Configuring SignalR in StructureMap Thursday, 04 Jun, 2015

Configuring SignalR in ASP.NET MVC, using StructureMap as the IoC container is fairly straightforward, but not without some subtleties that caught me out.

For the purposes of this post, I'm going to assume that you are familiar with both SignalR and StructureMap, and that you know how to configure them in an ASP.NET MVC application. I will also assume that through some google-fu you have seen the Dependency Injection in SignalR guidance, and have worked through it and got to the "Using IoC Containers in SignalR" section.

I would assume, although I've not tested it, that much of this could also be applied to a self-hosted SignalR server.

Library versions used

This post is based on:

Follow the guidance up to the section on using Ninject, at which point we now want to configure StructureMap.

Replace the SignalR Dependency Resolver

The implementation is nearly identical, with some obvious StructureMap specific differences:

public class StructureMapSignalRDependencyResolver : DefaultDependencyResolver
{
    private readonly IContainer _container;

    public StructureMapSignalRDependencyResolver(IContainer container)
    {
        _container = container;
    }

    public override object GetService(Type serviceType)
    {
        return _container.TryGetInstance(serviceType) ?? base.GetService(serviceType);
    }

    public override IEnumerable<object> GetServices(Type serviceType)
    {
        var objects = _container.GetAllInstances(serviceType).Cast<object>();
        return objects.Concat(base.GetServices(serviceType));
    }
}

The behaviour is fairly similar. TryGetInstance will attempt to resolve the type, and if it doesn't know about it, will return null, in which case we call the base resolver, which does.

Register this with StructureMap:

For<IDependencyResolver>().Singleton().Use<StructureMapSignalRDependencyResolver>();

In your Startup, where you configure SignalR, we need to use this new resolver implementation:

var resolver = DependencyResolver.Current.GetService<Microsoft.AspNet.SignalR.IDependencyResolver>();

var hubConfiguration = new HubConfiguration
{
    Resolver = resolver

/* other options as required */
};

Here, we are using the MVC DependencyResolver, which has already been replaced by StructureMap thanks to StructureMap.MVC5, to resolve an instance of the SignalR dependency resolver we've registered, which we then tell SignalR to use with a hub configuration object.

Now we just need to configure the StructureMap registry, and teach it how to resolve IHubConnectionContext<dynamic>:

For<IConnectionManager>().Use<ConnectionManager>();
For<IStockTicker>()
    .Singleton()
    .Use<StockTicker>()
    .Ctor<IHubConnectionContext<dynamic>>()
    .Is(ctx => ctx.GetInstance<IDependencyResolver>()
        .Resolve<IConnectionManager>()
        .GetHubContext<StockTickerHub>().Clients);

As in the guidance, we want the StockTicker instance to be a singleton, and we have specify how to resolve the IHubConnectionContext<dynamic> which the StockTicker requires. In the Is, I'm using the context to resolve the default SignalR connection manager we've registered. This isn't in the guidance, but I couldn't get it work without doing this.

If anyone has comments/improvements on this, I'd love to hear them.


MSBuild Code Analysis (on a build server) Friday, 17 Apr, 2015

It is possible to setup your build server to run code analysis on your solution/projects, without having to install VS on your build server.

The answer is here: http://stackoverflow.com/a/21731245/3181

I'm not going to reproduce the code here, there is no point. This post is just a reminder to myself as to where I found the solution to this.


Gitlab and Active Directory Wednesday, 15 Apr, 2015

Gitlab is an open source 'clone' of Github, although I don't think it's much of a clone anymore, to be fair. The Enterprise edition has full Active Directory support, and the Community edition does not.

The integration with Active Directory is of great benefit. To get the most out of it, I think that you would need to upgrade to the Enterprise edition, as it adds a number of additonal integrations which look to be really usefull for larger organisations with multiple projects and development teams.

It is possible to configure the Community edition to integrate with Active Directory, to the extent that you can restrict exactly who is allowed to login in. You have to manually configure the users permissions on groups/projects though. In the Enterprise edition, the tighter integration means that you can match up Active Directory groups with groups in Gitlab, and control access both to the server, and groups/projects, all through Active Directory.

