Building Real-time Systems with WebSub - Ballerina Community Call - 11/30/2021
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The document provides an overview of the WebSub protocol and its application in real-time systems, particularly in a news hub scenario where journalists publish updates to a centralized hub. It details the roles of publishers, subscribers, and hubs, and describes the implementation of WebSub in the Ballerina framework, including sample API requests and responses. The document also includes references to specifications and example libraries for further exploration.
Building Real-time Systems with WebSub - Ballerina Community Call - 11/30/2021
- 1. Community Call - November 2021 Building Real-Time Systems with WebSub
- 2. In this presentation Quick Overview of WebSub Protocol Real-world Use Case of WebSub Ballerina WebSub Framework
- 3. ○ Open Protocol for distributed pub/sub communication. ○ Based on HTTP webhooks. ○ Main Roles: ○ Publisher ○ Subscriber ○ Hub ○ Specification: https://www.w3.org/TR/websub/ What is WebSub ?
- 4. WebSub Cont…
- 5. Use Case: News Hub Scenario ○ News Hub is a centralized location to which the local journalists and News channels connect. ○ Journalists will publish the news updates to the News Hub. ○ News Hub will then distribute the updates to the News channels who are subscribed to the news feeds of the journalist.
- 7. Demo
- 8. Ballerina WebSub ○ In Ballerina, WebSub implementation is divided into two packages: ○ WebSub: ○ Subscriber ○ WebSubHub: ○ Hub ○ Publisher
- 9. Ballerina WebSub: Hub API public type Service distinct service object { // Sample POST request hub.mode=register&hub.topic=http://foo.com/bar // Sample 200 OK response hub.mode=accepted or 200 OK hub.mode=denied&hub.reason=unauthorized remote function onRegisterTopic(websubhub:TopicRegistration msg) returns websubhub:TopicRegistrationSuccess|websubhub:TopicRegistrationError|error; // Sample POST request hub.mode=unregister&hub.topic=http://foo.com/bar // Sample 200 OK response hub.mode=accepted or 200 OK hub.mode=denied&hub.reason=unauthorized remote function onDeregisterTopic(websubhub:TopicDeregistration msg) returns websubhub:TopicDeregistrationSuccess|websubhub:TopicDeregistrationError|error; // Sample POST request with content type x-www-form-urlencoded hub.mode=publish&hub.topic=http://foo.com/bar // for other content types such as xml, json and octect-stream hub.mode=publish should be in query string. // Sample 200 OK response hub.mode=accepted or 200 OK hub.mode=denied&hub.reason=unauthorized remote function onUpdateMessage(websubhub:UpdateMessage msg) returns websubhub:Acknowledgement|websubhub:UpdateMessageError|error; // Sample POST request hub.mode=subscribe&hub.topic=http://foo.com/bar remote function onSubscription(websubhub:Subscription msg) returns websubhub:SubscriptionAccepted|websubhub:SubscriptionPermanentRedirect|websubhub:SubscriptionTemporaryRedirect| websubhub:BadSubscriptionError|websubhub:InternalSubscriptionError|error; remote function onSubscriptionValidation(websubhub:Subscription msg) returns websubhub:SubscriptionDeniedError|error?; remote function onSubscriptionIntentVerified(websubhub:VerifiedSubscription msg) returns error?; // Sample POST request hub.mode=unsubscribe&hub.topic=http://foo.com/bar remote function onUnsubscription(websubhub:Unsubscription msg) returns websubhub:UnsubscriptionAccepted|websubhub:BadUnsubscriptionError|websubhub:InternalUnsubscriptionError|error; remote function onUnsubscriptionValidation(websubhub:Unsubscription msg) returns websubhub:UnsubscriptionDeniedError|error?; remote function onUnsubscriptionIntentVerified(websubhub:VerifiedUnsubscription msg) returns error?; }
- 10. ○ WebSub Specification: https://www.w3.org/TR/websub/ ○ Ballerina WebSub Libraries: ○ WebSub ○ WebSubHub ○ Hub Sample: https://github.com/ballerina-platform/module-ballerina-websubhub/tree/ main/examples/kafka-hub References
- 11. Questions?
- 12. Thank you!