flock

Flock

Flock loads real Twitter streams into Dgraph to make use of graph travesals.

Flock has two parts,

• Tweet loader - Connects to realtime Tweets via the Twitter Developer API and loads a graph model of Twitter into Dgraph via mutations.
• Query client - Runs interesting graph queries on the Tweets data stored in Dgraph.

Here is the graph schema of Flock:

Running Flock

Obtaining Twitter credentials

We need to create a Twitter developer account and an app to be able to fetch stream of Tweets using their APIs. Let's start with how to create a Twitter developer account.

• Apply for a Twitter developer account here and follow the instructions. The series of steps would end with your email verification.
• Create a Twitter app from this link. All fields are not required.
• You'll be redirected to the App details tab after creating the app. Go to the Keys and tokens tab and create new access and secret tokens.
• Create a copy of the credentials template.

  cp credentials-template.json credentials.json
  

• Open the crendentials.json file and replace the placeholders with the keys from the Twitter app's Keys and token tab.

Setup

• Clone the repository.

$ git clone https://github.com/dgraph-io/flock.git
$ cd flock

• Export the persistent data directory. Since Dgraph is run using Docker containers, it is nice to mount a directory on the host machine to persist the data across multiple runs.

$ mkdir ./data
$ export DATA_DIR=$(pwd)/data

• If you're running Linux, you can add the current user to the docker group to use Docker as a non-root user. newgrp creates a new terminal session. It is necessary after the user modification to see the effects.

$ sudo usermod -aG docker $USER
$ newgrp docker

• Ensure that credentials.json with the Twitter credentials exist in the root directory of Flock.

• Start the Dgraph servers and Ratel with Docker Compose. Visit http://localhost:8000 on your browser to view the UI.

$ docker-compose up

• On another terminal, start Flock:

$ docker-compose -f docker-compose-flock.yml up

Flock will begin printing out periodic log messages mentioning its loading rate. You're good to go if you see the commit_rate higher than 0/sec, which means data has been successfully committed to Dgraph.

A few minutes of running Flock is sufficient to get enough data for some interesting queries. To stop running Flock, press Ctrl+C on the terminal running Flock.

$ docker-compose -f docker-compose-flock.yml up
...
<Ctrl+C>
Killing flock ... done