs in the geographic domain. A strengthening of novelty and approach to this article would only reinforce this insight and perhaps provide more of a use case for federated querying rather than a novel approach.
Author Response
- The article makes the assertion that 'In this sense, to the best of our knowledge, there are no existing triple stores that support the combined implementation of GeoSPARQL and SPARQL 1.1 in order to allow performing federated geospatial queries on the Web of Data.' This is, of course, a very broad statement and more research into this needs to be done. Whilst an agreement on this could be reached that this assertion is true if an statement such as 'with good performance over large datasets', this does not seem to be what the authors are testing with their approach and if this were to be tested a similar conclusion would be found for SQL too. At Kadaster (Dutch Land Registry), a TriplyDB triple store instance is being used which makes use of Virtuoso and/or Jena Fuseki and federated queries across (large) knowledge graphs are being done here. Another example is Communica where complex federated queries are also being performed.
We added the following references following the recommendations of the reviewer:
Taelman R.; Van Herwegen J.; Vander Sande M.; Verborgh R. Comunica: A Modular SPARQL Query Engine for the Web. In: Vrandečić D. et al. (eds.) The Semantic Web – ISWC 2018. Lecture Notes in Computer Science, Springer, Cham, 2018, vol 11137, 239-255. https://doi.org/10.1007/978-3-030-00668-6_15.
Rowland, A.; Folmer, E.; Beek, W. Towards Self-Service GIS—Combining the Best of the Semantic Web and Web GIS. ISPRS Int. J. Geo-Inf. 2020, 9, 753. https://doi.org/10.3390/ijgi9120753
Rowland, A.; Folmer, E.; Beek, W.; Wenneker, R. Interoperability and Integration: An Updated Approach to Linked Data Publication at the Dutch Land Registry. In GeoLD 2021 Geospatial Linked Data Workshop 2021 – CEUR Workshop Proceedings, 2021, Vol-2977. Accessible online: http://ceur-ws.org/Vol-2977/paper3.pdf (accessed on January 06, 2022).
Additionally, the mentioned assertion was softened in the article.
- The article highlights an approach to perform federated queries (which is claimed as previously not possible), enrich knowledge graphs with geographic information and offer a single source for a QGIS or web-based GIS application. Based on the previous comment, the novelty of this approach in the article needs to be clarified before acceptance of this paper.
We added the reference mentioned in the previous comment related to contributions described by the reviewer. However, we did not identify that these works performed federated GeoSPARQL queries on the Web of Data. In this sense, we think that the novelty of our approach is clearly described as follow:
“we present an approach to request, retrieve, and consume (geospatial) knowledge graphs prototypically implemented on Apache Marmotta. This approach supports the combination of SPARQL 1.1 and GeoSPARQL standards, allowing performing federated geospatial queries on the Web of Data. Moreover, our approach enables consuming geospatial knowledge graphs displaying collected elements in a lightweight web application or adding them through an open-source GIS as QGIS. Additionally, our approach utilizes non-geospatial knowledge graphs to enrich the description of geospatial resources collected from knowledge graphs. The potential of our approach is shown with two examples that handle diverse GeoSPARQL-based knowledge graphs from the Web of Data.
In contrast to prior work, which uses the Linked Data paradigm from within a GIS [26], our approach focuses on a federated vision, is fully GeoSPARQL compliant, and is implemented on an open-source GIS like QGIS. Furthermore, this work contributes to filling a gap and makes possible the exploitation of GeoSPARQL-based resources in a distributed environment through federated (queries) practices, helping the GIScience community to use the richness of the Web of Data.”
- It is not, however, clear whether this federated querying is the central element to this article so, in addition to clarifying the novelty, the approach demonstrated in this paper as novel should also be defined more concretely.
According to previous comments, we checked the limitations of existing works in the literature, and we are convinced of our contribution and novelty.
- In various parts of the article there are some clumsy English formulations. A detailed review of this should sort out most of these issues and would improve the English quality of the paper.
