Canvas

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Server-side chat with Postgres and NextJS ​

This app demonstrates how a hybrid client/server implementation of Canvas can work.

  1. All signer state is stored on the frontend. Only signatures and signed actions are passed to the server, which handles all other Canvas-related functionality
  2. Effects recieved on the server are persisted into a local or cloud Postgres database
  3. Integrates with NextJS's static generation and frontend tooling features

Workspaces ​

This project uses NPM workspaces, and all commands are assumed to be executed in the root of the workspace. For commands specific to this chat project, use -w to specify the project name @canvas-js/chat-postgres

cd canvas/
npm run build
npm run build -w @canvas-js/chat-postgres

Setup ​

You need a Postgres instance running locally or remotely that conforms to a standard postgresql:// connection string. You can provide this string as a DATABASE_URL environment variable, or configure a local instance using the following credential format:

"postgresql://postgres:postgres@localhost:5432/chat_postgres":
  user: postgres
  password: postgres
  host: localhost
  port: 5432
  database_name: chat_postgres
  • You need standard node and npm versions (node 18+)

Run ​

To run, navigate to the root of the workspace and install dependencies:

  • npm i

Run the development server for compiling Canvas runtime files:

  • npm run dev

Finally, run the development server for this app:

  • npm run dev -w @canvas-js/chat-postgres

Build ​

To deploy remotely, you need to run (2) build steps and (1) command to start the server.

Make sure you have a valid Postgres connection string passed as DATABASE_URL.

  1. Build the core canvas files in the root repo:
  • npm run build
  1. Build the NextJS-related files in the chat-postgres app:
  • npm run build -w @canvas-js/chat-postgres
  1. Run the production server:
  • npm run start -w @canvas-js/chat-postgres

Open localhost:3000 with your browser to see the result