Dr. Random

About two weeks ago I crafted my first Fluent Interface.  Since then I’m finding myself seeing more and more places where I think such an approach would be useful.  The part that I’m finding odd is that it is something that just recently became a possibility for me.  The big motivating factor behind that I believe was reading the post that Martin Fowler did on the subject, in which he basically describes it as a super-great idea (okay, I’m paraphrasing, but you get the idea).  The concept is fairly simple; write an API that reads like a sentence. 

This isn’t a new concept, in fact I seem to recall reading quite a bit in the world of agile and TDD in which the authors encourage you to make method/property/variable names verbose and more like natural language in order to improve readability of code, and make the items more self-documenting.  I think the big difference, though, is that fluent interfaces tend to be more granular.  Instead of a single method that reads like a sentence, you are building a sentence using method and property names, with Intellisense there to help you determine what is possible at the end.

The big shift, I think, is in the realization that within this context method names like With, For, and And are perfectly okay, and as a matter of fact make things better in the end.  Its like a taboo has been lifted, and suddenly I have a whole new landscape of possibilities opened up.

Since the original implementation of a small fluent interface I created for a small part of my project (I’m using it to describe discrete elements of a document to be parsed), I’ve found myself creating a new fluent interface to play with .Net 3.5 extension methods (replicating the Ruby 10.Minutes.Ago semantics), and also adding a new interface to the same production project as the first which is being used to grab component services from my IoC container.

I’m not sure if this is a new paradigm, or just a new hammer looking for nails, but it is interesting none-the-less. It has also opened up new challenges around testing and intellisense documentation, which I’ve not quite figured out yet.

I found this little jewel in Martin Fowler’s recent post OneLanguage

… a jigger of 80 proof ugliness …

Check the post for the full context if you need to know what is a jigger of 80 proof ugliness, but this phrase, for whatever reason, gave me large amounts of joy just now.

I ran into this issue today when trying to find a quick and dirty script to enforce redirection from HTTP to HTTPS for an intranet site we’re enabling for HTTPS (yes, I know SSL on an intranet???  One word – Audit).  I thought this would be easy…I half expected that there would be an IIS setting to handle this for me; I was wrong on both counts.  So what I ended up doing is using an old DNN HttpModule which was set up to allow the user to specify specific tabs in DNN for SSL, and greatly simplifying things to work to my advantage.  I thought I would post it so I wouldn’t have to look for it again.

To give a quick overview of what is going on, this is an HTTP Module which looks at a value in the web.config to determine whether or not to enforce HTTPS or not.  If the setting is set to true (or yes), then I’m just grabbing the Url property from the Request object, loading it up in a UriBuilder, and setting the Scheme to “https”, and the port to 443 (this may not be necessary, but it was generating an URL with a port of 80 before, which defeats the purpose so I decided to play it safe).  It then feeds the generated URI to Response.Redirect(), and your off.  There is some additional code in there to disable the feature if your on localhost, which is mostly to keep from blowing up your dev box.

Here is the class:

using System;
using System.Configuration;
using System.Web;


namespace HTTPSRedirectHandler
{
    /// <summary>
    /// An HttpModule which redirects traffic to HTTPS based on configuration settings.
    /// </summary>
    public class HttpsRedirector : IHttpModule
    {
        HttpApplication _context;

        public HttpsRedirector()
        {
            //
            // TODO: Add constructor logic here
            //
        }

        #region IHttpModule Members

        /// <summary>
        /// Initializes a module and prepares it to handle
        /// requests.
        /// </summary>
        /// <param name="context">An <see cref="T:System.Web.HttpApplication"/> that provides access to the methods, properties, and events common to all application objects within an ASP.NET application</param>
        public void Init(HttpApplication context)
        {
            _context = context;
            _context.BeginRequest += new EventHandler(context_BeginRequest);
        }

        /// <summary>
        /// Disposes of the resources (other than memory) used by the
        /// module that implements <see langword="IHttpModule."/>
        /// </summary>
        public void Dispose()
        {
            _context.BeginRequest -= new EventHandler(context_BeginRequest);
            _context.Dispose();
        }

        #endregion

        /// <summary>
        /// Handles the BeginRequest event of the current Http Context.
        /// </summary>
        private void context_BeginRequest(object sender, EventArgs e)
        {
            bool useSSL = false;
            string result = null;
            if((result = ConfigurationSettings.AppSettings["RequireSSL"]) != null)
            {
                if(result.ToUpper() == "TRUE" || result.ToUpper() == "YES")
                    useSSL = true;
            }
            if (useSSL)
                EnforceSSL();
        }

