Coding on the Shoulders of
Giants Matt Biddulph DOPPLR DOPPLR Dopplr is a service for frequent travellers and their friends. It lets you share your travel plans with a group of trusted people that you choose. DOPPLR This worldmap shows where everyone on Dopplr came to London from on October 4th 2007 (the day this talk was given at FOWA) Where next?

DOPPLR DOPPLR Dopplr is a
service for frequent travellers and their friends. It lets you share your travel plans with a group of trusted people that you choose. DOPPLR This worldmap shows where everyone on Dopplr came to London from on October 4th 2007 (the day this talk was given at FOWA) Where next?

A quot;platformquot; is a system
that can be programmed and therefore customized by outside developers – users – and in that way, adapted to countless needs and niches that the platform's original developers could not have possibly contemplated, much less had time to accommodate. –Marc Andreessen, http://blog.pmarca.com/2007/09/the-three-kinds.html Today I’m going to talk about using the internet as a platform that your webapps can build on top of.

A quot;platformquot; is a system
that can be programmed and therefore customized by outside developers – users – and in that way, adapted to countless needs and niches that the platform's original developers could not have possibly contemplated, much less had time to accommodate. –Marc Andreessen, http://blog.pmarca.com/2007/09/the-three-kinds.html It’s impossible to predict all possible uses that your users might want to make of your app and its data, so we’re going to look at the technologies that developers can use today that maximise possibilities for integration and reuse.

Dopplr is a very targeted
web application, and we have no wish to reinvent the wheel on any technology or function that isn’t part of our core mission to find serendipity in travel. We designed Dopplr from the start to be a Small Piece, Loosely Joined. We believe that your data belongs to you, and that you should be able to have it anywhere you want it - even if you don’t frequently visit dopplr.com

Everything in this talk is
based on live code that’s running on dopplr.com today. I’ll be pointing out what libraries we used. Because Dopplr’s written in Ruby on Rails, that’s where all the examples will come from.

The most basic and most
important principle of integrating web apps today is sharing data. A good webapp helps its users make distinctive structured data (whether directly or indirectly) and does useful things with it.

Sharing Data The most basic
and most important principle of integrating web apps today is sharing data. A good webapp helps its users make distinctive structured data (whether directly or indirectly) and does useful things with it.

The simplest way to expose
data in a webapp is to supply feeds in machine-readable formats. Dopplr gives its users a “my trips” feed. As a newsfeed, it’s not all that useful as it tells you things you already know (the trips that you’ve added). As a lightweight read-only API, it works very well. We mark up our feed with all the appropriate machine-readable formats that we can find: GeoRSS, hCalendar and Google Calendar GData. This means it’s trivial to plug it into other systems like Yahoo Pipes, and mash it up with other data.

The simplest way to expose
data in a webapp is to supply feeds in machine-readable formats. Dopplr gives its users a “my trips” feed. As a newsfeed, it’s not all that useful as it tells you things you already know (the trips that you’ve added). As a lightweight read-only API, it works very well. We mark up our feed with all the appropriate machine-readable formats that we can find: GeoRSS, hCalendar and Google Calendar GData. This means it’s trivial to plug it into other systems like Yahoo Pipes, and mash it up with other data.

The simplest way to expose
data in a webapp is to supply feeds in machine-readable formats. Dopplr gives its users a “my trips” feed. As a newsfeed, it’s not all that useful as it tells you things you already know (the trips that you’ve added). As a lightweight read-only API, it works very well. We mark up our feed with all the appropriate machine-readable formats that we can find: GeoRSS, hCalendar and Google Calendar GData. This means it’s trivial to plug it into other systems like Yahoo Pipes, and mash it up with other data.

It’s also easy to transform
our data into KML and view it in Google Earth.

And NetNewsWire lets you import
trip details in iCal because of the hCalendar.

We also mark up our
contact lists using hCard.

We also mark up our
contact lists using hCard.

http://www.hauntedcastle.org/castle/ And via our API,
users are starting to create interesting tools like this Carbon Calculator.

If we want to integrate
your Dopplr data with your data from elsewhere, we need to know who you are on other sites.

User Identity If we want
to integrate your Dopplr data with your data from elsewhere, we need to know who you are on other sites.

DOPPLR DOPPLR DOPPLR People have
different identities spread across many sites. Where next? Where next? Where next?

OpenID is the obvious solution
to this mess - if you use the same URL everywhere then sites sharing data can be sure that you are the same person. It’s not just for login. OpenID can also be used to prove you own an identity. You may not want to use your AOL Instant Messenger identity as a login, but Dopplr can use the AOL OpenID provider to let you prove what your AIM ID is. This lets us write an AIM bot that talks to you by IM secure in the knowledge that we’re not leaking your information to an impostor.

