Christian Heilmann

Posts Tagged ‘mashups’

What the hack? Introducing hacking at the open hack day in Bangalore, India.

Saturday, July 24th, 2010

I am right now at the open hack day in Bangalore, India and just finished giving the keynote presentation showing people what hacking means and how to present at a hack day:

The slides

What the hack?

The resources I talked about:

The Audio recording

The audio of the recording is available on

And the demos:

FOWA Dublin – Powerful Tools that You Need (and Probably Don’t Know About)

Sunday, May 16th, 2010

Last Friday I was up in Dublin at the Future of Web apps and gave my talk “Powerful Tools that You Need (and Probably Don’t Know About)”. I took FOWA as an opportunity to (re-)introduce the audience to some of the tools Yahoo offers and to brand the drive of developers to do everything by themselves instead of using already built solutions as ineffective.

The slides of my talk are available on SlideShare:

The audio of the talk is on

The video of the talk is available on Ustream:

Here are the resources I talked about as links:

Also check the YDN blog in the next few days for a full FOWA report.

Things you can use – my talk at the Deveoper Evening with Yahoo and Opera in Oslo, Norway

Thursday, December 3rd, 2009

I am currently in (freezing) Oslo in Norway and about to leave for the NITH university for the Yahoo and Opera developer evening. Here are the slides and notes of what I am about to present tonight. Audio will follow laterAudio is now available.

For those who will attend tonight: stop right here, you’ll just spoil it for yourself :)



The audio recording is available on or as a 54MB MP3 file.


Things you can use (by the Yahoo Developer Network and friends)

In the following hour or so I will be talking to you about some of the things that have been done for you that you can build on. Web development is confusing enough as it is. There is no need to make it more complex by not using what has been done for us already. But first, a few facts about me:

I am Chris and I’ve been developing web sites for about 12 years. I’ve worked with numerous frameworks and CMS and I’ve delivered various international and high-traffic sites. I’ve written several books and dozens of articles and hundreds of blog posts on the subject of web development, accessibility, performance, maintainability, internationalization and many other things I had to battle in my day to day job.

Right now I work as a Developer Evangelist, which is a pretty new job in the market and as many people were confused about it, I wrote a Developer Evangelism Handbook which is free and creative commons online, but you can also buy a hard copy on

I work for the Yahoo Developer Network and you will find most of the things I will talk about today there.

Learning the basics

The good thing about these days we live in is that we have great resources on the web to learn good basics of web development. That we still learn it by viewing source and trial and error after copy and paste is human nature but also keeps us from evolving. The Opera Web Standards curriculum is an amazing resource to learn web standards based development (as is the WaSP interact) and the Yahoo Developer Network theatre is full of videos of talks and tutorials. All of this is free to use and to build upon.

Starting with a clean canvas

One thing I learnt is that in order to deliver products that work and are fun to maintain you need to work on a solid base. Web development is hindered by the fact that our deployment environment is totally unknown to us. This is why we need to even the playing field before we should go out on the pitch to play.

You achieve this by defining what you call “support” for browsers. In the case of Yahoo this is the graded browser support document. If you aim to make your web product look and work the same on every browser out there you are doing it wrong. Web design is meant to go with the flow and accustom itself to the ability of the user agent (browser in most cases). At Yahoo, we have the Graded Browser Support for this – browsers that are not capable of supporting new technologies will not get them. Web sites are not meant to look and work the same everywhere. On the contrary – the ability to accustom the interface to different user agents is what makes web development so powerful.

CSS frameworks and frontend libraries

The next step is to free ourselves from the limitations of browsers and especially their differences. This is what CSS frameworks and front end libraries like jQuery, Mootools, Dojo, YUI and many more are for. All of these have the same goal: allow you to build code that is predictable and limited to the bare necessities. We should not have to bloat our code just to make our products work with random browser implementation problems. These are a moving target as there is all kind of weirdness happening across the board. Libraries make our job predictable and allow us to use web standards without catering for browsers. If you build your code based on libraries you can fix your product for the next browser by upgrading the library. If you choose to do everything yourself – good luck.

