Friday, October 28, 2011

App Dev Hackathon

I met a bunch of Android developers at the AT&T Mobile Hackathon SF, who told me about the App Dev Hackathon at Santa Clara today. Since I had such a great experience at the AT&T one, I decided to attend.

Sponsors and Prizes

Same as last time, there was a list of sponsors and prizes:

  • Tropo: Amazon Kindle for all members of a winning team that uses the Tropo API in their application.
  • Pioneer: $1000 cash for the best mobile app using the Zypr API.
  • appMobi: Amazon gift cards to the most interesting apps using appMobi's SDK. $150 for 3rd place, $350 for 2nd place, $500 for 1st place.
  • iPad2 for the best use of the Box API.
  • immersion: 5 $100 gift cards awarded to the team that makes the best use of the appMobi plugin.
  • Rovi: Two $500 Amex gift cards for best apps using Rovi APIs.
  • Sierra Trading Post: Use the Sierra Trading Post API. $1000 cash + 5x$100 Sierra Trading Post gift cards for best app, $250 cash + 5x$50 Sierra Trading Post gift cards for most creativ app.
  • Crittercism: Use Crittercism SDK. Top prize: Kindle Fire. Runner up: Automatic Nerf Gun.
  • HTC: Best app with the pen api wins the AT&T Jetstream tablet.

Guess I got lucky, since I have two existing apps that play very well with two of these APIs.

Dr Mila

A few months ago I went to SuperHappDevHouse and wrote an email gateway to Freebase. The idea was that when I travel, I often need to look up something when I don't have internet: an artist from the magazine on the plane, a signpost on the road to a tourist spot, etc. I wanted a way to queue up my queries to run when I got to a wifi spot, and it occurred to me that my email outbox is the perfect solution. All I need is a server that can read email, search the internet, and reply with the results. The email client will take care of the queuing, fetching, and offline storage. So I coded that up in an afternoon, and named it Dr Mila, with Mila being an anagram of mail.

The email gateway works this way: you send an email to with your query as the subject line, and Dr Mila replies with information from Freebase, sending images as attachments. I wanted to use Tropo to add an SMS gateway to the service.

At the presentation Tropo mentioned that if all I needed was SMS, I should use some other service instead. I didn't catch the name, so I went to their table right away. The "other service" is Smsified, also provided by Voxeo, the parent company of Tropo.

I managed to receive SMS pretty easily, but sending didn't work. Back to the table, and Adam from Tropo debugged it with me, using curl. And it didn't work because I did not provide any authentication. I was wondering about that when I was following the instructions from the message sending documentation. Turns out authentication was covered in Overview, but of course I jumped right into the section that interested me, and missed it. Not a big deal, it was very easy to fix once I knew what I needed to do.

In my first test I just sent the whole article from freebase, and got maybe 12 SMS as a result, because it exceeded the 140 character limit. As a quick workaround I took the first sentence from the description. Most articles have the first sentence as the summary, so that worked pretty well.

Movie Jot

I finished adding SMS to Dr Mila around 1:30pm, so I decided to work on my second app, Movie Jot. The idea is that I want to take advantage of html5 offline storage to quickly record something, and look it up on the internet later. The keen reader will notice that both Movie Jot and Dr Mila share the same offline theme, which is not a co-incidence. I am rather frustrated that most apps assume that my device is always connected to the internet. I decided to target specifically for movies since my friends often mention interesting movies at dinner, and I just want to quickly jot that down instead of spend 3 minutes looking it up on the internet right away.

I had a working version of Movie Jot, powered once again by Freebase. Since rovi has a nice DVD database, I thought I would change the backend to point to it instead.

As I was loading up the rovi documentation, someone tapped on my shoulder. He saw my screen, and wanted to introduce himself since he was from rovi. I took the opportunity to tell him what I wanted to do, and he gave me a quick rundown of generating md5 signatures for the API, and how to fetch images and synopsis. That saved me quite some documentation searching time. I put everything together, and was rather pleased to see that the synopsis quality from rovi was quite a bit higher than freebase.

Sierra Shake

I was done with Movie Jot at around 4pm, and took a break to talk to people around the hall. We had until 6:30pm to enter our apps for demo, and since I heard so much about quick development on appMobi, I decided to give it a shot. I tried to get the XDK, but made the mistake of clicking "Deny" when it wanted to access my hard disk. I went to the appMobi table and they helped me by running javaws -viewer and deleting the appMobi entry so I could restart.

