This document discusses webhooks and how to implement them in a PHP application. It begins by defining webhooks as custom callbacks that can alter a web page or application behavior. It then provides examples of webhooks from Google Calendar and GitHub. The document outlines best practices for implementing webhooks, including using events, a webhook subscriber, RabbitMQ for scalability, and testing tools. It recommends leveraging webhooks to integrate an application with other services.

1. WEBHOOKS
PHPTour 2016

2. @guillaumepotier
Cofounder & CTO Wisembly
http://wisembly.com
http://getsolid.io

3. Who never heard of
webhooks?
Should be a rhetorical question..

4. Who never used some?

5. Who already implemented webhooks in their
application?

6. “A webhook in web development is a method of augmenting or
altering the behavior of a web page, or web application, with
custom callbacks. These callbacks may be maintained, modified,
and managed by third-party users and developers who may not
necessarily be affiliated with the originating website or
application.”
Wikipedia

7. “user defined callback made with HTTP POST”
Jeff Lindsay

8. Push notifications /
Reverse API

9. 1. consumer sets up a server to listen/consume callbacks
2. consumer registers callback URL with provider
3. provider makes requests to URL when a registered event happens

10. That’s all!
Easy right?

13. A few examples

14. Google calendar PUSH notifications

15. Google calendar PUSH notifications

16. Github webhooks

17. Github webhooks

18. Digging deeper

19. ‣ a verb: POST
‣ an event: which could be subscribed by any user
• for Github: pull_request, fork, commit, issues, etc..
‣ a payload: containing the relevant data for the related event
• often including: the resource itself, the sender (user who
triggered the webhook)
‣ (optional) a security hash: to ensure webhook was delivered
by the rightful authority
• for Github: sharing a common secret used to generate a hash
from the payload
‣ (optional) an ID
webhook specs

20. ‣ a CRUD API
• a payload URL: the server endpoint that will receive the
webhook payload
• events list: which events would you like to subscribe to
• (optional) the content type
‣ (optional) an history of recent deliveries
‣ (mandatory) a good documentation :)
• try to mirror API resources
• document possible events
• document security mechanisms
its registration

23. Let’s implement it in your PHP application!*
*We’ll see at least how we did it for Solid

25. https://getsolid.io

26. https://getsolid.io

27. https://getsolid.io

28. https://getsolid.io

29. 1. when a meeting is ended
2. when a task is created
3. when a task is assigned
Solid implements these webhooks events

30. ‣ Various entities in your codebase could trigger webhooks
‣ Action that triggers webhooks could be in your services,
your controllers, your commands. Pretty much everywhere
‣ You do not want to couple too much webhook logic from the
rest of your application
events to the rescue
=> use an event dispatcher
symfony/event-dispatcher if you’re not using Symfony

31. events to the rescue
‣ We dispatch a single event listened by a WebhookSubscriber. In the
DeliveryEvent we pass:
• the event / action name
• the related entity
• the user that made the action triggering the webhook
• (optional) changeset or other extra contextual params

32. ‣ lookup for registered users for each webhook could be
consuming
‣ sending many POST requests for potential registered users
*is* slow and consuming
‣ the API call that creates, updates or delete a resources and
triggers the webhook does not need at all to be aware of all
that stuff and worse, waiting for hooked URLs answers!
RabbitMQ for the scalability
=> no need to do that stuff synchronously, use AMQP
btw swarrot/swarrot is a great lib for RabbitMQ

33. RabbitMQ for the scalability

34. Command
Entity
Exporter
(Sender)
(Extra)
Registred hooks
HTTPs POST
…
HTTPs POST

35. The command
‣ pros
• well decoupled from the rest of the codebase
‣ cons
• some extra queries (need to re-fetch entities we had in previous context)
• works only for stored entities retrievable with unique ID

36. The command

37. The exporter

38. The exporter

39. Testing / Tools

40. ngrok

41. requestb.in

42. symfony2 profiler

43. Zapier

44. Connect with 400+ apps

45. Still some work to do…
https://github.com/Wisembly/Zapier

46. Still some work to do…
https://github.com/Wisembly/Zapier

47. Bonus

48. Leverage webhooks for your company

49. Thank you
Questions ?
https://joind.in/talk/3c147