Is using Google Pub/Sub possible on the frontend (React)

Question

I'm fairly new to things that aren't strictly front end, so after reading the Google pub/sub docs and doing a few searches its not clear to me whether using it with react is possible.

My use case is I (hypothetically) have tens of thousands of people on my webpage at a time that all need to be told at the same time that some external event occurred (the message would be very small).

I know Google Firestore has a listener feature but based on this specification it would not be within the free tier usage anymore. I've seen libraries that allow Google Pub/Sub to be used with IOT devices so I'm confused on why I can't find any resources on using it in the browser.

Answer 1

Creating a Cloud Pub/Sub subscriber in the frontend would be an anti-pattern for several reasons. First of all, the quota limits only allow 10,000 subscriptions per topic. Since you say you have tens of thousands of people on the web page at a time, you would not be able to create enough subscriptions for this case. Additionally, subscriptions created when users come to the website would not be able to get any notifications from before the time the subscription was created; Cloud Pub/Sub only guarantees delivery of messages published after the subscription was successfully created. Finally, you'd have the issue of security and authentication. In order to start a subscriber from the client, you'd need to pass it credentials that it could use. If you use separate credentials for each webpage viewer, then you'd have to create these credentials on the fly and revoke them when the user disappears. If you use the same credentials across all of the subscribers, then one subscriber could intercept the feed of another subscriber.

Overall, Cloud Pub/Sub is designed for the torrents use case: fewer feeds with a lot of data that has to be processed by fewer subscribers. What you are talking about is the trickles use case: a small number of messages that need to be distributed among a large number of subscribers with individual ACLs. Firebase Cloud Messaging is the product designed for this latter case.

While it is true that Cloud Pub/Sub is on the path for Google Cloud IoT, it is used on the publish side: many devices send their events to a topic that can be processed by subscribers. Note that these messages from devices don't come directly into Cloud Pub/Sub; they go through a Cloud IoT server and that server is what publishes the messages to Cloud Pub/Sub. Device authentication is done via Cloud IoT and not via permissions on Cloud Pub/Sub topics. The delivery of messages to IoT devices is not done with Cloud Pub/Sub.