RDF Delta Container Image

Usage

This repository builds and publishes the rdf-delta container image that has the RDF Delta server jar file and the delta patch log enabled Fuseki server jar.

RDF delta is an RDF patch based server that enables high availability scenarios for Fuseki. See the documentation and the rdf-delta GitHub repository for more information.

Pre-built container images are available at https://github.com/Kurrawong/rdf-delta-container-image/pkgs/container/rdf-delta.

See the compose.yml for general container setup.

Quickstart

Use task to run the commands in Taskfile.yml.

# Start the services using docker compose
task up

# Load the example data to RDF Delta server
task load

You will now have an RDF Delta server with the initial data loaded and two Fuseki servers synced to it.

RDF Delta Server HTTP API

The HTTP API is documented at rdf-patch-logs.html.

Operation	Effect
POST http://.../{shortName}/	Append to log
GET http://.../{shortName}/{id}	Get a patch
GET http://.../{shortName}/version	Get a patch

Creating Patch Logs

When creating new patch logs, a downstream client will always need to ask the RDF Delta Server for the latest patch id in order to create and send a valid patch log.

You can use the rdf-delta-python DeltaClient class and its describe_log method to retrieve the version information.

The load_patch.py script shows how to get / submit patches using rdflib and httpx

Or you can also use any other http client to interact with the server.

For an example with curl

# get the datasource id
payload="
  {
    'opid': '',
    'operation': 'describe_datasource',
    'arg': {
      'name': 'ds'
    }
  }
"
response=$(curl -s -X POST http://172.19.0.1:1066/$/rpc --data "$payload")
echo "$response"
datasource_id=$(echo "$response" | jq -r '.id')

# get the latest patch log version
payload="
  {
    'opid': '',
    'operation': 'describe_log',
    'arg': {
      'datasource': '$datasource_id'
    }
  }
"
response=$(curl -s -X POST http://172.19.0.1:1066/$/rpc --data "$payload")
echo "$response"
latest=$(echo "$response" | jq -r '.latest')

# send a new patch
patch="H id <uuid:$(uuidgen)> ."
if [ "$latest" ]; then
  patch+="
H prev <uu$latest> ."
fi
patch+="
TX .
A <a> <b> <c> .
TC .
"
echo "$patch"
curl -s -X POST http://172.19.0.1:1066/ds \
  --data "$patch" \
  -H "Content-Type: application/rdf-patch"