Thursday, June 25, 2009

iPhoto Faces Awesomeness

I've been using iLife '09 since it came out. I've made heavy use of its integration with Facebook and Flickr. One of the features that I've wanted to experiment with is Faces. This is face recognition technology. Using it is simple. You have to train it by taking a few pictures and telling iPhoto who are in those pictures. This is very easy. Look at a picture, click on the "Name" button, and iPhoto immediately recognizes the faces in the picture. There is a little text box next to each face, and you just type in the name. It remembers previously typed names or names from your Address Book, so there is usually very little typing to do. Obviously the more training you do, the better the results that iPhoto will have.

Despite this being so easy, I've been too lazy to use this. Until now. I was importing a handful of pictures taken with my iPhone. These were mostly pictures of my boys playing and being goofy. Here is a picture of Michael, Jr. (age 5):

And here is a picture of Raymond (age 3):

Now the reason that I show the pictures and mention the ages will become obvious momentarily. Back to the narrative. After tagging my kids in these pictures, iPhoto was ready to show me other pictures with the same faces. The very first one that it showed me nearly made me cry:

Yes that is my oldest son. He was just six months old in that picture. The pics I used to train iPhoto were all very recent. It was really cool that it recognized his face, even though he certainly looks a lot different today than he did four and a half years ago. Similarly, iPhoto served up this gem for Raymond:

Monday, June 22, 2009

Buyer Beware: ProFlowers

Last month I was in Israel for three weeks. These three weeks included the date of my anniversary. I still wanted to do something nice for my wife on our anniversary, so I decided to send her flowers. I used a company that I had seen an ad for ProFlowers. While I was checking out, they gave me an offer for $15 off my order. All I had to do was fill out a survey, which I did. As part of this process I agreed to sign up for a service called EasySaver. Joining was oh-so easy as ProFlowers shared my credit card information with EasySaver. Of course EasySaver then starts charging me $15 per month for membership.

Now I was clearly stupid for falling for something like this. I was quite embarassed when my wife noticed the charges on our credit card. Luckily we only got nailed for May and June. Anyways, clearly my fault. However, I really hate shady operations like this. I will never use ProFlowers again. As far as I can tell, EasySaver is completely worthless anyways. Hopefully other folks will be smarter than me and not fall for scams like this.

Thursday, June 18, 2009

Scala and Android

Recently I was working on an article for developerWorks about using Scala on Android. Stay tuned to developerWorks to see that article. Since then I have started a little side project to create a set of Scala libraries for working on Android. Now you may ask, why bother with this? Is this just a classic case of mental masturbation? Well, no, at least I hope not.

I think Scala is well suited as a programming language for mobile devices. I am not an expert on all mobile platforms, my experience is mainly around iPhone and Android development. For the iPhone you are developing in Objective-C, and for Android in Java. Now in general, I think the Android development environment is superior in almost every way to the iPhone. IDE is mostly a matter of taste, but Eclipse+ADT certainly has a lot more features than XCode. Debugging is definitely better on the Android. It is much easier to debug on a device, and the emulator gives you more ways to vary the environment (cpu/memory/network resources) for more realistic emulation. The only thing advantage I would give to iPhone is that XCode and the iPhone emulator both startup much faster than Eclipse and the Android emulator.

Programming in Java gives you a lot more options than Objective-C. There are just a lot more open source Java libraries out there to help you avoid reinventing wheels. In addition, I think the platform specific APIs added by Google are much better than the ones on the iPhone. A simple example is XML processing. Java and Objective-C both already have XML parsing APIs. However, Android adds extra APIs as they recognize this as a common task for mobile applications that leverage web services. They added convenience APIs for SAX based parsing. They also leveraged a StAX-style parser by leveraging an Apache project. There is nothing like this in iPhone, despite the fact that the iPhone has been around longer and should be more mature. It may be an oversimplification, but I think this comes back to the corporate cultures that produced these platforms. Apple has always been a company that uses software to sell hardware, and this continues with the iPhone. Google is much more of a software company, with strong ties to open source software. It should be no surprise that Android is a much more development friendly platform. And don't even get me started when it comes to garbage collection (Android has it, iPhone does not, despite the fact that Objective-C 2.0 has it.)

