I’m messing around with Boxstarter and Chocolatey and one of the things I wanted to do was install the various “Command Prompt Here” context menu extensions I use all the time. These extensions are .inf files and, unfortunately, there isn’t really any documentation on how to create a Chocolatey package that installs an .inf.

So here’s how you do it:

First, package the .inf file in the tools folder of your package alongside the chocolateyInstall.ps1 script..inf files are pretty small anyway and you want the file to be around for uninstall, so it’s best to just include it.

Next, set your chocolateyInstall.ps1 to run InfDefaultInstall.exe. That’s an easier way to install .inf files than the rundll32.exe way and it’ll work with Vista and later. So… no XP support. Aw, shucks.

Here’s a sample chocolateyInstall.ps1:

$packageName = 'YourPackageNameHere'
$validExitCodes = @(0)

try {
  $scriptPath = split-path -parent $MyInvocation.MyCommand.Definition
  $target = Join-Path $scriptPath "YourInfFileNameHere.inf"
  $infdefaultinstall = Join-Path (Join-Path $Env:SystemRoot "System32") "InfDefaultInstall.exe"
  Start-ChocolateyProcessAsAdmin "$target" "$infdefaultinstall" -validExitCodes $validExitCodes
  Write-ChocolateySuccess "$packageName"
} catch {
  Write-ChocolateyFailure "$packageName" "$($_.Exception.Message)"
  throw
}

To support uninstall, add a chocolateyUninstall.ps1 script. This will have to use rundll32.exe to uninstall, but it’s not too bad.

    $packageName = 'YourPackageNameHere'
    $validExitCodes = @(0)

    try {
      $scriptPath = split-path -parent $MyInvocation.MyCommand.Definition
      $target = Join-Path $scriptPath "YourInfFileNameHere.inf"
      Start-ChocolateyProcessAsAdmin "SETUPAPI.DLL,InstallHinfSection DefaultUninstall 132 $target" "rundll32.exe" -validExitCodes $validExitCodes
      Write-ChocolateySuccess "$packageName"
    } catch {
      Write-ChocolateyFailure "$packageName" "$($_.Exception.Message)"
      throw
    }

That’s it! Run the packaging and you’re set to go. This will support both installation and uninstallation of the .inf file.

Note: At one point I was having some trouble getting this to run on a Windows Server 2012 VM using the one-click Boxstarter execution mechanism. I found this while testing an install script that installs something like 40 things. After rolling back the VM to a base snapshot (before running the script) I’m no longer able to see the failure I saw before, so I’m guessing it was something else in the script causing the problem. This INF install mechanism appears to work just fine.

net comments edit

I was testing out some changes to versioning in Autofac. We have a MyGet feed, but all of the internal dependencies of the various NuGet packages when they’re built point to the CI versions, so it’s sort of hard to stage a test of what things will look like when they’re released – you have to rename each .nupkg file to remove the “-CI-XYZ” build number, open each .nupkg file, change the internal .nuspec file to remove the “-CI-XYZ” build number info, then re-zip everything up. In testing, I had to do this a few times, so I scripted it.

I put everything in a folder structure like this:

  • ~/TestFeed
    • backup – contains all of the original .nupkg files (renamed without the “-CI-XYZ”)
    • msbuildcommunitytasks – contains the MSBuild Community Tasks set

Then I wrote up a quick MSBuild script for doing all the extract/update/rezip stuff. I could have used any other scripting language, but, eh, the batching and file scanning in MSBuild made a few things easy.

msbuild fixrefs.proj /t:Undo puts the original packages (from the backup folder) into the test feed folder.

msbuild fixrefs.proj Does the zip/fix/re-zip.

One of the challenges I ran into was that the zip task in MSBuild Community Tasks seemed to always want to add an extra level of folders into the .nupkg – I couldn’t get the original contents to live right at the root of the package. Rather than fight it, I used 7-Zip to do the re-zipping. I probably could have gotten away from the MSBuild Community Tasks entirely had I some form of sed on my machine because I needed that FileUpdate task. But… Windows. And, you know, path of least resistance. I think this was a five-minute thing. Took longer to write this blog entry than it did to script this.

