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Is it possible / does it make sense to use an Android app as a "Producing client" for Apache Kafka?

Let's say my Android App need to capture and analyse reaction time data. Goal is to collect all data and show the average reaction time in real-time in the App.

The alternative is having an app server of some kind as an intermediary that accepts messages from the android app and posts them to Kafka, rather than having the app be a Kafka Producer on its own.

Answers

Even if it's possible, in my opinion it has some disadvantages.

In general I like clients to be as simple as possible to avoid maintenance issues. Instead I'd route all client requests through a REST API on my app server. The disadvantages are not related to Kafka, but are common problems of native clients.

Coupling

You're coupling the Android app closely to your messaging infrastructure. If you later decide that a Kafka solution is too much and Plain Old Java would be good enough, you'll first have to update the Android app and wait until enough users do an update.

Network issues + delivery guarantees

Kafka clients also require a direct connection to each of the brokers. Mobile clients can have very inconsistent/spotty network connectivity, making direct client access susceptible to dropped events and overall network connectivity issues.

Authentication

Probably you already have some kind of authentication in your app. You can also create authenticated connections to Kafka. So you'll have two authentication paths, whereas with an app server Kafka only needs to check if the requests are coming from the trusted app server, which means less implementation effort.

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