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72 lines
1.8 KiB
Markdown
72 lines
1.8 KiB
Markdown
# Explore NATS Queueing
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NATS supports a form of load balancing using queue groups. Subscribers register a queue group name. A single subscriber in the group is randomly selected to receive the message.
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## Prerequisites
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Go and the NATS server should be installed.
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### 1. Start the NATS server
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```sh
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nats-server
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```
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### 2. Clone the repositories for each client examples
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```sh
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go get github.com/nats-io/nats.go
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git clone https://github.com/nats-io/nats.js.git
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git clone https://github.com/nats-io/nats.rb.git
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```
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### 3. Run the Go client subscriber with queue group name
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```sh
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cd $GOPATH/src/github.com/nats-io/nats.go/examples
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go run nats-qsub/main.go foo my-queue
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```
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### 4. Install and run the Node client subscriber with queue group name
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```sh
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npm install nats
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cd nats.js/examples
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node node-sub --queue=my-queue foo
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```
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### 5. Install and run the Ruby client subscriber with queue group name
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```sh
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gem install nats
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nats-queue foo my-queue &
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```
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### 6. Run another Go client subscriber *without* the queue group.
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```sh
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cd $GOPATH/src/github.com/nats-io/nats.go/examples
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go run nats-sub/main.go foo
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```
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### 7. Publish a NATS message using the Go client
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```sh
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cd $GOPATH/src/github.com/nats-io/nats.go/examples
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go run nats-pub/main.go foo "Hello NATS!"
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```
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### 8. Verify message publication and receipt
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You should see that the publisher sends the message: *Published [foo] : 'Hello NATS!'*
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You should see that only one of the my-queue group subscribers receives the message. In addition, the Go client subscriber not in the my-queue group should also receive the message.
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### 9. Publish another message
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```sh
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go run nats-pub/main.go foo "Hello NATS Again!"
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```
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You should see that a different queue group subscriber receives the message this time, chosen at random among the 3 queue group members.
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