Codetecture

Moved to Blogger

2011-04-23T12:17:00.007+02:00

I've started building my new web site few weeks ago, I wanted it to be more attractive and easier to customize than the old one (dasBlog engine). I’ve started with Orchard CMS on Windows Azure, but quickly realized that some features I wanted were not yet available. I decided then to go for a hosted blogging service that would allow me to focus on the content and forget about the platform. This blog post describes why I chose Blogger and what’ve done to make this beautiful web page you’re looking at.

Blogger as my new platform

It took me about 10 minutes to get my blog up and running with a default template. All the features I needed were there:

Search engine friendliness
Integration with Google AdSense
Integration with Google Analytics
Custom domain
OpenID support
Picasa integration
FeedBurner integration
Support for standalone pages
Generous quota (Blogger does not appear to impose bandwidth limits at all).
Easy to customize, allows JavaScript

All I had to do was to create my own theme, add DISQUS, my tweets and all those nice things bloggers need to have. I’ve downloaded and tried some templates from btemplates.com and learned Blogger’s template system that way. In the end I wrote my own template from scratch and the JavaScript I needed (thanks jquery). It came as a surprise to me to learn that Blogger didn't support the BlogML format, so I couldn't simply import my old blog. In a way, I didn't mind because I had less than a dozen blog posts to import and I wanted to adapt the html to fit with my new Css.

The last step was to find somewhere to upload my static content. After some experimentation again, I decided to use Google App Engine (GAE) for that.

Offloading static content to Google App Engine (GAE)

Another advantage of storing static content on a separate domain is to parallelize and speed up the download process (web browsers usually limit the number of sockets to download resources from a single host). GAE is not meant to be a fully-fledged CDN, but it’s more than enough for my humble web site (2 megabytes of static content) and it is free. These are the limits when billing is disabled:

request size	10 megabytes
response size	10 megabytes
request duration	30 seconds
maximum total number of files	3,000
maximum size of an application file	10 megabytes
maximum size of a static file	10 megabytes
maximum total size of all application and static files	150 megabytes

(*)More information here

The procedure to upload content to GAE is described here, it works really well. Note that it's more complicated to set the cache-control header (Cache-Control: max-age=3600) with GAE java sdk that's why people are still using Python.

My notes about GAE

I've learned few interesting things on GAE Google Group:

GAE makes a best effort to do caching, but there is no guarantee that responses will be cached.
Edge caching for requests that use the cache-control header is only active when billing is enabled

Conclusion

I've spent many hours working on this blog, I've learned many things about Blogger and GAE, I think it was worth it. Hopefully I will be able to concentrate on blogging in the future and the current design will satisfy me for the next couple of years.

Multi-file archive with Tar

2010-12-01T11:48:00.013+01:00

Recently, I needed to copy 40GB of home videos out of my ReadyNAS duo and immediately thought about using a USB hard disk. The problem was that the maximum possible size for a file on a FAT32 volume is 4 GB and reformatting my hard disk to NTFS was not an option. So I thought about creating a multi-file archive with Tar, primarily because Tar is the only compression program available on the ReadyNAS out of the box. Here is the recipe for creating multi-file archive with Tar.

Creating the archive

The command line I used is:

$tar -c -M --tape-length=4096000 --file=HomeVideos.tar /media/Videos/HomeVideos

After some time, Tar prompted for volume 2 like this:

Prepare volume #2 for disk1.tar and hit return

I entered the following command line to specify the new filename and pressed RETURN:

n disk2.tar

Tar prompted again, but this time it showed the new filename "disk2.tar" and I pressed RETURN to continue. I repeated the operation about 10 times and was able to copy all these files on my USB drive and then onto my latop.

Putting the videos back together

The process is quite similar to extract the videos (I'm using Cygwin):

$tar -x -M --file=/cygdrive/e/disk1.tar

After some time you'll need to specify the name of the next volume, like this:

Prepare volume #2 for disk1.tar and hit return:
n /cygdrive/e/disk2.tar

I repeated the process until everything was extracted.

Preparation guide: (70-583) designing and developing windows azure applications

2010-11-11T11:49:00.004+01:00

About

This is my preparation guide to the Windows Azure exam 70-583. It was right for me, but it might be too little (or too much) for you, dear reader. With my current experience I felt that this was enough for me (I’ve been experimenting with the Windows Azure platform since the CTP, back in 2008); For more information about the exam, take a loot at Microsoft’s overview.

ELearning

I recommend pluralsight’s on-demand course called "Windows Azure Fundamentals".
As a MSDN subscriber you can get free access to this course and many others for 1 month.

Books

I have read 2 books about Windows Azure so far:

Both are worth reading, but if you have to choose, Azure in Action is the one: It’s a concise introduction to the platform from a developer perspective.