Building interfaces that work

The next thing to consider is that an application interface is not just the look and feel. In order to make it work for everybody we’ll need to understand the ways users interact with our products. This includes simple usability (not overloading the user, not confusing the user) but also means knowing about different interaction channels – for example keyboard users. A great resource for starting the journey towards usable interfaces is the Yahoo Design pattern library. There we collected information how our end users use the web and reach a goal easily. If anything, have a look at these patterns before you start building your first widget or application. They even come with stencils for different designer tools.

Using the web

The big change in web development over the last few years was that we stopped trying to do everything ourselves. The web is full of specialized systems such as YouTube, Flickr and Google Maps that allow you to host data in specific formats and make it dead easy for you to convert and re-use that data in web formats. Using this information happens via Application Programming Interfaces or short APIs. These allow you to demand data in a certain format and get back only what you need. There are hundreds of APIs available on the web. For an idea of what is available, check out

Thinking data first

The main thing to be aware of if you want to build great products is to separate your data from your presentation. This is essential to allow for localization, internationalization and to keep your code maintainable. In the case of a mashup of different data sources this means you need to think about making it as easy as possible for you to use different APIs. The complexity of your product increases with the number of APIs you use. Every API has different ways to authenticate, expects different parameters and returns data in different formats.

Mixing the web with YQL

YQL is a solution that Yahoo built for its own needs. All of our products are built on APIs – for scalability reasons. Having to learn all these APIs and negotiating access cost us a lot of our time so we thought we’d come up with a better solution. This solution is called YQL. YQL is a SQL-style language to get data from the web. The following query would get us photos of London from flickr:

select * from geo.places where text=”london”

Or would it? Actually it would give us photos with the text “london” and not photos taken in Oslo. If we wanted that we need to use another API. The Yahoo Geo APIs allow you to define any place on earth and get it back as a “where on earth ID” or short woeid. This format is supported by flickr, so we can use these APIs together. Twitter will also soon support this.

select * from where woe_id in (
select woeid from geo.places
where text=”london”

This gives you some data of the photos you want to show but not all, so let’s use another API method to get that information.

select * from where photo_id in(
select id from where woe_id in(
select woeid from geo.places where text=”london”


This is a lot of data so in order to only retrieve what we really need we can filter the data down by replacing the *:

select farm,id,secret,owner.realname,
from where photo_id in(
select id from where woe_id in(
select woeid from geo.places where text=”london”


Using this query in the YQL console, choosing YQL as the output format and “flickr” as the callback will give us a valid URL to use in a browser or script:

Using this in the src attribute of a script tag and writing a few lines of Dom Scripting displays the photos.

Is this limited to Yahoo?

No, of course not. First of all you can use any data on the web as a source using the atom, csv, feed, html, json, microformats, rss and xml tables.

Scraping HTML with YQL

The HTML table is quite interesting as it allows you to get data from any HTML document, cleans it up by running it through HTML Tidy and then allows you to access parts of it using XPATH.

This allows you for example to take a simple web site like this one about TV jokes and turn it into a wiget to include into other pages with a few lines of JavaScript.

Extending YQL

You can also add your own data by providing a simple XML schema called an open table. In this schema you need to tell YQL what the data endpoint is, what parameters are expected and what gets returned.

Open tables also allow for an execute block which allows you to write JavaScript that will be executed by YQL on the server side using Rhino and has full e4x support.

Using this we can turn the earlier example of the Flickr photos returned as a list into an open table and make it much easier to get Flickr photos in the right format:

select * from flickr.photolist where text=”me” and location=”uk” and amount=20

Using the JSON-P-X output this means we can simply use innerHTML to render out photos.

If you want your tables to be available in YQL, all you need to do is to add to the open tables repository on GitHub. For more information, check out the YQL documentation.

