Reactive Pulsar Client show case application

This application was originally written as a demonstration of Reactive Pulsar which predates Pulsar Reactive Client and Spring for Apache Pulsar. It has been updated in 12/2023 to use the latest versions of Pulsar Reactive Client and Spring for Apache Pulsar. This code base uses Pulsar Reactive Client directly, without the special annotation support Spring for Apache Pulsar.

Prerequisites

Pulsar standalone

Starting Pulsar standalone

docker run --name pulsar-standalone -d -p 8080:8080 -p 6650:6650 apachepulsar/pulsar:4.0.1 /pulsar/bin/pulsar standalone -nss -nfw

Tailing logs

docker logs -f pulsar-standalone

Stopping

docker stop pulsar-standalone

Deleting container

docker rm pulsar-standalone

Usage

Running the application

./gradlew :bootRun

Running the webhook application

./gradlew :webhook-target-app:bootRun

Telemetry ingest demonstration

Sending 1M telemetry entries with curl, all in one request

{ for i in {1..1000000}; do echo '{"n": "device'$i'/sensor1", "v": '$i'.123}'; done; } \
    | curl -X POST -T - -H "Content-Type: application/x-ndjson" localhost:8081/telemetry

Sending 1M telemetry entries with curl, 1 message per request, with up to 50 parallel requests

Note: this requires gnu xargs (on MacOS: brew install findutils, use gxargs instead of xargs) and gnu parallel (brew install parallel/apt install moreutils).

{ for i in {1..1000000}; do echo -ne 'curl -s -X POST -d '\''{"n": "device'$i'/sensor1", "v": '$i'.123}'\'' -H "Content-Type: application/x-ndjson" localhost:8081/telemetry''\0'; done; } \
  | xargs -0 -P 2 -n 100 parallel -j 25 --

Sending 10000 telemetry entries with curl, 1 message per request (slow!)

for i in {1..10000}; do
  echo '{"n": "device'$i'/sensor1", "v": '$i'.123}' \
    | curl -X POST -T - -H "Content-Type: application/x-ndjson" localhost:8081/telemetry
done

Sending 1M telemetry entries with k6

Requires installing k6.

cd k6
k6 run -u 100 -i 1000000 telemetry_ingest.js

Telemetry processing demonstration

Start pulsar-client to consume from telemetry_median

pulsar-client consume -n 0 -s sub telemetry_median

Sending 1M telemetry entries (1000 devices, 1000 metrics) with curl, all in one request

{ for i in {1..1000}; do for j in {1..1000}; do echo '{"n": "device'$i'/sensor1", "v": '$j'.123}'; done; done; } \
    | curl -X POST -T - -H "Content-Type: application/x-ndjson" localhost:8081/telemetry

SSE / Server Sent Events demonstration

SSE/Server Servet Events uses text/event-stream which is defined in the HTML standard.

curl with -N parameter can be used to demonstrate SSE. The backend support passing last event id in Last-Event-ID header or lastEventId query parameter. In addition, there is a poll parameter which takes a boolean value expressed with true/1/yes/false/0/no. The /firehost path uses the telemetry_ingest topic as the source and /firehost/median uses telemetry_median.

# use telemetry_ingest topic
curl -N localhost:8081/firehose/ingest
# use telemetry_median topic
curl -N localhost:8081/firehose/median

To demonstrate this, use one of the previous commands to send 1M telemetry entries with curl while the SSE curl command is running.

The SSE firehost example supports the lastEventId query parameter to continue from a specific message id. An application can use this for resuming message processing after a specific message id.

The poll query parameter can be used to control whether the SSE connection should be kept open or closed after the last message has been sent. The default value for poll is 1 which means that the connection will be kept open. Setting poll to 0 will close the connection after the currently last message has been sent from the server to the client.

curl -N 'localhost:8081/firehose/median?lastEventId=CLoYEOEHIAAwAQ==&poll=0'