Here’s “fixrefs.proj”:

<?xml version="1.0" encoding="utf-8"?>
<Project DefaultTargets="All" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="4.0">
  <PropertyGroup>
    <MSBuildCommunityTasksPath>.</MSBuildCommunityTasksPath>
    <SevenZip>C:\Program Files\7-Zip\7z.exe</SevenZip>
  </PropertyGroup>
  <Import Project="$(MSBuildProjectDirectory)\msbuildcommunitytasks\MSBuild.Community.Tasks.Targets"/>
  <ItemGroup>
    <Package Include="*.nupkg"/>
  </ItemGroup>
  <Target Name="All">
    <MakeDir Directories="%(Package.Filename)" />
    <Unzip ZipFileName="%(Package.FullPath)" TargetDirectory="%(Package.Filename)" />
    <ItemGroup>
      <NuSpec Include="**/*.nuspec" />
    </ItemGroup>
    <FileUpdate Files="@(NuSpec)" Regex="(.)\-CI\-\d+" ReplacementText="$1" WarnOnNoUpdate="true" />
    <Delete Files="@(Package)" />
    <CallTarget Targets="ZipNewPackage" />
    <RemoveDir Directories="%(Package.Filename)" />
  </Target>
  <Target Name="Undo">
    <Delete Files="@(Package)" />
    <ItemGroup>
      <Original Include="backup/*.nupkg" />
    </ItemGroup>
    <Copy SourceFiles="@(Original)" DestinationFolder="$(MSBuildProjectDirectory)" />
  </Target>
  <Target Name="ZipNewPackage" Inputs="@(Package)" Outputs="%(Identity).Dummy">
    <Exec
      Command="&quot;$(SevenZip)&quot; a -tzip &quot;$(MSBuildProjectDirectory)\%(Package.Filename)%(Package.Extension)&quot;"
      WorkingDirectory="$(MSBuildProjectDirectory)\%(Package.Filename)" />
  </Target>
</Project>

net comments edit

Until now, Autofac assemblies have changed version using a slow-changing assembly version but a standard semantic version for the NuGet package and file version.

The benefit of that approach is we could avoid some painful assembly redirect issues.

The drawback, of course, is that even minor changes (adding new functionality in a backwards-compatible way) can cause problems – one project uses version 3.0.0.0 of Autofac and works great, a different project also uses version 3.0.0.0 of Autofac but breaks because it needs some of that newer functionality. That’s hard to troubleshoot and pretty much impossible to fix. (It’s the wrong version of 3.0.0.0? That’s a new kind of dependency hell.)

As a compromise to that, we’ve switched to work sort of like MVC and Web API – for major and minor (X.Y) changes, the assembly version will change, but not for patch-level changes; for all changes, the NuGet package and file versions will change.

This initial switch will potentially be a little painful for folks since it means every Autofac package has to be re-issued to ensure assembly dependencies line up. After that, we should be running smooth again.

You’ll see a 0.0.1 update to the packages – all of those have the new assemblies with the new versions and proper prerequisite references. (Not entirely sure 0.0.1 was the right semantic version increment, but, well, c’est la vie.)

Really sorry about the bit of upgrade pain here. I had hoped we could sneak the change out on a package-by-package basis, but as each integration or extras package gets released, it gets its dependencies set and has assembly references, so we’d end up releasing everything a few times – the first time for when the version of the integration package changes; a second time for when core Autofac changes; and one more time for every time any other dependencies change. For packages like Autofac.Extras.Multitenant.Wcf (which relies on Autofac, Autofac.Integration.Wcf, and Autofac.Extras.Multitenant), it’d mean releasing it a minimum of four times just for the assembly reference changes. Best just to rip the bandage off, right? (I hope?)

