Overview

• Create a new subproject with typescript support
• Install node-nats-streaming library and connect to nats streaming server
• We should have two npm scripts, one to run code to emit events, and one to run code to listen for events
• The program will be ran outside of kubernetes!

Publisher

        graph TD
            subgraph Publisher
            data[data] --> stan[stan client]
            subject[subject </br> name of the channel] --> stan
            end

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Listener

        graph TD
            subgraph Listener
            subject[Subject to listern to] --> stan[stan client]
            stan[stan client] --> subscription
            end

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NATS Streaming Server

        graph TB
            subgraph NATS Streaming
                subgraph List of Channels
                    subgraph ticket:created
                    end
                end
                subgraph List of Clients
                    direction TB
                    subgraph abc
                    end
                    subgraph 123
                    end
                end
            end

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• Publisher: Publish the subject:data to NATS streaming channel
• Listerner: Any service subscribe the chaannel listern the channel get the subject:data
• port-forwarding: kubectl port-forward nats-depl-647c78564d-xtbz6 4222:4222 (To get pod name kubectl get pods)

Concurrency Solutions

• Share state between services of last event processed
  • It execute in a sequential way
  • Only one update happens at a time. It's a draw back
• Last event processed tacked by resource ID

Event based updates

    graph LR
        A[Network Request to Create/Update/Delete Resources XYZ] --> B[Service that owns XYZ]
        B --> C[(Database Storing XYZ)]
        C --> B
        B --> D[Event Describing Change to XYZ]
        D --> E[NATS]
        E --Event--> F[Service that needs to update its data based up on the Event]

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