FoWA: From web site to web application – Cal Henderson

Works at Flickr. Ten things that have been learnt from Flickr than can be applied to other web apps. Ways to move from a web site to an app. Not very geeky. Not going to talk about MySQL and nerd stuff.


Is awesome. Photo sharing app. Has tags. Has an API. All these Web 2.0 buzzwords. Obviously there’s been the Web 2.0 conference for a couple of years. Has taken off as a term. Lots of people will be talking about what web 2.0 means whether they say it or not, and trying to explain some of those principles. It’s nothing really, just a name for a tech that’s been around for a while.

Flickr is going to be 2 on Friday. Big party in San Francisco with cake. All welcome to go.

Flickr has 2m users, who are very passionate. Passionate users are important to Flickr, but the developers who built it who are also passionate. People don’t start a business to make money. you do it because you care about what you’re doing. BNy having passionate developers you get passionate users.

have to start from a pov where you care about what you’re building.

With Flickr, there’s a difference between what users want and what they need. People didn’t necessarily want the things that Flickr built, but maybe they needed it. We thought about feature that people needed first and foremost. You don’t listen to what your users say because they will tell you what they think they want. You have to watch what users do and look at their behaviour to understand what they need not what they say they want. If you give them what they need you’ll make them passionate.


First of the ten things is collaboration. At the beginning of Flickr, before Flickr, there was Game Neverending, which was a realtime MMP game, based around a realtime engine. Flickr was built on the same tech – massively multiplayer photosharing.

Very much like a game – social network, friends list, etc. Already a load of photo site, not a new tech. That’s not a big deal. What is a big deal is sharing your photos with your friend. Very bottom up, is social network.

Create network effect, by create incentive to add people to the network, so people add value by encouraging others to sign up.

Collaborative metadata also core. Tags, notes, great, but if i can add tags to others, then that’s collaborative metadata. More uses than just pointing out things you missed.


A lot of web apps where you upload your own data would all be siloed into users, a ghettoised space. So huge collection by data, but instead of showing by user, show by other ways, e.g. latest photos. Loads of interesting slices of the data. So think about the whole bunch of photos as one big blob, can slice by tag, by geolocation, relation to other tags, interestingness etc.

Open APIs

Many apps have open API, but what’s the point? We needed it for our own development, for building in throttling and abuse protection etc., so why not let other people use it? Had a bit impact early on with it.

Whole tonne of value in just pushing out read data, without exposing your system.

Started build sites, then web apps, now web services. We can allow other peopel to build our interfaces, and allows othe rpeople to do really interesting things, stuff we hadn’t thought of, wouldn’t have had time fork, or which sounded insane.

Something really cool is that people built a game called Fastr, multiplayer game with a series of photos and you have to figure out as fast as poss which take the photos came from. It’s really cool, but there’s no reason for usto have built it.

If you don’t provide an API, people will just scrape data, so it makes it easier for you and them.

Clean URLs

Getting very popular in Web 2.0. Core reason is that you don’t need to expose the core workings of your system in your URL. Use mod_rewrite under Apache. So the URL doesn’t have to point to a file name, so just translate from file name to URL using mod_rewrite. Core to Flickr URL.

The URLs don’t reflect the folder structure at all, so none of the URLs map to physical part of the disk. But that’s good because they are human readable and they are guessable. If you can guess the URL to a page, then people can get around fast.

Sometimes we’ll find we’ve removed a link from the nav, though, and never realise because the developers always type in the URL.

URLs can’t change. If they point to one resource now, they have to point to that resource forever. When we started Flickr we picked some really bad URLs, but we can’t change them because people have used those URLs and you can’t break those links.

This was a problem when scaling. When the URL scheme was changed, have to support the old URLs forever, because you can’t have them break for people.

AJAX, been around for a while. Worst name ever. Asynchronous Javascript And XML. Not always about XML or Javascript, because you could write an AJAX-like script in VB if you wanted. But the Asynchronous bit is important.

After you’ve loaded a Flickr page and you want to add a tag, the box appears without the page reloading, and when you submit it the page doesn’t need to reload either.

Need strong API so that it can be accessed via AJAX. It’s used primarily to streamline interactions that you already have. E.g. keeping the tags on the same page instead of having to go to a new page to add them in. AJAX saves a bit of bandwidth, stops page reloading, don’t lose context etc.

Also use it for creating new experiences. Not seeing this so much on the web yet, but we build self-contained apps in AJAX which have no way to address in to them.


Internationalisation comes first, and localisation later. Important thing to consider is whether you want basic international support from the beginning. E.g. do you store all your data in unicode?

Usual use is to store, present and receive data in UTF-8. Some apps use UTF-16.

Desktop integration

Or platform integration, because your platform isn’t necessarily a desktop. Need to move interactions out of the browser. Most of this is grounded in APIs.

Bunch of desktop apps which work with Flickr, e.g. the upload app. Some tasks are crappy on the web, especially uploading photos, and especially more than one photo. Desktop app allows people to perform tasks that would be difficult, suck or just be stupid, in a browser.

Not just desktop apps. Also possible to do browser apps, such as bookmarklets.

More complex platform integration, e.g. toolbars or dialogues into the browsers.

Also integrating the app with email. Everyone has email, and email is integral to the way people interact online, but we don’t often think about building it in to a web app, e.g. to send email to our system as well as receive it. Difficult to get a photo off a mobile phone, but most can email, so as soon as Flickr could accept photos via email then that’s an uploader for every phone.

Also, simple notification emails to draw people back to the system.


Will become the most important platform. Heard this for the last five years. You probably remember WAP and how influential that was… but there are some standards so you can build stuff, and so some people will use them. But they usually all support XHTML Mobile, quite a sensible standard.

Build small apps for mobile devices using XHTML Mobile will work on most phones.

People used to think that it was about creating a smaller logo, but that just doesn’t work. Can’t have more than a couple of lines of text and expect anyone to interact with it. It’s not just a case of re-presenting the same content using a different format. Need to think about what you’re presenting. Needs to be snappy. Think about stuff you wouldn’t want to do on the website, maybe. But not all data is suitable for mobile devices. Need to think in small chunks.

Open data

Import and export of data from systems we build. Export through RSS feeds, but can only get 10, 15 or 20 most recent photos. But doesn’t give a mechanism to get a few hundred out of Flickr. Provide a method to get all their data out, or to import everything in from another app.

If you give people the feeling that they can leave at any time, they are more likely to stay.

It’s not just primary data that’s important. People may already have a photo back up because they upload it from somewhere. But they don’t have the metadata, so what’s important are the notes, tags, comments etc. and getting some sort of local back up. That’s done through the API.

There are 3rd party services that back up your photos to a DVD and then sell you the DVD. Makes people feel safer.

Open Content

Previous to Flickr, a lot of web apps that stored data, once you uploaded your data, they own it. Still the case with Google Video, and other photos sites – they can sell it, use it, do whatever with it because they own it. Flickr does not own their user’s data. Allow users to use Creative Commons licences if they wish.

Through the open APIs, open data, open content, and allowing people to reuse and remix and use the data for interesting purposes. There’s a video someone did with CC licensed photos,, and wrote a song about it.

All photos used in presentation were CC’d, and attributed in presentation, which is online at

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