NuGet should take care of the assembly redirect issues for you, but if you see assembly dependency conflict warnings in your build, it’s because you’ve not updated all of your Autofac packages.

Relevant GitHub issues: #502, #508

net, aspnet comments edit

I just spent a day fighting these so I figured I’d share. You may or may not run into them. They do get pretty low-level, like, “not the common use case.”

PROBLEM 1: Why Isn’t My Data Serializing as XML?

I had set up my media formatters so the XML formatter would kick in and provide some clean looking XML when I provided a querystring parameter, like http://server/api/something?format=xml. I did it like this:

var fmt = configuration.Formatters.XmlFormatter;
fmt.MediaTypeMappings.Add(new QueryStringMapping("format", "xml", "text/xml"));
fmt.UseXmlSerializer = true;
fmt.WriterSettings.Indent = true;

It seemed to work on super simple stuff, but then it seemed to arbitrarily just stop - I’d get XML for some things, but others would always come back in JSON no matter what.

The problem was the fmt.UseXmlSerializer = true; line. I picked the XmlSerializer option because it can create prettier XML without all the extra namespaces and cruft of the standard DataContractSerializer

UPDATE: I just figured out it’s NOT IEnumerable<T> that’s the problem - it’s an object way deep down in my hierarchy that doesn’t have a parameterless constructor.

When I started returning IEnumerable<T> values, that’s when it stopped working. I thought it was because of the IEnumerable<T>, but it turned out that I was enumerating an object that had a property with an object that had another property that didn’t have a default constructor. Yeah, deep in the sticks. No logging or exception handling to explain that one. I had to find it by stepping into the bowels of the XmlMediaTypeFormatter.

PROBLEM 2: Why Aren’t My Format Configurations Being Used?

Somewhat related to the first issue - I had the XML serializer set up for that query string mapping, and I had JSON set up to use camelCase and nice indentation, too. But for some weird reason, none of those settings were getting used at all when I made my requests.

Debugging into it, I could see that on some requests the configuration associated with the inbound request message was all reset to defaults. What?

This was because of some custom route registration stuff.

When you use attribute routes…

  1. The attribute routing mechanism gets the controller selector from the HttpConfiguration object.
  2. The controller selector gets the controller type resolver from the HttpConfiguration object to which it holds a reference.
  3. The controller type resolver locates all the controller types for the controller selector.
  4. The controller selector builds up a cached list of controller name-to-descriptor mappings. Each descriptor gets passed a reference to the HttpConfiguration object.
  5. The attribute routing mechanism gets the action selector from the HttpConfiguration object.
  6. The action selector uses type descriptors from the controller type selector and creates a cached set of action descriptors. Each action descriptor gets passed a reference to the HttpConfiguration object and get a reference back to the parent controller descriptor.
  7. The actions from the action selector get looked at for attribute route definitions and routes are built from the action descriptor. Each route has a reference to the descriptor so it knows what to execute.
  8. Execution of an action corresponding to one of these specific routes will use the exact descriptor to which it was tied.

Basically. There’s a little extra complexity in there I yada-yada’d away. The big takeaway here is that you can see all the bajillion places references to the HttpConfiguration are getting stored. There’s some black magic here.

I was trying to do my own sort of scanning for attribute routes (like on plugin assemblies that aren’t referenced by the project), but I didn’t want to corrupt the main HttpConfiguration object so I created little temporary ones that I used during the scanning process just to help coordinate things.

Yeah, you can’t do that.

Those temporary mostly-default configurations were getting used during my scanned routes rather than the configuration I had set with OWIN to use.

Once I figured all that out, I was able to work around it, but it took most of the day to figure it out. It’d be nice if things like the action descriptor would automatically chain up to the parent controller descriptor (if it’s present) to get configuration rather than holding its own reference. And so on, all the way up the stack, such that routes get their configuration from the route table, which is owned by the root configuration object. Set it and forget it.

net, aspnet, autofac comments edit

I’m working on a new Web API project where I want to use AutoMapper for some type conversion. As part of that, I have a custom AutoMapper type converter that takes in some constructor parameters so the converter can read configuration values. I’m using Autofac for dependency injection (naturally).

