How I Saved My Friends Lots of Money

Last night I got a phone call from one of my neighbors. She told me that she needed to use some courseware for a class at her university and said that she was unable to use it, and that she was told by someone that she needed to upgrade Windows to use it. They further said that, since a Windows license costs on the order of $200, she should just buy a new laptop. Now, this courseware is a web application—just a web site—yet she was told to get a new laptop. Naturally, my BS-meter went off, and I asked if I could come take a look.

I went over and looked, and saw that the real problem was not that the web site didn’t work—it worked just fine—but that the course documents were Microsoft Word .docx files. Not having Office or any other office apps, she had nothing with which to open them. So, I told her the nature of the problem and installed LibreOffice. Problem solved for $0.

The moral of this story? These points:

• “Computer literacy,” so called, is woefully scarce in our society. I don’t really fault my neighbor so much as the yahoo she spoke with who told her such outrageous nonsense.
• Professors should make their course documents available as PDFs, which is the proper interchange format for important documents. (What’s interesting about this is that Microsoft Word 2007 and 2010, which use the .docx format natively, make producing PDFs from Word easier than ever before.)

Making System.Data.SQLite Work in an NServiceBus Endpoint

Today a colleague and I worked on getting an an NServiceBus endpoint in a .NET 4.0 project that referenced System.Data.SQLite to work properly. It turns out that this is not as straightforward as it may seem.

The System.Data.SQLite binaries are targeted for the .NET 2.0 runtime. When referencing a .NET 2.0 mixed mode assembly in a .NET 4.0 project, additional configuration is required:


OK, that's fine. But when running an NServiceBus endpoint in the NServiceBus.Host.exe executable, it seems that this setting in App.config does not get applied in the context of NServiceBus.Host.exe. So, to get this to work, we had to turn the NServiceBus endpoint into a console application with a Main method that used reflection to invoke the Main method of NServiceBus.Host.exe. Doing this enables the above setting to be applied in the context of NServiceBus.Host.exe.

It took us the better part of a day to figure this out, so I'm memorializing it here for (my own) future reference.

Generate Test Files From the Command Line

Note to self: I had to generate some files quickly to test the behavior of the .NET FileSystemWatcher. This little bash script will create 6 zero-filled files of of size \( 2 \times 10^i \) KiB, where \( i \in \{0, 1, \dots, 5\} \).

Retrying Code Execution

I have a bit of code I'm working on at work that makes use of an HTTP endpoint to notify a legacy system of certain events. Because the network is not reliable, we have to handle the case when the network may be down. In this situation, it means to try again a few times, after which the processing request goes into an error queue, where it can be handled manually. So, I started out with something like this:

This calls the HTTP endpoint up to five times. If one of those times succeeds, it returns the result and stops trying. If it gets to the sixth time, it gives up.

Now, in my project, I have several of these types of calls to make. Much of the above code, namely the exception handling and flow control stuff, is common to all of them. So, using some functional .NET and an extension method, we can do this:

This will attempt to execute and return the value of func up to times times, and give up after that. With this extension method, we can now put our endpoint-calling code in a Func<int> and tell it to try to call the endpoint up to five times, like this: Now, is this the best way to do this? Maybe; maybe not. It's just something I've been toying around with in my attempts to eliminate duplication of the aforementioned ugly flow control code. I'll have to walk around in these shoes for a while and see whether I like them.

IE Doesn't Support the trim() Method(!)

Here's yet another shocker from the half-baked world of Internet Explorer. Start up IE 8. Press F12 or start the Developer Tools. Then, click the Script tab and then the Console tab on the right pane. At the command line at the bottom, type
[sourcecode language="javascript"]
" this has padded whitespace ".trim();
[/sourcecode]
press Enter, and behold:



Insane! Thankfully, the folks at jQuery have taken care of this.

The ASP.NET MVC Request-Handling Pipeline

[scribd id=44539131 key=key-mb5rsfz5wd7wk3u95t1 mode=list]

Java as DSL

I love it:

http://twitter.com/#!/avalanche123/status/7062890318143488