Ethereum events and reading past events by devrajsinghrawat

$0.07

Ethereum events and reading past events

## WHAT THE HACK ARE EVENTS
• Events are a mechanism which let the world know about the state change
happening with in a blockchain.
• This information plays an important role for processing further steps in process .i.e. information update on a dApp or execute next step in business process
• Log entries represent the result of events having fired from a smart contract.

## HOW TO GET THE FISH OUT
• Any receivers which are interested on events from a smart contract can listen the Ethereum node over JSON-
RPC OR WS
• This can be either a locally hosted node or can utilized a public hosted node like INFURA.

Ex:
/** HTTP provider using Infura**/

const provider = 'https://mainnet.infura.io/v3/<API - Key>'
const web3 = new Web3(new Web3.providers.HttpProvider(provider));

/** Websocket provider using Infura**/
const provider = 'wss://mainnet.infura.io/ws';
const web3 = await new Web3(new Web3.providers.WebsocketProvider(provider));

• One who has missed the train to capture the real time event logs can also get the fish out using reading the past event logs using web3js methos getPastEvents

Example : myContract.getPastEvents(event[, options][, callback])

Code Sample is reading ***event bidRevealed*** from ENS smart contract hosted on ethereum blockchain 

![image.png](https://ipfs.busy.org/ipfs/QmWjPM8CoHhN1YNci8xN5YSHVsrprDPmapLGd1D1zMrB3g)

Sample code Repo
https://github.com/devrajsinghrawat/Web3nSolidity/tree/master/eventScan

👍 minnowsupport, broadcast, garena, isalea, busy.org, gregoryhedrich
👎 trollshunter

`author`	devrajsinghrawat
`permlink`	ethereum-events-and-reading-past-events
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`created`	2019-05-10 06:47:00
`last_update`	2019-05-10 06:47:00
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properties (23)vote details (7)

voter	rshares	pct
busy.org	148,679,666	0.77%
minnowsupport	123,378,924,475	3%
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