services.md

Services

Bitcore Node has a service module system that can start up additional services that can include additional:

• Blockchain indexes (e.g. querying balances for addresses)
• API methods
• HTTP routes
• Event types to publish and subscribe

The litecore-node.json file describes which services will load for a node:

{
  "services": [
    "bitcoind", "web"
  ]
}

Services correspond with a Node.js module as described in 'package.json', for example:

{
  "dependencies": {
    "litecore-lib": "^0.1.0",
    "litecore-node": "^0.2.0",
    "insight-api": "^3.0.0"
  }
}

Note: If you already have a litecore-node database, and you want to query data from previous blocks in the blockchain, you will need to reindex. Reindexing right now means deleting your litecore-node database and resyncing.

Using Services Programmatically

If, instead, you would like to run a custom node, you can include services by including them in your configuration object when initializing a new node.

//Require litecore
var litecore = require('litecore-node');

//Services
var Bitcoin = litecore.services.Bitcoin;
var Web = litecore.services.Web;

var myNode = new litecore.Node({
  network: 'regtest'
  services: [
    {
      name: 'litecoind',
      module: Litecoin,
      config: {
        spawn: {
          datadir: '/home/<username>/.litecoin',
          exec: '/home/<username>/litecore-node/bin/litecoind'
        }
      }
    },
    {
      name: 'web',
      module: Web,
      config: {
        port: 3001
      }
    }
  ]
});

Now that you've loaded your services you can access them via myNode.services.<service-name>.<method-name>. For example if you wanted to check the balance of an address, you could access the address service like so.

myNode.services.bitcoind.getAddressBalance('1HB5XMLmzFVj8ALj6mfBsbifRoD4miY36v', false, function(err, total) {
  console.log(total.balance); //Satoshi amount of this address
});

Writing a Service

A new service can be created by inheriting from Node.Service and implementing these methods and properties:

• Service.dependencies - An array of services that are needed, this will determine the order that services are started on the node.
• Service.prototype.start() - Called to start up the service.
• Service.prototype.stop() - Called to stop the service.
• Service.prototype.blockHandler() - Will be called when a block is added or removed from the chain, and is useful for updating a database view/index.
• Service.prototype.getAPIMethods() - Describes which API methods that this service includes, these methods can then be called over the JSON-RPC API, as well as the command-line utility.
• Service.prototype.getPublishEvents() - Describes which events can be subscribed to for this service, useful to subscribe to events over the included web socket API.
• Service.prototype.setupRoutes() - A service can extend HTTP routes on an express application by implementing this method.

The package.json for the service module can either export the Node.Service directly, or specify a specific module to load by including "litecoreNode": "lib/litecore-node.js".

Please take a look at some of the existing services for implementation specifics.