chainops-provider

The chainops-provider module allows your application to call multiple data providers for data.

• define a prioritised list of providers for each method
• if an error is thrown, it will fallback to the next provider

See test/test.js for an example

Configuration

Instantiate the ProviderRouter class with a configuration object as defined in src/ProviderRouter.ts/IOptions.

Example:

const config = {
  routing: {
    //[method call]: [provider keys in order]
    getBlockNumber: ['cloudflare', 'etherscan', 'infura'],
    getBlock: ['cloudflare', 'etherscan', 'infura'],
    getTransaction: ['cloudflare', 'etherscan', 'infura'],
    getTransactionReceipt: ['cloudflare', 'etherscan', 'infura']
  },
  providers: {
    infura: infura,
    etherscan: etherscan,
    cloudflare: cloudflare
  }
}

'providers' property is an object that takes a name (used later): provider

The providers can be found in the providers/ folder and are exposed in the index require.

3 providers exist (at the moment)

Webthree

Instantiate a Web3 connection and pass it as a constructor prop

Etherscan

Constructor prop expects an ApiKeyToken (get it from the Etherscan site)

Cloudflare

Cloudflare has no keys and can be instantiated with no props

Extending

Providers

Unless a custom API endpoint is used (like Cloudflare or Etherscan) there shouldn't be a need to create new providers. The Webthree provider is designed to wrap a Web3 endpoint which itself can call http, websocket providers

Methods

Each method must be implemented in this module before being called. Each provider must then support passing through that method to their respective sources.

Stats

ProviderRouter has a prop called stats you can just print this to console. Here's an example:

{ 
  cloudflare: { 
    getBlockNumber: { '0': 1 },
    getBlock: { '0': 4 },
    getTransaction: { '0': 358 } },
  chainops: { 
    getTransaction: { '1': 12 }, 
    getBlock: { '1': 4 } 
  } 
}

This prints the provider 'cloudflare', the method 'getBlockNumber' and the number of calls expressed as an object. This keys in this 'calls' object has the index number as the key and the number of calls as the value. For example, {'0': 358} shows that it was called 358 times as the first provider {'1': 12} means it was called 12 times as the second provider (fallback)