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@browser-network/database

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@browser-network/database

A type of distributed database built on top of the distributed browser-network

0.1.1
Source
npm

Version published: 2 years ago

Weekly downloads: 14

Maintainers: 1

Weekly downloads

Created: 3 years ago

Source

Browser-Network Database

A distributed, decentralized, trustless, peer to peer database that exists in the browser on top of The Browser Network.

This database was created to allow apps to be developed completely client side. I don't mean serverless in the modern sense, I mean truly apps running without servers at all.

It works by allowing each user to have one "state". The state can be anything. When a user updates their state, the db passes it to other users on the network who hold on to it. If a third user wants to see the first user's state and the first user is not online, whoever else may have it can pass it along.

The database works more as a list of distinct state objects rather than one big shared state of things.
Each user can modify only their own state.
Each user holds a copy of every state on the network.
If user A updates their state, and then is simultaneously online with user B at any point, user B will pick up that state. If then user A closes their browser window, then user C opens theirs, user C will get, via user B, user A's state.
Each client periodically broadcasts which states they have (just a list of id's associated with a timestamp of their last modification), and if there's a version in there that's newer than what it has, it will request that update from the node that broadcasted it. This way full state objects are never sent over the network unnecessarily, preserving bandwidth.
This database uses the excellent eccrypto elliptic curve public key cryptography system to prove veracity of state, ensuring one user cannot update another user's information.

Installation

Installing this is mostly like usual:

npm install @browser-network/database

or if you're old school and want a umd import:

<script src="//unpkg.com/@browser-network/database/umd/database.min.js"></script>

Quick Start

Here's a very simple app you can get up and running using @browser-network/database super quick and easy:

<!doctype html>

<html lang="en">
  <body>

    <code id='state'></code>

    <script src="//unpkg.com/@browser-network/crypto/umd/crypto.min.js"></script>
    <script src="//unpkg.com/@browser-network/network/umd/network.min.js"></script>
    <script src="//unpkg.com/@browser-network/database/umd/db.min.js"></script>
    <script>

      const network = new Network({
        switchAddress: 'http://localhost:5678', // default address of switchboard
        secret: Bnc.generateSecret(),
        networkId: 'test-network'
      })

      const db = new Db({
        network: network,
        secret: Bnc.generateSecret(),
        appId: 'db-app-id' // this just needs to be unique for your app, which it is for this
      })

      db.onChange(() => {
        console.log("We've got updates!:", db.getAll())
        document.querySelector('#state').innerHTML = JSON.stringify(db.getAll())
      })

      window.setState = (state) => db.set(state)

    </script>
  </body>
</html>

Copy and paste that html into some html file of your choosing on your machine. Then in one terminal:

npx @browser-network/switchboard

And in another, host your html file. I've always found this to be easiest:

python -m SimpleHTTPServer

Now navigate to localhost:8000 or whatever port you're hosting it on, with a few browser windows.

Now, in one of them, open up the console, and run setState('hello, world!')

You should see, eventually, that state appear on the screens of all the different browser windows you have open.

Usage

import Network from '@browser-network/network'
import Bnc from '@browser-network/crypto'
import Db from '@browser-network/database'

// This is a database that operates on top of the browser network.
const network = new Network({
  switchAddress: 'localhost:5678',
  networkId: 'whatever-network-id-just-make-it-unique',
  clientId: '<clientId>' // usually stored in the localStorage
})

// Instantiate the db
const db = new Db({
  appId: 'just-needs-to-be-unique-from-other-appIds-on-the-network',
  network: network,
  secret: Bnc.generateSecret() // your users will reuse this, saving it somewhere safe and secret.
})

// Listen for changes. This will be called every time we discover a new
// user on the network or someone we already know has updated their state.
db.onChange(() => {

  // Get the whole state of the network as far as we are aware
  const userStates = db.getAll()

  // Maybe if you are using react, we are in a top level component and call
  // something like
  setState({ userStates })

  // To see just one user's state
  // (`clientId` represents the id of the user on the network)
  const oneState = db.get(<clientId>)

  // To set our own state
  db.set(<ourState>)
})

// Now we can interact with the database

// Set your own state. It can be whatever type you want.
db.set({ whatever: 'we want' })

// Get a state
db.get(<id>) // where id is a clientId, which is the same as the WrappedState['id'] type.

// Get all of the states
db.getAll()

// Clear the local Storage. Note that if you're still connected to others on the network,
// your storage will rapidly begin to repopulate.
db.clear()

Allow/deny lists

Db also has allow/deny lists. The lists are just an exposed array of clientIds, so add to it like db.allowList.push('<clientId>'). Or swap in denyList.

If a user is on the denyList, we will never accept any messages from them.
If there're any ids in the allowList, and a user is not in there, then we will not accept any messages from them.

generateSecret()

Db uses a public key cryptography system to ensure only a user can update their own state. The public key is derived from the secret. @browser-network exposes an easy way to make a db acceptable private key, which your users can store and then put back in as the secret field when Db is instantiated.

import { generateSecret } from '@browser-network/crypto'
generateSecret() // -> hex string

On removing items

This database has an interesting take on removing items: there's explicitly no concept of it, because that'd take it from declarative kinda to imperative kinda, whereby only the people online at the time of removal would know to remove it from their own local storage. For users offline at the time of deletion, they'd happily send out that state to everyone and everyone else would pick it up as if it was new state they'd never seen before. If instead a user sets their state to null or undefined, it can be dealt with on the app level, and the update will make it to everyone.

If need be, later some logic can be put in to remove al the state that's set to null or undefined or {} or [] or ''.

Building

Because this project is using eccrypto and simple-peer, it's pretty much locked into the browserify ecosystem. Modern webpack does not automatically shim for browserify requires, but you can get it working with determination. However using browserify directly will be easier without a doubt.

TODO

Max state age specification
Only send a certain number of states per unit time. Or a certain volume of data.

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Package last updated on 24 Nov 2022

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