# Source diagrams

Downloaded unchanged and visually inspected on 2026-09-26. All three PNGs have transparent backgrounds; display them against white so black labels remain visible.

Credit: WuChong (伍翀 / Jark), Jark's Blog. These are original image files served by the source articles, not newly created diagrams. The source articles are dated 2016 and describe Flink 1.0-era behavior.

## Runtime architecture

- Local file: `flink-runtime-architecture.png`
- Dimensions: 851 × 613
- Source article: https://wuchong.me/blog/2016/05/03/flink-internals-overview/
- Article title: Flink 原理与实现：架构和拓扑概览
- Publication date: 2016-05-03
- Image URL embedded by source: http://img3.tbcdn.cn/5476e8b07b923/TB1ObBnJFXXXXXtXVXXXXXXXXXX
- Download URL: https://img3.tbcdn.cn/5476e8b07b923/TB1ObBnJFXXXXXtXVXXXXXXXXXX
- Suggested caption: “Flink's historical runtime architecture (2016): a client builds and submits a dataflow, the JobManager coordinates execution, and TaskManagers execute tasks and exchange data streams. The Actor System labels reflect the implementation at the time.”
- Use as historical context only. It is not a diagram of current Flink control-plane internals.

## Operator chaining and parallel subtasks

- Local file: `operator-chaining.png`
- Dimensions: 911 × 759
- Source article: https://wuchong.me/blog/2016/05/09/flink-internals-understanding-execution-resources/
- Article title: Flink 原理与实现：理解 Flink 中的计算资源
- Publication date: 2016-05-09
- Image URL embedded by source: http://img3.tbcdn.cn/5476e8b07b923/TB18Gv5JFXXXXcDXXXXXXXXXXXX
- Download URL: https://img3.tbcdn.cn/5476e8b07b923/TB18Gv5JFXXXXcDXXXXXXXXXXXX
- Suggested caption: “A WordCount pipeline expands into parallel subtasks, then chains each KeyAggregation subtask with its corresponding Sink. With source parallelism 1 and the other operators at parallelism 2, the resulting example has five tasks.”

## Task slot sharing

- Local file: `slot-sharing.png`
- Dimensions: 885 × 416
- Source article: https://wuchong.me/blog/2016/05/09/flink-internals-understanding-execution-resources/
- Article title: Flink 原理与实现：理解 Flink 中的计算资源
- Publication date: 2016-05-09
- Image URL embedded by source: http://img3.tbcdn.cn/5476e8b07b923/TB1VTj4JFXXXXX8XFXXXXXXXXXX
- Download URL: https://img3.tbcdn.cn/5476e8b07b923/TB1VTj4JFXXXXX8XFXXXXXXXXXX
- Suggested caption: “Slot sharing in the WordCount example: two TaskManagers provide six slots. With source parallelism 1 and downstream parallelism 6, tasks from different stages share slots; each KeyAggregation–Sink pair remains one chained task.”
- This picture illustrates placement, not a guarantee that an actual scheduler chooses this exact layout.

## Reuse notices found on the site

- Both articles display a CC BY-NC-SA 4.0 link and an author-copyright notice.
- License link: https://creativecommons.org/licenses/by-nc-sa/4.0/
- Source copyright page: https://wuchong.me/copyright/
- The copyright page names 伍翀 or Jark for attribution, requests prominent credit and an original-source link near the start of noncommercial reprints, and separately asks that reprints remain unchanged. It requests separate authorization for modifications/adaptations or commercial use. This prose includes an additional restriction compared with the linked CC license's adaptation permission; this record reports both notices rather than resolving that discrepancy.
- Preserve original image pixels and link the source article in each figure credit. A top-level credit can read: “Original diagrams: WuChong (伍翀 / Jark), Jark's Blog, 2016. Reproduced unchanged.” Link the article titles, copyright page, and CC license.

Source page HTML snapshots were retained during research. The article links above are the canonical public sources.

## Local–global aggregation (Figure 4)

# Local–Global Aggregation source image

- Local file: `local-global-aggregation.png`
- Original filename: `local_agg.png`
- Format: PNG with alpha channel
- Dimensions: 1945 × 870 pixels
- File size: 464216 bytes
- SHA-256: `2a739cf779e932461f7654fdc81c40bd7de9a17f09c19a9a3caa736c3c7eeed4`
- Official page: https://nightlies.apache.org/flink/flink-docs-stable/docs/dev/table/tuning/#local-global-aggregation
- Exact image URL found in the page HTML: https://nightlies.apache.org/flink/flink-docs-release-2.3//fig/table-streaming/local_agg.png
- License: Apache License 2.0, based on the source page license header and official Flink repository LICENSE.
- Source LICENSE: https://github.com/apache/flink/blob/release-2.3/LICENSE
- Source NOTICE: https://github.com/apache/flink/blob/release-2.3/NOTICE
- Copyright attribution from NOTICE: Copyright 2014-2026 The Apache Software Foundation.
- Downloaded: 2026-09-26. Original image bytes saved without cropping, resizing, recoloring, or other modifications.

Visually inspected: the left half shows three Map operators forwarding raw red and purple records to two keyed aggregation operators, with the more frequent red key producing a hot aggregation task. The right half adds one green Local Agg after each Map, reducing the red records to partial sums 17, 18, and 15 before the shuffle. Two Global Agg operators receive the reduced accumulators grouped by color. The image has a transparent background; preserve the source asset and choose a suitable display background in the article.

Suggested attribution: “Source: Apache Flink documentation, ‘Local–Global Aggregation’, The Apache Software Foundation, Apache License 2.0. Original image, unchanged.”

Local license files: flink-LICENSE.txt and flink-NOTICE.txt.