So Android is great, why do we need Scala? First there is verbosity. Actually both Objective-C and Java are quite verbose -- Objective-C is even more verbose than Java. Scala is a much more concise language than either. Objective-C can actually be more dynamically typed than Java/Scala, but this rarely makes the code any more concise or readable, and often makes it harder to debug. Next, neither Objective-C or Java have much support for functional programming. This is a bigger deal than you might think at first. UI frameworks are full of events that you must write code to handle. Writing a function to handle those events is so much easier than writing a class. On the iPhone you can often set any type of object as an event handler, and you just have to know the magic methods to implement. On Android, you usually have an interface to implement, and that interface has a single method. This is actually better than what you do on the iPhone, but the interface and its implementation class are both classic cases of boilerplate.

Thus it is my goal to make it possible to write Android applications in a much more concise way by using Scala. In general, you can replace Java code with Scala that is much easier to read and understand. I think this will be especially true on Android, and the contrast will be even more true.

The last reason that I think Scala is a great language for mobile development is threading. Both iPhone and Android support multi-threading, as any UI framework must. Any good UI will perform any non-trivial operations on a background thread, to keep the main UI thread responsive to the user. However, threads are tricky, especially this kind of multi-threading. Updating your UI from a background thread is a recipe for disaster. Android enforces this by using a Handler on the main thread that your background threads send messages to. If you are familiar with Scala then message passing as a way to implement multi-threading should ring a bell. This is exactly how actors work in Scala. I haven't tried using Actors on Android yet, but it sure seems like a good fit.

So there is some of the motivation. I think Scala on Android could be really compelling. My side project is pretty small so far: a handful of wrapper classes and implicit conversions to bring some syntactic sugar and functional programming into the mix on some common Android classes. The project also has a special build of the Scala library that I found necessary to get the library to work on Android and its compiler. I am hoping to add more sugar and to add the actors ideas listed above. I am also hoping to come up with a nice way to integrate something like Proguard to optimize the bytecodes that get compiled for Android.

Tuesday, June 16, 2009

HTML 5: Don't Believe The Hype

In case you haven't heard, HTML 5 is The New Hotness. I have been watching this tide rising for awhile. There have been many skirmishes between The Unite Emirates of JavaScript and The Kingdom of Flash over how plugin technologies were going to be made obsolete by HTML 5. To hear some folks talk about the future of HTML 5, it is a veritable morality play. HTML 5 is all about the nobleness of open source and open standards. It is democracy and freedom. Everything else is closed and tyrannical.

Things really took off a few weeks ago at Google's IO conference. GOOG officially put its chips in the HTML 5 pot. This should not have been a surprise, as Google has invested in improving browser technology first through Gears and then through its own browser, Chrome. Of course Chrome actually uses the now ubiquitous WebKit for its rendering engine. This is at the heart of not only Apple's Safari browser, but also the mobile browsers on the iPhone, Android, and Palm Pre. Google used the "standardization" of WebKit on mobile devices to deliver mobile versions of GMail and Calendar thus punting on native applications.

So HTML5 is the future, right? Not so fast. I know it seems this way to a lot of people, especially the emphatic fans of open standards. However, those guys live in a different world than I. In the world I live in, browser fragmentation is at an all-time high. In a world of fragmentation, standards are an amusing concept. If history has taught us anything, it is that standards are set by whoever has the most users.

