The “real-time web” is a popular topic right now. My WebHooks initiative is both riding on this success and helping make it a reality. One sector of this trend is about notifications. Real-time notifications to you about events you care about.

For a long time we’ve had helper apps like the Google Notifier and more recently the Facebook Desktop Notifications app that bring events from the web to your desktop. Twitter has created a whole ecosystem of clients that not only let you actively check Twitter, but passively get updates from Twitter.

Simultaneously, we’ve had a bunch of systems like Growl emerge that give you a consistent, well-designed and customizable system for local applications to give you notifications. While your IM client is in the background, it can tell you somebody IM’d you and what they said in an unobtrusive way. It integrates with email applications to tell you of new emails. It gives any application developer a nice way to present notifications to the user in a way that’s in their control.

Some of the apps that bring web applications to your desktop like Tweetie, Google Notifier, etc will integrate with Growl (which has a counterpart on pretty much every platform, including the iPhone). The problem is that you only get these notifications when the desktop apps are running, despite the fact web apps are always running. And yes, you have to have an app running for each web application you use.

And that’s only if they built a desktop app and you were convinced to download it. Most web applications are never be able to notify you with any means other than email. But as I’ve argued before, notifications don’t belong in your inbox!

Another minor point is that all these apps use polling to get updates. In some cases this doesn’t matter, but as data starts moving in real-time, this batches your notifications into bursts that you may not be able to parse all at once. I use Tweetie to get Growl notifications from Twitter at the moment, and if a lot of people are updating, I get a huge screen of updates that I don’t have time to read before they disappear. It becomes useless.

A while back I attempted to make an app called Yapper that lets anybody send real-time notifications to your desktop via XMPP. It was an experiment, and ultimately not the answer. It was only part of the solution.

But today I’m announcing the full solution: a free, public, open-source web service called (Notify-I-O). integrates with Growl and other local notifiers (as well as email, Jabber, Twitter, and webhooks) and provides a dead-simple API for any web developer to send real-time notifications to their users.

You can think of as a web-level Growl system. It empowers users with a consistent, controllable way to get notifications, and it provides developers with a simple, consistent way for sending those notifications. is an open platform for notifications. It’s still in a pre-alpha state, but it already has several useful notification sources. Last Thursday I built Feed Notifier, which uses PubSubHubbub to give you real-time desktop notifications of Atom and RSS feed updates.

At SHDH 35 last Saturday, Abi Raja built a Facebook notification adapter for that’s yet to be released. And there a couple more in the pipeline (by me and others) to show the power of

Again, it’s pre-alpha, so before I talk much more about it, I should probably finish more of it. I just wanted to make sure I blogged about it in somewhat of a timely fashion. I seem to have a backlog of blog posts about apps I’ve built recently. However, is a pretty significant one. Feel free to check it out, just remember that despite its looks, it’s nowhere near finished — but it does work.

Public Open Source Services

October 29, 2009

Last night I went off and put up a wiki about an idea I’ve been thinking about for a while: public open source services or POSS. Think: public services or utilities on the web run as open source.

Unlike open source software, web services aren’t just source code. They’re source code that runs. They have to be maintained in order to keep running, and the resources they consume have to be paid for. This is why most web services are built using a business as the vehicle. This effectively constrains what you can build by framing it as something that needs to turn a profit or support you to work on it. But does it need to be that way? Can web services be built in a way that make it self-sufficient? Not needing some ambivalent leader to take responsibility for it?

I originally blogged about it in February 2007, 6 months after I first wrote about webhooks. Unfortunately my old blog isn’t online right now. Back then, I was trying to solve the administrative problem. How do you maintain the servers in an open source way? My idea then, was to build a self-managing system using something like cfengine or Puppet, where the recipes and configurations are kept with the publicly available source code. As new configurations are checked in, the server(s) adopt the new directives and continue to self-manage.

The practicality of such a setup is a little far fetched, but seemed pretty feasible for smaller projects. However, since the release of Google App Engine, this concern for simple web applications has disappeared. Google just automates the system administration, and scaling! This means to run the app, you just have to write the code and hit deploy. That’s a huge step! Administration concerns? Pretty much solved.

