autofac, dotnet comments edit

It’s taken some time and a couple of long Google Groups threads, but with a kick in the right direction from Nick Blumhardt, I’ve got multitenant dependency injection working with Autofac and available as a contributed library.

The basic usage pattern is:

  • Determine a strategy by which tenants are identified. That is, which tenant is making a given request? This might come from an environment variable, a request parameter, a role on the user’s principal, or wherever.
  • Build up your application container with the default dependency set. For tenants that don’t override anything, they’ll use these defaults.
  • Create a multitenant-aware container based on the application defaults. This is where the magic of AutofacContrib.Multitenant comes into play.
  • Configure tenant-specific overrides with the multitenant-aware container. Tenants can override things, add new dependencies, or whatever they need to do.
  • Resolve everything out of the multitenant-aware container. All of the resolutions will automatically use your tenant identification strategy so you’ll always get a tenant-specific result.

In practice, it looks like something this:

// First, create your application-level defaults using a standard // ContainerBuilder, just as you are used to. var builder = new ContainerBuilder(); builder.RegisterType<Consumer>().As<IDependencyConsumer>().InstancePerDependency(); builder.RegisterType<BaseDependency>().As<IDependency>().SingleInstance(); var appContainer = builder.Build();  // Once you've built the application-level default container, you // need to create a tenant identification strategy. var tenantIdentifier = new MyTenantIdentificationStrategy();  // Now create the multitenant container using the application // container and the tenant identification strategy. var mtc = new MultitenantContainer(tenantIdentifier, appContainer);  // Configure the overrides for each tenant by passing in the tenant ID // and a lambda that takes a ContainerBuilder. mtc.ConfigureTenant('1', b => b.RegisterType<Tenant1Dependency>().As<IDependency>().InstancePerDependency()); mtc.ConfigureTenant('2', b => b.RegisterType<Tenant2Dependency>().As<IDependency>().SingleInstance());  // Now you can use the multitenant container to resolve instances. // Resolutions will be tenant-specific. var dependency = mtc.Resolve<IDependency>();

The usage is very similar to the existing Autofac usage you know and love.

The multitenancy support works for standard non-web/service apps (e.g., console apps or Windows services), ASP.NET web forms and MVC apps, and WCF service apps.

There’s a ton of documentation about how to use the multitenancy that includes sample code snippets.There are also somesample console, WCF, and ASP.NET MVC applications in the source treeso you can see it in action.

It’s not currently out there as a binary, so you’ll have to do a source checkout and compile it manually, but I’m sure it’ll show up soon. It was released as part of AutofacContrib 2.5.1 and is available for download.

We’re looking for early adopters to give us feedback on it. If you try it out, please let us know what you think in the Autofac Google Group. What did you like? What were the pain points? Did you find a scenario that didn’t work? How was the documentation? The more feedback we get, the better we can make it! Thanks!

General Ramblings comments edit

It’s my birthday today and I’m 34 years old. A hearty thanks to the folks who have sent me good birthday wishes via the various communication mechanisms at their disposal including, but not limited to: Twitter, Facebook, email, snail mail, text message, BlackBerry messenger, Google Chat, and telephone. I do appreciate it.

The day ain’t over yet, but it’s been a good birthday so far.

Last night my parents came by for a little while to visit. It was good to see them and they left a funny “Dadcat” shirt (because my girl cat lays on my stomach just like the cat on the shirt), some cool Hawaiian boxer shorts made from bamboo, and a pin from the Maui Hard Rock Cafe (I have a small collection).

One of our cat boys, Stan, started the day out by wishing me a happy birthday very loudly from outside the bedroom door. He provided an enthusiastic serenade about the day from 5:00a all the way until 6:00a when Jenn got up to get ready for work. He is outside the office door right now wishing me a happy birthday still. Still loud. Still enthusiastic. Lovely.

Jenn gave me her gifts before she left:

I’ve got the day off from work, which means I can do whatever I want, including not putting any gel in my hair. My head looks like a dandelion puff, but I’m cool with that.

After I’m done here, I’m going to go to McDonald’s and treat myself to a bacon, egg, and cheese McGriddle, my favorite. Then I’ll probably do some more mundane things like shopping at Costco, but I’ll be savoring the memory of that McGriddle, man.

