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Comment by annnnd | Hacker News Reader

Am I the only one who has trouble sifting through all this marketing? Even "read more" link leads to an article where half of the text promises what will be covered and another half talks about some subscriptions and how they are managed (they might have been mentioned in the first half, I agree - and I also read text only twice).

If someone has a better understanding of how this works, I would appreciate a TL;DR version for programmers (which are probably the target audience?). Thanks!

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Same for me i miss the How? part.

And i got oversold on an idea that sounds good but i have no clue how it works.

http://en.wikipedia.org/wiki/Webhook

We are pushing some copy updates to the homepage, most of the technical details were in docs. TL;DR coming to the homepage soon, but the gist is:

    REST Hooks itself is not a specification, it is a collection of patterns that
    treat webhooks like subscriptions. These subscriptions are manipulated via a
    REST API just like any other resource. That's it. Really.

Thanks for the feedback!

Better. That's practically the only thing that needs to be on the home page.

You also need to explain who you are and why you're doing this, too. Right now it looks like you have an interest in selling something but you never explain what it is. It reminds me a lot of those sites which sell some miracle product, and are deliberately very long and vague, and it ends finally with some button to order an ebook or something.

At the bottom of the page I saw:

> An initiative by Zapier 2013.

Zapier is a company that makes money off sites having REST endpoints to push and pull data. It looks like Zapier would prefer that more sites have endpoints to accept push, and this marketing effort is a brand-campaign (think Public Service Announcement) to get more people to tailor their products to work with Zapier.

That explains why more emphasis was put on marketing, etc. The primary audience is not developers but PHBs and PMs to have sound bytes to parrot to developers.

(I'm not cynical, I work in advertising, most of my products already have 'REST hooks'...)

Bingo!

As I read through the website, I felt mislead by the title "REST Hooks - Stop the polling madness" in that I believed we were talking directly about reducing something like AJAX long polling for an alternative means of retrieving data from the backend.

Having felt that pain before, and not opting for WebSockets yet, I was hoping for some kind of simple alternative. I have a portion of code that occurs during a registration process that is currently polling the backend for status updates as to the worker queue's progress (it's a lengthy registration with several moving pieces and calls to multiple remote APIs).

Try playing with WebSockets, they're pretty easy to get going. Is there something about them keeping you away? Or would it require quite a re-architecture?

There's a lack of browser support (IE10+, no Android), and the fallbacks drain your mobile battery. It's just not quite there. I've done full presentations on WebSockets and toyed/demoed with it for a number of trivial and less than trivial applications, so I would like to think I'm more informed than most.

server sent events? although they are push only. I can't tell if you also want write capabilities

Good point. For us (Zapier), we just waste a lot of time and resources polling. We talked to some of the SaaS services we integrate with and it is the same on their side as well. That is our motivation.

Ditto.

Great - if you're just up front about that I would read this.

Then again if I'm not the audience, well, I guess you know what you're doing.

I have no idea how this solves the fundamental push/pull networking problem.

Is a network connection kept open? Is there an assumption that the user has some port open that can be contacted?

I see that you somehow reduced your calls, but I don't see how. Please tell me in actual socket level networking terms how this is done; who establishes a connection to what, for what, and for how long?

Also how do you deal with disconnects, timeouts, and missed realtime data.

I think they are just suggesting that services which are being polled frequently instead implement a rest-like subscription service which would accept an endpoint and then push the data to all of the subscribed endpoints when it changes. In many cases it is more work from the developers of those services but would reduce their bandwidth and server load immensely.

This is a very good summary.

Ohhh, so it's really a server-side technology to better consume third-party APIs. For whatever reason, this wasn't at all obvious to me. I had initially assumed that this was technology between client and server sides of a single-page application.

As did I. I've built these systems (socket-like systems that work efficiently across browser in diverse environments). And if you think you can just get that right the first time, then either you have the hacking skills of which I have never seen or you are (more likely) wrong.

But this thing here they are talking about is something I've been doing for a long time. I didn't think about making a brochure site for it though.

Just follow the principle of making the parts as dumb as possible. They should be the stupidest simplest things ever. Sometimes you can't get to this model on the first try, and that's ok. But the closer you get to it, the better the product becomes. I swear this is true and part of the soul of the machine's ghost.

If you can't make things laterally connect this way, then make them vertically stack this way and then laterally connect this way. But don't obfuscate the objective.

Thats what I thought too.

Server A has events Server B wants to know about. With REST Hooks, Server A provides an API that Server B use to tell Server A "Please POST notifications about those events to this URL". Then Server B keeps a web server listening for requests to that url. There is no persistent connection.

As for timeouts, check out http://resthooks.org/docs/retries/ for ideas on how those problems can be solved.

So it's an API to configure webhooks on Server A?

I think it's more of an API to allow Server B to register its interest in receiving notifications from Server A.

Of course, Server A must "speak Rest Hook" in order to enable that, so in a manner of speaking I guess it is a way to configure Webhooks on Server A.

But, it basically exposes a common interface for Server A and Server B to establish Webhooks. Server A can tell Server B which notification subscriptions are available (i.e. for which events), and Server B can then choose to subscribe, providing the callback URL for the Webhook.

This is definitely better, but what I would expect is a short explanation of what happens to REST requests - why are there fewer of them? Are you caching the responses, serving them to clients (who are still polling, but they are polling you instead of the REST server) and waiting for PUSH request from server to invalidate the cache? Or is this a client-side solution too which allows a client to trigger a REST request only when data is available?