The next thing is the financial concern. How do you pay for it? Or rather, how does it pay for itself? This took longer to figure out, but here we are. From the wiki essay:

You use the same Google Merchant account that App Engine debits as the one that accepts donations. This way no bank account is involved. Then you track the money that goes into the account (using the Google Merchant IPN equivalent). Then you look at your usage stats from the App Engine panel and predicate future usage trends. Then calculate the cost per month. Then divide the cash in the account by that and you have how long the service will run. You make this visible on all pages (at the bottom, say) that this service will run for X months, “Pay now to keep it running.” You accept any amount, but you are completely clear about what the costs are. And this is all automated.

Take the humans out of the loop! (That’s a WarGames reference)

Then you rely on the same sort of community approach of open source to contribute to the application. Like a few members of the project community are given certain rights, some will be given permission to deploy the app from time to time for updating the running service.

If the service isn’t useful, nobody uses it, it’s not paid for, it disappears. If it is useful, people will pay for it to keep it running. They are assured they are paying operating costs, which are significantly lower than most because it doesn’t include paying for human resources! Volunteers might need to meddle with settings, but otherwise, the coders are in control and the community accepts or denies changes made by whoever wants them.

So if this is interesting, read the full essay I wrote up on the wiki. It’s been my intention to prototype and validate this model with many of my projects.

This is about ten days old, but still worth mentioning. I was working on PostBin trying to support file uploads. I realized I really wanted to have icons for the files to help differentiate them from other POST params and make it feel more polished. Of course, this would mean I’d have to find icons for the popular file/mime types … and if I were going to do that, I might as well build a service … but I didn’t want to build a service.

I turned to Twitter. In that past, I’d mentioned wanting something and somebody actually built it (using my tools no less). I figured this was a bit more work than last time, but it couldn’t be that much more. So I gave it a shot and tweeted it. Next thing I know, Paul Tarjan is on it. Some hours later:

I’m credited at the bottom, but really, I just had the idea and came up with the domain. Paul wrote all the code and even collected all the icons (and manually uploaded them to the app). We discussed implementation details over IM, but that was it. Pretty rad!

The idea is that given a file extension (“txt”, “gif”, etc) or a mimetype (“text/plain”, “application/zip”, etc) you can get a resizable icon by putting together a simple URL, like or from a particular icon set Here are some examples from various sets:

Nuvola set: text/plain jpg application/pdf mp3
Apache set: text/plain jpg application/pdf mp3
Crystal set: text/plain jpg application/pdf mp3

And that’s it! Paul wrote a post about it. Somebody requested a simple API for just doing the mimetype to file extension conversion, so Paul added it. Strangely, the same day, MIME API was released. That’s fine. Just means stdicon can focus on icons.

Anyway, I pulled this same stunt just the other day, using Twitter to get more cool infrastructure built, but I’ll have to write about it later.

So I recently put this blog’s feed through FeedBurner. If I recall, I think I wanted to get subscriber statistics, as well as to try out their integration of PubSubHubbub publishing. But since I didn’t think I would get new subscribers often and I’m too lazy to check stats, I really wanted a way to be notified when people subscribed. Since the means of subscribing would be a link, it hit me: click-through webhooks.

I wanted a link wrapper that would trigger a URL callback (aka a webhook) when people clicked through the link. Similar to a URL shortener, you’d just give it a URL and it would give you another URL, but instead of being shorter, it would be tied to a callback that would run as it redirected the user to the original URL. What could you do with this, you ask? It’s a webhook; you can do anything with this event.

Coming back to my original use case, I’d probably tie it to a script that sent me an IM that somebody subscribed. Or better yet, with something like Yapper, I could get a Growl notification. Sweet, right?

I knew it would be trivial to build, and even though it was a feature that I really wanted, it was still just a feature. I thought, it really doesn’t need its own app, does it? So I went to my URL shortener of choice,, and suggested it as a feature. I also happened to mention to all my friends they should vote it up. Well, it ended up being the 6th most requested feature because of that. I thought for sure they’d implement it. I mean it was so much easier than the others, and I gave them code to help do it and everything.

