WebSub-Subscriber

This repository contains an open source implementation of a generic W3C WebSub-Subscriber. The implementation consists of two parts:

• Part 1: This is the Web-Application implemented in index.html which functions as the role Discovery.
• Part 2: This is the Server-side implementation which functions as the role Subscriber.

The first part is a generic Javascript-based Web-Application that demonstrates the topic discovery via an HTTP HEAD request to a publisher. The Web-App also initiates that the server-side part initiates subscribe and unsubscribe with the WebSub Hub. Finally, the Web-App displays the data received via a WebSocket that was created with the server-side.

The server-side part functions as a WebSub Subscriber as defined in the W3C WebSub Recommendation.

Deployment

After cloning this repository, cd into the docker directory and create a .env file to configure the behavior of the WebSub Subscriber. See the next section Configuration for details.

To start the subscriber, simply use the command docker-compose up -d --build. After a successful startup, you can visit the Web-Subscriber in the Web Browser.

Please modify the index.html URLs as they are hard-coded and pointing to the Secure Dimensions demo deployments.

Configuration

Using a .env file in the docker directory configures the WebSub-Subscriber

• PORT is the port that the subscriber starts listening. Default: 3000
• URL is the homepage URL for the Web-Sub Subscriber.
• WEBSOCKET_DOMAINS is a comma separated list of domain names that are allowed to create a WebSocket
• LOG_LEVEL is the log level to use. Default INFO
• LEASE_SECONDS is the number of seconds used with the subscribe request to the Hub as parameter hub.lease_seconds. Note: The actual lease_seconds value is received with the validation of intent!
• LEASE_SKEW_SECONDS is the number of seconds that the subscriber calls for a period subscription earlier than hub.lease_seconds received from the Hub with the validation of intent. For example, if hub.lease_seconds=300 and LEASE_SKEW_SECONDS=30, the periodic re-new of the subscription is done after 270 seconds.