Claude
78fc41e586
Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_01RjfyTgmERTWLqzafu34Cth
45 lines
2.0 KiB
Markdown
45 lines
2.0 KiB
Markdown
# kafka-streams
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Companion code for *Kafka Streams with Spring Boot 4: Real-Time Fraud Detection with Vector
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Similarity* on [ankurm.com](https://ankurm.com). The whole topology runs under
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`TopologyTestDriver`, so **no Kafka broker is needed** to run anything here.
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| Stack | Version |
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| JDK | 25 (Temurin 25.0.4.1+1) |
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| Spring Boot | 4.1.1 |
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| Spring for Apache Kafka | 4.1.1 |
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| kafka-streams / kafka-streams-test-utils | 4.2.1 (what Boot 4.1.1 manages) |
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## Run it
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```bash
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./scripts/run-all.sh # runs the tests, rewrites output/*.txt
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```
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## What is where
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| File | Role |
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| `FraudTopology` | The topology as plain Kafka Streams code: similarity scoring, 5-minute velocity count, blocklist KTable join |
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| `Embedder` | A hand-built 6-number feature vector and cosine similarity (not a learned model) |
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| `FraudStreamsConfig` | The only Spring wiring: `@EnableKafkaStreams` plus handing the `StreamsBuilder` to the topology |
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| `FraudTopologyTest` | Five tests; each one writes the matching `output/NN-*.txt` |
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| `ContextLoadsTest` | Loads the Spring context with `auto-startup=false` to show the wiring without a broker |
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## Captured output
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Every file in `output/` is written by a test that also asserts it.
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| File | Shows |
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| `01-similarity-scores.txt` | Scores for five sample transactions against the 0.98 threshold |
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| `02-similarity-alerts.txt` | Only the fraud-shaped transaction produces an alert |
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| `03-velocity-window.txt` | Six transactions in two minutes give one alert; the next window starts from one |
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| `04-blocklist-table-join.txt` | Join before blocking, after blocking, and after a tombstone |
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| `05-topology-description.txt` | `Topology.describe()` of the whole graph |
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| `06-spring-context.txt` | The Spring factory bean is wired and not running |
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| `07-ambiguous-null-tombstone.txt` | The real `javac` error for `pipeInput("c5", null)`; source in `src/broken/`, regenerated by `scripts/compile-broken.sh` |
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The article carries the explanations; there is deliberately no `docs/` folder.
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