The Knowledge Graph management system

LinkedDataHub (LDH) is open source software you can use to manage data, create visualizations and build apps on RDF Knowledge Graphs.

LDH features a completely data-driven application architecture: generic server and client components process declarative RDF/OWL, SPARQL, and XSLT instructions. The default application structure and user interface are provided, making LDH a standalone product, yet they can be completely overridden and customized, thus also making LDH a low-code application platform. Unless a custom processing is required, no imperative code such as Java or JavaScript needs to be involved at all.

Setup

Install Docker
- Install Docker Compose, if it is not already included in the Docker installation
Fork this repository and clone the fork into a folder
In the folder, create an .env file and fill out the missing values (you can use .env_sample as a template). For example:

COMPOSE_CONVERT_WINDOWS_PATHS=1
COMPOSE_PROJECT_NAME=linkeddatahub

PROTOCOL=https
PROXY_HTTP_PORT=81
PROXY_HTTPS_PORT=4443
HOST=localhost
ABS_PATH=/

OWNER_MBOX=john@doe.com
OWNER_GIVEN_NAME=John
OWNER_FAMILY_NAME=Doe
OWNER_ORG_UNIT=My unit
OWNER_ORGANIZATION=My org
OWNER_LOCALITY=Copenhagen
OWNER_STATE_OR_PROVINCE=Denmark
OWNER_COUNTRY_NAME=DK
OWNER_KEY_PASSWORD=changeit

Run this from command line:

docker-compose up

LinkedDataHub will start and create the following sub-folders:
- certs where your WebID certificates are stored
- data where the triplestore(s) will persist RDF data
- uploads where LDH stores content-hashed file uploads
Install certs/owner.p12 into a web browser of your choice (password is the OWNER_KEY_PASSWORD value)
- Google Chrome: Settings > Advanced > Manage Certificates > Import...
- Mozilla Firefox: Options > Privacy > Security > View Certificates... > Import...
- Apple Safari: The file is installed directly into the operating system. Open the file and import it using the Keychain Access tool.
- Microsoft Edge: Does not support certificate management, you need to install the file into Windows. Read more here.
Open https://localhost:4443/ in that web browser

After a successful startup, the last line of the Docker log should read:

linkeddatahub_1    | 02-Feb-2020 02:02:20.200 INFO [main] org.apache.catalina.startup.Catalina.start Server startup in 3420 ms

Notes

You will likely get a browser warning such as Your connection is not private in Chrome or Warning: Potential Security Risk Ahead in Firefox due to the self-signed server certificate. Ignore it: click Advanced and Proceed or Accept the risk to proceed.
- If this option does not appear in Chrome (as observed on some MacOS), you can open chrome://flags/#allow-insecure-localhost, switch Allow invalid certificates for resources loaded from localhost to Enabled and restart Chrome
.env_sample and .env files might be invisible in MacOS Finder which hides filenames starting with a dot. You should be able to create it using Terminal however.
On Linux your user may need to be a member of the docker group. Add it using

sudo usermod -aG docker ${USER}

and re-login with your user. An alternative, but not recommended, is to run

sudo docker-compose up

Configuration

Base URI

Besides owner WebID configuration, the most common case is changing the base URI from the default https://localhost:4443/ to your own.

Lets use https://ec2-54-235-229-141.compute-1.amazonaws.com/linkeddatahub/ as an example. We need to split the URI into components and set them in the .env file using the following parameters:

PROTOCOL=https
HTTP_PORT=80
HTTPS_PORT=443
HOST=ec2-54-235-229-141.compute-1.amazonaws.com
ABS_PATH=/linkeddatahub/

ABS_PATH is required, even if it's just /.

Dataspaces

Dataspaces are configured in config/system.trig. Their base URIs need to be relative to the base URI configured in the .env file.

Reusing the https://ec2-54-235-229-141.compute-1.amazonaws.com/linkeddatahub/ as the new base URI, the easiest way is to simple replace the default https://localhost:4443/ value with it. It can be done using the following shell command:

sed -i 's/https:\/\/localhost:4443\//https:\/\/ec2-54-235-229-141.compute-1.amazonaws.com\/linkeddatahub\//g' config/system.trig

Note that sed requires to escape forward slashes / with backslashes \.

Reset

If you need to start fresh and wipe the existing setup (e.g. after configuring a new base URI), you can do that using

sudo rm -rf certs data && docker-compose down -v

This will remove the persisted data, server and owner certificates as well as their Docker volumes.

l-i-p-f / LinkedDataHub

The Knowledge Graph management system

Setup

Notes

Configuration

Base URI

Dataspaces

Reset

Documentation

Demo applications

Test suite

Dependencies

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