Once I had the XDK up and running, I just stared at it, looking for a place to type my code. Finally realized that the XDK was like the browser, and you use a separate editor to write the html and javascript. Once I realized that I was able to code up my app pretty quickly. Since I didn't have a lot of time, all I did was use the Sierra Trading Post API to display a random product when you shake the phone. Actually I didn't even have time to implement the shake detection, so I just hooked a click event on an empty area to trigger the fetch.

Even though I wrote a rather silly app, I got a chance to see the whole appMobi tool chain, which was quite interesting. It was a Chrome extension that uses Java to access your local file. To test on the device, you download an Android app called applab, and use the mobile browser to authenticate and load the app you want to test. Pretty neat.


The organizers did not set up a projector for demoing on the device, so it was a little bit tricky. I used the Google Voice interface to show the SMS messages for Dr Mila, and passed my phone around for the judges to test. One of them entered "tears" as the query, and Dr Mila replied with "Tears are the secretions of the glands that clean and lubricate the eyes." Not bad. Movie Jot is an html5 app, so I just demoed it on Chrome on my laptop. For Sierra Shake, I used the XDK, which sufficed.


Turns out Movie Jot was the only app using rovi, so I won the prize. It wasn't really a competition when there were no competitors, but hey, I am not complaining. I also won a iPod nano from Tropo, which I didn't even know was on the prize list. Again, not complaining at all.

The only complaint I have for the event was that the tables were way too high for a small person like me. Maybe I should bring a cushion next time. But that's going a bit overboard, no? I already brought a salad for dinner since last time I was starving at the SF hackathon. At this rate I would be lugging along my whole house!

Further reading: See all the winners at the official blog post

Monday, October 24, 2011

AT&T Mobile Hackathon SF

I have not been doing Android development for a while, and decided to get my feet wet again by signing up for my very first hackathon. Most hackathons last until the wee hours of the night, so I was rather excited to find one that was scheduled for 10am to 8:30pm, when I am normally awake. It was the AT&T Mobile Hackathon in San Francisco on October 22, 2011.


Since it was a mobile hackathon, I knew I was going to be coding either in Android or html5. Last time I did any Android development was more than a year ago though, so I downloaded the latest SDK and updated my Eclipse setup. I then read through the email from the organizers to see if there were any rules. I didn't see any, because the email mostly consisted of the list of hot sponsored prizes:

  • Tons and tons of Apple Gift Certificates for the top 3 teams, provided by AT&T and Apigee
  • Top hackathon team (yes, the entire team) will receive AT&T Mobile Hotspot Elevate devices (wifi pucks) with 1 month of free service courtesy of Sierra Wireless
  • $200 Gift Certificate for Best App Built with Apigee OAuth API
  • Amazon certificates for Best App Built with the YP API
  • The top two apps built with the HTC OpenSense SDK's Pen API will get two exclusive new AT&T Jetstream tablets
  • Top two apps which leverage the Galaxy S2's GPU the best (can be GPU tweeks for exisiting games) - Two (2) Galaxy S2 - Sponsored by ARM
  • Top app built with ARM NEON instruction API - ODROID - Sponsored by ARM

The sponsored prizes really reminded me of Iron Chef. The secret ingredient was the API, and the dish was the app. Of course you can also just write any mobile app without using the sponsor APIs, but I thought it was much more fun to compete with a common ingredient. Though I wasn't sure how anyone was going to build an app with the ARM NEON instruction API just like that...

Tables and Talks

I took the Caltrain up, and arrived quite a bit earlier than 10am. They were still setting up the breakfast area and the sponsor tables when I got there. Since I ate already, I went to check out the different sponsors. The HTC table really caught my eyes with their gadget - the new JetStream tablet. Michael from HTC carefully unwrapped one from his towel (!) and showed me the cool apps using the pen. I was hooked, and decided then and there that I my secret ingredient would be the pen api.

As more participants showed up, we were ushered into a big conference room, where the organizers explained the schedule for the day. Each sponsor then gave a quick overview of their api, before we broke for lunch.

Environment setup

With a plate of Mediterranean food in my hand, I looked around for a nice table to set up shop, and stumbled upon a conference room with a few other developers who were already looking at the HTC pen api. Perfect.

My home for the day. Picture by @htcdev

First order of business: get an emulator running with the pen api enabled. The HTC dev site has instructions with screenshots, but unfortunately the Ice Cream Sandwich UI was rather different, so it took me a while to figure out how to give it my downloaded zip files. Even more unfortunate, I could not create an AVD even after importing the HTC add-ons! I asked David from HTC for help, and he had the exact same problem. Perry, a fellow hackathon participant, got an AVD created before he upgraded to Ice Cream Sandwich, so David and I decided to blame Ice Cream Sandwich.