Historically, I’ve been able to hook AutoMapper into dependency injection using the ConstructServicesUsing method and some sort of global dependency resolver, like:

Mapper.Initialize(cfg =>
{
  cfg.ConstructServicesUsing(t => DependencyResolver.Current.GetService(t));
  cfg.CreateMap();
});

That works great in MVC or in other applications where there’s a global static like that. In those cases, the “request lifetime scope” either doesn’t exist or it’s managed by the implementation of IDependencyResolver the way it is in the Autofac integration for MVC.

Retrieving the per-request lifetime scope is much more challenging in Web API because the request lifetime scope is managed by the inbound HttpRequestMessage. Each inbound message gets a lifetime scope associated, so there’s no “global static” from which you can get the request lifetime. You can get the global dependency resolver, but resolving from that won’t be per-request; it’ll be at the application level.

It’s also a challenging situation because AutoMapper really leans you toward using the static Mapper object to do your mapping and you can’t really change the value of ConstructServicesUsing on the static because, well, you know, threading.

So… what to do?

The big step is to change your mindset around the static Mapper object. Instead of using Mapper to map things, take an IMappingEngine as a dependency in your class doing mapping. Yes, that’s one more dependency you’d normally not have to take, but there’s not really a better way given the way the IMappingEngine has to resolve dependencies is actually different per-request.

This frees us up to now think about how to register and resolve a per-request version of IMappingEngine.

Before I show you how to do this, standard disclaimers apply: Works on my machine; I’ve not performance tested it; It might not work for you; etc.

Oooookay.

First, we need to understand how the IMappingEngine we build will come together.

  1. The implementation of AutoMapper.IMappingEngine we’ll be using is AutoMapper.MappingEngine (the only implementation available).
  2. MappingEngine takes in an IConfigurationProvider as a constructor parameter.
  3. IConfigurationProvider has a property ServiceCtor that is the factory we need to manipulate to resolve things out of a per-request lifetime scope.
  4. The main AutoMapper.Mapper has a Configuration property of type IConfiguration… but the backing store for it is really an AutoMapper.ConfigurationStore, which is also an IConfigurationProvider. (This is where the somewhat delicate internal part of things comes in. If something breaks in the future, chances are this will be it.)

Since we need an IConfigurationProvider, let’s make one.

We want to leverage the main configuration/initialization that the static Mapper class provides because there’s a little internal work there that we don’t want to copy/paste. The only thing we really want to change is that ServiceCtor property, but that’s not a settable property, so let’s write a quick wrapper around an IConfigurationProvider that lets us override it with our own method.

public class ConfigurationProviderProxy : IConfigurationProvider
{
  private IComponentContext _context;
  private IConfigurationProvider _provider;

  // Take in a configuration provider we're going to wrap
  // and an Autofac context from which we can resolve things.
  public ConfigurationProviderProxy(IConfigurationProvider provider, IComponentContext context)
  {
    this._provider = provider;
    this._context = context;
  }

  // This is the important bit - we use the passed-in
  // Autofac context to resolve dependencies.
  public Func<Type, object> ServiceCtor
  {
    get
    {
      return this._context.Resolve;
    }
  }

