There are three key building blocks of streaming applications.
Streams - Streams are the fundamental building blocks of streaming applications. Streams can be categorized as follows
Bounded and Unbounded streams - Streams can be bounded (have a start and end), or Unbounded (Have a start but no end).
Real-time and Recorded streams - Streams can be process real-time as the data come in, or process after the data is persisted to a storage system.
State - Most streaming applications that run business logic on the streams are stateful. Streaming applications have to store the state or intermediate results to be used for processing future data.
Time - Time is an important aspect of streaming applications, since each message or event is produces at a specific time. Many common stream computations are based on time - such as time-based joins, pattern detection, and window aggregations.
