coding on the shoulders of giants

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Where next?Where next?

Where next?

Coding on the Shoulders of Giants

Matt Biddulph

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.

This worldmap shows where everyone on Dopplr came to London from on October 4th 2007 (the day this talk was given at FOWA)

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Where next?

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.

This worldmap shows where everyone on Dopplr came to London from on October 4th 2007 (the day this talk was given at FOWA)

A "platform" 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 "platform" 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.

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.

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.

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People have different identities spread across many sites.

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 Cashflickr.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_identitiesend

http://identity-matcher.googlecode.com/

We’re releasing the code we use to match identities across sites as a Rails plugin.


This is an example of running the “match_twitter” call on Chris Messina’s profile.

>> Traveller.match_twitter("factoryjoe") [0].map(&:name)



>> Traveller.match_twitter("factoryjoe") [0].map(&:name)

=> ["Alexander Ljung", "George Kelly", "Amy Raymond", "Andrew Crow", "Jonathan Greene", "Aubrey Sabala", "Matt Jones", "Blaine Cook", "Brian Oberkirch", "Buzz Andersen", "David Ulevitch", "Michael Buffington", "Eric Costello", "Kaustubh Srikanth", "Brian Del Vecchio", "Jack Dorsey", "joshua schachter", "Kevin Lawver", "Scott Beale", "Lisa McMillan", "Mary Hodder", "Dan Saffer", "Rob Hayes", "Thomas Vander Wal", "James Walker"]



“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.3. Facebook caches images, so you should test carefully if you do any dynamic image creation4. Facebook will give up if you take more than about 7 seconds to respond, so make sure your app is snappy even when you’re under load or it will look like your app is down.

proxies directly to your server




rewrites your HTML, CSS and JS





caches what it can





needs you to respond quickly

caches what it can



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="dopplr-blog-badge"> <script src="dopplr.com/blogbadge/..."> </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.

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


S3 Data Storage

Pre-built EC2 Rails


S3 Data Storage

MySQL Slave

Pre-built EC2 Rails


Sharing Data

User Identity

Social Network

Delegating Authority

Widgets & Plugins

Utility Computing

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Where next?

Thank you

Matt Biddulph

coding on the shoulders of giants

Technology

dopplr data

distinctive structured

dopplrdopplr dopplr

trips feed

useful things

outside developers users

simplest way

good webapp