Receivers are those entities that consume data from different data sources and then move them to Spark for processing. They are created by using streaming contexts in the form of long-running tasks that are scheduled for operating in a round-robin fashion. Each receiver is configured to use up only a single core. The receivers are made to run on various executors to accomplish the task of data streaming. There are two types of receivers depending on how the data is sent to Spark :
Reliable receivers : Here, the receiver sends an acknowledegment to the data sources post successful reception of data and its replication on the Spark storage space.
Unreliable receiver : Here, there is no acknowledgement sent to the data sources.
