• Single Machine - Most of the recommendations around machine keys involve synchronizing machine keys across multiple machines. There is, however, value in setting static machine keys for a single machine, single worker process environment. Quite simply, if machine keys are not static, the generation of a dynamic machine key for an IIS reboot or application pool recycle will cause any machine key related elements (e.g. view state) rendered before the event to be invalid. This will likely result in exceptions that will impact normal user processing.

• Single Machine / Web Garden - The introduction of the Web Garden option to IIS can be viewed as the "poor man's load balancing". This option provides for a simple round robin routing across multiple worker processes, usually with each process owing affinity to a particular processor. Due to the simple load balancing approach taken, there is no option for web gardens but to synchronize machine keys. This is of course, unless you've managed to make your application completely stateless, in which case (congratulations) none of this advice applies to you.

• Multiple Machines / Web Farms - The applicability of static machine keys to a web farm environment applies, theoretically, only to web gardens in which the load balancing approach does not guarantee server affinity. Once again, to avoid impacting user processing during load balance machine failover or due to recycles or reboots, I'd always recommend using static machine keys. Even when these areas are not concerns, I've found other troubles just seem to arise when you can't guarantee static machine keys across machines. For web events regarding cryptographic exceptions or viewstate verification issues, I've found it best to start troubleshooting with synchronizing machine keys and then working down from there.

• VisualSVN Server - The VisualSVN server, as mentioned earlier is a freely distributed product. You can get this piece of software whether or not you ultimately decide to buy and use the Subversion Visual Studio plugin. The server runs exclusively over HTTP / HTTPS (using OpenSSL) and does not support Subversion's binary protocol or running Subversion over SSH. Obviously, this means that Apache is in play. A version of Apache is included in the distribution. Initial configuration of the server is very easy, the setup instructions describe the extent of it. As I blogged about previously, this changes a bit if you try to get Apache and IIS to run side-by-side. In this case, you need to be very explicit and tell the very greedy IIS to stop listening on other IP addresses so that port 80 can be shared by IIS and Apache. I included links to the Microsoft article in my earlier post. In this case, you'll want to use httpcfg delete iplisten -i xxx.xxx.xxx.xxx to stop IIS from listening on the port Apache is running on.      
  

• VisualSVN Visual Studio Plugin - As useful as the server is, the real product is the VisualStudio plugin. The most recent version of this plugin works on VisualStudio 2008 so I thought I'd install it and give it a whirl. Installation is fairly easy. Both TortoiseSVN and the VisualSVN plugin must be installed. I don't know exactly how VisualSVN communicates with Tortoise but it seems to make sense to leverage an existing Windows Subversion library rather than building everything from scratch. Using both the plugin and Tortoise gives you two ways to work with Subversion. In my experience with other Java IDE plugins (Netbeans and Elcipse), this is sometimes necessary to get around the shortcomings of the browser plugin.

• Mac OS X Leopard - I'm running NetBeans 6.0 with the Ruby-only configuration. Much to the chagrin of many Mac developers, Leopard did not ship with Java 6 even though it was included in some of thepre-releases. This proved to be a non-issue for the installation of the latest version of NetBeans. Obviously, running NetBeans in Ruby-only mode means that I'm not exercising the JDK and thus avoiding what could potentially be a lot of issues.
• Windows Vista - Although I've had issues getting used to the Vista operating system from the Windows 2003 Server / Windows XP I've become so familiar with, I've had few issues actually running Vista. I'm running Vista with the 1 GB RAM that Fusion recommended and have had no issues thus far. The only issue I encountered was trying to install Vista in Fusion Easy Install mode with multipleCDs , as opposed to a DVD. This is a documented issue with Fusion that I didn't become aware of until I ran into it head-on. Simply switching to a normal install solved all of my issues. On top of Vista, I'm running Visual Studio 2008. This runs pretty quick - even on 1 GB and builds of moderately sized solutions are pretty fast. TheIDE is really responsive and you really only notice that your running in a virtualized environment if you try to resize the entire Vista window to get more real estate for the IDE.
• Ubuntu 7.10 - Despite the size of the operating system, this installation took longer than Vista. I chose not to use one of VMware's canned virtual appliances and go with a fresh install.  I would probably re-examine this decision if I had the chance to do it all over again. Ubuntu is running NetBeans 6.0 with the full Java EE stack. The install of NetBeans downloaded directly from netbeans.com went really well once the proper Sun JDKs were installed. Both the Java 5 and Java 6 JDKs were available directly from Ubuntu's installation utility. I installed Java 5 first and, after realizing that it was a vanilla 1.5.0 release that didn't meet the requirements for NetBeans 6.0, I installed Java 6. Things have been just dandy since then.

Another in the installment of Rails on Windows “gotchas”, there are some things to be wary of when working with the Simple_Captcha plugin in the Windows environment. In terms of basic background, the Simple_Captcha plugin facilitates the integration of CAPTCHA (Computer Automated Public Turing test to tell Computers and Humans Apart) image recognition tests, like the example below, into a Rails application. Facilitates is perhaps not a strong enough term. The plugin makes CAPTCHA integration dirt simple.

The Simple_Captcha plugin uses RMagick for generation of the CAPTCHA recognition images, allowing for various image styles and distortion levels. The CAPTCHA can be integrated via the controller (this one is dirt simple) or via the model (this one is just silly simple). You can find out more about these and various other integration options on the plugin’s page.  

