NATS

stands for Neural Autonomic Transport System

the rationale why choose NATS over other messaging system comes from this

Getting Started

tldr

if you prefer to quickly run through this repository to see what is possible, and familiar enough using docker compose, you can read composing

Installation

• nats server

brew install nats-server

another way to install nats-server

• nats cli

brew tap nats-io/nats-tools
brew install nats-io/nats-tools/nats

another way to install nats cli

• nats monitoring

go install github.com/nats-io/nats-top@latest

another way to monitor

Core NATS

• start nats server first

nats-server --config nats-core/nats.conf

Subscribe to all event

• subscribe

go run nats-core/monitor/main.go ">"

Publish Subscribe

• publish

go run nats-core/pub/main.go "profit"

• subscribe

go run nats-core/sub/main.go "profit"

Fan In

• publish

go run nats-core/pub/main.go "profit.sg"

go run nats-core/pub/main.go "profit.id"

• subscribe

go run nats-core/sub/main.go "profit.*"

Fan Out

• publish

go run nats-core/pub/main.go "profit.id"

• subscribe

go run nats-core/sub/main.go "profit.id"

go run nats-core/sub/main.go "profit.id"

Queue Load Balanced

• publish

go run nats-core/pub/main.go "profit.id"

• subscribe using queue

go run nats-core/subq/main.go -q poc "profit.id" 

go run nats-core/subq/main.go -q poc "profit.id" 

Request Reply

• start replier first

go run nats-core/rep/main.go -q poc "profit.get" 

• request

go run nats-core/req/main.go "profit.get"

Jetstream

• start nats server first

nats-server --config nats-jetstream/js.conf

Stream

what kind event data to persist

• check list of stream

nats str ls --server 0.0.0.0:5222

• check report of stream

nats stream report --server 0.0.0.0:5222

• create stream profit in which interest to persist event data from subject profit.*

go run nats-jetstream/manager/main.go --cmd add -n profit -s "profit.*"

• check stream detail

nats stream info profit --server 0.0.0.0:5222

• update stream profit in which interest to persist event data from subject profit.sg profit.id

go run nats-jetstream/manager/main.go --cmd update -n profit -s "profit.sg,profit.id"

• delete stream

go run nats-jetstream/manager/main.go --cmd delete -n profit 

Publish

• sync publish

go run nats-jetstream/producer/sync/main.go -msgs 1000 "profit.id"

• async publish

go run nats-jetstream/producer/async/main.go -msgs 1000 "profit.id"

Consumer

how application getting a messages from stream

• check list of consumer

nats consumer ls --server 0.0.0.0:5222

• push consumer

go run nats-jetstream/consumer/main.go --cmd add-push -sn profit -cn one-push-cprofit_id -s profit.id

• push consumer with shared load balanced queue

go run nats-jetstream/consumer/main.go --cmd add-push -sn profit -cn queue-push-cprofit_id -qn poc -s profit.id

• pull consumer is automatically shared if there are multiple subscriber

go run nats-jetstream/consumer/main.go --cmd add-pull -sn profit -cn pull-cprofit_id -s profit.id

• check consumer detail

nats consumer info --server 0.0.0.0:5222

• delete consumer

go run nats-jetstream/consumer/main.go --cmd add-push -sn profit -cn test-delete -qn poc -s profit.id

go run nats-jetstream/consumer/main.go --cmd delete -sn profit -cn test-delete

Ephermeral (direct) consumer

• publish

go run nats-jetstream/producer/sync/main.go -msgs 1000 -d 1 "profit.id"

• subscribe

go run nats-jetstream/consumer/push/main.go -sn profit -s "profit.id"

Durable consumer

(save last state if disconnected)

push one subscriber only

• publish

go run nats-jetstream/producer/sync/main.go -msgs 1000 -d 1 "profit.id"

• subscribe

go run nats-jetstream/consumer/push/main.go -sn profit -cn one-push-cprofit_id -s "profit.id"

push load balanced queue consumer

• publish

go run nats-jetstream/producer/sync/main.go -msgs 1000 -d 1 "profit.id"

• subscribe

go run nats-jetstream/consumer/push/main.go -sn profit -cn queue-push-cprofit_id -qn poc -s "profit.id"

go run nats-jetstream/consumer/push/main.go -sn profit -cn queue-push-cprofit_id -qn poc -s "profit.id"

Shared pull consumer with batch processing

• publish

go run nats-jetstream/producer/sync/main.go -msgs 1000 -d 1 "profit.id"

• subscribe

go run nats-jetstream/consumer/pull/main.go -sn profit -cn pull-cprofit_id -s "profit.id"

go run nats-jetstream/consumer/pull/main.go -sn profit -cn pull-cprofit_id -s "profit.id"

Delayed messaging

• create stream scheduled-message that interest to persist event data from subject delayed.profit

go run nats-jetstream/manager/main.go --cmd add -n scheduled-message -s "delayed.profit"

• create durable push consumer to get data from stream scheduled-message

go run nats-jetstream/consumer/main.go --cmd add-push -sn scheduled-message -cn queue-push-delayed_profit -qn poc -s "delayed.profit"

• subscribe

go run nats-jetstream/consumer/push/main.go -sn scheduled-message -cn queue-push-delayed_profit -qn poc -s "delayed.profit"

• publish

go run nats-jetstream/producer/delayed/main.go -msgs 5 -d 10 "delayed.profit"