Setup

Running prototypical ProGS validation requires the Clingo ASP system, which consists of the Gringo grounder and Clasp solver. Clingo is free software published under the MIT license. The GitHub repository can be found here. In addition, Python 3 is required. Bash is required for utility scripts only. Python requirements can be installed with:

pip install -r requirements.txt

Debian/Ubuntu

On Debian and derivatives, Clingo is available through two separate packages:

sudo apt install gringo clasp

Other platforms

For other GNU/Linux distributions, you may find the clingo package in your distro package repository. For macOS, clingo packages are available via Homebrew and MacPorts. For download and setup instructions on other platforms, please consult the official documentation. Alternatively, an instance of Clingo is hosted here. In order to use the online version, simply copy & paste the contents of progs.lp (and display.lp) and example graphs and shapes (or your custom instances).

Quick Start

After installing clingo you can validate the example graph as follows:

./progs.py validate -g paper-example/graph.lp paper-example/example1_fixed.progs

For documentation of the validate mode, use:

./progs.py validate --help

For more information about the useage of the ProGS CLI, use ./progs.py --help or ./progs.py <mode> --help for all modes, such as validate.

Validation

The examples in folder paper-example demonstrate the usage of this validator. It requires encoding a property graph using the predicates edge/3, label/2 and property/3, which correspond to the components , and of a property graph . Node and edge shapes can be defined using a concrete syntax defined by the grammar in grammar.ebnf. For examples of the concrete syntax of constraints and target queries, please see paper-example (all examples from the ProGS paper, including alternative "fixed" variants for shapes that do not validate the graph) or movie-example/shapes.progs or the example below.

NODE s1 [BOTTOM] {
    >= 1 :colleagueOf.:person
};

NODE s2 [name = "Gareth Keenan"] {
    >= 2 role.string &
    s1
};

For more information about the ProGS shape validation language, see the following paper:

@inproceedings{DBLP:conf/semweb/SeiferLS21,
  author    = {Philipp Seifer and
               Ralf L{\"{a}}mmel and
               Steffen Staab},
  title     = {ProGS: Property Graph Shapes Language},
  booktitle = {The Semantic Web - {ISWC} 2021 - 20th International Semantic Web Conference,
               {ISWC} 2021, Virtual Event, October 24-28, 2021, Proceedings},
  series    = {Lecture Notes in Computer Science},
  volume    = {12922},
  pages     = {392--409},
  publisher = {Springer},
  year      = {2021},
  url       = {https://doi.org/10.1007/978-3-030-88361-4\_23},
  doi       = {10.1007/978-3-030-88361-4\_23},
  timestamp = {Tue, 05 Oct 2021 10:03:09 +0200},
  biburl    = {https://dblp.org/rec/conf/semweb/SeiferLS21.bib},
  bibsource = {dblp computer science bibliography, https://dblp.org}
}

More details about the ASP encoding can also be found in an extended report.

Validating Neo4j/Cypher Graphs

ProGS can be used to validate Neo4j graphs via the validate-neo4j.sh script. This relies on exporting a cypher graph through the cypher-shell (in JSON format) and converting the JSON encoding to our ASP encoding:

./progs.py validate -d <neo4j-db-location> <shapes>

where <shapes> is a progs shape file and <neo4j-db-location> the local path of the Neo4j instance. Note, that the configuration option apoc.export.file.enabled=true has to be set for the Neo4j instance. The folder movie-example contains shapes for validating the Neo4j example movie database. Note, that we convert all property names and labels to lower case. We also replace " with ' in strings. We only support integer and string property values. All other properties are converted to strings via the Python str function.

Validation of other property graph models is possible by either exporting graphs in the same JSON format as Neo4j or by writing a custom conversion to the ASP encoding used by ProGS. For validating a JSON dump obtained by other means, such as through the Neo4j Browser or a remote Neo4j instance, use:

./progs.py validate -j <json> <shapes>

The progs.py tool can also perform individual steps, such as dumping JSON to an intermediate file. For more information, see ./progs.py --help.

References

This ASP encoding is inspired by SHaclEX, an implementation of SHACL and ShEx that features a prototypical ASP-based validation engine. See also this talk.