Assigning blame made me feel better, but did not actually address the problem. I was going to beg David to let me develop directly on the device, but then I got this brilliant idea - I could just copy the AVD from Perry! Armed with a USB thumb drive, I obtained the precious AVD files, and voila! Emulator up and running.

Next task: try out the demo projects that came with the pen api add-on. This was when hacking with others really helped, since someone in the room already tried running the demo projects, and found out that only the compatibility demo worked. That saved me the trouble of running into dead ends.

The idea

Finally I was ready to hack out my app. With the pen api as my secret ingredient, I thought it would be natural to use it to write. Not just write anything, but write Chinese, since I still don't type Chinese very fast. But then I realized that not everyone knows Chinese, so hey, I could build an app to teach people to write Chinese! The idea was simple enough for a day's work - load a Chinese character in the background, use the pen to trace it, and when you are done, hide the character so you could see what you actually wrote.

Technical hurdles

The compatibility demo has code for converting onTouchEvent into lines on a SurfaceView, so my little app was already capturing the pen strokes and drawing them on the screen. I thought I would just wrap the SurfaceView with FrameLayout and stick in a view underneath to display the Chinese character. Alas, not so simple, since you cannot put anything beneath a SurfaceView. I brought my problem to Leigh from HTC, and she casually commented, "couldn't you just draw the background directly on the SurfaceView?" And I said, "you're right!", and rushed back to code some more.

At this point the inevitable happened: the wifi stopped working. With so many contests accessing the net at the same time, I was not surprised. My app did not actually need the internet, but to code it, I need access to Android documentation. I wished I downloaded the documentation when I was at home! Oh well. Stephan, who was sitting to my right, just calmly pulled out his tether device and moved on. Now that's what I call prepared! Fortunately we were sitting in a conference room, and I noticed ethernet cables coming out of the phones in the middle of the table. I grabbed one, plugged it in, and phew, it was connected. Back to business again.

The rest of the app was relatively straight-forward. Initially I used drawText for the background Chinese character, but the default font was really ugly. I didn't have time to figure out how to include a prettier font, so I took a shortcut and just displayed an image of a beautiful Chinese character.


By now it was 6pm, and I had a working demo. But it didn't really use the pen api. Yes, you could use the pen to trace the character, but you could also use your finger. We need to submit our app by 7pm, so I didn't have a lot of time. I decided to use the pressure from the pen to vary the stroke width, and started pouring over the HTC documentation. Not sure if I was stressed or what, but for the life of me I just couldn't find the function to get the pressure. I asked David from HTC for help. He couldn't find the function in the documentation either, but had some unpublished sample code, so once again I whipped out my USB thumb drive and got some precious files. The function turned out to be dead simple: it was just event.getPressure() from the MotionEvent. I added that to my app, and spent the rest of the time tweaking the numbers to make the strokes look alright.

Show time

At 7:30pm we all went back to the big conference room for demos. I was the second in line to present, and gave a pretty short demo. But people seemed to like it!

There were a lot of interesting apps, and I was rather impressed by the work everyone managed to do in a day. It took an hour for everyone to demo, and then the judges got together to vote. Afterwards, it was the announcements. They first announced the overall winners. I was very pleasantly surprised when they called out "Calligraphy" for first prize! They tagged on to say that I was also one of the two winners for the pen api category. Double happiness!

Winners of the pen api contest. Bruce from HTC brought giant zucchinis as prizes!

During the day someone from Microsoft developer relations was going around asking people to fill out a survey. They would raffle out two people to win an XBox 360 with Kinect, and they announced the results at the end. As luck would have it, I was one of the winners! Beginner's luck, I suppose?

The organizers and sponsors were quite generous, and gave out a lot of prizes. More at the AT&T Developer Program Blog.

Parting thoughts

I had so much fun at my first hackathon. Working side by side other developers was really nice, and have direct help from the API publishers made the process much smoother. If are were sitting on the fence, I definitely recommend going to one.

Here are a few things I learned:

  1. Assume that the internet will stop working at some point, and download the SDK/documentation beforehand.
  2. Sit with people working on similar projects. The cross pollination is amazing.
  3. Don't be shy to ask for help. People are super friendly, and you don't really have a lot of time to repeat mistakes anyway.

A big hand for the organizers and sponsors! Thank you for this very fun event. I especially enjoyed working with the HTC team.

Last but not least, some pictures of my loot :-)