It would be interesting if browsers could accept HTTP requests.

There is no middle intermediary, its just two servers. For example, Facebook & your app.

Instead of polling `facebook.com/api/posts` every 2/5/15/60 minutes, you'd set up a subscription for Facebook to ping you at `yoursite.com/hook.php`. The subscription would be managed under `facebook.com/api/subscriptions`.

Why make effort to explicitly state that it's not a specification? That makes it more confusing, as it really is defining a standard interface for exposing and establishing Webhooks--i.e. pretty much a spec. So, when I read that it's not a spec, it made me question for a second whether I truly understood it.

I also agree with a previous commenter who said it's unclear what you guys' role is. Are you just defining this "spec" to help the world, and hoping that the world gets on board? Or, are you offering some sort of service? Also, how would a dev just start using these, when it requires that the services they are consuming "speak Rest Hook?". It just seems like a good idea, but not immediately useful. If there was a simple call to action that said, "Hey devs, let's all use these when building services", then the pitch would be more understandable (assuming that's what you guys are promoting).

BTW, I do think it's a worthwhile idea. Personally, I've found Webhooks to be very simple, thus I'm not really sold on the "research" that indicates devs struggle with them more than they would Resthooks. So, that's not the sell to me. It's having a standard, programmatic way of discovering Webhook availability and consuming them across various services/APIs that's the draw in my book.

Anyway, good luck.

This is how webhooks work in any API that has sufficiently embraced them (see Freshbooks for an example). Why are we pretending like this is something different?

And here I thought I was being dense.

Seems like it adds data that would normally be included in a poll response to requests that were going to be made anyway, and possibly adds requests that were normally going to be made independently to long polls, though I'm not sure about any of this.

If I am right, would be nice to explain this and how it compensates if there is not a "regular" request within a certain period of time. And well, to basically explain WTH REST hooks are....

Is the most important piece of information really: "REST Hooks itself is not a specification, it is a collection of patterns that treat webhooks like subscriptions"? That seems of tertiary importance at best. How about telling us what REST Hooks are and how they are that - not what they aren't from a marketing perspective.

This is targeting a technical audience. It shouldn't so drastically underestimate its readers.

You are not the only one. I read though it, clicked around, looked at the demos, thought about bookmarking it, got to the documentation page and saw this `/api/v1/subscription/`, thought That breaks HATEOAS then left.

I'm sure if I put more time into trying to understand what is going on I could figure it out, but to me, the message isn't that clear.

How does it break HATEOAS?

People argue that, with REST, versioning should be done in headers and not the url. Maybe that?

Nooe, HATEOAS is about links. The official-sounding thing that this would violate is the "server should be able to organize its own namespace."

That said, I don't think this actually mandates any URLs. I read that part as just a suggestion for how it could be done.

Does that mean it should be possible to just have the link be "subscription"?

It means that the spec shouldn't specify URIs, and instead publish link relations.

(I'm not saying that I think it should be that way, just elaborating.)

I'm interested since my application publishes URLs just like that. What's wrong with it as far as HATEOAS is considered? How would it be better?

Did you actually use HATEOAS? I'm currently designing an API and it's just way too much work and overhead to add links when everyone is just going to hardcode them anyway. Do you have any examples where HATEOAS actually prevents or solves problems? Do you have any tips on how to get people to follow the links instead of hardcoding?

The last API that I wrote used versioning in the headers and it saved us a ton of headaches when we updated our API. Our V2 upgraded some JSON fields of the API and our users who were on V1 were never affected. The funny the whole concept is that, you use it every day without even thinking about it. If you think about the web when you're looking at an PDF; What tells you if what version of the PDF file it is? Not the URL, it's the meta-data in the PDF tells you. You'll never see a link like:

  server.com/files/a-cs3/important.pdf
  server.com/files/a-cs4/important.pdf
  server.com/files/a-cs5/important.pdf

You'll see

  server.com/files/important.pdf

The information about the version of that pdf is contained in the document and managed document itself. What this allows for is you updating the PDF in any PDF editor without breaking how everyone else on the internet will process the file. You can edit the pdf with anything, re-save it and not break older version. This is the same concept that you should use to extend an API. If you think of the API as an document for a version of DATA (Just like any file/image is an endpoint), it will help you get a better grasp of why you shouldn't version in URL's.

Here is a more accurate description of the how you should design a REST API from the Author of the HTTP spec: http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hyperte...

Here's my basic understanding of it: This sounds like webhooks, but they have a set payload, so that the server that is sent the webhook just calls the rest endpoint it is given in the payload.

Basically we're taking webhooks and adding a RESTful subscription layer to it. This way users don't have to go copy and past webhook urls into other applications... the applications they use automatically create and destroy the subscriptions for them.

Yeah, it's pretty bad. I think it comes down to "assuming WebHooks, a suggested 'pattern' to set up the subscription programmatically".

Agree with you. If the audience is developers, give it to us in black in white instead of some new jargon and marketing blah.

I looked through several pages (waste of time) and I still can't figure out how this is real time without websockets, polling, server side events. No way I would use this service if they don't know who their audience is.

Yep the missing part of the description is 'server-to-server', or 'client-with-a-listen-port (i.e. not a browser) to server'.

Unfortunately a lot of us developers see the term REST API and think a-ha, this is something I can consume in my browser. This isn't that, so confusion ensues.

Agreed. I came here to ask if anyone actually understood anything about the product from the front page.

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