This has long been a source of pain for Google and others. In all fairness, IE8 implements some of the HTML 5 features, but not all of them. Also, the IE family of browsers has been losing share for several years. However, it is going to be awhile before web developers can forget about IE6, not to mention IE7. Given the update cycle of IE in the past, we can expect the older versions to stick around a long time before IE8 finally becomes the king. Again it does not even implement all of the highly touted HTML 5 features. Maybe more will be supported in IE9? How long before that becomes the dominant browser?

My point is that if you want to hitch yourself to HTML 5, you are not hitching yourself to Firefox, Safari, and Chrome. Well ok, you can hitch yourself to those browsers (or IE+Gears), but you are saying go away to 60-70% of the world. So assuming you don't want to do that, then hitching your app to HTML5 means hitching your app to future IE adoption. That just seems like a scary proposition to me.

But what about mobile devices? Here things are clearly better. Again the standards are set by the dominant player. WebKit is the dominant technology in high-end mobile browsers. Still there is fragmentation. The exact same APIs do not work on Mobile Safari as on the Android browser (don't know about the Pre.) Thus you may have to do some abstractions to smooth over the differences. Oh wait, that is starting to sound a lot like the situation with desktop browsers... Anyways, many HTML 5 features are present on the iPhone and Android browsers, so you have much more latitude to use them. However, there is another, more important question to answer when considering going down the path of GMail/Calendar on the iPhone/Android. Can a browser based be as good as a native app? Probably not, but maybe it's "good enough." However, I have to wonder, how many GMail users use the GMail web app on their iPhone instead of using the native Mail application? The GMail web app gives you all of the features you are used to, like conversations, labels, stars, and awesome search. The native Mail app provides none (or at best much weaker implementations) of this, but yet I would guess that most people still prefer it over the web app.

Sunday, June 07, 2009

Scala Concurrency

I got to see Scala creator Martin Odersy speak twice last week. First time was at the June BASE meeting, and the second was at the Scala LiftOff. At both meetings, he stated that he wants Scala to be the best language for concurrent programming. He also mentioned two types of concurrency. One is the type you hear about most often, where processes work in parallel and need to simultaneously affect some shared data or global state. This is the kind of problem that becomes hard to deal with using primitives common in Java and C++, but can be a little easier using Actors in Scala. The other kind is where a big process needs to be split up into smaller ones that can be run in parallel. It wasn't clear to me if Actors were a good fit for this or not, or maybe improvement is needed. So I decided to experiment with this.

I took one of the algorithms I wrote for my JavaOne talk on language performance, and I used Actors to do some processing parallel. In my original "driver" code, I took a list of files and sequentially passed each file to the sort class. In the new code, I created an Actor to pass the file to, and the Actor then fanned out the processing to an internal list of Actors that could sort the words in the file. When sorter Actors finish, they send back the results to the "master" Actor. Here is the code:

// messages
case class FileToSort(fileName:String)
case class SortResults(fileName:String, words:List[String])

class WordSortActor(master:Actor) extends Actor{
def sortedWords(fileName:String) = {
val dataFile = new File(fileName)
var words:List[String] = Nil
_.split(" ").foreach(words ::= _))
words.sort(_.toLowerCase < _.toLowerCase)
def act {
loop {
react {
case FileToSort(fileName:String) => {
println("Sorting file = " + fileName +
" on thread " + Thread.currentThread.getName)
val words = sortedWords(fileName)
master ! SortResults(fileName,words)
// why doesn't sender work instead?
//sender ! SortResults(fileName, words)

class SortMaster(docRoot:String, numActors:Int) extends Actor{
var sorted : List[List[String]] = Nil
var workers:List[ScalaWordSort] = Nil
var latch:CountDownLatch = null

def beginSorting {
workers = (for (i <- 0 until numActors)
yield new WordSortActor(this)).toList
val dir = new File(docRoot)
var cnt = 0
dir.list.foreach(file =>{
workers(cnt % numActors) ! FileToSort(docRoot + file)
cnt += 1
latch = new CountDownLatch(cnt)

def waitUntilDone = latch.await

def act {
loop {
react {
case SortResults(fileName:String, words:List[String]) => {
sorted ::= words
println("Received results for file=" + fileName)

So I don't know if this is a good use of Actors or not. Seems like you might need to tune the number of threads in the thread pool sitting behind the pool of Actors. It seems like the pattern might be useful. It takes advantage of Actors for combining the results done in parallel. The results of each sort are sent back to the master, who could then do useful things. In this example, it only dumps the results into a list, but you could imagine some kind of coordination, like adding to a map, that would require locking in a typical Java implementation.

