Pact Smart Contract Language TodoMVC demo

Setup

• Install Pact >= 3.0.0
  • brew install kadena-io/pact/pact
• Install Node >= 8.11.4
• Install All Dependencies. The dependencies include Pact Lang API.
  • npm install
• Navigate into pact-todomvc and create a log folder in the top-level folder mkdir log

Scripts

npm run start:pact: Start the Pact Server

npm run pact:seed: Seed the blockchain

npm start: Start the Web Application

Starting the Project

1. npm run start:pact
2. npm run pact:seed
3. npm start
4. http://localhost:3000

Using the Pact Dev Server

Configuration File

The pact dev server (pact-serve) requires a configuration Yaml file (e.g. server.conf) to operate. The documentation for it is:

➜  pact git:(feat/dev-server) pact --serve --help
Config file is YAML format with the following properties:
port       - HTTP server port
persistDir - Directory for database files.
             If ommitted, runs in-memory only.
logDir     - Directory for HTTP logs
pragmas    - SQLite pragmas to use with persistence DBs
verbose    - [True|False] Provide extra logging information

Initializing the server

When running pact-serve with persistence enabled the development server will automatically replay from disk when it starts. In this demo, we are persisting to log/ which causes pact-serve to create or use log/commands.sqlite to store Commands and CommandResults.

The first time you run pact-serve the SQLite DBs will be created empty (as no commands have been run yet). To upload todos.pact, which the front end needs loaded to interact with, you run initialize-todos.sh. The important thing to note is that until you delete log/commands.sqlite (or run pact-serve in memory) pact-serve will replay every command (e.g. load todos.pact -> UI interactions) on start up.

If you think of it like a blockchain, deleting the commands.sqlite file or running in memory gives Pact a "fresh" chain to work with.

Credit

The front-end of this app was built on React TodoMVC example.