This is an application that allows users to conduct chess matches over the Hedera Consensus Service. Chess moves (and chat messages) are submitted to the consensus service, where they are ordered as an immutable log of events. These events are then translated into board states and messages that are served to the client.
In order to use this application, you will need a Hedera account as well as a HashPack wallet version v2.4.6+.
Note: This is a proof-of-concept application that was intended to demonsrate the technical feasibility of storing gamestates in the HCS. This is not intended to replace traditional online chess venues. I have made this repo open source to assist other developers in creating Hedera dApps. The app's design is likewise a proof-of-concept not intended for production.
This is a NuxtJS application that leverages several useful node modules, most notably: chess.js, hashconnect, and of course hedera-sdk-js. It comes with a compose file for docker containerization which is intended for use with Elastic Beanstalk..
The app can be run locally via either its compose file, or the usual "npm install" -> "npm run dev" method. Since matches are stored on the HCS, you'll be able to access your match data regardless of where you run this application. You also need to be using HTTPS in your local environment. I recommend using mkcert for 'localhost' and putting the .pem keys in the ./app directory.
- Players connect their HashPack wallet to the app via HashConnect. This will allow the app to use their Hedera wallet to create HCS topics and send messages.
- The cost of submitting a message to the HCS is typically $0.0001 USD, and the cost of creating a new topic is $0.01 USD.
- Each match is a unique HCS topic, whose messages consist of JSON payloads containing information on chess moves and chat messages. The application processes these messages into the session state as it receives them.
- When connected to a match page, the app regularly (every 4 seconds) queries that HCS topic via a mirror node REST api.
- The game state is stored in vuex, making it readily accessible from any component via a plethora of mutations, actions, and getters. The state is kept in session storage, meaning that it persists within a tab even after a page refresh.
- A dummy game is used client-side to display board states, and validate moves before sending them to the HCS. Instead of sending individual moves to the HCS, the Portable Game Notation from the dummy game is sent. The canonical game state is only updated when it receives a new PGN from the topic. This is done to prevent deviation in game states in case of a failed message submission.
None! If you are planning on making a similar app, I would recommend using a server-side HCS operator to avoid players having to constantly approve transactions.
- The chess sprites are from Daniela De Lena's spritesheet.