One other strange thing, in the WordSortActor, I tried to send the results back to the sender, but this did not seem to work. I had to keep an explicit reference to the master Actor, and then it worked fine. One other annoying thing that came out of this little exercise ... I discovered how hard it is to debug Actors. I was using IntelliJ, and it was completely useless to set a break point in an Actor. This is not the case with Java threads. I did not try Eclipse or NetBeans.

Friday, June 05, 2009

JavaOne Talk: Performance Comparisons of Dynamic Languages on the Java Virtual Machine

Below are the sldies. Major thanks to Charlie Nutter for great feedback and advice on the Ruby code and tuning JRuby performance. Thanks to Chouser and Timothy Pratley for help with the Clojure code. And major thanks to Brian Frank for help with the Fan code.

JavaOne Talk: RIAs Done Right

Thursday, June 04, 2009

Liveblogging of Scala Actors Talk from JavaOne

Today I was attending a talk on Scala Actor by Phillipp Haller and Frank Sommers. Tyler asked me to live blog it. I thought that was a good idea, and that Twitter would be the way to do it. This did not work out, as Twitter shut me down for too many tweets in a given hour. So now I am posting the full live blog, both the tweets that went through and the ones that Twitter rejected. However, pulling out the text of all of the good tweets is not totally straightforward. I figured the easiest was to do this was to use some Scala with the Twitter API via the REPL:

scala> import

scala> import scala.xml._
import scala.xml._

scala> val url = new URL(" =

scala> val conn = url.openConnection conn: =

scala> val tweets = XML.load(conn.getInputStream) tweets: scala.xml.Elem =

scala> (tweets\\"text").foreach{ node => println(node.text) }

The result of the last call produces the following:

