Archive for October 2008:

Thoughts on Google Chrome

I admit it, I am a fan of the new Google Chrome browser.

This made me chuckle, however:
Google vs Microsoft ... ?

Is Google preparing to dominate the world ?


Making The HTC Touch Diamond Vibrate

One of the minor problems I had when making the Stopwatch for my HTC Touch Diamond, was to make the phone vibrate automatically. It seems there are no managed way of doing this. However, after a bit of googling around, I found out that the vibrator typically can be addressed as a LED object using the Open NET CF Framework. So I decided to throw together a tiny wrapper class around this functionality, so I can use it generally in the future. The most useful thing here, I think, is the ability to have the phone vibrate using a given on-off pattern in a fire-and-forget pattern that works well when programming Compact Framework forms.

This is the simple Vibrator class:

         1: using System;
         2: using System.Threading;
         3: using OpenNETCF.WindowsCE.Notification;
         4:  
         5:  namespace dr.WM.Common
         6: {
         7:     /// <summary>
         8:     /// Vibrator class. Works on HTC Touch Diamond, not tested anywhere else.
         9:     /// (Mostly, The LED index could be different on other devices.)
         10:     /// </summary>
         11:     public class Vibrator
         12:     {
         13:         /// <summary>
         14:         /// Index of the Vibrator LED.
         15:         /// </summary>
         16:         private const int VibratorLedIndex = 1;
         17:         /// <summary>
         18:         /// LED instance.
         19:         /// </summary>
         20:         private readonly Led led = new Led();
         21:         /// <summary>
         22:         /// Whether the Run thread is allowed to run.
         23:         /// </summary>
         24:         private bool allowRun = false;
         25:         /// <summary>
         26:         /// Starts this instance.
         27:         /// </summary>
         28:         public void Start()
         29:         {
         30:             allowRun = true;
         31:             led.SetLedStatus(VibratorLedIndex,Led.LedState.Blink);
         32:         }
         33:  
         34:         /// <summary>
         35:         /// Stops this instance.
         36:         /// </summary>
         37:         public void Stop()
         38:         {
         39:             allowRun = false;
         40:             led.SetLedStatus(VibratorLedIndex, Led.LedState.Off);            
         41:         }
         42:  
         43:         /// <summary>
         44:         /// Starts a vibrating sequence by specifying the vibrate and pause times.
         45:         /// Vibration will run until the Stop method is called.
         46:         /// </summary>
         47:         /// <param name="msVibrate">The vibrate time in milliseconds.</param>
         48:         /// <param name="msPause">The pause time in milliseconds.</param>
         49:         public void StartSequence(int msVibrate, int msPause)
         50:         {
         51:             StartSequence(msVibrate,msPause,0);
         52:         }
         53:         /// <summary>
         54:         /// Starts a vibrating sequence by specifying the vibrate and pause times.
         55:         /// Vibration will run for the specified total time, or until the Stop method is called.
         56:         /// </summary>
         57:         /// <param name="msVibrate">The vibrate time in milliseconds.</param>
         58:         /// <param name="msPause">The pause time in milliseconds.</param>
         59:         /// <param name="totalLength">The total time to vibrate.</param>
         60:         public void StartSequence(int msVibrate, int msPause, int totalLength)
         61:         {
         62:             allowRun = true;
         63:             ThreadPool.QueueUserWorkItem(Run,
         64:                                          new RunState
         65:                                              {VibrateTime = msVibrate, PauseTime = msPause, TotalTime = totalLength});
         66:         }
         67:  
         68:         /// <summary>
         69:         /// Thread worker for a vibrating sequence.
         70:         /// </summary>
         71:         /// <param name="state">The state.</param>
         72:         private void Run(object state)
         73:         {
         74:             long begin = Environment.TickCount;
         75:             RunState runState = (RunState)state;
         76:             while(allowRun && (runState.TotalTime <= 0 || Environment.TickCount - begin < runState.TotalTime))
         77:             {
         78:                 led.SetLedStatus(VibratorLedIndex, Led.LedState.Blink);
         79:                 Thread.Sleep(runState.VibrateTime);
         80:                 led.SetLedStatus(VibratorLedIndex, Led.LedState.Off);
         81:                 Thread.Sleep(runState.PauseTime);
         82:             }
         83:         }
         84:  
         85:         /// <summary>
         86:         /// Helper for passing vibration state to the worker thread.
         87:         /// </summary>
         88:         private struct RunState
         89:         {
         90:             public int VibrateTime { get; set; }
         91:             public int PauseTime { get; set; }
         92:             public int TotalTime { get; set; }
         93:         }
         94:     }
         95: }

Please note that this might (propably) will not work on other devices, since the vibrator might not be on the same LED index. One could refactor the class and make a couple of vibrator on/off virtual protected methods, and call these from the Start / Stop methods. That way, it could be easy to make the class general enough for use on other devices, you would just need to implement the start and stop operations. However, there might be an easier way of doing this using an unmanaged API (actually I hope there is, since collecting info about all types of devices in order to figure out how to fire the vibrator, seems as an unfeasible task).

It seems that the Klaxon Open-Source alarm clock for Windows Mobile has just been made Open Source. I think I will have a look at the source to see whether my way of using the vibrator is feasible, or the Klaxon author uses a better approach ;-)


A Stopwatch for Windows Mobile

I have got a new mobile phone, a HTC Touch Diamond. Besides the fact that it has a sleek design and is much easier to work with when reading email and browsing the web than my old phone.

