Olares/docs/developer/develop/mw-view-nats-data.md

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2 3	Learn how to subscribe to and publish messages in Olares using NATS CLI, and understand the NATS Subject naming rules and permission model.

Subscribe and publish messages with NATS

This guide explains how to use the nats-box CLI tool to test NATS message subscription and publication within the Olares cluster, and provides an overview of the NATS Subject naming rules and permission model.

Get connection information

Before connecting, obtain NATS connection details from the Control Hub.

1. Open Control Hub from Launchpad.

2. In the left navigation pane, go to Middleware and select Nats.

3. On the Subject panel, select a target Subject and record the corresponding information from the same row:

   • Subject: The target message subject.
   • User: The connection username.
   • Password: The connection password.

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Access via CLI

nats-box provides a convenient way to test NATS subscriptions and publications from within the cluster.

Deploy nats-box

1. Download the example nats-box.yaml file, then upload it to the Olares machine.
2. Navigate to the directory containing the YAML file and deploy nats-box:

   kubectl apply -f nats-box.yaml
   

3. Retrieve the name of the nats-box Pod:

   kubectl get pods -n os-platform | grep nats-box
   

4. Enter the nats-box container:

   kubectl exec -it -n os-platform <nats-box-pod> -- sh
   

Subscribe to messages

Use the Subject, User, and Password obtained from Control Hub to subscribe:

nats sub <subject-from-controlhub> --user=<user-from-controlhub> --password=<password-from-controlhub> --all

Publish messages

Publish a message to the specified Subject:

nats pub <subject-from-controlhub> '{"hello":"world"}' --user=<user-from-controlhub> --password=<password-from-controlhub>

Subject naming and permission reference

This section describes the Subject naming convention and permission model used in Olares.

Subject structure

NATS Subjects use a three-level structure separated by dots (.): <prefix>.<event>.<olaresId>.

Level	Name	Description
1st	<prefix>	Source Identifier. System services: Fixed as os. Third-party apps: Uses the corresponding appId.
2nd	<event>	Event type or Domain. Examples: users, groups, files, notification.
3rd	<olaresId>	Represents the Olares ID of the user space.

Permission model

Read and write permissions for Subjects vary depending on the application type.

App type	Permission scope	Description
User space app	Read-only	Can only subscribe to Subjects with a three-level structure containing its own <olaresId>.
System/Cluster app	System-level access	Subscribe: Can subscribe to system-level Subjects (e.g., os.users, os.groups). Write: Can write to second-level Subjects within its own space. Global Read: Requires separate approval to subscribe to all second-level Subjects.