Here is the ldap section from my gitlab.yml (please be aware, I'm no Active Directory expert):

ldap:
enabled: true
  servers:
    main:
      label: 'domain'
      host: 'ad.example.com'
      port: 389 
      uid: 'sAMAccountName'
      method: 'plain' 
      bind_dn: 'CN=Git Lab,OU=AB,OU=example,DC=example,DC=com'
      password: 'secret'
      allow_username_or_email_login: true
      active_directory: true
      base: 'OU=example,DC=example,DC=com'
      user_filter: '(memberOf=cn=devs,ou=groups,dc=example,dc=com)'

The bind_dn is for a user called 'Git Lab', and you must suppoly the password. This user was expressly setup just for this, but you can use any user. The base is the level of Active Directory that Gitlab searches for users from. Finally, the user_filter states that users must members of devs in order to be able to login.


ASP.Net Bootstrap 3 form control width Thursday, 19 Mar, 2015

Having just been stumped on this for longer than I care to admit, and only finding the answer to my problem buried in a comment on StackOverflow, I'm posting it here for my own future reference:

Q: Using ASP.Net MVC with Bootstrap 3, why won't my <input> stretch to the full width of a <div class="form-group">, even though I am putting form-control on the css class?

A: Because Microsoft override input, select and textarea to have max-width: 280px in the default Site.css which is added to new projects. Removing this will allow the 100% width from form-control.


Fluent NPoco mappings with StructureMap Tuesday, 17 Mar, 2015

I like using NPoco, it's a really nice library that allows you stop having to write raw ADO.NET. Recently I just switched one of my projects at work to use the Fluent Mapping features, essentially so that my POCO's do not need to have the mapping attributes in them.

I started wth the example on the NPoco wiki of creating a database factory, and adding the mapping class to the fluent configuration. As the number of mapping classes has grown, this has quickly become unwieldy and a bit of a maintainance issue.

As I already utilise Structuremap in the application, I wanted to configure it to automatically pick up my mapping classes and build the configuration object for me. This is easy to in the registry:

public DefaultRegistry()
{
    Scan(
        scan =>
        {
            scan.TheCallingAssembly();
            scan.WithDefaultConventions();
            scan.With(new ControllerConvention());
            scan.AddAllTypesOf<IMap>();
        });

    For<FluentConfig>().Use(context => FluentMappingConfiguration.Configure(context.GetAllInstances<IMap>().ToArray()));
    For<DatabaseFactory>().Singleton().Use<DatabaseFactory>();
    For<IDatabase>().HttpContextScoped().Use(context => context.GetInstance<DatabaseFactory>().GetDatabase());
}

The mapping classes must inherit from Map<T>, which itself inherits from IMap. Thus we can confidently add all types of IMap in the scan.

Then an instance of FluentConfig must be registered, which can be done with an overload of .Use, from which we get the StructureMap context and pull out all the types of IMap which have been found and pass it to the static .Configure method of the FluentMappingConfiguration, which constructs the instance.

The DatabaseFactory (see below) is then registered, and it accepts a 'FluentConfig' instance in its constructor. As per the original example on the NPoco wiki, it is marked as a singleton to ensure that only one instance is created, so that the mappings do not get registered more than once. I don't know what would happen if the mappings were to be registered more than once, but I assume that it would be a Bad Thing™.

Then, for the NPoco IDatabase instance that we register, we want to always create it using the instance of the DatabaseFactory that has already been registered, which again is accessible using the overload of .Use to get the Structuremap context. It's marked as .HttpContextScoped(), but I'm honestly not sure if that's required or not given that I'm using Structuremap.MVC5 nested containers.

For completeness, here is the DatabaseFactory:

public class DatabaseFactory
{
    private static NPoco.DatabaseFactory _internalFactory;

    public DatabaseFactory(FluentConfig fluentConfig)
    {
        Configure(fluentConfig);
    }

    private static void Configure(FluentConfig fluentConfiguration)
    {
        _internalFactory = NPoco.DatabaseFactory.Config(x =>
        {
            x.UsingDatabase(() => new Database("ConnectionString"));
            x.WithFluentConfig(fluentConfiguration);
        });
    }

    public NPoco.Database GetDatabase()
    {
        return _internalFactory.GetDatabase();
    }
}