Review Comment:
This manuscript aims to present solutions for mobile access to the Web of Data in developing countries, where connectivity is limited. Unfortunately, it does not succeed at this goal: the paper meanders from a far-fetched motivating case, to a description of P2P (not relevant to the SWJ audience), to a short overview of distributed RDF approaches, but fails to bring the point home on how this concretely helps in low-connectivity environments. I am missing new insights, and am worried about the correctness of some of the descriptions and discussions in there (as discussed below).
As such, I do not think this paper is a good fit for the journal.
INTRODUCTION
- The introduction is quite chaotic. It jumps from very basic Linked Data to connectivity problems on the African content to quite specific details of peer-to-peer networks, then back to high-level solutions and back to peer-to-peer. The claimed contributions are then around gossip protocols on a high level, and then specifically RDF sharing systems.
- The long introduction about linked data is not appropriate for SWJ; our readers know these concepts already, and at a deeper level than is in the introduction.
- Reference 1: who is J. Timothy?
- Reference 7 seems to be a very obscure work to back up a broad statement on P2P; I don't think it is appropriate here.
MOTIVATION
- The motivation case is quite contrived; such activities are not performed even when there is connectivity. There is no indication whatsoever that anyone would want to engage in such activities.
- Additionally, it seems like a very small amount of data, that would be a couple of kilobytes at most.
- And there is no indication further in the manuscript that the motivational case is actually addressed appropriately.
PEER-TO-PEER AND SEMANTIC DATA EXCHANGE
- The authors write "Research on RDF data exchange on peer-to-peer networks has made great progress.", but this statement is not backed up; the closest reference [14] is not related to RDF.
- This section is devoted to an explanation of gossip protocols, which already exists elsewhere (notably [14]).
- Pages 4–9 not related to RDF at all. While announced in the intro, they are not relevant to SWJ readers.
- The discussion on RDF-aware systems is quite haphazard and unstructured; it it not helpful to our audience.
- KBox is a technique for sending the entire knowledge graph to the client; its relevance here is unclear.
RDF GRAPH SHARING AND COLLABORATIVE MODIFICATION
- The RDF explanation is too basic for the Semantic Web Journal, and not all information is correct or appropriately phrased.
– "RDF Schema is a [special] vocabulary"
- N3 is not a representation of RDF
– Jena, Sesame, and Virtuoso are entirely irrelevant here
- HDT is not a solution to limitations of RDF
- …
- There is some value in 5.2.2 where different replication approaches are considered; similar for 5.3.3. Those are the most valuable parts of the paper. However, they are only a limited part of the whole.
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