# WebSub

## Overview

WebSub provides a common mechanism for communication between publishers of any kind of Web content and their subscribers, based on HTTP web hooks. Subscription requests are relayed through hubs, which validate and verify the request. Hubs then distribute new and updated content to subscribers when it becomes available. WebSub was previously known as PubSubHubbub. For more information, read [W3C WebSub](https://www.w3.org/TR/websub/).

## WebSub in MOSIP

In MOSIP, WebSub is used to share data with services and partners. [Kafka](https://kafka.apache.org/) message broker has been used to implement the WebSub APIs. Message brokers are a natural fit for the implementation of WebSub hubs as they serve a similar purpose.

![](/files/hOIUexMmhRhabgeNxaNe)

The relationship of WebSub with other services is explained here. *NOTE: The numbers do not signify sequence of operations or control flow.*

1. Topic is registered and published or subscribed by MOSIP Services.
2. Content delivery and Intent Verification is done by WebSub to Mosip Services.
3. Content delivery and Intent Verification is done by WebSub to Partners.
4. Topic is registered and published or subscribed by the Partners.
5. Data and metadata needed for delivery, delivery reports and other functionalities are stored in Kafka.

Refer [WebSub repo](https://github.com/mosip/websub/tree/release-1.2.0) for further details.

## Developer Guide

To know more about the developer setup, read [WebSub Developers Guide](https://docs.mosip.io/1.2.0/modules/websub/websub-developer-guide).


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.mosip.io/1.2.0/id-lifecycle-management/supporting-services/websub.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.