Hacker News Reader

Comment by nitrogen | Hacker News Reader

I like link previews. I don't like when they are managed server-side instead of client-side.

Caching a link's title and thumbnail server-side will save your site potentially millions of requests from Facebook and elsewhere.

Seems like a benefit for site owners to me.

Not to mention that the server is reducing the image size of a thumbnail, potentially converting from HTTP to HTTPS, and so on.

> Seems like a benefit for site owners to me.

Maybe, but it’s definitely less control for the site owner.

Maybe she wants to do analytics on the previews (how far shared, which ip regions) or delete the content at a specific time. Etc.

Also considering the sibling story, at least the server-side preview builder is definitely entirely unauthenticated to every possible service. A preview builder running on the client side might conceivably pick up your authentication to something in various circumstances.

The issue with doing them client side (other than the missed cache opportunity of using a server) is that it means you're having every user in the chat send a request to an arbitrary URL from their device. Also CORS makes this impossible 99% of the time.

The third approach, which Signal uses as a privacy preservation measure, is for the sender to generate the link preview on send. Of course, this then opens up abuse where the sender can arbitrarily control the "link preview" to say whatever they want.

Reply on news.ycombinator.com