[epaulson]

Are there any examples of good web APIs that offer something like a unified log as an abstraction? I'm not looking for systems, but actual companies that have some kind of "streaming" data feed where you can (re)connect to an endpoint and say "give me everything from [logical] timestamp X". Ideally one where you stay connected and get longpoll SSE/WebSockets/MQTT-style streaming responses.

I kind of want the opposite of webhooks.

[jkarneges]

There are certainly "client oriented" (as opposed to webhooks) push APIs out there. However, such APIs that let you specify a starting position to read from are rare.

Sometimes APIs will give you tokens to use for resumption (e.g. SSE event IDs, or any long-polling API), but typically these are for a time-limited session rather than a stateless query against any point in a long-lived log.

Years ago, services like Friendfeed, Livefyre, and Convore had stateless long-polling APIs that returned a log of data, I believe. These kinds of APIs seem to have fallen out of fashion, though. There are still stateless long-polling APIs, but most of the ones I'm aware of don't return logs of data. For example, Dropbox and Box will let you query for a change notification against a starting position, but then you have to fetch the actual data separately.

That said, just because streaming APIs that let you set a starting position are rare doesn't mean they're impossible to make. My company (https://fanout.io) has built tools to help with this.

Edit: since you asked for a real example, Superfeedr is one such API: https://documentation.superfeedr.com/subscribers.html#stream...