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Category: Kafka / Flink

Transforming a REST API into a Data Stream

Published 2024-06-18 by Kevin Feasel

Lucia Cerchie and Dave Troiano build a stream:

In the space of APIs for consuming up-to-date data (say, events or state available within an hour of occurring) many API paradigms exist. There are file- or object-based paradigms, e.g., S3 access. There’s database access, e.g., direct Snowflake access. Last, we have decoupled client-server APIs, e.g., REST APIs, gRPC, webhooks, and streaming APIs. In this context, “decoupled” means that the client usually communicates with the server over a language-agnostic standard network protocol like HTTP/S, usually receives data in a standard format like JSON, and, in contrast to direct database access, typically doesn’t know what data store backs the API.

Of the above styles, more often than not, API developers settle on HTTP-based REST APIs for a number of reasons. They are incredibly popular. More developers know how to use REST APIs and are using them in production compared to other API technologies. For example, Rapid API’s 2022 State of APIs reports 69.3% of survey respondents using REST APIs in production, well above the percentage using alternatives like gRPC (8.2%), GraphQL (18.6%), or webhooks (34.6%). 

Click through for a demonstration of how to take an existing REST API and build a data stream out of it using Apache Kafka and Apache Flink.

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Combining Flink SQL, Streamlit, and Kafka

Published 2024-06-13 by Kevin Feasel

Lucia Cerchie has a pair of posts. First up, Lucia sets the stage:

n part 1 of this series, we’ll make an app, hosted on Streamlit, that allows a user to select a stock, in this case SPY, or the SPDR S&P 500 ETF Trust. Upon selection, a live chart of the stock’s bid prices, calculated every five seconds, will appear.

What are the pieces that go into making this work? The source of the data is the Alpaca Market Data API. We’ll hook up a Kafka producer to the websocket stream and send data to a Kafka topic in Confluent Cloud. Then we’ll use Flink SQL within Confluent Cloud’s Flink SQL workspace to tumble an average bid price every five seconds. Finally, we’ll use a Kafka consumer to receive that data and populate it to a Streamlit component in real time. This frontend component will be deployed on Streamlit as well.

Part 2 then closes the trap:

In part one of this series, we walked through how to use Streamlit, Apache Kafka®, and Apache Flink® to create a live data-driven user interface for a market data application to select a stock (e.g., SPY) and discussed the structure of the app at a high level. First, data with information on stock bid prices is moved via an Alpaca websocket, then, it’s produced to a Kafka topic in Confluent Cloud where it is also processed with Flink SQL. 

Now comes the tricky part: running the Kafka consumer and producer in the same application.

Click through for a good demonstration of a practical solution. Lucia also has a GitHub repo with all of the code, a demo of the site in action, and some links to additional resources.

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Dual-Write Issues and Kafka

Published 2024-06-05 by Kevin Feasel

Wade Waldron solves a common but difficult problem:

However, the dual-write problem isn’t unique to event-driven systems or Kafka. It occurs in many situations involving different technologies and architectures.

When I started building event-driven systems, I encountered the dual-write problem almost immediately. I eventually learned effective ways to solve it but tripped over some anti-patterns along the way.

I want to break down the details of the dual-write problem so you can understand how it occurs and avoid making the same mistakes I did. I’ll outline a few anti-patterns that might look promising, but don’t solve the problem. Finally, we’ll look at accepted solutions that eliminate the dual-write problem.

Read on for a few techniques that will not work (assuming you are using Apache Kafka to flow events into some external systems) and some that will.

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Working with the Schema Registry in Confluent

Published 2024-04-11 by Kevin Feasel

Italo Nesi shows off the schema registry:

If you are new to Schema Registry or don’t know the difference between schema, schema type, subject, compatibility type, schema ID, and subject version, I would recommend starting with this free course: Schema Registry 101 by Danica Fine.

This article will show the bits and bytes of what happens behind the scenes in Apache Kafka® producer and consumer clients when communicating with the Schema Registry and serializing/deserializing messages.

Read on to learn more about data quality rules and how the schema registry works.

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Processing GitHub Data with Kafka Streams

Published 2024-03-28 by Kevin Feasel

Lucia Cerchie hits the GItHub API:

GitHub’s data sources (REST + GraphQL APIs) are not only developer-friendly, but a goldmine of interesting statistics on the health of developer communities. Companies like OpenSauced, linearb, and TideLift can measure the impact of developers and their projects using statistics gleaned from GitHub’s APIs. The results of GitHub analysis can change both day-to-day and over time. 

Apache Kafka is a large and active open source project with nearly a million lines of code. It also happens to be an event streaming platform. So why not use Apache Kafka to, well, monitor itself? And learn a bit about Kafka Streams along the way?  

Click through for the full article, including a demonstration.

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Exposing Kafka Data in Iceberg using Tableflow

Published 2024-03-20 by Kevin Feasel

Marc Selwan announces a new product:

We’re excited to talk about our vision for Tableflow, which makes it push-button simple to take Apache Kafka® data and feed it directly into your data lake, warehouse, or analytics engine as Apache Iceberg® tables. Making operational data accessible to the analytical world is traditionally a complex, expensive, and brittle process and we believe we can do better to unify the operational and analytical estates.

Tableflow removes all this erroneous, duplicative work and helps convert Kafka topics and associated schemas to Iceberg tables in one click. This is central to our Confluent’s vision to build the world’s leading data streaming platform that fuels any operational and analytical workload with real-time data products. 

It looks like this is currently in early access, but you can see where Confluent intends to take the product.

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Apache Kafka 3.7 Released

Published 2024-02-28 by Kevin Feasel

Stanislav Kozlovski makes an announcement:

We are proud to announce the release of Apache Kafka® 3.7.0. This release contains many new features and improvements. This blog post will highlight some of the more prominent features. For a full list of changes, be sure to check the release notes.

See the Upgrading to 3.7.0 from any version 0.8.x through 3.6.x section in the documentation for the list of notable changes and detailed upgrade steps.

Read on to see what’s new. Looks like they’ve taken care of a couple dozen items in this release, so plenty to read there.

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Combining Kafka and Flink

Published 2024-02-20 by Kevin Feasel

Gautam Goswami shares some thoughts:

In short, the process of collecting data in real-time as streams of events from event sources such as databases, sensors, and software applications is known as event streaming. With real-time data processing and analytics in mind, Apache Flink is a potent open-source program. For situations where quick insights and minimal processing latency are critical, it offers a consistent and effective platform for managing continuous streams of data. 

I’ve found it interesting that Confluent people have spent a lot of time the past several months talking up Apache Flink and Kafka+Flink combinations.

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