CODEWITHSUNDEEP
websocketapache-kafkastrimzi
Nick
Nick

Reputation: 189

How to use Strimzi Kafka Bridge as a streaming service

Using CNCF's Strimzi Kafka Bridge I have created a small API that can interact with Kafka server using a HTTP/1.1 protocol. This is all good for a request-response scenario. However, my requirement is to stream events received on the Kafka topic to the subscribed client(s) (through the Strimzi bridge) as soon as I receive them preferably on a long lived HTTP connection (as per my understanding). It's a waste of client resources to continuously poll the bridge for messages and come back empty handed. I would like the Kafka server stream these events to the client directly.

I am a little unsure about SSE or Websockets or long polling. I did quite a bit of reading on these methodologies to stream data to the client. However, I am unable to figure out if these changes are at the communication or the application layer or both.

Do you just build an API (irrespective of the technology) using a traditional HTTP communication protocol and somehow upgrade it to use Websockets OR use of Websockets should be embedded in your application libraries ground up?

I can provide more information if needed. The Strimzi Kafka bridge website does not mention anything about "server side streaming" OR maybe I am misunderstanding the real purpose of the tool.

Upvotes: 2

Views: 1795

Answers (2)

ppatierno
ppatierno

Reputation: 10075

@Nick thinking more, actually you can do "long polling". The GET on the /records endpoint for getting messages has a timeout parameter on the query string. Its value is used as timeout for the internal native Kafka poll in the bridge. It somehow provides you the long polling behaviour because the poll doesn't return until there are available records or the timeout expires. If you set a high timeout, you can have the behavior you want avoiding polling more times with opening/closing more HTTP connections for that. More details on the timeout parameter here:

https://strimzi.io/docs/bridge/latest/#_poll

Upvotes: 1

ppatierno
ppatierno

Reputation: 10075

The Strimzi Kafka HTTP bridge is meant as a "translator" for HTTP to Kafka native protocol and vice versa. It means that the HTTP client has to have the same behavior as a native Kafka client so, in the case of a consumer, doing a poll for getting messages which is how Kafka works natively. Imho HTTP 1.1 is not for streaming at all. Websockets is a completely different protocol to which you can upgrade of course starting from an HTTP connection but it's not supported by the Strimzi bridge. Actually, the AMQP 1.0 protocol which is in the bridge (as a POC) can support this kind of scenario so establishing a connection and having the bridge pushing on that connection instead of polling from the client side.

Upvotes: 3

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