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Many facilities are working to align with FAIR data principles. The publishing of both human and machine readable metadata in a common manner and leveraging open and standards based protocols are supporting activities. Better alignment with FAIR principles is also a component in many facility certification efforts while commercially backed tools like Google DataSet Search leverage this work to provide expansive and easy searching of data resources. Within the geoscience community, the work at Science on Schema is a key community partner to help providers with this publishing work. Gleaner also leverages this work.

Gleaner is an open source tool, written in Go, that compiles to a simple single static binary across most platforms. It is designed to leverage sitemaps to access resources and extract JSON-LD encoded structured data. It can perform various actions on these collected resources then. Validation through calling SHACL services like Tangram, form checking (making sure the basic structure is proper) and generating indexes. The basic index generated is a graph, formed from the various individual data graphs for each resource. This can then be fed into a graph database and used for searching, analysis or exposed through Web APIs or other approaches like GraphQL. Results of Gleaner could also be used to feed Elasticsearch or other data systems though spatial or even temporal indexes could be formed from the exposed data.

Gleaner can also be used as a tool to quickly test and evaluate facility or community resources publishing patterns to ensure better alignment with commercial or other indexing services. As such, Gleaner is part of a "Data Ops" approach to rapid and iterative data publishing.

Gleaner is simply an implementation of web architecture patterns and client code focused on accessing and indexing these resources.

Basic Gleaner

A set of cloud based tools and functions can be found These can be usd online via the browser or through command line calls.
They are also available for use in Jupyter notebooks do develop out workflows with.


The Summoner, which uses site map files to access and parse facility resources pages. Summoner places the results of these calls into a S3 API compliant storage.

The Miller, which takes the JSON-LD documents pulled and stored by summoner and runs them through various millers. These millers can do various things.

Basic Gleaner

The current millers are:

  • text: build a text index in raw bleve
  • spatial: parse and build a spatial index using a geohash server
  • graph: convert the JSON-LD to RDF for SPARQL queries

A set of other millers exist that are more experimental

  • tika: access the actual data files referneced by the JSON-LD and process through Apache Tika. The extracted text is then indexed in text system allowing full text search on the document contents.
  • blast: like text, but using the blast package built on bleve
  • fdptika: like tika, but using Frictionless Data Packages
  • ftpgraph: like graph, but pulling JSON-LD files from Frictionless Data Packages
  • prov: build a basic prov graph from the overall gleaner process
  • shacl: validate the facility resoruces against defined SHACL shape graphs

How to run (or at least try..., this is still a work in progress)

A key focus of current develoipment is to make it easy for groups to run Gleaner locally as a means to test and validate their structured data publishing workflow.


Some early documentation on running gleaner can be found at: Running Gleaner.

Validation (SHACL Shapes)

Work on the validation of data graphs using W3C SHACL shape graphs is taing place in the GeoShapes repository. Gleaner leverages the pySHACL Python package to perform the actual validation.

Profiling (for dev work)

You can profile runs with

go tool pprof --pdf gleaner /tmp/profile317320184/cpu.pprof  > profileRun1.pdf

Example CPU and Memory profile of a recent release.


Tool for working with structured data on the web to support geosciences



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