Fix typos and add detailed documentation to services.md with examples for programatic use of services as well as using indexes within services.

docs/errors.md

@@ -4,7 +4,7 @@ description: Errors for Bitcore Node
 ---
 # Errors
 
-Many times there are cases where an error condition can be gracefully handled depending on a particular use. To assist in better error handling, errors will have different types so that it's possible to determine the type of error and handle appropriatly.
+Many times there are cases where an error condition can be gracefully handled depending on a particular use. To assist in better error handling, errors will have different types so that it's possible to determine the type of error and handle appropriately.
 
 ```js
 node.services.address.getUnspentOutputs('00000000839a8...', function(err, outputs) {

docs/services.md

@@ -37,6 +37,59 @@ Services correspond with a Node.js module as described in 'package.json', for ex
 
 *Note:* If you already have a bitcore-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 bitcore-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.
+
+```js
+//Require bitcore
+var bitcore = require('bitcore-node');
+
+//Services
+var Address = bitcore.services.Address;
+var Bitcoin = bitcore.services.Bitcoin;
+var DB      = bitcore.services.DB;
+var Web     = bitcore.services.Web;
+
+var myNode = new bitcore.Node({
+  datadir: '~/.bitcore',
+  network: {
+    name: 'livenet'
+  },
+  "services": [
+    {
+      name: "address",
+      module: Address,
+      config: {}
+    },
+    {
+      name: 'bitcoind',
+      module: Bitcoin,
+      config: {}
+    },
+    {
+      name: 'db',
+      module: DB,
+      config: {}
+    },
+    {
+      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.
+
+```js
+myNode.services.address.getBalance('1HB5XMLmzFVj8ALj6mfBsbifRoD4miY36v', false, function(err, total) {
+  console.log(total); //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:
@@ -51,4 +104,106 @@ A new service can be created by inheriting from `Node.Service` and implementing
 
 The `package.json` for the service module can either export the `Node.Service` directly, or specify a specific module to load by including `"bitcoreNode": "lib/bitcore-node.js"`.
 
-Please take a look at some of the existing services for implemenation specifics.
+Please take a look at some of the existing services for implementation specifics.
+
+### Adding an index
+
+One quite useful feature exposed to services is the ability to index arbitrary data in the blockchain. To do so we make
+use of leveldb, a simple key-value store. As a service we can expose a 'blockHandler' function which is called each time
+a new block is added or removed from the blockchain. This gives us access to every new transaction received, allowing 
+us to index them. Let's take a look at an example where we will index the time that a transaction was confirmed.
+
+```js
+//Index prefix, so that we can determine the difference between our index 
+//and the indexes provided by other services
+MyService.datePrefix = new Buffer('10');
+
+MyService.minPosition = new Buffer('00000');
+MyService.maxPosition = new Buffer('99999');
+
+//This function is automatically called when a block is added or receieved
+MyService.prototype.prototype.blockHandler = function(block, addOutput, callback) {
+
+  //Determine if the block is added or removed, and therefore whether we are adding
+  //or deleting indexes
+  var databaseAction = 'put';
+  if (!addOutput) {
+    databaseAction = 'del';
+  }
+
+  //An array of all leveldb operations we will be committing
+  var operations = [];
+
+  //Timestamp of the current block
+  var blocktime = new Buffer(block.header.time);
+
+  for (var i = 0; i < block.transactions.length; i++) {
+    var transaction = block.transactions[i];
+    var txid = new Buffer(transaction.id, 'hex');
+    var position = new Buffer(('0000' + i).slice(-5));
+
+    //To be able to query this txid by the block date we create an index, leading with the prefix we
+    //defined earlier, the the current blocktime, and finally a differentiator, in this case the index
+    //of this transaction in the block's transaction list
+    var indexOperation = {
+      type: databaseAction,
+      key: Buffer.concat([this.datePrefix, blockTime, position]),
+      value: txid
+    };
+
+    //Now we push this index into our list of operations that should be performed
+    operations.push(indexOperation);
+  }
+
+  //Send the list of db operations back so they can be performed
+  setImmediate(function() {
+    callback(null, operations);
+  });
+};
+```
+
+### Retrieving data using an index
+With our block handler code every transaction in the blockchain will now be indexed. However, if we want to query this 
+data we need to add a method to our service to expose it.
+
+```js
+
+MyService.prototype.getTransactionIdsByDate = function(startDate, endDate, callback) {
+
+  var error;
+  var transactions = [];
+
+  //Read data from leveldb which is between our startDate and endDate
+  var stream = this.node.services.db.store.createReadStream({
+    gte: Buffer.concat([
+      MyService.datePrefix,
+      new Buffer(startDate),
+      MyService.minPosition
+    ]),
+    lte: Buffer.concat([
+      MyService.datePrefix,
+      new Buffer(endDate),
+      MyService.maxPosition
+    ]),
+    valueEncoding: 'binary',
+    keyEncoding: 'binary'
+  });
+
+  stream.on('data', function(data) {
+    transactions.push(data.value.toString('hex'));
+  });
+
+  stream.on('error', function(streamError) {
+    if (streamError) {
+      error = streamError;
+    }
+  });
+
+  stream.on('close', function() {
+    if (error) {
+      return callback(error);
+    }
+    callback(null, transactions);
+  });
+};
+```

docs/services/db.md

@@ -23,7 +23,7 @@ CustomService.prototype.blockHandler = function(block, add, callback) {
 };
 ```
 
-Take a look at the Address Service implementation for more details about how to encode the key, value for the best effeciency and ways to format the keys for streaming reads.
+Take a look at the Address Service implementation for more details about how to encode the key, value for the best efficiency and ways to format the keys for streaming reads.
 
 Additionally the mempool can have an index, the mempool index will be updated once bitcoind and the db have both fully synced. A service can implement a `resetMempoolIndex` method that will be run during this time, and the "synced" event will wait until this task has been finished: