There are two primary components with which users of the heka-node library should be aware. The first is the Basic Usage clientFromJsonConfig factory function.
The HekaClient exposes the Heka API, and is generally your main point of interaction with the Heka system. The client doesn’t do very much, however; it just provides convenience methods for constructing messages of various types and then passes the messages along. Actual message delivery is handled by a stream. Without a properly configured stream, a HekaClient is useless.