Google is dipping into the cloud computing market.  They are claiming to have solved the issue of scalability for web applications, a direct hit against Amazon Web Services.  It doesn't matter whether your application gets 10 hits per day or 1 million hits per day. 

Picture taken from internetnews

One inconvenience of App Engine is that it is restricted to the Python language.  Python is a good language, but it would be nice to see multiple platforms allowed.  Another problem is that data is not relational, people are saying that it uses Bigtable, a distributed storage system.

There were only 10,000 initial free accounts offered and guess what they are gone.  Each account has a 500MB storage limit and is allowed 5 million hits per month.  Hopefully more accounts will become available soon, I am on a waitlist that is probably a mile long :).

If you are interested, Google I/O is from May 28th - 29th.  They will be discussing App Engine and different APIs such as Google Gears, Google Web Toolkit, Google Data APIs, and more.

There are already a bunch of applications popping up.  Hopefully Google will continue to provide this as a free service when as it goes live.

I came across this nifty application today called Process Explorer.  I needed to delete a file but had to find out what application had a file Handle open because I kept getting the following error. 

A file cannot be deleted if there exists any handle that is associated with it.  Process explorer lets you view handles by a process.  Process explorer also allows you to view Hardware Interrupts, Deferred Procedure Calls, and process parent/child relationships.

This is not the best way to find a handle when you are not sure what process has control.  There is a feature to find a Handle or DLL at Find | Find Handle or DLL ... Ctrl+F. 

Once the Handle is found you can close the correct application and delete the file in use.  It is not good practice to delete the handle because the file may be in use and could lead to data corruption.

Another nice feature of the process explorer is the System Information.  It extends the default Task Manger's Performance view.

This application is from Sysinternals, which was acquired by Microsoft in July of 2006.   They have many other interesting system tools.

Microsoft Surface will be released on April 17th in select at&t stores.  This item is a bit pricey for the average tech gadget consumer estimated from $5,000 to $10,000.  It will be a great educational tool once the price comes down. 

Press Release

 

 

Microsoft Surface Demo

There are a few other competitors in this arena.  The linux community has been working on the multi touch devices too.  You can already download this software and start playing.

Jeff Han seems to be a bit ahead of the game.

 

 

However, at ten times the price, the Microsoft Surface may be a little more realistic.

When picking a data structure to store key/value pairs and the size is unknown the HybridDictionary object (System.Collections.Specialized) is a great tool for the job.  The data structure will internally use a ListDictionary while the count is <= 10 and will convert to using a Hashtable afterwards.  If the starting item count is greater than 10, the HybridDictionary will start out with the Hashtable to reduce the overhead generated by the conversion.

A ListDictionary uses an single linked list data structure for implementation so the Item, Add, Remove, and Contain operations are all in linear time.

The Hashtable works off the Object.GetHashCode method for storage.  For each entry, a key, value, and a hashcode is stored.  The entry is placed into a bucket based on this hashcode.  Each time a item is added to the Hashtable, an actual load factor is computed  and is compared to the specified load factor.  The default load factor of 1.0 can be changed during the Hashtable creation, but must be between 0.10 and 1.0.  The load factor is directly related to the probability that a bucket will contain more than one entry.  The lower the value, the less chance of a collision but the trade-off is memory consumption.  Then the actual equals the specified load factor, the Hashtable is reallocated to contain the smallest prime number larger than twice the current number of hashtable buckets.  Dan Mabbutt has some interesting benchmarks regarding the load factor. 

Customized hashing can be achieved by overriding the Object.GetHashCode, and Object.GetEquals methods.  Using the IEqualityComparer interface will enforce these methods.

The operations for the Hashtable are all in constant time on average with the exceptions of reallocation, hash collisions, and multiple items in a bucket.  The Hashtable will automatically rehash collisions.

For a hash table review visit Wikipedia.

Remember that all key objects must be immutable!

applicationSettings was introduced into the .Net 2.0 Framework.  This is not the same as appSettings which most developers used 1.1, but what is the difference?

Application settings give us more control and most important, intelliscence.  To create an application setting simply view your projects properties and select Settings.

Here you can see that there are more parameters than the standard appSettings.  Additionally there are the fields Type, and Scope.  This Type is used for intelliscence in Visual Studio.

Within the config file, the following section is added:

    <userSettings>
        <applicationSettings_vs_appSettings.My.MySettings>
            <setting name="MySetting" serializeAs="String">
                <value>MySettingString</value>
            </setting>
        </applicationSettings_vs_appSettings.My.MySettings>
    </userSettings> 

This allows us to use intelliscence in our application now.

        Console.WriteLine(My.Settings.MySetting)

This can be very useful and it is strongly typed so it is faster.  However, applicationSettings are only in console applications, forms applications and web applications, they do not exist in websites.  For the websites you must resort to the old appSettings standard.

To set the setting to a new value simply, set the property and save the settings.

        Console.WriteLine(My.Settings.MySetting) 'MySettingString
        My.Settings.MySetting = "new setting"
        My.Settings.Save()
        Console.WriteLine(My.Settings.MySetting) 'new setting

I am not sure why this doesn't exist in the websites.  I came across this when I was getting the error: Configuration system failed to initialize from trying to use the Configuration manager versus using My.Settings.

I remember when MIT came out with MITOPENCOURSEWARE.  I thought this would fuel other online training programs, but nothing ever came of it. 

Google is taking another stab at it with Google Code University.  They offer courses in AJAX Programming, Distributed Systems, Web Security, and Languages.  The courses are provided by Google and different Universities.  Outside the lectures are different tools and a nice CS Curriculum Search.  The CS Curriculum Search is specific to materials posted by different CS Departments.

It is another great step for online education.  This is very different from Microsoft's great Webcasts because MS Webcasts target only their products.  MIT's and Google's online training target the fundamentals of Computer Science which is what we need.

I am leaving on vacation in two days so today I set out to use the internet connection sharing feature of the HTC Touch. It's simple and quick!

1. Navigate to The Comm Manager

• Start -> Settings -> Connections -> Comm Manager

2. Click on Internet Sharing

• Select PC connection, for me it is Bluetooth PAN. I suppose this also works via USB.
• Select Network Connection to share, mine is Altel Wireless

3. Connect devices via searching from PC - HTC83

• This was a bit dificult because I did not know the passcodes so I tried 0000 (zeros) and viola!

4. Each device will display a connection confirmation and display the number of services the other device offers.

• Select the Network Access point on the PC.

5. Open up a Web Browser and start surfing.

After the devices are synced the first time, simply use the shortcut on the PC in My Bluetooth Places for the Network Access Point.

I haven't blogged about the project for a while but I am changing the context of this blog. This blog will be about technology in general as I encounter and learn new concepts.

Well we have decided to port everything over to Linux because of our software defined radio. After installing Ubuntu I realized Linux has become a lot easier to install. I have to say I like the Feisty look and feel.

However we are having some issues with our bluetooth dongle. There is an error in the current Broadcom driver. I will be playing with this it seems for a few days.

I will then code up a short prototype providing communication between the PC and the lab's cell phone.

In the meantime Manish is working on the SDR. It looks as if we will have to learn some python programming. I will pick-up a book over the weekend.

I have started a research project with WMU's Oppnet group in the WISE lab. This project should be very exciting and expose me to a different style of programming. My first task is to go through the Tinyos Tutorials located at http://www.tinyos.net/.

My first challenge is to understand the nesC programming language. There is a nice manual by Philip Levis.