I don’t know if we have some friends coming over tonight or not. If so, cool. Either way, I may end up rolling some Borderlands with my dad. We’re trying to crack level 40. Since the DLC for it is on sale next week, we’ll probably grab it then.

Tomorrow… well, there’s a family gathering, but it’s not for my birthday - it’s for my cousin who recently passed. Sort of a downer, so we’ll just move on. (Also, I anticipate a lot of “What have you been up to?” questions which I can’t answer because how do you explain “implementing multitenant dependency injection in Autofac” to a non-technical person?)

Sunday I do have some friends coming over and I anticipate there being some Rocking and Banding the likes of which have never been seen before. Or maybe we’ll just get some dinner. Either way, that’ll be fun.

So, again, thanks to those who’ve sent in birthday wishes. It’s time for me to go get my McGriddle!

General Ramblings comments edit

For the second year in a row, Western Display Fireworks decided to trust Jenn and I to run our own show. This year we were in Happy Valley, OR.

The show was a little smaller than last year with around 300 shells and seven pre-fused boxes. It lasted about 18 minutes.

We had a good crew and both setup and cleanup went surprisingly quickly. Some of the crew are folks who had worked with me in previous years, some were new.

Here are the edited highlights:

One of my crewmembers, Alex, also took some great photos.

We had a lot of visits from city and state officials this year, way more than any other show I’ve ever been on. Fire crews checking things out, asking where to be stationed; police figuring out what the best way to secure things might be; the fire marshal running around with his checklist making sure we’re doing things to spec… it was pretty intimidating, to be honest. Shows how much they’re cracking down on this stuff. I guess they had something like 12 police units out patrolling for illegal fireworks that night.

From a retrospective standpoint there are a couple of things to mention:

  • I still hate driving the truck. Just thinking about driving a moving truck makes me tense up. Lighting explosives next to my head? No problem. Driving the moving truck? Problem. Jenn is a freaking truck-driving maniac so she took care of it most of the time, but I still had ample opportunity to tense up behind the wheel.
  • It is really, really hard to get a crew together. Really hard. Beyond hard. We had a really great crew this year, just as we did last year, but even giving people over a month’s notice it’s difficult to get folks to commit to being there… and you really need people you can count on to be there, or the whole thing will be a tough stunt to pull off. People cancel at the last minute, people don’t show up… and folks don’t realize that this isn’t like “Hey, I’m having a party, show up if you can” - it’s more “Hey, I truly need some help, so if you say you’re going to make it, I need to actually be able to count on you to be there 100% guaranteed.” Plus, it’s difficult work, lots of lifting and digging and such, and it’s not for everyone, so you sort of “burn through your contacts list” pretty quickly looking for folks. I was working on getting crew together until a week ago.
  • We probably could have gone just a tad faster. Looking back at the video, things felt a little slow overall. I don’t remember it being that way when we were there, and watching fireworks on video is sort of dumb and anticlimactic anyway, but there were a few dead spots where I feel like we should have had something in the sky. Granted, we couldn’t have gone too fast or the show would have finished in ten minutes or less… but I think this was maybe more of a 12 - 15 minute show than the 18 minutes we got out of it. Live and learn. You don’t really get to “practice” this stuff.

All in all, it was a great show.

As for next year, I’m not sure what the plan is. It was so hard to get a crew together this year, and there was so much work around coordinating the whole thing - getting the truck, scheduling people to be where they need to be, making sure people have their questions answered, following up to make sure everyone brought everything they were supposed to, etc.

  • that it’s really started to be much less fun than it used to be.

In some cases getting a show together is like getting a small wedding together. Is the caterer there? Did the cake arrive? How many people are showing up? Did you plan for enough food? Too much food? Where the hell is the groom? In the end, I’m questioning whether it might be time to take a break.

If I do, I’d either have to let my pyro license expire or do a make-up show (since you have to have a minimum number of shows to renew your license)… but the only reason I have my license is to do shows, so it’s sort of Catch-22-ish. The only reason to be licensed besides that is basically just to have the ability to say I’m licensed.