However, that it is not the only reason for buying the Diamond. Another, very important reason, is that it runs Windows Mobile 6.1 - and therefore I can write my own programs for it using pretty much the same toolset as I use for any other .NET program. Granted, there are stuff missing in the Compact Framework compared to the full-blown framework (Expression trees anyone ?), but it is normally quite easy to find alternatives, and the Compact Framework does make it quite easy to program the device.

My first application for the Touch is a simple Stopwatch program. I wrote it, because there was no stopwatch and/or timer program on the Touch when I got it, so why not write my own ;-) The application it is quite simple, but I learned quite a deal about the device and the Compact Framework while developing it. It essentially relies on the Environment.TickCount counter to measure time, so it might not be 100% accurate - but for my needs (such as heating pizza's), it is quite sufficient.

If anyone's interested, you may download the source from here. If you want to compile it, you will need a copy of the OpenNET CF Framework, because I needed to use some parts of it for making the phone vibrate when the alarm goes off. (It could be replaced with some P/Invoke calls, but i got lazy ;-)

The application itself has the following features:

  • Simple stopwatch
  • Timer with alert (vibration and sound)
  • Configurable alarm sound (only .wav files, sorry).
  • Settings are remembered (stored in Application Data)


Last Day at Jaoo

Wednesday was the last official day of the JAOO conference, and once again it featured a bunch of interesting talks. I attended these:

50 in 50
This was todays keynote by Richard P. Gabriel and Guy L. Steele Jr. Before the talk, there had been some speculations about the title; was it 50 programming languages in 50 minutes ? Or what did it mean exactly ? It turned out to be 50 comments about programming and programming languages, in 50 minutes. These focused on the history of programming and did so in an entertaining and enlightening manner. This was a certainly a great talk - and for a "young" programmer like my self what was not even born when Ada and Algol 60 appeared; it provided also some historical insight. Only downside to this talk, is that the schedule was affected by the fact that it was more like 50 in 75 - the talk took about 75 minutes; but with this quality of technical and on the same time entertaining talk, that does not really matter for me.

Five Considerations For Software Developers
This was also a dual talk with two presenters - Frank Bushmann and Kevlin Henney. They talked about architecure and specifically five considerations that drives design quality. Those were:
  • Economy - the idea that software must be built for a reason and should not have an complicated or elaborate design just because it *might* be needed in the future.
  • Visibility - in the sense that the design must be easily discoverable.
  • Spacing - basically the idea to separate concerns and make sure not to bake the design into deep inheritance hierarchies that xould better be expressed with composition.
  • Symmetry - in that API's should be symmetric with the example that if you can create something with a Factory, said Factory should also be able to destroy it
  • Emergence


LINQ + New Microsoft Things
This talks title is actually wrong, since Erik Meijer primarily talked about LINQ, and very little about "New Microsoft Things". To be fair, he did not have much time to cover it all since the talk got started late because of the schedule slip at the keynote earlier on the day. LINQ was covered well, however, and from a slightly different angle than Anders Hejlsberg talked about earlier in the week. Erik talked about Expression trees and how they represent code as data. This makes it possible to hand an expression tree to an interpreter for a given query language, that can then execute it in the given domain. This is why we (in theory) could forget all other query languages such as XQuery or SQL, and only use Linq-to-Xxx - given that someone writes a Xxx extension to LINQ, of course.

Real World Refactoring
This talk about Refactoring by Neal Ford addressed the challenges that goes into actually performing refactorings in code. It was very hands-on and offered some good advice on how to structure refactorings. One of the best pieces of advice, I think, was to time-restrain major (multi-day) refactoring efforts to an estimated period of time before-hand. If you cannot complete the planned refactoring in the planned time, take the time to rethink the problem, and find out if you are doing it right. If not, you can throw the refactored code away and try again, instead of keeping on a track, that might resolve to more complicated code than before; because new knowledge has beeng gained during the process or because the refactorings was not well enough planned and thought out in advance.

JavaScript As An Assembly Language
This second presentation by Erik Meijer was primarily about Volta, an exciting new technology from Microsoft's Live Labs. The project basically promises to make it easier to make multi-tier applications that can run on the server and work with any client, with parts being executed on the client. This is done by decorating methods with custom attributes, that marks them for running on the client. The Volta compiler will then "compile" those to javascript, that can run on any client (or, if Silverlight is available on the client, the code will run in Silverlight as .NET IL). Erik explained the technology behind, and how they generate javascript code and the various problems involved in that. I do not think that this technology is quite ready to be used in the wild yet, but it should definitely be interesting to see how it evolves in the future. The documentation site on Live Labs seems to be down for the moment, however, this blogpost also explains the technology in more detail.

Concurrent Programming with Concurrent Extensions to .NET
In this talk, Joe Duffy, gave an introduction to the parallel extensions to .NET, a new API for writing concurrent applications with .NET. These extension is in CTP right now (so it's preview technology, not recommandable for production use). Joe promised though, that these APIs will be part of the .NET Framework version 4 release. These new APIs promise to make it easier to write concurrent applications with .NET with little overhad, both mentally for the programmer, but also performance-wise for the machine. The presentation featured running demos and code, and I believe that the new APIs are quite well-designed and that there is definitely a need for this kind of API in todays world of multi-core hardware. However, as Joe pointed out, there is no such thing as a free lunch; and even when using this API, of course you need to think hard over concurrency issues and side-effects before you can put it to use. The system makes it easier for you to program concurrently; but you can still fail badly if you do not understand what it does under the covers.