We performed an in-depth review of the grammar.
Reviewer 2 Report
The “Bringing federated semantic queries to the GIScience scenario” article is a valuable study on the application of semantic queries, but it’s necessary to say that Geographic information science (GIScience) is the scientific discipline that studies the techniques to capture, represent, process, and analyze geographic information.
This article concentrated on use of semantic queries in spatial analysis. Spatial analysis is one of the techniques that process, and analyze geographic phenomenons. Then suggest the title change to “Bringing federated semantic queries to the GIS based scenario”. This idea have about 20th years background with “Bishr, Y. (1997). Semantic aspects of interoperable GIS. ITC.” Book.
All parts of the article are professionally and I think it could help GIS engineers to develop new tools based on this approach.
Related article same as “[Stoimenov, L., & Đorđević-Kajan, S. (2002). Framework for semantic GIS interoperability. FACTA Universitatis, Series Mathematics and Informatics, 17(2002), 107-125], [Bishr, Y. (1998). Overcoming the semantic and other barriers to GIS interoperability. International journal of geographical information science, 12(4), 299-314.], [Karan, E. P., Irizarry, J., & Haymaker, J. (2016). BIM and GIS integration and interoperability based on semantic web technology. Journal of Computing in Civil Engineering, 30(3), 04015043.], [Lee, K., Lee, J., & Kwan, M. P. (2017). Location-based service using ontology-based semantic queries: A study with a focus on indoor activities in a university context. Computers, Environment and Urban Systems, 62, 41-52.] and more)” focused on semantic queries usages in GIS and also in location-based studies, but in this article use of open source apps same as QGIS could help to popular of this approach.
I suggest the article publish after changing title because there are not any problems related to language, manuscript structure, or data presentation.
Author Response
This article concentrated on use of semantic queries in spatial analysis. Spatial analysis is one of the techniques that process, and analyze geographic phenomenons. Then suggest the title change to “Bringing federated semantic queries to the GIS based scenario”. This idea have about 20th years background with “Bishr, Y. (1997). Semantic aspects of interoperable GIS. ITC.” Book.
We modified the title according to the reviewer’s suggestion.
Additionally, we included a mention of Bishr’s work (1998) in our paper.
I suggest the article publish after changing title because there are not any problems related to language, manuscript structure, or data presentation.
Finally, we thank the comments of the reviewer.
Reviewer 3 Report
The paper is well written and organized. The result is interesting and has some new findings.
Author Response
We thank the comments of the reviewer.
Reviewer 4 Report
This article presents a new procedure for the request, retrieval, and consummation of knowledge graphs from different platforms based on accepted standards for Linked Data. Results are assessed and visualized through custom-made web apps and QGIS. the work is interesting, innovative, and should be published. Specific remarks:
Title: the "GIScience scenario" is a rather vague term
Line 81: utilises ->is?
Line 95: as -> at?\
Line 280-281: this statement is contradicting to previous sentences.
Figure 1 workflow: the GeoSPARQL & SPARQL arrow should be towards the data
Line 413: link does not work
Line 500-501: change style
Map in Figure 3 needs a legend
Good luck in publishing your work!!!
Author Response
Title: the "GIScience scenario" is a rather vague term
We modified the title to specify the scope of our work.
Line 81: utilises ->is?
Fixed
Line 95: as -> at?\
We checked, and it was modified.
Line 280-281: this statement is contradicting to previous sentences.
We modified the paragraph to clarify the idea.
Figure 1 workflow: the GeoSPARQL & SPARQL arrow should be towards the data
We modified Figure 1.
Line 413: link does not work
It is an error of the pdf generation. We checked and it is running.
Line 500-501: change style
Fixed
Map in Figure 3 needs a legend
We modified Figure 3.
Round 2
Reviewer 1 Report
The changes made to the paper by the authors reflect the feedback given. I can recommend an acceptance.