This allows for many more actors than worker threads #javaone
Work stealing makes this even more efficient. Let worker threads steal work from other worker threads #javaone
So decouple from threads using thread pools from java.util.concurrent. #javaone
A naive impl of thread-per-actor has overhead from thread creation, context-switching and memory use. #javaone
How event-based actors decouples threads and actors. How the execution enviro is setup. How the DSL works #javaone
Now time to go under the hood of Scala Actors #javaone
Only use receive when you must return a value from an Actor #javaone
Use react whenever possible and only use receive when necessary #javaone
When to use receive vs. react? #javaone
Replace while(true) { ... } with loop { ... } #javaone
Go from 5,000 actors/JVM to 1,000,000/JVM using event based Actors #javaone
Replace receive with react, receiveWithin with reactWithin, and while(condition) with loopWhile (condition) #javaone
To scale to a large number of Actors, go for event based Actors #javaone
The sender of a message is still sent across the network #javaone
Everything else works exactly the same as it would for local actors #javaone
Use the select function to get a proxy to the remote Actor #javaone
To make an actor remote is very easy. Call the alive function and the register function #javaone
So far everything has been within a single VM, but Scala Actors scales using remote actors #javaone
To specify timeouts, use receiveWithin. This takes a timeout and sends a TIMEOUT message #javaone
All of this makes it easy to keep track of subscribers and send them messages, like new chat messages #javaone
You can also wait for futures using receive function #javaone
When you try to access the future, it will then block if the reply has not been received #javaone
For async with assurance that the message was received using double-bang !! Returns a future representing the reply #javaone
Synchronous messages are allowed too using !? This blocks until reply received #javaone
Bang is asyc, returns immediately and passes a reference to the sender #javaone
To subscribe a user to the chat room, just send a message using the "bang" operator (method): ! #javaone
There is another API shortcut for creating an actor inline using the "actor" function #javaone
Creating a subscription is just a matter of sending message stating as much. Lets recipient capture the state #javaone
Common pattern of "child actors", benefits from asych communication of actors #javaone
Make each user an Actor as well to maintain state, such as who sent a message to the chat room #javaone
Now going back to the chat application to demonstrate Actor subscriptions #javaone
Patterns are tried in order, and the first match wins. No fall-through. Looks like a factory method call. #javaone
This is all based on Scala's pattern matching, think Java's switch statement but on steroids #javaone
If no message in mailbox, the actor will suspend until there is a message. Syntax for matching messages is super simple #javaone
Use the receive function to process messages within the act method of your Actor. Receive gets a message from the Actor's mailbox #javaone
Defining messages is made easy by using Scala's case classes. These are pure data classes typically. #javaone
Creating an actor is very similar to creating a thread in Java. #javaone
Creating an Actor is easy, just do 3 things. Extend Actor. Implement act method. Start the actor. #javaone
Frank showing a chat application architecture that uses Actors "the quintessential Actor system" #javaone
Actor implemented entirely as a DSL, but part of Scala std. library. Used in big systems such as Twitter #javaone
Actors can be local or remote, no change to programming model. #javaone
Actors are event based in Scala, not tied to Java threads. So much more lightweight. A single JVM can have millions of actors #javaone
Actors use several Scala language features: pattern matching, closures, traits/multiple inheritance, and Java interop. #javaone
Actors in Scala are probably the closest implementation of Erlang model on the JVM #javaone
OTP: library of Erlang modules for building reliable distributed systems #javaone
Erlang has support for Actors built-in. Erlang VM is process-oriented, makes Actor model very scalable. #javaone
Best known example of Actors though is from Erlang, "a pure message passing language" #javaone
Actors are an established pattern. Research dates to 70s at MIT in Smalltalk and Simula #javaone
Mutable messages are also possible. Actors can also be local or remote -- same programing model #javaone
Actors share nothing, private state. Thus no synchronization. Actors send messages, but the message are immutable #javaone
Actors are active objects and has a mailbox. Actors consume messages, perform actions but the code is sequential within an actor #javaone
There is an existing concurrency model that fits with the described solutions: Actors. #javaone
The solution: DSL + sequential programs. Shared nothing. Message passing. Asynchronous communication #javaone
Why learn about Scala actors? Concurrency presents opportunity and problems for developers, especially large teams of developers #javaone
Frank and Phillip are writing a book on Scala actors #javaone
Phillip Haller and Frank Sommers talking about Scala actors now #javaone

So that's the good tweets. Here are the ones that did not go through...

The actor method takes a closure creates an Actor
The react method saves pattern matching as a closure to be executed later
Uses exception for control flow, any code after react will not execute
Actors usually execute on different threads, but you can control what threads
This is useful for threadLocals and for Swing
A demo of SwingActor
Example of using link and trapExit, but not much detail of this shown
Scala Actors provide a simple programming model to write concurrent code on the JVM
Many projects already use actors: Twitter, Lift, Scala OTP (@jboner), partest
Future of Scala Actors in 2.8
Pluggable schedulers -- create actors with daemon-like behavior for example
Integrating exceptions and Erlang-style error handling. Get the best of both Java and Erlang error handling
Support for continuations. Currently requires optional compiler-plugin. Allows for more flexible control structures
Actor migrations (from machine to machine) could also be done with continuations
More static checking of messages, in particular an @immutable annotation
Actor isolution -- no accidentally sharing mutable state
This will allow for better passing mutable messages for performance benefits
No problem passing large methods, as they are passed by reference