Author: Andrew Huey

I spent a few hours on Friday working on a problem that’s weird enough that I feel it warrants a blog entry. I made a few changes to one of our systems at work recently, and rolled them out Friday morning. This system is a VS 2008 solution with several projects in it. One of the projects is a bunch of web services, both SOAP and REST, that are deployed as a single DLL. I made a minor change to one of the REST services, but didn’t touch the SOAP services. And I made a minor change to a class in what is essentially a data access layer project that is referenced in the web service project, but nothing that should have affected the SOAP services. I’m saying all this to establish that I did not change anything that should have changed the SOAP services at all.

Returning to the data access project: this project was initially auto-generated through some CodeSmith templates, long before I started working for the company. The idea was that every class was implemented as a partial class broken into two files, with one file that contained auto-generated code, and one that could be used to add custom code. Now, some of these classes are used as output for the SOAP services. And those services just use the default XML serialization. (Some of you may see where this is heading.)

So we’re got a class called, let’s say, “Location,” broken into file X and file Y. File X contains properties A, B, and C, and file Y contains properties D, E, and F. Up until Friday, these properties had always been serialized from file X, then file Y, so they appeared in the output as A, B, C, D, E, and F. For some reason, on Friday, the compiler decided to process file Y before file X, and give me an XML document ordered as D, E, F, A, B, C. And, of course, the C# programs we have that actually call these web services don’t like getting their properties out of order. They expect everything to look exactly like the WSDL that was pulled in when they were last deployed. Oh, and most of them don’t have any useful error-handling or logging, and do a lot of their work in a declarative manner, through controls in the .aspx files rather than in code-behind, where I can see what’s going on step-by-step in the debugger. So figuring out what had gone wrong was interesting.

It had never really occurred to me, though I’m sure I read it at some point, that there is no guarantee as to the order in which the C# compiler will process the individual files that make up a partial class. (See this Stack Overflow question for reference.) I think the reason it changed now is that I moved the project from VSS to Mercurial recently, and that change probably caused enough of a disturbance to muck things up a bit.

I think if I had been the one that had implemented this thing in the first place, I would probably have done custom XML serialization, just because I’m a bit of a control freak, so I wouldn’t have ever had this problem.

Well, anyway, the moral of this story is that you shouldn’t assume that, just because a bit of code has been working for years, and you honestly haven’t touched it at all, that nothing can go wrong with it, and that the compiler will always output the same code given the same source code.

I’m going to be doing some maintenance programming on a PHP/MySQL site pretty soon. I know a little PHP, probably enough to get by on this project, but I’d like to learn more. I have an old introductory PHP book around here somewhere, but I wanted to pick up something more substantial. So I picked up O’Reilly’s PHP Cookbook at Borders on my way home from work today. I have so many programming books that I’ve barely started reading, but this one looks like it’ll be a good reference.

I upgraded to TortoiseHg 2.1 yesterday.
This item, under the “improvements” list, is huge:

(file history) added context menu for file revision features

Thank you so much for implementing this! I’m using it every day now. Of course, I see that a bug fix release, 2.1.1, was made available this morning, so now I need to upgrade again. Well, the install is pretty painless, so that’s OK.

I just finished working on a module to automatically post news stories from a client web site to Twitter and Facebook. I know that’s not a big deal, but it was kind of cool, and it took a bit of effort to get the Facebook thing figured out. (See this stackoverflow.com post for some detail on that.)

I used the Facebook C# SDK for the Facebook stuff, Twitterizer for the Twitter stuff, and EasyHttp to access the bit.ly API, for URL shortening. And of course I pulled them all into the project with NuGet. I feel like the master of all social media APIs now.