Building with Blocks

The best thing you can do right now if you want to build a web application is using already tested and working building blocks. The Yahoo User Interface library is full of these as this is exactly how we build our own tools.

For creating layouts with CSS without having to know all the hacks that browsers need you can use the YUI grids and if you are really lazy you can even use the WYSIWYG grids builder.

Using the CSS grids and some of the YUI widgets it is very easy to build a working application that is tested across all the browsers defined in the graded browser support. Examples are this geographical Flickr search and a showcase to get information for Delhi.

One thing that is really useful about the widgets provided in YUI is that they are all driven by custom events. That way you can extend and change their functionality without having to mess around with the code. Simply write an event listener for the custom event, add your functionality and prevent the original functionality.

Another great benefit of YUI is the very detailed documentation and the hundreds of examples you can use to get you started.

Wanna get super famous?

The last thing I want to talk about today is the Yahoo Application Platform or short YAP. Using YAP you can build a web application using JavaScript, HTML and CSS and add it to the Yahoo Homepage, My Yahoo and in the future even more properties of Yahoo.

You start at and develop your application to the largest part in your Applications Dashboard. Yahoo apps have two views: a small view which is more or less static (but allows for some Ajax) and a large view which gives you full access and much wider screen space. The small view is overlayed over the Yahoo page and will show Yahoo ads next to it. The large view can be monetized by you.

One thing that can be a bit of a frustration about YAP when you go at it with a normal web development mindset is that not all CSS/HTML and JavaScript is allowed as YAP uses Caja to keep our applications secure. Therefore we’ve put together some Caja-ready code examples to get you on track.

The easiest way to build YAP apps is by using the Yahoo Markup Language (YML) and YUI as YUI was re-written to be Caja compliant.

If you want to take a look at what a YAP application looks like, check out the source of TweetTrans on GitHub. In essence it is a simple PHP API call using YQL and a YML interface to display the results using Ajax. No JavaScript involved as YML does that for us.

You can install TweetTrans by clicking the following link: This is also the way to promote your own applications (simply replace the application ID with yours) until the YAP application gallery is up and running.

The more powerful way of promoting your application in Yahoo is to piggy-back on our social connections and you can do this by diving into the social graph API. The easiest way to do that is to use the social SDK also available on GitHub. Notice that the SDK will not work on a localhost – you need to run it inside the application dashboard or a Yahoo container on the homepage.

Elevator pitches

Yahoo User Interface Library – YUI

YUI is the system that Yahoo uses to build its web sites. It is constantly tested to work for the largest amount of users, free, open source and covers everything from design patterns to out-of-the-box widgets. It is modular and you can use only what you need. You can either host it yourself or get it from a network of distributed servers.

Yahoo Query Language – YQL

YQL is a web service that allows you to mash-up any data on the web from various sources with a simple SQL-style language. You can filter the data down to what you need and you can convert the data with server-side JavaScript before returning it. Data providers can use YQL to publish an API on the web on top of Yahoo’s infrastructure and cloud storage.

Yahoo Application Platform – YAP

YAP is the Yahoo Application Platform which allows you to build applications that run on the Yahoo homepage and soon other properties. You can dive into Yahoo’s social graph to promote your applications and you can create highly secure web apps as YAP uses Caja to ensure code quality.

Getting a list of Flickr photos by location and/or search term with a YQL open table

Monday, November 2nd, 2009

Displaying photos from Flickr can be daunting. The API needs authentication and the RSS, JSON or LOLcode output is very limited. The way around is using YQL and its Flickr tables. That way it is pretty easy to search Flickr:

select * from where text=”panda”

Try out the Panda search in the YQL console.

The output format has a lot of information in there, but sadly enough, not all. For example the real name of the owner or the description is missing. Therefore you need to go through yet another Flickr API to get the whole data set:

select * from where photo_id in(
select id from where text=”panda”

Guess what? You can also try this more detailed query in the console.

