ably-postgres-connector
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    1.0.1 • Public • Published

    Streaming PostgresDB changes to millions of clients in realtime

    The Ably-Postgres connector publishes a message on a given Ably channel whenever any operations (insert/update/delete) are executed on the tables of your PostgreSQL database.

    You can setup the connector with the configuration details of your database, as well as the Ably app, including your API Key, channel names for various types of updates, etc.

    Check out the example config for more info.

    Prerequisites

    Installation

        npm install ably-postgres-connector --save

    Setup config

    • The first step is to add in your configuration. You can do this via env file or a JSON file.

    Option 1 - Adding config via a JSON file

    • Create config/default.json file (refer to the example JSON config).
    • Add your database and Ably account credentials as needed.
    Example usage
        const { Connector } = require("ably-postgres-connector");
        const useWithJSONConfig = () => {
          const ablyconnector = new Connector("config/default.json");
          ablyconnector.start();
        };
        useWithJSONConfig();
    Running
        node examples/with-json-config.js

    Option 2 - Adding config via a env file

    • Create config/.env file (refer to the example env config).
    • Add your database and Ably account credentials as needed.
    Example usage
        const { Connector } = require("ably-postgres-connector");
        const useWithEnvConfig = () => {
          const ablyconnector = new Connector("config/.env");
          ablyconnector.start();
        };
        useWithEnvConfig();
    Running (Using the example file)
        node examples/with-env-config.js

    Option 3 - Adding config via a env file through docker-compose

    • Create config/.env file (refer to the example env config).
    • Add your database and Ably account credentials as needed.
    • Add path of .env file to your docker-compose file (refer to the example docker-compose).
    Example usage
        const { Connector } = require("ably-postgres-connector");
        const useWithEnvDockerCompose = () => {
          const ablyconnector = new Connector();
          ablyconnector.start();
        };
        useWithEnvDockerCompose();
        # connector-block
        connector:
          build:
            context: .
          env_file: ./config/.env
          depends_on:
            - db
          ports:
            - "3000:3000"
    Running (Using the example docker-compose file)
    • Uses the Docker folder to setup the postgresql image with a dummy DB & users table.
    • Uses the Dockerfile to create the container with node, build the connector & add the config file.
        docker-compose run connector

    Connector in Action!

    Visit your Ably dev console and connect to the channel ably-users-added (or whichever channel you specified in your config). Try performing various operations (insert, update, delete) on your table. For every change, you should see a new message in the specific channel(s).

    How does the connector work?

    ably-to-db-postgres@2x (3)

    • The config file contains the details related to the tables you want to listen for data changes on and your Ably API key.
    • Using that config file, the connector creates an Ably config table ablycontroltable to maintain the table to Ably channel mapping in the DB.
    • The connector then creates a DB procedure/function which performs the pg_notify function that publishes data changes on a data channel.
    • The connector then creates triggers for the table-operation combination specified in the config. The job of the trigger is to execute the procedure created above.
    • The connector is listening for changes on that particular data channel using the LISTEN feature. When it gets a notification it publishes the data on the appropriate Ably channel.

    Keywords

    none

    Install

    npm i ably-postgres-connector

    DownloadsWeekly Downloads

    2

    Version

    1.0.1

    License

    Apache-2.0

    Unpacked Size

    305 kB

    Total Files

    9

    Last publish

    Collaborators

    • vardhanapoorv