swarm-feed-sequential

Swarm Feed Sequential

Abstract

Swarm Feed Sequential is a previously unreleased FDP library that implements Swarm Feeds as Sequential type. There are three types of feeds: Epoch, Sequential and Streaming.

What can you do with a Sequential Feed

You can use it as off-chain, verifiable append-only log, either client or server side.

Utilities

Additionally, this library includes FeedStorage and BeesonMultiformatFeedStorage, where you can use to store Uint8Array values or JSON values formatted as IPLD Beeson blocks.

Table of Contents

• Install
• API
• License

Install

npm install swarm-feed-sequential

API

SequentialFeed

Creates a SequentialFeed instance.

const f = new SequentialFeed(fdp.connection.bee)

makeFeedR

Creates a sequential feed reader - SwarmFeedR

const topic = `/crdt/document/test1`
const address = `0x1111111254fb6c44bac0bed2854e76f90643097d`
const feedR = f.makeFeedR(topic, address);

makeFeedRW

Creates a sequential feed reader/writer - SwarmFeedRW

const topic = `/crdt/document/test1`
const privateKey = `.....`
const feedR = f.makeFeedRW(topic, privateKey);

SwarmFeedR interface

getLastUpdate

Gets the last update in the feed

const feedUpdate = await feedR.getLastUpdate()

getLastIndex

Gets the last index in the feed

const feedIndex = await feedR.getLastIndex()

findLastUpdate

Gets the last appended chunk in the feed.

const chunk = await feedR.findLastUpdate()

getUpdate

Downloads a chunk by index number.

const index = 0
const chunk = feedR.getUpdate(index)

getUpdates

Download all chunk by indices.

const indices = [0, 1, 2]
const chunks = feedR.getUpdates(indices)

SwarmFeedRW interface

setUpdate

Sets the upload chunk to update.

import * as Block from "multiformats/block";
import { codec, hasher } from "@fairdatasociety/beeson-multiformats";
import { BeeSon, Type } from "@fairdatasociety/beeson";
import { SequentialFeed } from "./sequential-feed";
import { Bee } from "@ethersphere/bee-js";
import { BlockDecoder } from "multiformats/block";
import { JsonValue } from "@fairdatasociety/beeson/dist/types";

const bee = new Bee()
const postageBatchId = `...`
const topic = `/crdt/document/test1`
const signer = makePrivateKeySigner(`...`)
const feedRW = f.makeFeedRW(topic, signer);

const beeson = new BeeSon({
  json: {
    ...state,
    timestamp: Date.now(),
  },
});
const value = beeson;

// encode a block
const block = await Block.encode({ value, codec, hasher });

const reference = await bee.uploadData(
  postageBatchId,
  block.bytes
);
const index = 1
return feedRW.setUpdate(index, postageBatchId, reference.reference);

setLastUpdate

Sets the next upload chunk.

import * as Block from "multiformats/block";
import { codec, hasher } from "@fairdatasociety/beeson-multiformats";
import { BeeSon, Type } from "@fairdatasociety/beeson";
import { SequentialFeed } from "./sequential-feed";
import { Bee } from "@ethersphere/bee-js";
import { BlockDecoder } from "multiformats/block";
import { JsonValue } from "@fairdatasociety/beeson/dist/types";

const bee = new Bee()
const postageBatchId = `...`
const topic = `/crdt/document/test1`
const signer = makePrivateKeySigner(`...`)
const feedRW = f.makeFeedRW(topic, signer);

const beeson = new BeeSon({
  json: {
    ...state,
    timestamp: Date.now(),
  },
});
const value = beeson;

// encode a block
const block = await Block.encode({ value, codec, hasher });

const reference = await bee.uploadData(
  postageBatchId,
  block.bytes
);
const index = 1
return feedRW.setLastUpdate(postageBatchId, reference.reference); 

Maintainers

molekilla

License

Apache License 2.0