OpenID is the obvious solution
to this mess - if you use the same URL everywhere then sites sharing data can be sure that you are the same person. It’s not just for login. OpenID can also be used to prove you own an identity. You may not want to use your AOL Instant Messenger identity as a login, but Dopplr can use the AOL OpenID provider to let you prove what your AIM ID is. This lets us write an AIM bot that talks to you by IM secure in the knowledge that we’re not leaking your information to an impostor.

“OpenId is the game changer
for social networks, allowing for portability of the social graph and preferences.” –Simon Willison ©2007 Julian Cash flickr.com/photos/juliancash/673891099/ For more about OpenID, read Simon Willison’s many talks and writings. He knows.

Once we know who you
are on other sites, we’d like to help you import your social network from those sites to Dopplr.

Social Network Once we know
who you are on other sites, we’d like to help you import your social network from those sites to Dopplr.

For example, Twitter mark up
their contact lists with XFN and hCard. Using the heuristic of “if you use the same username and real name on two systems, you’re probably the same person”, we can show our users a suggested list of users who might be the same on Twitter and Dopplr.

http://mofo.rubyforge.org http://code.whytheluckystiff.net/hpricot/ We use the
Mofo library to parse microformats, and Hpricot to scrape raw HTML.

class Traveller < ActiveRecord::Base matches_identities
end http://identity-matcher.googlecode.com/ We’re releasing the code we use to match identities across sites as a Rails plugin.

http://identity-matcher.googlecode.com/ This is an example
of running the “match_twitter” call on Chris Messina’s profile.

>> Traveller.match_twitter(quot;factoryjoequot;) [0].map(&:name) http://identity-matcher.googlecode.com/ This
is an example of running the “match_twitter” call on Chris Messina’s profile.

>> Traveller.match_twitter(quot;factoryjoequot;) [0].map(&:name) => [quot;Alexander
Ljungquot;, quot;George Kellyquot;, quot;Amy Raymondquot;, quot;Andrew Crowquot;, quot;Jonathan Greenequot;, quot;Aubrey Sabalaquot;, quot;Matt Jonesquot;, quot;Blaine Cookquot;, quot;Brian Oberkirchquot;, quot;Buzz Andersenquot;, quot;David Ulevitchquot;, quot;Michael Buffingtonquot;, quot;Eric Costelloquot;, quot;Kaustubh Srikanthquot;, quot;Brian Del Vecchioquot;, quot;Jack Dorseyquot;, quot;joshua schachterquot;, quot;Kevin Lawverquot;, quot;Scott Bealequot;, quot;Lisa McMillanquot;, quot;Mary Hodderquot;, quot;Dan Safferquot;, quot;Rob Hayesquot;, quot;Thomas Vander Walquot;, quot;James Walkerquot;] http://identity-matcher.googlecode.com/ This is an example of running the “match_twitter” call on Chris Messina’s profile.

“the best way for you
to manage your network is to stop thinking about all of the little pieces and to start focusing on the big picture” As Gavin Bell has been telling us for a while, the tools for social network portability are reaching maturity. David Recordon (pictured) is working on open systems at Six Apart to aggregate and share social network information.

To make interesting mashups, we
often need to delegate authority to 3rd-party automated services. Code running elsewhere needs to have access to users’ accounts to act on their behalf.

Delegating Authority To make interesting
mashups, we often need to delegate authority to 3rd-party automated services. Code running elsewhere needs to have access to users’ accounts to act on their behalf.

The worst way to do
this (we’re guilty too) is for the 3rd-party to ask for the users login details and fake a login as them. This is not only bad for privacy but also teaches users terrible habits.

BBAuth AuthSub Authentication OpenAuth There
are several standards for delegating API access to a 3rd-party but they all work slightly differently.

“An open protocol to allow
secure API authentication in a simple and standard method from desktop and web applications.” http://oauth.net So the OAuth project is standardising a single protocol that everyone can use. This will mean one client library per language (rather than one per language per site) and an easier landscape for users to understand.

There are many ways to
get a piece of screen real-estate on other sites.

Widgets & Plugins There are
many ways to get a piece of screen real-estate on other sites.

Dopplr has a Facebook app
that puts a Dopplr profile box on your profile page. It doesn’t try to cram the Dopplr user experience into a small box; it just displays a useful summary of your travel information.

It also publishes cute little
items in your mini-feed.