Anyway, something to think about. In the meantime, we had a great show this year, so thanks to the crew for all their hard work in making it happen!

media comments edit

I went looking for a list of YouTube URL hacks so I could send a link to a video and have it start at a particular time. I ended up coming across a couple of great posts that have some neat tricks.

My favorite two:

  • View high quality videos: Add “&fmt=18” for stereo 480 x 270 resolution or “&fmt=22” for stereo 1280x720 resolution.
  • Start at a specific time: Add “#t=XmYs” where X is the number of minutes and Y is the number of seconds, like “#t=5m16s” to start at 05:16. If you just want seconds (like to start at 0:14) you can just put the number, like “#t=14”.

Check out the rest of the tips on the original sites - good stuff!

dotnet, aspnet, testing, gists, csharp comments edit

The VirtualPathProvider class is (in my opinion) a fairly underused mechanism for extending where different files in your application come from. You can create providers that get files from zip archives, databases, or anywhere else you need.

The problem is, unit testing them is a nightmare. You either have to run the tests from inside a real web app or you have to set up so many mocks that your tests become fragile or unmanageable. Ugh.

Turns out there’s a third option - create a special AppDomain that has just enough real setup to support working with the ASP.NET HostingEnvironment and VirtualPathProviders.

Here’s a sample test fixture that does just that:

using System;
using System.IO;
using System.Reflection;
using System.Web.Hosting;
using NUnit.Framework;

namespace MyTests
{
  [TestFixture]
  public class MyTestFixture
  {
    // Instance property for the HostingEnvironment-enabled AppDomain.
    private AppDomain _hostingEnvironmentDomain = null;

    [TestFixtureSetUp]
    public void TestFixtureSetUp()
    {
      // Create the AppDomain that will support the VPP.
      this._hostingEnvironmentDomain =
        AppDomain.CreateDomain("HostingEnvironmentDomain",
        AppDomain.CurrentDomain.Evidence,
        AppDomain.CurrentDomain.SetupInformation,
        AppDomain.CurrentDomain.PermissionSet);

      // Set some required data that the runtime needs.
      this._hostingEnvironmentDomain.SetData(".appDomain", "HostingEnvironmentDomain");
      this._hostingEnvironmentDomain.SetData(".appId", "HostingEnvironmentTests");
      this._hostingEnvironmentDomain.SetData(".appPath", Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location));
      this._hostingEnvironmentDomain.SetData(".appVPath", "/");
      this._hostingEnvironmentDomain.SetData(".domainId", "HostingEnvironmentTests");

      // Initialize the hosting environment.
      HostingEnvironment environment = this._hostingEnvironmentDomain.CreateInstanceAndUnwrap(typeof(HostingEnvironment).Assembly.FullName, typeof(HostingEnvironment).FullName) as HostingEnvironment;

      // Finally, register your VPP instance so you can test.
      this.Execute(() =>
        {
          HostingEnvironment.RegisterVirtualPathProvider(new TestVirtualPathProvider());
        });
    }

    [TestFixtureTearDown]
    public void TestFixtureTearDown()
    {
      // When the fixture is done, tear down the special AppDomain.
      AppDomain.Unload(this._hostingEnvironmentDomain);
    }

    [Test]
    public void FileExists()
    {
      // Use the special "Execute" method to run code
      // in the special AppDomain.
      this.Execute(() =>
        {
          Assert.IsTrue(HostingEnvironment.VirtualPathProvider.FileExists("~/Root/Folder1/Page1.aspx"));
        });
    }

    // This method allows you to execute code in the
    // special HostingEnvironment-enabled AppDomain.
    private void Execute(CrossAppDomainDelegate testMethod)
    {
      this._hostingEnvironmentDomain.DoCallBack(testMethod);
    }
  }
}

The difficult bit is setting up the special AppDomain, but once you do that and initialize the HostingEnvrionment, you can use the VirtualPathProvider just like you would in a real environment. The special AppDomain thinks the “root” of your application is in the same location as the executing unit test assembly, so there shouldn’t be any issues with the runtime locating assemblies or anything.

Standard disclaimers apply: YMMV, I’m not responsible if it crashes your server, etc.