A couple weeks went by and nothing happened. I got no response. I emailed them and got nothing back. They didn’t even mark it as “under review.” It may have had to do with the fact they were then deciding to shut down … which I hear they’ve changed their mind about. Nevertheless, it still hadn’t happened. And I really wanted to be able to do this notification on subscription thing!

Along came my WebHooks and PubSubHubbub meetup where I wanted to demo this bit of plumbing. Of course, I had no way to do it because nobody had implemented it. So I figured I’d just build it that day before the meetup. Twenty minutes later, I had it live: ClickHooks.

Okay, so that part’s done. How do I get it to IM me? Well, Scriptlets was made to write the glue code to use with these kinds of webhooks. And my project Protocol Droid was made to make it easy to use other protocols from HTTP. So I just threw this little baby on Scriptlets and I was done:

import urllib

payload = {
 'username': '',
 'password': 'secret',
 'to': '',
 'body': "You got a new subscriber on blogrium!"

fetch("", urllib.urlencode(payload), "POST")

Yes, that pdroid endpoint is live. No, I don’t recommend using it for production. Stand up your own Protocol Droid gateway. ;)

Anyway, simple enough to understand though, right? It should be. And it was simple to get set up. That’s the whole point of a world of webhooks: you can easily do so much cool stuff if this simple infrastructure is there.

As an aside, later I realized I could generalize my IM scriptlet to use a GET param for the body of the message, allowing me to make a personal messaging micro-webservice:, world! The data in this URL could then be hidden behind a URL shortener, giving me a regular looking URL that I could then give to people that would IM me the message when they clicked it. Kind of silly, but I almost set up a link that would IM me “At the door!” that people could click from their phone browsers as a doorbell for the WebHooks meetup.

Ah, fun with infrastructure.

Twitter Hooks

June 15, 2009

When I first gave a public talk on webhooks in 2007, the guys at Twitter were the first ones to come up to me saying they wanted to implement them. Unfortunately it never happened, and this was well before they were as popular as they are now. It wouldn’t scale, they said.

As an alternative, just a few months ago, they released a stream API using long-running HTTP. It not only included a firehose stream, but a stream that allowed you to pull updates from selected users. I knew immediately from this I could build a webhook transformer, effectively giving Twitter webhooks. Unfortunately, the stream for selected users was behind a EULA that prevented that use of their API. Something about not redistributing data.

Then a few weeks ago, they added a selective stream that was publicly available. I had already designed the system and started writing some code before when I found out about the EULA. It took me a while to find some time, but last night and today I did it. I finished a proof of concept service called Twitter Hooks.

Twitter Hooks

It’s very simple and is mostly about the plumbing behind it. You sign in with your Twitter account using OAuth, then you just give it a callback URL. Behind the scenes, it has a stream consumer listening for updates from the users that have a callback URL. When it gets an update from you, it posts it to your callback URL.

Obviously, there is only so much you can do with your own tweets. The next step is to listen to updates from your friends and post them to your callback URL. After that, using some trickery not involving the stream API, it will post direct messages and new followers to your URL. Throw in keyword tracking, and you have hooks for almost every significant event in Twitter. John Herren would be proud.

The problem is… Twitter is still too limiting with their stream API. As it stands, the non-EULA stream only allows following 200 users. That means Twitter Hooks can only support 200 users. It also means there’s no way we can roll out the friend update hook because some people have over 200 friends by themselves. Until that’s resolved, Twitter Hooks will remain a proof of concept demo.

But I have to say, having this is pretty sweet. The stream API is about as real-time as you can get. While experimenting, I was getting updates from the stream quicker than the page reload from posting a new tweet. This is, of course, then posted to your URL immediately for you to do whatever you want with. Here’s a tweet of mine posted to PostBin:

Tweet in PostBin

If you want to play with Twitter Hooks, it’s currently limited to users I authorize since it can only have 200 users and it’s terribly early/rough. Just @ me on Twitter and I can get you set up.