Queryable Kafka Topics with Kafka Streams

Robert Schmid
Nov 30, 2018 · 10 min read

Architecture of a Kafka Streams application with state stores

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The Kafka Stream Processors responsible for the Partitions 4 to 9 are left out in this illustration. The dashed arrows indicate that new messages in a partition are also propagated to additional stream processors and their state stores, allowing for a fast fail-over if the primarily assigned processor should fail.

Adding a REST endpoint to stream processors

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An HTTP client can send lookup requests to any of the REST endpoints of the stream processors. The dashed arrow indicates how a request is internally forwarded among the stream processors, if it cannot be answered from a local state store.

Ensuring scalability of the application

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A suitable stream partitioning scheme ensures a well-balanced load on the State Stores. Photo Credit: Unsplash

Building the Kafka Streams application

Creating a REST service for the state store

Selecting the right processor in the load balancer

The ProcessorInfo class has Lombok annotations for automatic serialized.
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The final application architecture.

Conclusion

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