Gleaner (https://gleaner.io)

About

Gleaner is a tool for extracting JSON-LD from web pages. You provide Gleaner a list of sites to index and it will access and retrieve pages based on the sitemap.xml of the domain(s). Gleaner can then check for well formed and valid structure in documents. The product of Gleaner runs can then be used to form Knowledge Graphs, Full-Text Indexes, Semantic Indexes Spatial Indexes or other products to drive discovery and use.

About

The image above gives an overview of the basic workflow of Gleaner.

This image show that the product of Gleaner is really a populated data warehouse (document warehouse). Where those documents are either the JSON-LD structured data document harvested or the the provenance graphs generated by Gleaner during the process of harvesting.

Gleaner talks to an S3 compliant object store as part of its configuration. This can be AWS S3, Google Cloud Storage (GCS) or other S3 compliant object stores. A typical set up might see the use the open source Minio package in this role.

Note also the use of headless chrome in this diagram. A headless chrome instance is use for those cases where the resources to be harvested are placing the JSON-LD documents into the document object model (DOM) dynamically. In this case then the headless chrome is used to render the page and run the Javascript to form the rendered HTML document that can be parsed for the JSON-LD.

This previous image gives a view of a typical completed installation and use of Gleaner. In this image we now see the use of the Nabu package (also in this Gleaner.io organization) to synchronize the data warehouse with a triple store.

Nabu is described in its own repository but it basically reads the the JSON-LD document and performs ELT, ETL workflows on it. In this case, a simple ETL of the JSON-LD. Extracted from the S3, translated from JSON-LD into ntriples and then loaded into the triplestores. If your triplestore natively handles the JSON-LD serialization of the RDF then this could be a simple extract and load.

Code and Git Branch Patterns

Go versions

Gleaner is written in Go and we ask that the developers stay in sycn with the latest stable release. Go is a very stable language API so generally there are little issues with being off a version or two.

Note that conflicts with the go.mod and go.sum are not unexpected. As noted here, please resolve conflicts with these files by doing a union followed by a

go mod tidy

following the merge. Once you have resolved the conflict and done tidy can add, if needed, the go.mod and go.sum files and commit.

Branches

If you are interested in working on Gleaner we ask that you use the following git pattern. Branches should start with your initials followed by -- and then a name. This can be a descriptive name or an issue name.

Please branch off of dev and merge back into dev. Given the small number of developers we hope this wont result in many conflicts. As we agree on a version of dev that we like, we will make merges to master from which builds for releases and container will be done.

``` $ git checkout -b [initialsorteamname]--[yourbranchtitlesnakecase] $ git checkout -b df--devdoc_updates < make some code changes > $ git add . $ git commit -m '[initials]