TIBCOSoftware/flogo

Issue in kafka subscriber

Open

#408 opened on Oct 13, 2018

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good first issuekind/bug

Description

Current behavior (how does the issue manifest):

When using flogo api, kafka sub with multiple handlers for different topics, will deliver same message from every topic to every handlerFunc.

Expected behavior:

Only messages for the specified handler topic should be delivered to the handler's handlerFunc.

Minimal steps to reproduce the problem (not required if feature enhancement):

Here is example code.

	app := flogo.NewApp()
	kafkaSettings := map[string]interface{}{
		"BrokerUrl": brokerUrl,
	}
	trg := app.NewTrigger(&kafkasub.KafkaSubTrigger{}, kafkaSettings)
	trg.NewFuncHandler(map[string]interface{}{"Topic": topic1}, HandleEvent1)
	trg.NewFuncHandler(map[string]interface{}{"Topic": topic2}, HandleEvent2)
	e, err := flogo.NewEngine(app)
	if err != nil {
		logger.Error(err)
		return
	}
	engine.RunEngine(e)

Messages delivered to topic1 will be sent to handlerFunc's HandleEvent1 and HandleEvent2.

Look at line 358 in the trigger.go for the subscriber.

Contributor guide

Tech stack
go
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Go programmingKafka messaging basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Examine the subscriber implementation in trigger.go around line 358. The bug suggests that the Kafka message is delivered to all handlers regardless of topic. Investigate how handlers are registered and how messages are dispatched. Ensure that only the handler with the matching topic receives the message. Check the mapping between topics and handlers.