Minimal Collaborative Filtering Implementation on a Blockchain

This repository contains an implementation of a custom blockchain that serves as a proof-of-concept for a novel kind of decentralized machine learning applications. For more information, see the website.

Demo

Click below to watch a screencast of a minimal demo:

Installation

1. Clone the repository and its submodules:

   git clone --recursive git@github.com:robamler/blockchain-machine-learning-demo.git

   • If you forgot the --recursive switch, just cd in the directory and run git submodule update --init.

2. Set up rust and substrate:

   curl https://getsubstrate.io -sSf | bash -s -- --fast

   • For more information, see the corresponding section of the "substrate recipes" tutorial.

3. Build the node (this will take a while):

   cd blockchain-machine-learning-demo/blockchain-node
   cargo build --release -p kitchen-node

   • Don't worry about the name "kitchen-node", this is just reminiscent of the substrate recipe on which this custom blockchain implementation is based.

4. Start a node: from the blockchain-node directory, run

   ./target/release/kitchen-node --dev

5. Optional: start a second node (if you want to test two nodes communicating with each other). To do this, look for a log message saying "Local node identity is:" in the output of the above command and copy the ID that follows to the clipboard. Then, from the blockchain-node directory, run the following command, replacing NODE1_IDENTITY with the ID in your clipboard:

   ./target/release/kitchen-node --dev -d /tmp/node2 --ws-port 9945 --reserved-nodes /ip4/127.0.0.1/tcp/30333/p2p/NODE1_IDENTITY

   If the ID was correct, then the two running nodes should see each other, and they both should print "(1 peers)" to the command line every few seconds.

6. Start a user interface:

   cd ../ui/
   yarn run start

   Wait until you see an output similar to the following (this may take a few minutes):

   [../../node_modules/html-webpack-plugin/lib/loader.js!./public/index.html] /home/robamler/Documents/projects/decentralized-matrix-factorization/src/ui/node_modules/html-webpack-plugin/lib/loader.js!./public/index.html 853 bytes {HtmlWebpackPlugin_0} [built]
   

   Then open http://localhost:3000 in your browser. If you see an error message "Not Found / 404" then the UI is still compiling. Wait until you see the above confirmation message and then reload the page.

7. Optional: if you started a second node in step 5 above, then you can connect a second UI to it. From the ui directory, run:

   yarn run start2

   Wait again until you see the above confirmation message, then open http://localhost:3001 in a new browser tab.

8. To connect a UI to a node, click on the circle in the upper left corner. A dialog saying "select network" should pop up.

   • To connect to the primary node you started in step 4 above, select "Local Node (own, 127.0.0.1:9944)".
   • To connect to the optional additional node from step 5 above, toggle the option "custom endpoint" and enter ws://127.0.0.1:9945/

   Click "Save & Reload".

9. In the left-hand pane of the UI, click on "Matrix Factorization" and enjoy playing with an overly simplistic recommendation system :)

10. If you want to delete the blockchain and start over: stop all running nodes (Ctrl + C); then, from the blockchain-node directory, run

    ./target/release/kitchen-node purge-chain --dev
    rm -rf /tmp/node2 # (only necessary if you executed the optimal step 5 above)

    Then restart the node(s) following step 4 (and optionally 5) above, and reload the UI(s).

Copyright

Robert Bamler