IPFS Block Service JavaScript Implementation

IPFS implementation of the BlockService and Block data structure in JavaScript.

Description

BlockService - A BlockService is a content-addressable store for blocks, providing an API for adding, deleting, and retrieving blocks. A BlockService is backed by an IPFS Repo as its datastore for blocks, and uses an IPFS Exchange implementation to fetch blocks from the network.

┌────────────────────┐
│     BlockService   │
└────────────────────┘
           │
     ┌─────┴─────┐
     ▼           ▼
┌─────────┐ ┌────────┐
│IPFS Repo│ │Exchange│
└─────────┘ └────────┘

Example

const BlockService = require('ipfs-block-service')
const Block = require('ipfs-block')
const IPFSRepo = require('ipfs-repo')  // storage repo
const memstore = require('abstract-blob-store')  // in-memory store

// setup a repo
var repo = new IPFSRepo('example', { stores: memstore })

// create a block
const block = new Block('hello warld')
console.log(block.data)
console.log(block.key)

// create a service
const bs = new BlockService(repo)

// add the block, then retrieve it
bs.addBlock(block, function (err) {
  bs.getBlock(block.key, function (err, b) {
    console.log(block.data.toString() === b.data.toString())
  })
})

outputs

<Buffer 68 65 6c 6c 6f 20 77 61 72 6c 64>

<Buffer 12 20 db 3c 15 23 3f f3 84 8f 42 fe 3b 74 78 90 90 5a 80 7e a6 ef 2b 6d 2f 3c 8b 2c b7 ae be 86 3c 4d>

true

Installation

npm

> npm i ipfs-block-service

Setup

Node.js

const BlockService = require('ipfs-block-service')

Browser: Browserify, Webpack, other bundlers

The code published to npm that gets loaded on require is in fact a ES5 transpiled version with the right shims added. This means that you can require it and use with your favourite bundler without having to adjust asset management process.

var BlockService = require('ipfs-block-service')

Browser: <script> Tag

Loading this module through a script tag will make the Unixfs obj available in the global namespace.

<script src="https://npmcdn.com/ipfs-block-service/dist/index.min.js"></script>
<!-- OR -->
<script src="https://npmcdn.com/ipfs-block-service/dist/index.js"></script>

API

const BlockService = require('ipfs-block-service')

var bs = new BlockService(repo[, exchange])

Creates a new block service backed by IPFS Repo repo for storage, and IPFS Exchange for retrieving blocks from the network. Providing an exchange is optional.

bs.addBlock(block, callback(err))

Asynchronously adds a block instance to the underlying repo.

bs.addBlocks(blocks, callback(err))

Asynchronously adds an array of block instances to the underlying repo.

Does not guarantee atomicity.

bs.getBlock(multihash, callback(err, block))

Asynchronously returns the block whose content multihash matches multihash. Returns an error (err.code === 'ENOENT') if the block does not exist.

If the block could not be found, expect err.code to be 'ENOENT'.

bs.getBlocks(multihashes, callback(err, blocks))

Asynchronously returns the blocks whose content multihashes match the array multihashes.

blocks is an object that maps each multihash to an object of the form

{
  err: Error
  block: Block
}

Expect blocks[multihash].err.code === 'ENOENT' and blocks[multihash].block === null if a block did not exist.

Does not guarantee atomicity.

bs.deleteBlock(multihash, callback(err))

Asynchronously deletes the block from the store with content multihash matching multihash, if it exists.

bs.deleteBlocks(multihashes, callback(err))

Asynchronously deletes all blocks from the store with content multihashes matching from the array multihashes.

Does not guarantee atomicity.

License

MIT