added basic tutorial like Readme

README.md

@@ -1,4 +1,138 @@
 mongo-metrics
 =============
 
-Tracking Metrics with mongo
+When its comes to metrics, aggregations plays a huge role. If that fails, then there is no use of collecting metrics. Here is the how `mongo-metrics` thinks about it.
+
+* There are sources who generate metrics
+* metrics will be collected with the awareness of the source
+* When it comes aggregations, metrics will be aggregated in 2 steps
+* It will first aggregate values in each source, then result will be aggregated 
+* function which used to aggregate metrics can be specified in runtime
+* result will be grouped into time resolutions
+
+## Design Decisions
+
+* Cloud Ready
+* Portable and Flexible Design
+* Simple to use
+
+## Dependencies
+
+* Mongodb (2.1+)
+* NodeJs
+
+## Tracking Metrics
+
+>Currently tracking is only supported for `nodejs` apps. For other apps, you have to wait for UDP and HTTP APIs (patches are welcome)
+
+~~~js
+	var MongoMetrics = require('mongo-metrics');
+
+	var MONGODB_URL = "mongodb://localhost/test";
+	var metrics = new MongoMetrics(MONGODB_URL);
+
+	metrics.track('no-of-users', 344, 'my-source', function(err) {
+
+	});
+~~~
+
+## Aggregate Metrics
+
+>This API is for developer who need to play with metrics. Use dashboard(see below) which build on top of this API
+
+#### API
+
+ 	@param {String} name - name of the metric
+        @param {Constant} resolution - resolution type
+            possible values: "DAY", "HOUR", "MINUTE", "FIVE_SECS"
+        @param {String} valueAggregator - aggregation function to be used for aggregating metric of the each source
+            possible values: "sum", "avg", "min", "max"
+        @param {String} sourceAggregator - aggregation function to be used for the aggregating sources(value from metricsAggregation)
+            possible values: "sum", "avg", "min", "max"
+        @param {Object} query - mongodb query for filtering out metrics
+            only supports date and source only
+        @param {Function} callback - callback function
+            callback(err, results)
+
+    MongoMetrics.aggregate = function(name, resolution, valueAggregator, sourceAggregator, query, callback){}
+
+#### Example
+
+~~~js
+
+var MongoMetrics = require('mongo-metrics');
+
+var MONGODB_URL = "mongodb://localhost/test";
+var metrics = new MongoMetrics(MONGODB_URL);
+
+metrics.aggregate('no-of-users', 'hour', 'avg', 'sum', {date: { $gte: 1361030882576 }}, function(err, result) {
+
+});
+~~~
+
+## Dashboard 
+
+With Dashboard you can correlate and visualize your metrics. There are few ways you can access the dashboard.
+
+![Dashboard](docs/dashboard.png)
+
+#### 1. Standalone App
+
+##### Install `mongo-metrics` binary via `npm`
+    npm install mongo-metrics -g
+
+##### Start Dashboard
+    mongo-metrics -m <mongodb url>
+
+#### 2. With NodeJS
+
+~~~js
+var dashboard = require('mongo-metrics/dashboard');
+
+var MONGO_URL = "mongodb://localhost/test";
+var PORT = 5005;
+dashboard.listen(MONGO_URL, PORT);
+~~~
+
+#### 3. Embed with an existing `express` webapp
+
+~~~js
+var express     = require('express');
+var dashboard   = require('mongo-metrics/dashboard');
+var webapp      = express();
+
+var MONGO_URL = "mongodb://localhost/test";
+dashboard.listen(MONGO_URL, webapp);
+
+webapp.listen(5005);
+~~~
+
+### Defining Graphs
+
+![Dashboard](docs/configure-dashboard.png)
+
+Inside the Dashboard you can create as many graphs as you need. You can correlate metrics too. (use area chart type)
+
+There is no UI for defining graphs. But we have simple and flexible syntax to define them. 
+>We simply did no use JSON since, it is too heavy for taking user inputs 
+
+#### Syntax
+
+Here is how you define a graph. 
+
+    <title for graph> | <graph-type> | <metric-name> | <value-aggregator>, <source-aggregator> | <resolution> | <time-length>
+
+eg:-
+    CPU Usage | area | cpu | avg, sum | five_secs | 1000 * 60 * 15
+
+* Supported values for `graph-type` : `area`, `line`
+* Supported values for `value-aggregator` : sum, avg, min, max
+* Supported values for `source-aggregator` : sum, avg, min, max
+* Supported values for `resolution` : five_secs, minute, hour, day
+* You can use multiple lines to specify multiple graphs
+* Empty lines add empty block to dashboard instead of the graph
+
+
+Todo
+
+See: [Issues](https://github.com/arunoda/mongo-metrics/issues?labels=todo&milestone=none&page=1&state=open)