[samwillis]

In my case I was aiming for low latency with a dynamically generated image. To send a url to a saved image, I would have to save it first to a location for the browser to download it form. That would add at least 400ms, probably more.

Ultimately what I did was run an SSE request and long polling image request in parallel, but that wasn’t ideal as I had to coordinate that on the backend.

[bckr]

I'm curious if you could have kept the image in memory (or in Redis) and served it that way

[samwillis]

That’s actually not too far from what we do. The image is created by a backend service with communication (queue and responses) to the front end servers via Redis. However rather than saving the image in its entirety to Redis, it’s streamed via it in chunks using LPUSH and BLPOP.

This lets us then stream the image as a steaming http response from the front end, potentially before the jpg has finished being generated on the backend.

So from the SSE we know the url the image is going to be at before it’s ready, and effectively long poll with a ‘new Image()’.