10 Replies
Could you say more? This might mean "every time a query updates, send an HTTP request to a url," but I'm guessing, there are a few other ways webhooks could be relevant.
For the server to send call-back notifications to the web-app.?
I meant call back,
sorry for the confusion
The main way this works is a websocket: a ConvexReactClient instance in the browser has a websocket that receives messages, and from there you describe what you want to happen when queries update.
Does that mean useCallback("....") hook?
or using query?
In React it's a
useQuery hook: that hook causes the React component to rerender each time a query updates.
If you're not using React the API is a little different, but the idea is always that you subscribe to a query function, and whenever it changes it runs your callback.
Here's a bit in the tutorial that talks about this: https://docs.convex.dev/how-it-works#hooking-up-react-componentsThat is great!
Also coming back to the webhook question, can the back-end interact with a client other than the web page which is creating the state
Other users on the same webpage, other web pages subscribed to the same query, and even node server or Python clients or command line tools can use the same queries and mutations.
The HTTP API is useful for asking for the current value of a query, or a websocket can be used from node to get updates.
So, what about a classic trigger use case, where I send a notification through SMS using Webhook
Do we need to write a node express API to encapsulate the webHook?
Stay tuned, there are plans for that kind of thing soon! But if you're doing this today, you'd write at node program (doesn't need express, because it won't be receiving HTTP requests) that uses a websocket to listen for query updates and does the SMS sending, or polls once a minute via HTTP api.
@guru we just launched support to hit Convex from other services via HTTP: https://blog.convex.dev/announcing-convex-0-9-0/
The Convex Blog
Announcing Convex 0.9.0
HTTP endpoints are here! Convex 0.9.0 extends the platform by allowing you to build your HTTP API right within Convex.