bda20adf_Cascading_2_1_User_Guide__Pipe_type
[Purpose] join 1 or more streams on matching field values [Input] one or more tuple streams [Output] a single tuple stream, joined on key field(s) [Pipe type] 
CoGroup
P i p e
S u b A s s e m b l y
E a c h
M e r g e
G r o u p B y
E v e r y
C o G r o u p
H a s h J o i n
Cascading 2.1 User Guide
Pipe type