If you’re doing Rails development on the Windows platform and are not feeling especially masochistic, the rmagick-win32 gem, which is bundled with a copy of the ImageMagick Windows installer, is really the only way to use RMagick. For a long while, the 1.13.0 rmagick-win32 gem was the standard. However, this gem is likely to cause you issues and you should really upgrade your gem to the 1.14.1 gem or greater. These gems are fixed to work with RubyGems 0.9.4, which is the most recent version of this gem as of this blog post. If you don’t perform this update, you’re likely to see ImageMagick issues bubble up at runtime.

On Windows, these runtime errors frequently manifest themselves as ‘cur_image’ issues. Several of these issues have been reported on the plugin’s page. My post on 10/6 covered fixing these issues by upgrading your RMagick gem. Please don’t downgrade other gems, as suggested in some other posts; this will only make your life more miserable in the future.

All-in-all, the RMagick Windows gem is an excellent way to make powerful image processing capabilities available to all, including those unfortunate enough to be stuck on a Rails on Windows development platform. The plugins built on top of RMagick such as Simple_Captcha and Attachment_Fu are incredibly powerful and remain very simple by leveraging RMagick’s capabilities. Just beware if you’re developing on Windows, a little bit of tweaking and debugging may be necessary to get these plugins to work as advertised.

Continuing my Rails on Windows thread, I’m going to spend a bit of time on something that’s brought me both some substantial gains and some minor woes lately, running the Attachment_Fu plugin on Windows. I’ll start off with some general Attachment_Fu information and then get into some of the quirks, which are, as expected, mostly specific to the Windows environment.

First, for those not in the know, Attachment_Fu is a Rails plugin that allows you to store binary data (e.g. images, video, documents) and associate it with other models in your Rails application. Metadata (content type, size, height, width) about the attachment is stored in a separate model. Attachment_Fu’s sweet spot is handling images. It can handle automatic image conversion and thumbnailing using a number of popular image processors such as ImageScience, RMagick, or minmagick. Although not provided, you can imagine that Attachment_Fu might be extended to handle other types of binary processing utilities such as PDF converters or audio/video transcoding software. The other very cool thing about Attachment_Fu is that it provides support for pluggable persistence mechanisms. Out of the box, it allows for storage on the file system, as binary information in a database or on Amazon’s S3 storage service.

There is an abundance of information already written about Attachment_Fu so to avoid re-inventing the wheel, I’ll provide what I found to be the best sources of information to start.

• Mike Clark’s tutorial is the gold standard introduction to using Attachment_Fu. The code is simplistic but rock solid. It covers using both the file system and S3 for storage and will get you up and running on Attachment_Fu in no time.
  

• This post on the Attachment_Fu message board provides a solution to associating the attachment model with another model (i.e. making it an attachment to something). The post provides both the controller and the view code for uploading the initial attachment and rendering it. Handling the attachment relationship in your MVC is going to be a fairly common requirement and most Attachment_Fu users will benefit from this post.
  

For my part, I’m going to provide some controller source code for updating the attachment when you have a relationship with another model (an extension of the second item above) since this is one area that wasn’t covered well anywhere else and might save you some time in your travels. In the code below, my main model is the product and the image is the model where a photo and thumbnail are stored using Attachment_Fu.

The links above, in combination with my snippet, should get you through creating an attachment and handling CRUD for an attachment and its parent model from a single view. Now comes the Windows quirkiness. Not knowing to expect these Attachment_Fu quirks and then having to root out the cause of the behavior took up a lot of time. It turns out that most of I found that most of the quirks are documented in some way, shape, or form. I’ve pulled together a list of the quirks as well as some best practice workarounds.

• When running Attachment_Fu on Windows, the most commonly accounted problem is the “Size Is Not Included In List” validation error. This post goes into some details and speculation around the cause of the issue. It appears that no amount of fixing in the Ruby code is going to help here since it appears to be a Windows file system issue. The workaround is really simple, just add a wait x statement before your attachment processing and things will be golden. The x (which denotes seconds) time will vary based upon the size of the attachments you are processing. Bigger attachments require more of a wait. Also, be sure to comment this code out in production since this is a Windows only issue.

7/19/2007 Update - Rick suggested using RUBY_PLATFORM to determine if the wait should be invoked. I tested this and it worked as suggested

• When you invoke the destroy method on your attachment using Attachment_Fu on Windows, your models reference to the attachment will be deleted but the physical attachments themselves will not be deleted if you have persisted them to the file system. If you look at the Attachment_Fu source code or your log files, you’ll see that Attachment_Fu assumes that you are using a UNIX-based system and executes UNIX commands like rm to remove these files. These commands will obviously not work in a Windows environment, leaving you with a bunch of zombie files. This should not be a problem if you use a database or S3 persistence mechanism since these mechanisms are independent of the operating system.

7/19/2007 Update - Rick corrected me. He is indeed calling the OS safe FileUtils.rm in the file system backend. It still isn't working though - at least on my machine.

• My last Windows specific quirk is actually an Internet Explorer issue. If your attachments are images, you may have problems with uploading JPEG’s using the default Attachment_Fu plugin. From what I’ve been able to determine, if you upload a JPEG from IE with a file extension of .JPEG, IE will set the MIME type to image/pjpeg for a progressive JPEG. However, if the image extension is simply .jpg, IE will set the MIME type to image/jpg. This MIME type, however, is not included in the default list of content types accepted by Attachment_Fu. My suggestion is to add this type to the list in the source code until Rick can get around to modifying the source.

7/19/2007 Update - The MIME type was added to source. For reference, Rick suggested that this could have been done without changing the source simply by adding
    Technoweenie::AttachmentFu.content_types << 'image/jpg