[[extending_core_components]]
== Extending
We decided to make this client low-level, and as such we probably have not implemented all the features you are looking for. For this reason, we made extending or even replacing the core components simple.

=== Connection
Extending a connection provides the powerful ability to change requests as they go out to the ElasticSearch REST API.

For example, you can extend the `HttpConnector` to force the default HTTP method to be `POST`:
[source,js]
---------------
var elasticsearch = require('elasticsearch');
var util = require('util');
var HttpConnector = require('elasticsearch/src/lib/connectors/http');

function MyHttpConnector(host, config) {
  HttpConnector.call(this, host, config);
}
util.inherits(MyHttpConnector, HttpConnector);
MyHttpConnector.prototype.makeReqParams = function(params) {
  params = params || {};
  params.method = params.method || 'POST';
  returh HttpConnector.prototype.makeReqParams.call(this, params);
};

var client = new elasticsearch.Client({
  connectionClass: MyHttpConnector
});
---------------

=== ConnectionPool
Coming Soon

=== Log
see <<logging>>.

=== Client/API
Extending or replacing the API that Elasticsearch.js provides is a simple as it should be in JS. To provide an entirely new API, just add it to the Client constructor's `api` property like so:

[source,js]
--------------
var myApi = {
  getDog: function () { ... }
};

elasticsearch.Client.apis.mine = myApi;

var client = new elasticsearch.Client({
  apiVersion: 'mine'
});

client.getDog( ... );
--------------

When the client is created, its prototype is set to the API version selected, and therefore you can access the client via the `this` variable within your API methods. Make requests within your methods using `this.transport.request(params, cb)`. For more information about the transport, see <<transport-reference>>.