        /// <summary>
        /// Enforces a redirection to HTTPS if the current connection is using HTTP (port 80).
        /// </summary>
        private void EnforceSSL()
        {
            if(_context.Request.ServerVariables["SERVER_NAME"].ToLower() != "localhost")
            {
                if(_context.Request.ServerVariables["SERVER_PORT"] == "80")
                {
                    UriBuilder uri = new UriBuilder(_context.Request.Url);
                    uri.Scheme = "https";
                    uri.Port = 443;
                    _context.Response.Redirect(uri.ToString());
                }
            }
        }
    }
}

Here is the web.config settings you need to use it:

<httpModules>
    <add name="SSLRedirect" type="HTTPSRedirectHandler.HttpsRedirector, HTTPSRedirectHandler" />
</httpModules>

<appSettings>
    <add key="RequireSSL" value="True" />        
</appSettings>

I’ve been doing a lot of poking around the MythTV and Knoppmyth sites recently trying to figure out what is going to work best in my current situation.  Since I’ve got cable, and not satellite, it would seem that it is possible to get all of the non-encrypted content from my provider, as long as I have a capture card with QAM support.  These cards seem to be HD cards overall (at least I haven’t found one that is supported that is not HD), which makes sense given the QAM signal will be a digital signal.  It sounds like getting the channel mapping put together for the QAM content can be somewhat tedious depending on how well Myth can auto-discover your channels (which it would seem is not that good), so I know there is some work involved in getting the digital channels.  For analog, any of the supported analog capture cards would work, and it seems that my wife and I tend to watch more of the analog stations than the digital (though, in my current line-up all of the “expanded” cable stations (Discovery, Comedy Central, TBS, etc) have both an analog station and a digital station…pretty strange.  I also know that I want the ability to watch and record at the same time, which means at least two tuners.  Here is the trick, though, since I need different tuners for digital vs analog, how many tuners do I really need?  And how many PCI slots do I want to eat up in the quest for multiple record?

So here is what I’ve decided.  Since I’m mostly concerned with analog, I went with a Hauppauge WinTV PVR-500, which is a dual-tuner analog PCI card, and which seems to be supported just fine in myth (looks like two PVR-150 cards from the sound of it).  That by itself takes care of my analog needs.  As for the digital, I haven’t decided for sure yet, but I’m leaning towards the DVICO FusionHDTV RT Lite, which seems to have good support in Myth.  It also has the advantage of being one of the few HD cards with a hardware encoder.

I should take a step back here and explain this.  You have two choices when watching or recording TV on a PC.  You can have your machine take care of encoding and decoding the MPEG4 video that is your TV show, or you can let the capture card do it.  If you let the capture card do it, then your machine is going to not be nearly as busy as it would otherwise.  This presents a couple advantages: 1.  You can get away with less horse-power on the machine, which means parts will be cheaper (spend the cash on storage if you can). 2. You’re machine will consume less power (I’m talking wattage here), and so therefore you are less likely to have a machine in your living room that sounds like a Lear jet taking off when your trying to watch all of your recorded episodes of “Eating bugs with the Stars”, or whatever the latest reality fad is. 

The PVR-500 contains a hardware encoder, so if I can get the same thing on the digital side, I’ll be in good shape.  While I’m on the subject of power, I’m also seriously looking at an AMD Turion based system.  This is the AMD mobile processor, so it is designed with a low-power footprint in mind.  It also seems that there are several motherboards out there which will support it, and some additional components which will help keep it cool.  The only other major sources of noise are the power-supply, and the hard-drive.  Cooler-Master makes some nice quite power supplies, so I will probably check there first.  As for hard drives, I haven’t really started looking yet.  If I can find noise specs on them, then I may use that as a criteria when deciding which to buy, but my primary concern is how many GB can I get for my money.

The other components have been moved to the end of the decision-tree.  I like the Sliverstone cases I mentioned in my last post, but I decided that I should get the components together first, since I didn’t really want to end up with a nice-looking case where I couldn’t fit all of my goodies.  I also need to decide whether or not to go with a DVD writer in the case….could be handy, but then I can also grab stuff off the network, so is it really needed (I’ve got a CD writer lying around, which may be my stand-in for a while)?

Overall this is going to be a fun project, and lets face it, how often do you get a geek project that your wife is behind 100%?