The Facebook F8 platform is
actually very nice to work with. There are a few gotchas: 1. Pages served under apps.facebook.com are proxied directly to your server at request time. This makes development versions a bit of a pain as your dev server must be visible on the internet. We do this with an SSH tunnel. 2. FBML is a subset of XHTML with some extra elements in the Facebook namespace. Facebook rewrite all your IDs and classes in the HTML and CSS so that you can’t accidentally change another app’s style.

proxies directly to your server
The Facebook F8 platform is actually very nice to work with. There are a few gotchas: 1. Pages served under apps.facebook.com are proxied directly to your server at request time. This makes development versions a bit of a pain as your dev server must be visible on the internet. We do this with an SSH tunnel. 2. FBML is a subset of XHTML with some extra elements in the Facebook namespace. Facebook rewrite all your IDs and classes in the HTML and CSS so that you can’t accidentally change another app’s style.

proxies directly to your server
rewrites your HTML, CSS and JS The Facebook F8 platform is actually very nice to work with. There are a few gotchas: 1. Pages served under apps.facebook.com are proxied directly to your server at request time. This makes development versions a bit of a pain as your dev server must be visible on the internet. We do this with an SSH tunnel. 2. FBML is a subset of XHTML with some extra elements in the Facebook namespace. Facebook rewrite all your IDs and classes in the HTML and CSS so that you can’t accidentally change another app’s style.

proxies directly to your server
rewrites your HTML, CSS and JS caches what it can The Facebook F8 platform is actually very nice to work with. There are a few gotchas: 1. Pages served under apps.facebook.com are proxied directly to your server at request time. This makes development versions a bit of a pain as your dev server must be visible on the internet. We do this with an SSH tunnel. 2. FBML is a subset of XHTML with some extra elements in the Facebook namespace. Facebook rewrite all your IDs and classes in the HTML and CSS so that you can’t accidentally change another app’s style.

proxies directly to your server
rewrites your HTML, CSS and JS caches what it can needs you to respond quickly The Facebook F8 platform is actually very nice to work with. There are a few gotchas: 1. Pages served under apps.facebook.com are proxied directly to your server at request time. This makes development versions a bit of a pain as your dev server must be visible on the internet. We do this with an SSH tunnel. 2. FBML is a subset of XHTML with some extra elements in the Facebook namespace. Facebook rewrite all your IDs and classes in the HTML and CSS so that you can’t accidentally change another app’s style.

http://rfacebook.rubyforge.org We use the RFacebook
library to abstract a lot of the low-level details away. It helps.

We also have a blog
badge that follows the same style as the Facebook profilebox.

<div id=quot;dopplr-blog-badgequot;> <script src=quot;dopplr.com/blogbadge/...quot;> </script>
</div> The user only has to paste a tiny piece of code into their template to enable it. It looks for its div and insert HTML and CSS there.

“Javascript is the extra layer
above the mark-up ‘what is this text’ and the CSS ‘how should it be displayed’. It adds a new dimension, ‘how should this element behave.’” –Christian Heilmann This follows the principle of unobstrusive Javascript.

(function(i) {u = navigator.userAgent; e
= /*@cc_on!@*/false; st = setTimeout; if(/webkit/i.test(u)){st(function(){dr = document.readyState;if(dr==quot;loadedquot;|| dr==quot;completequot;){i();}else{st(arguments.callee,10);}},10);}else if((/mozilla/i. test(u)&&!/(compati)/.test(u))||(/opera/i.test(u))){document.addEventListener (quot;DOMContentLoadedquot;,i,false);} else if(e){(function(){t=document.createElement ('doc:ready');try{t.doScroll('left');i();t= null;}catch(e){st(arguments.callee, 0);}})();}else{window.onload = i;}})(function() { // make the badge }); http://www.kryogenix.org/days/2007/09/26/shortloaded We also avoid the need for pulling in a full Javascript library such as jQuery just to get a proper ‘page is loaded’ event, using this code.

Even application hosting is starting
to become an on-demand commodity.

Utility Computing Even application hosting
is starting to become an on-demand commodity.

We’re currently experimenting with using
Amazon S3 for MySQL backups, and EC2 to run a complete copy of the Dopplr application and a MySQL slave replicated over an SSH tunnel from live. This is looking like a good way to scale, and it’s a great way to run stats reports and live backups without disturbing our main servers.

S3 Data Storage We’re currently
experimenting with using Amazon S3 for MySQL backups, and EC2 to run a complete copy of the Dopplr application and a MySQL slave replicated over an SSH tunnel from live. This is looking like a good way to scale, and it’s a great way to run stats reports and live backups without disturbing our main servers.

S3 Data Storage Pre-built EC2
Rails We’re currently experimenting with using Amazon S3 for MySQL backups, and EC2 to run a complete copy of the Dopplr application and a MySQL slave replicated over an SSH tunnel from live. This is looking like a good way to scale, and it’s a great way to run stats reports and live backups without disturbing our main servers.

S3 Data Storage Pre-built EC2
Rails MySQL Slave We’re currently experimenting with using Amazon S3 for MySQL backups, and EC2 to run a complete copy of the Dopplr application and a MySQL slave replicated over an SSH tunnel from live. This is looking like a good way to scale, and it’s a great way to run stats reports and live backups without disturbing our main servers.

Sharing Data User Identity Social
Network Delegating Authority Widgets & Plugins Utility Computing

Thank you Matt Biddulph DOPPLR
DOPPLR DOPPLR Where next?