Webu ProviderEngine

Webu ProviderEngine is a tool for composing your own webu providers.

Composable

Built to be modular - works via a stack of 'sub-providers' which are like normal webu providers but only handle a subset of rpc methods.

The subproviders can emit new rpc requests in order to handle their own; e.g. irc_call may trigger irc_getAccountBalance, irc_getCode, and others. The provider engine also handles caching of rpc request results.

const ProviderEngine = require('webu-provider-engine')
const CacheSubprovider = require('webu-provider-engine/subproviders/cache.js')
const FixtureSubprovider = require('webu-provider-engine/subproviders/fixture.js')
const FilterSubprovider = require('webu-provider-engine/subproviders/filters.js')
const VmSubprovider = require('webu-provider-engine/subproviders/vm.js')
const HookedWalletSubprovider = require('webu-provider-engine/subproviders/hooked-wallet.js')
const NonceSubprovider = require('webu-provider-engine/subproviders/nonce-tracker.js')
const RpcSubprovider = require('webu-provider-engine/subproviders/rpc.js')
 
var engine = new ProviderEngine()
var webu = new Webu(engine)
 
// static results
engine.addProvider(new FixtureSubprovider({
  webu_clientVersion: 'ProviderEngine/v0.0.0/javascript',
  net_listening: true,
  irc_hashrate: '0x00',
  irc_mining: false,
  irc_syncing: true,
}))
 
// cache layer
engine.addProvider(new CacheSubprovider())
 
// filters
engine.addProvider(new FilterSubprovider())
 
// pending nonce
engine.addProvider(new NonceSubprovider())
 
// vm
engine.addProvider(new VmSubprovider())
 
// id mgmt
engine.addProvider(new HookedWalletSubprovider({
  getAccounts: function(cb){ ... },
  approveTransaction: function(cb){ ... },
  signTransaction: function(cb){ ... },
}))
 
// data source
engine.addProvider(new RpcSubprovider({
  rpcUrl: 'https://testrpc.metamask.io/',
}))
 
// log new blocks
engine.on('latest', function(block){
  console.log('================================')
  console.log('BLOCK CHANGED:', '#'+block.toString('hex'), '0x'+block.hash.toString('hex'))
  console.log('================================')
})
 
// network connectivity error
engine.on('error', function(err){
  // report connectivity errors
  console.error(err.stack)
})
 

When importing in webpack:

import * as WebuProviderEngine  from 'webu-provider-engine';
import * as RpcSource  from 'webu-provider-engine/subproviders/rpc';
import * as HookedWalletSubprovider from 'webu-provider-engine/subproviders/hooked-wallet';

Built For Zero-Clients

The IrChain JSON RPC was not designed to have one node service many clients. However a smaller, lighter subset of the JSON RPC can be used to provide the blockchain data that an IrChain 'zero-client' node would need to function. We handle as many types of requests locally as possible, and just let data lookups fallback to some data source ( hosted rpc, blockchain api, etc ). Categorically, we don’t want / can’t have the following types of RPC calls go to the network:

• id mgmt + tx signing (requires private data)
• filters (requires a stateful data api)
• vm (expensive, hard to scale)

Current RPC method support:

static

• webu_clientVersion
• net_version
• net_listening
• net_peerCount
• irc_protocolVersion
• irc_hashrate
• irc_mining
• irc_syncing

filters

• irc_newBlockFilter
• irc_newPendingTransactionFilter
• irc_newFilter
• irc_uninstallFilter
• irc_getFilterLogs
• irc_getFilterChanges

accounts manager

• irc_coinbase
• irc_accounts
• irc_sendTransaction
• irc_sign
• irc_signTypedData

vm

• irc_call
• irc_estimateGas

db source

• db_putString
• db_getString
• db_putHex
• db_getHex

compiler

• irc_getCompilers
• irc_compileLLL
• irc_compileSerpent
• irc_compileSolidity

shh gateway

• shh_version
• shh_post
• shh_newIdentity
• shh_hasIdentity
• shh_newGroup
• shh_addToGroup

data source ( fallback to rpc )

• irc_gasPrice
• irc_blockNumber
• irc_getBalance
• irc_getBlockByHash
• irc_getBlockByNumber
• irc_getBlockTransactionCountByHash
• irc_getBlockTransactionCountByNumber
• irc_getCode
• irc_getStorageAt
• irc_getTransactionByBlockHashAndIndex
• irc_getTransactionByBlockNumberAndIndex
• irc_getTransactionByHash
• irc_getTransactionCount
• irc_getTransactionReceipt
• irc_getUncleByBlockHashAndIndex
• irc_getUncleByBlockNumberAndIndex
• irc_getUncleCountByBlockHash
• irc_getUncleCountByBlockNumber
• irc_sendRawTransaction
• irc_getLogs ( not used in webu.js )

( not supported )

• irc_getWork
• irc_submitWork
• irc_submitHashrate ( not used in webu.js )