NOISSUE - Set subtopic for messages published outside adapters

[SammyOina]

Signed-off-by: SammyOina sammyoina@gmail.com

What does this do?

Sets message subtopic to subject/routing key when not set as in the case for messages published using external clients as in heartbeat service of mainflux/agent#56.

To test on nats:

git clone https://github.com/nats-io/nats.go
cd github.com/nats-io/nats.go/examples/nats-pub
go run main.go -s http://localhost:4222 heartbeat.<service-name>.<service-type> ""; 

Using rabbitmq:

package main

import (
	"context"
	"log"
	"time"

	amqp "github.com/rabbitmq/amqp091-go"
)

func failOnError(err error, msg string) {
	if err != nil {
		log.Panicf("%s: %s", msg, err)
	}
}

func main() {
	conn, err := amqp.Dial("amqp://mainflux:mainflux@localhost:5672/")
	failOnError(err, "Failed to connect to RabbitMQ")
	defer conn.Close()
	ch, err := conn.Channel()
	failOnError(err, "Failed to open a channel")
	defer ch.Close()

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	body := ""
	err = ch.PublishWithContext(ctx,
		"mainflux-exchange",  // exchange
		"heartbeat.svc.name", // routing key
		false,                // mandatory
		false,                // immediate
		amqp.Publishing{
			ContentType: "text/plain",
			Body:        []byte(body),
		})
	failOnError(err, "Failed to publish a message")
	log.Printf(" [x] Sent %s\n", body)
}

Which issue(s) does this PR fix/relate to?

None

List any changes that modify/break current functionality

Have you included tests for your changes?

No

Did you document any new/modified functionality?

Notes

[codecov]

Codecov Report

Merging #1867 (13b8ebb) into master (106b710) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 13b8ebb differs from pull request most recent head 053edd6. Consider uploading reports for the commit 053edd6 to get more accurate results

@@           Coverage Diff           @@
##           master    #1867   +/-   ##
=======================================
  Coverage   64.73%   64.74%           
=======================================
  Files         118      118           
  Lines        9702     9704    +2     
=======================================
+ Hits         6281     6283    +2     
  Misses       2753     2753           
  Partials      668      668           

Files Changed	Coverage Δ
things/policies/auth.pb.go	11.36% <ø> (ø)
things/policies/auth_grpc.pb.go	0.00% <ø> (ø)
users/policies/auth.pb.go	4.47% <ø> (ø)
users/policies/auth_grpc.pb.go	0.00% <ø> (ø)
pkg/messaging/nats/pubsub.go	72.72% <100.00%> (+0.35%)	⬆️
pkg/messaging/rabbitmq/publisher.go	68.18% <100.00%> (ø)
pkg/messaging/rabbitmq/pubsub.go	69.04% <100.00%> (+0.37%)	⬆️

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[drasko]

I think it is safe to close this one, as Subject can be derived from broker's metadata in the subscription handler.

[drasko]

Why is this needed? This is confusing.

If there is no subtopic, it should stay an empty string.

[SammyOina]

I am going to update the example in the docs instead which should have the same result