[APEXMALHAR-2085] Implement Windowed Operators

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.5.0
• Assignee: David Yan
• Reporter: Siyuan Hua
• Created: 11/May/16 18:39
• Updated: 15/Sep/16 03:42
• Resolved: 12/Jul/16 22:55

Description

As per our recent several discussions in the community. A group of Windowed Operators that delivers the window semantic follows the google Data Flow model(https://cloud.google.com/dataflow/) is very important.
The operators should be designed and implemented in a way for
High-level API
Beam translation
Easy to use with other popular operator

Operator Hierarchy

Hierarchy of the operators,
The windowed operators should cover all possible transformations that require window, and batch processing is also considered as special window called global window

                   +-------------------+
       +---------> |  WindowedOperator | <--------+
       |           +--------+----------+          |
       |                    ^      ^--------------------------------+
       |                    |                     |                 |
       |                    |                     |                 |
+------+--------+    +------+------+      +-------+-----+    +------+-----+
|CombineOperator|    |GroupOperator|      |KeyedOperator|    |JoinOperator|
+---------------+    +-------------+      +------+------+    +-----+------+
                                   +---------^   ^                 ^
                                   |             |                 |
                          +--------+---+   +-----+----+       +----+----+
                          |KeyedCombine|   |KeyedGroup|       | CoGroup |
                          +------------+   +----------+       +---------+

Combine operation includes all operations that combine all tuples in one window into one or small number of tuples, Group operation group all tuples in one window, Join and CoGroup are used to join and group tuples from different inputs.

Components

• Window Component
  It includes configuration, window state that should be checkpointed, etc. It should support NonMergibleWindow(fixed or slide) MergibleWindow(Session)

• Trigger
  It should support early trigger, late trigger with customizable trigger behaviour

• Other related components:
  • Watermark generator, can be plugged into input source to generate watermark
  • Tuple schema support:
    It should handle either predefined tuple type or give a declarative API to describe the user defined tuple class

Most component API should be reused in High-Level API

This is the umbrella ticket, separate tickets would be created for different components and operators respectively

Issue Links

• is related to: APEXMALHAR-2099 Identify overlap between Beam API and existing Apex Stream API
• is related to: APEXMALHAR-1939 Stream API
• is related to: APEXMALHAR-2089 Apache Beam support
• is related to: APEXMALHAR-2130 Scalable windowed storage
• relates to: APEXMALHAR-2048 Create concrete implementation of ArrayListMultiMap using managed state.
• relates to: APEXMALHAR-2142 High-level API window support
• links to: GitHub Pull Request #319

Sub-Tasks

• Window state management: Open
• Replace content from Project Gutenberg in sample wordcount.txt with something that is ASF license compatible: Closed