task-graph-protocol

A task graph runner and a protocol for task <-> runner communication that enables very efficient watch pipelines.

taskfiles

Your tasks are declared in so-called "taskfiles". A taskfile can contain multiple tasks and you can also have as many taskfiles as you wish. Tasks can depend on tasks from other taskfiles.

Example:

// frontend/taskfile.json
{
  "build": {
    "command": "tsc",
    "dependencies": [{ "path": "../lib", "name": "build" }]
  }
}

// backend/taskfile.json
{
  "build": {
    "command": "tsc",
    "dependencies": [{ "path": "../lib", "name": "build" }]
  }
}

// lib/taskfile.json
{
  "build": {
    "command": "tsc"
  }
}

Running tgp build:frontend build:backend will then first build the project lib and then the projects frontend and backend in parallel. If the task build of lib fails, then it won't attempt building frontend or backend.

protocol

The main goal of this project is coordinating multiple watch processes. These are processes that don't exit after a build, but instead continue to rebuild as soon as file-changes are detected. The problem with such processes is that they cannot coordinate themselves with each other. So if both lib and app detect filechanges at the same time, both processes will immediately start re-building. This is a problem, because re-building app only makes sense after lib is built successfully.

So what I came up with to solve this problem is a protocol for such processes to communicate with the task coordinator or task runner. With this protocol, a watch process can notify the runner abount changes, and the runner can notify the process when it's time to re-start the task. Additionally, the task can tell the runner if it was successful or not.

For this all to work, watch-processes of course have to implement this protocol. But don't worry, this library provides some helpers to make this very easy.

license

MIT