personal-backend

A simple backend for personal projects

This is a simple Socket.io server for getting, putting, patching JSON-encodable data on a per-user basis.

Allows users to add collaborators which have read/write access to the granter's data. That's right! A personal backend with collaboration! I wrote this initially for a home inventory management app to be shared with my wife; so, kind of personal.

User data has a version number. Clients specify the current version for updates.

Updates may be full replacements or patches/merges.

Clients can fetch or get the full data or just some paths therein (e.g. a.b.c).

Clients can watch for changes to a user's data (including their own) as long as they are the owner of the data or a collaborator thereof.

UserData

{
	"metadata": {
        "username": String,
        "version": Number,
        "collaborators": [Username],
        "createdAt": Date,
        "lastUpdate": { "at": Date, "by": Username }
    },
    "userdata": Object
}

Client Messages

'signup'    
'auth', token    
'update', newData, version, targetUsername=null, patch=false    
'fetch', targetUsername=null, fields=null
'watch', targetUsername
'unwatch', targetUsername

Server Messages

'auth', username, token    
'version', username, version    
'error', message    
'data', targetUsername, data
'change', targetUsername, data

Error Messages

'invalid token'
'version mismatch'
'unauthorized'

Updates

newData = {
  metadata: {
    version: int,             // expected server version of data
    collaborators: [String]   // replaces entirely regardless of patch
  },
  userdata: Object            // replacement or changes (for patch)
}

Fields

fields = [
  'a.b',                      // {a: {b: 1}}
  'c',                        // {c: 'foo'}
  'd.e.f'
]

Fields are a poor man's GraphQL. Specifying some fields to fetch or watch will only return some fields and the data in a data or change message from the server will take the same shape.

Configuration

ENV

PORT=8080
CACHE_SIZE=100
CACHE_MAX_AGE=900000
JWT_SECRET=...
MAX_DATA_SIZE_JSON=65536
DEBUG=api

TODO

• Rate limit signups from the same IP but this is a cat and mouse game

Author

Brian Hammond [e-mail]