I’ve shown before how easy it is to display Flickr Photos retrieved that way:

The issue with that though is that it uses JavaScript and JavaScript may be turned off (think Blackberries). Of course you can do the same thing in PHP but I’d wager to say more people to JavaScript than PHP these days.

The main issue is that Flickr returns the photos in a pretty weird format and that you need a script like the one above to turn it into a simple HTML list.

The good news is that YQL with the execute command allows you to embed JavaScript in your open tables. That way you can write a table that does all the necessary transformations and returns the data as a simple list for immediate use:

select * from {table} where location=”london,UK”
Christian Heilmann
Searches Flickr by location and/or search term and returns an HTML list that can be immediately used in a mashup.

You’ll notice that while the E4X support is very powerful, it can be a bit confusing to look at on first sight. Once you got your head around though it becomes much cleaner that way.

You can use this table like any other open table via the use command in YQL:

use “” as flickr;
select * from flickr where text=”me” and location=”uk” and amount=20

try it in the console.

I’ve wrapped one more API in there – the Yahoo Geo API to determine a place from a name should you want to search by location. All in all you have three parameters in this open table – all of which are optional:

  • text – the search text
  • location – the geographical location
  • amount – the amount of photos to be returned

If you look at the table source, you can also see that I hard-wired the license of the photos to 4 which is CC-BY. So if you link the photos back to Flickr you both satisfied Flickr’s terms and the original photographer’s.

Now, the easiest way to use this output is by using YQL’s JSON-P-X output format. This is XML with a callback which returns a JSON object with the HTML as a string instead of a convoluted JSON object. See the JSON-P-X output here.

That way you can easily use it in JavaScript:

And also in PHP:

$url = ‘;%20select%20*%20from%20flickr%20where%20text=%22me%22%20and%20location=%22uk%22%20and%20amount=20&format=xml&diagnostics=false’;
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$output = curl_exec($ch);
$output = preg_replace(‘/.*
      $output = preg_replace(‘/
$output = preg_replace(‘//’,’‘,$output);
$output = preg_replace(‘//’,’‘,$output);
echo $output;

You can see both in action on the demo page.

So by using YQL open tables you can not only access complex APIs with YQL, but you could also write complete mashups in JavaScript and have them executed in a safe environment on Yahoo’s servers. Your end of the mashup is simply the display which could be a form that works with Ajax when JavaScript is available and renders a static page in PHP (or whatever other server-side language) when JavaScript is turned off. You only need to do one HTTP request – the rest is executed and cached on the YQL server farm – everybody wins.

On being cleverly lazy – my talk at the WebExpo in Prague

Monday, October 19th, 2009

I am currently in Prague, Czech Republic and gave a talk on re-use, professionalism and ease of development at the WebExpo.

Webexpo Prague by  you.Webexpo Prague by  you.

Today I am going to have a longer chat with the people at the University about accessibility and creating a WAI-ARIA enabled framework for web applications.

For now, here are the slides of the WebExpo presentation and the audio recording of the talk. There was a video streaming, too, and it is up to Microsoft now to get this out as a recording.


Audio recording

You can download on being cleverly lazy as an MP3 - 36MB or see other audio options on

Notes / Transcript

Today I will talk about the fact that being cleverly lazy will make you a better developer.

First of all, I am Chris, a developer evangelist. This means I am a developer who evolved into a role where I can tell other developers how to have an easier life and tell my company what other things developers would want to make it even easier for them. I’ve written a developer evangelism handbook if you are interested in learning more about this role and why your company would benefit from having someone like me.

Cleverly lazy

Let me quickly define cleverly lazy here. Lazy is “I don’t want to do it” wheres cleverly lazy is “I don’t want to do that ever again so I do it right this time”. In development the difference between lazy and cleverly lazy is that lazy products do the job but are impossible to maintain whereas cleverly lazy products do the job, are easy to understand, extend and are built on a solid base.