  //
  // EVERYTHING ELSE IN THE CLASS IS JUST WRAPPER/PROXY
  // CODE TO PASS THROUGH TO THE BASE PROVIDER.
  //
  public bool MapNullSourceCollectionsAsNull { get { return this._provider.MapNullSourceCollectionsAsNull; } }

  public bool MapNullSourceValuesAsNull { get { return this._provider.MapNullSourceValuesAsNull; } }

  public event EventHandler<TypeMapCreatedEventArgs> TypeMapCreated
  {
    add { this._provider.TypeMapCreated += value; }
    remove { this._provider.TypeMapCreated -= value; }
  }

  public void AssertConfigurationIsValid()
  {
    this._provider.AssertConfigurationIsValid();
  }

  public void AssertConfigurationIsValid(TypeMap typeMap)
  {
    this._provider.AssertConfigurationIsValid(typeMap);
  }

  public void AssertConfigurationIsValid(string profileName)
  {
    this._provider.AssertConfigurationIsValid(profileName);
  }

  public TypeMap CreateTypeMap(Type sourceType, Type destinationType)
  {
    return this._provider.CreateTypeMap(sourceType, destinationType);
  }

  public TypeMap FindTypeMapFor(ResolutionResult resolutionResult, Type destinationType)
  {
    return this._provider.FindTypeMapFor(resolutionResult, destinationType);
  }

  public TypeMap FindTypeMapFor(Type sourceType, Type destinationType)
  {
    return this._provider.FindTypeMapFor(sourceType, destinationType);
  }

  public TypeMap FindTypeMapFor(object source, object destination, Type sourceType, Type destinationType)
  {
    return this._provider.FindTypeMapFor(source, destination, sourceType, destinationType);
  }

  public TypeMap[] GetAllTypeMaps()
  {
    return this._provider.GetAllTypeMaps();
  }

  public IObjectMapper[] GetMappers()
  {
    return this._provider.GetMappers();
  }

  public IFormatterConfiguration GetProfileConfiguration(string profileName)
  {
    return this._provider.GetProfileConfiguration(profileName);
  }
}

That was long, but there’s not much logic to it. You could probably do some magic to make this smaller with Castle.DynamicProxy but I’m keeping it simple here.

Now we need to register IMappingEngine with Autofac so that it:

  • Creates a per-request engine that
  • Uses a per-request lifetime scope to resolve dependencies and
  • Leverages the root AutoMapper configuration for everything else.

That’s actually pretty easy:

// Register your mappings here, but don't set any
// ConstructServicesUsing settings.
Mapper.Initialize(cfg =>
{
  cfg.AddProfile<SomeProfile>();
  cfg.AddProfile<OtherProfile>();
});

// Start your Autofac container.
var builder = new ContainerBuilder();

// Register your custom type converters and other dependencies.
builder.RegisterType<DemoConverter>().InstancePerApiRequest();
builder.RegisterApiControllers(Assembly.GetExecutingAssembly());

// Register the mapping engine to use the base configuration but
// a per-request lifetime scope for dependencies.
builder.Register(c =>
{
  var context = c.Resolve<IComponentContext>();
  var config = new ConfigurationProviderProxy(Mapper.Configuration as IConfigurationProvider, context);
  return new MappingEngine(config);
}).As<IMappingEngine>()
.InstancePerApiRequest();

// Build the container.
var container = builder.Build();

Now all you have to do is take an IMappingEngine as a dependencyand use that rather than AutoMapper.Mapper for mapping.

public class MyController : ApiController
{
  private IMappingEngine _mapper;

  public MyController(IMappingEngine mapper)
  {
    this._mapper = mapper;
  }

  [Route("api/myaction")]
  public SomeValue GetSomeValue()
  {
    // Do some work and use the IMappingEngine for maps.
    return this._mapper.Map<SomeValue>(otherValue);
  }
}

Following that pattern, any mapping dependencies will be resolved out of the per-request lifetime scope rather than the application root container and you won’t have to use any static references or fight with request contexts. When the API controller is resolved (out of the request scope) the dependent IMappingEngine will be as well, as will all of the chained-in dependencies for mapping.

While I’ve not tested it, this technique should also work in an MVC app to allow you to get away from the static DependencyResolver.Current reference. InstancePerApiRequest and InstancePerHttpRequest do effectively the same thing internally in Autofac, so the registrations are cross-compatible.