# Package cascading.pipe

Interface Summary
Interface | Description
--- | ---
Group |

Class Summary
Class | Description
--- | ---
Boundary | The Boundary class is only used internally by the planner to mark the boundaries between partitions within the element graph.
Checkpoint | The Checkpoint pipe, if supported by the current planner, will force data to be persisted at the point in the tuple stream an instance of Checkpoint is inserted into the pipe assembly.
CoGroup | The CoGroup pipe allows for two or more tuple streams to join into a single stream via an optional `Joiner`.
Each | The Each operator applies either a `Function` or a `Filter` to each entry in the `Tuple` stream.
Every | The Every operator applies an `Aggregator` or `Buffer` to every grouping.
GroupBy | The GroupBy pipe groups the `Tuple` stream by the given groupFields.
HashJoin | The HashJoin pipe allows for two or more tuple streams to join into a single stream via a `Joiner` when all but one tuple stream is considered small enough to fit into memory.
Merge | The Merge Pipe allows for multiple branches, with the same fields to be spliced back into a single stream.
Operator | An Operator is a type of `Pipe`.
Pipe | Class Pipe is used to name branches in pipe assemblies, and as a base class for core processing model types, specifically `Each`, `Every`, `GroupBy`, `CoGroup`, `Merge`, `HashJoin`, and `SubAssembly`.
Splice | The base class for `GroupBy`, `CoGroup`, `Merge`, and `HashJoin`.
SubAssembly | Subclasses of SubAssembly encapsulate complex assemblies of `Pipe`s so they my be reused in the same manner a Pipe is used.

Exception Summary
Exception | Description
--- | ---
OperatorException | Class OperatorException is thrown during field name resolution during planning