| Class | Description | 
|---|---|
| ConsoleIO | 
 Print to console. 
 | 
| ConsoleIO.Write | 
 Write to console. 
 | 
| ConsoleIO.Write.Unbound<T> | 
PTransform writing PCollection to the console. | 
| CreateStream<T> | 
 Create an input stream from Queue. 
 | 
| EmptyCheckpointMark | 
 Passing null values to Spark's Java API may cause problems because of Guava preconditions. 
 | 
| MicrobatchSource<T,CheckpointMarkT extends UnboundedSource.CheckpointMark> | 
 A  
Source that accommodates Spark's micro-batch oriented nature and wraps an UnboundedSource. | 
| SourceRDD | 
 Classes implementing Beam  
Source RDDs. | 
| SourceRDD.Bounded<T> | |
| SourceRDD.Unbounded<T,CheckpointMarkT extends UnboundedSource.CheckpointMark> | 
 A  
SourceRDD.Unbounded is the implementation of a micro-batch in a SourceDStream. | 
| SparkUnboundedSource | 
 A "composite" InputDStream implementation for  
UnboundedSources. | 
| SparkUnboundedSource.Metadata | 
 A metadata holder for an input stream partition. 
 |