Evolving the web

Our job as developers, designers, planners and organisers of web products is to evolve the web. We should have the chance to concentrate on building solutions that make people happy to use them rather than having to work out how one browser or another fails or how we convert data into a format the web technologies can display and understand.

In order to achieve this, we need to be free to do new things rather than worrying about the past.

The feature loop trap.

One problem is that as developers, we stand in our own way. The biggest trap that there is for developers is the feature loop:

  • As developers we love to take a complex problem and tackle it. We love solving problems, that is why we become developers.
  • We then normally and quite quickly find a simple solution to the complex problem.
  • We then release the solution to the world and get feedback.
  • This is where it goes pear-shaped. We get stuck in a feature adding and feedback loop until the elegant, easy and simple solution becomes a complex one again.
  • Other developers will find our former simple solution and will think “hey, this is a complex problem, let’s make that easy!”

This keeps us from evolving as web developers. We don’t develop the web, we fill it up with solutions to the same problem.

My solution

The next issue is that as developers we love to find solutions ourselves and not use other people’s information. We appreciate other people’s work but in the end we only trust ourselves to come up with the best solution ever.

Short attention span

The problem with finding and building own solutions is that we tend to lose interest in them really fast and then leave them behind as we already another complex problem to simplify. This leads to lots of half-finished solutions on the web that don’t get any love any longer.

Unmaintained code is a security problem

All the code that is not getting any love stays unmaintained on the web and becomes a wonderful attack vector for new security threats or vulnerability exploits. Nothing beats being up-to-date when you want to build secure systems.

Things web developers must know to do their job.

Looking at our job as web developers, here are the things you have to be aware of to build things that people can use.

  • The technologies involved
  • How browsers deal with these technologies and how they fail to support them
  • Security concerns and attack vectors
  • Usability and accessibility of the product
  • Internationalisation of our products
  • Performance concerns
  • Multiple platform support
  • Flexibility of the interface

Browsers suck

Browsers are the bane of our existence as they are unpredictable, unreliable, there are hundreds of them (in various configurations) and they are not being updated by people out there.

That is a lot to know and deal with. The good news is that you don’t need to know all of it.

Good developers are like librarians

Librarians are great people. Instead of knowing everything that is in the library they know exactly where to find the information to solve a problem. As a cleverly lazy developer you should do the same.

Build on a solid foundation

Web development libraries came around for one simple purpose: Make our life as developers easier and our work as web developers predictable. They make browsers suck less and work around differences in browsers. They allow us to use web standards and get results instead of bugs to fix.

Build with components

If you build web applications and interfaces take a look around for what has already been created for you. Almost every library comes with widgets that are tested, work for everybody regardless of ability and can be changed to your needs. If you build your own component you are very likely indeed to forget some very necessary functionality that a collaborative product already had put in.

Use a good debugging environment

You can’t write great products without being able to know what is going on. Luckily enough nowadays we have great debugging tools like Firebug, Yahoo Profiler, JSLint and validators of all kind.

Plan for extensions

If you build a solution, plan a way so that people can extend it without having to change the central code. The central code should only have to change when there is a new browser or platform to be supported or there’s a security fix. Other than that people should be allowed to extend by listening for events or using other API hooks into your product.

Read, use and write documentation

If you build something, document it. There is no such thing as code that explains itself, that is a myth and an arrogant one at that.

Use the web

One of the really cleverly lazy things to do these days is to use the web to build your product rather than building your product and putting it on the web. Distribute your content on specialised systems like Flickr, YouTube, Delicious and LinkedIn and then put it together in a centralised CMS. That way your site will be easy to maintain and not vulnerable to a single point of failure.

Use APIs

To achieve this you need to use APIs. APIs can take a lot of your time to read up on and understand which is why it is a good plan to use YQL as an in-between to avoid going crazy on authentication and understanding what parameters go in and what data comes out.

An example

As an example, let’s take a look at a web site built solely from data on the web, using YQL and PHP.


Thank you, remember if you use what is out there you have time to be creative. I want us to write code most of our time, not to fix bugs.