Articles

In addition to the books, the following articles are a must:

For even more reading, take a look at J.D Meier's Guidance Map, it’s a giant index of Windows Azure content collections for developers. (Code Samples, How to, Videos, Training etc.…).

Learning by doing

I cannot emphasis enough the importance of experiencing the platform by yourself. You’re a MSDN subscriber so create a Windows Azure Platform MSDN Premium Account (and yes you'll need to assign a valid credit card, but you won't be charged unless you overrun your quota). Now go ahead, download Windows Azure Platform Training Kit and start programming.

Good luck!

Access to modified closure

2009-10-01T22:55:00.004+02:00

Resharper is a fantastic tool and gives plenty of warnings that shouldn’t be neglected. One warning I want to describe here is “Access to modified closure”:

private void WriteString(string str)
{
 var newMsg=string.Format("New message: {0}", str);
 _syncContext.Post((param) => listBox1.Items.Add(newMsg), null);
 newMsg=String.Empty;
}

WriteString is called by a non UI Thread, hence the SynchronizationContext. The question I’ve been asking myself is: “Why can’t I access the variable newMsg from within my lambda?” The answer to that question is that if the lambda refers to a variable defined outside of its scope, the variable may be changed while the lambda is running. If you execute the example above, you’ll see that an empty text is added to the listbox, which means that the variable newMsg is changed before the lambda runs (because the post method is asynchronous). I need to pass newMsg as a parameter to solve the problem (actually, I should pass a copy of the object, but since a String is immutable it doesn’t matter for this example)

private void WriteString(string str)
{
 var newMsg=string.Format("New message: {0}",str); 
 _syncContext.Post((param) => listBox1.Items.Add(newMsg),newMsg); 
 newMsg = String.Empty; 
}

No more warning!

Web application's startup delay resolved with ASP.NET 4.0 and IIS 7.5

2009-09-16T22:49:00.000+02:00

One of the problems I experienced while developing ASP.NET/SharePoint applications is the warm-up latency. Every time the application pool is recycled, the first user to hit the website get a very slow response time or even a timeout. This is due to all the initialization code inside application_start() and it's worsen if there is set of back-end WCF services. The solution has always been to make a script that maintains the web applications up and running, or to only recycle the application pool once during the night (I really don't like this one).

Looks like IIS7.5/ASP.NET4.0 have solved the initialization delay quite nicely, by auto-starting the application pool as quickly as possible. I guess this is a good excuse to move from Windows Server 2003 to Windows Server 2008 ! Check out the whitepaper: http://www.asp.net/learn/whitepapers/aspnet40Beta1/#_Toc223325464

Google Vs Bing

2009-09-07T22:41:00.000+02:00

I’ve tried hard to use Microsoft’s new search engine everyday at work. Unfortunately I had to switch back to Google because I was wasting too much time searching… Let me explain.

I’m pretty good at searching with Google, I always find what I need and even more. Google just works and it’s ranking algorithm amazes me. Few years ago I worked on building a search engine from scratch and I learned how the retrieval process works (thanks to Managing Gigabytes and Modern Information Retrieval). My point is that if you throw a crisp query to Google you will always get the right result.

Bing is a big improvement from Microsoft Live search, it’s really fast and returns much more relevant links. But unfortunately it’s not gone be enough to dethrone Google. I hope Microsoft will manage to fix it's ranking algorithm in the next upgrade, until then Google is king.

Just married

2009-09-01T21:33:00.006+02:00

I've been off work for a month during which I got married and traveled to Canada and the USA. We managed to visit Banff, Calgary and Chicago in 15 days (we’ve been pleasantly surprised by Chicago, it’s big and beautiful).

Now it's hard to get back to work after a long break, but I'm currently working on a really cool project and that helps a lot. Hopefully I'll be able to post more technical stuff on my blog in the coming weeks, I’m planning to install windows server 2008 R2 on a virtual hard disk and try the VHD boot. I’m looking forward to experiment with Visual Studio 2010 and the .Net 4.0.

Virtualbox: Highly recommended

2009-03-13T23:06:00.001+01:00

I've been using VirtualBox for months now and it works pretty well. I’ve previously tried VirtualPC (too slow), Virtual Server (not user friendly), VMware (expensive) and HyperV (requires Windows 2008 x64). Then I discovered VirtualBox, it’s actively developed and has everything I need:

It's fast (fast enough for me).
It supports x64 hosts and guests.
It has plenty of options such as raw partitions.
It supports .vhd and .vmdk
It has NCQ support for SATA raw disks and partitions

The only thing that isn’t great is the seamless mode. When I first heard about VirtualBox’s seamless mode, I expected something like VMware fusion. Instead I got something not so useful and even buggy. I wonder why seamless desktop integration only works on Macs… Anyway, try VirtualBox today! You won't be disappointed.