Sunday, October 31, 2010

RavenDb Indexes : 1st Attempt

I’ve been playing with RavenDb’s pre-defined indexes today. They use a map reduce model with Linq, which is very nice. A recent new feature is the ability to define them in your application code. Here a couple I’ve just created:

public class Child_ByName : AbstractIndexCreationTask<Child>
{
    public Child_ByName()
    {
        Map = children => from child in children
                          select new { child.Name };
    }
}

public class Child_ByPendingSchedule : AbstractIndexCreationTask<Child>
{
    public Child_ByPendingSchedule()
    {
        Map = children => from child in children
                          from schedule in child.Account.PaymentSchedules
                          select new { schedule.NextRun };
    }
}

You register them with the RavenDb document store (a bit like a session factory in NHibernate) like this:

IndexCreation.CreateIndexes(typeof(Child_ByName).Assembly, store);

When you want to use them, you have to use a rather nasty magic string (RavenDb converts the underscore in the class name to a forward slash ‘/’).

var results = session.Advanced.LuceneQuery<Child>("Child/ByName").WhereEquals("Name", "two").ToList();

It would be much nicer if you could write something like this instead:

var results = session.Advanced.LuceneQuery<Child_ByName>().WhereEquals("Name", "two").ToList();

Here a couple of tests showing them at work:

[TestFixture]
public class RavenDbSchedulingWithIndex : LocalClientTest
{
    IDocumentStore store;
    Parent parent;
    DateTime now;

    [SetUp]
    public void SetUp()
    {
        store = NewDocumentStore();
        IndexCreation.CreateIndexes(typeof(Child_ByName).Assembly, store);
        parent = new Parent("Dad", "mike@mike.com", "xxx");

        now = new DateTime(2010, 4, 5);

        // create some children with accounts and schedules
        using (var session = store.OpenSession())
        {
            session.Store(CreateChildWithSchedule("one", 1M, now.AddDays(-2)));
            session.Store(CreateChildWithSchedule("two", 2M, now.AddDays(-1)));
            session.Store(CreateChildWithSchedule("three", 3M, now));
            session.Store(CreateChildWithSchedule("four", 4M, now.AddDays(1)));
            session.Store(CreateChildWithSchedule("five", 5M, now.AddDays(2)));
            session.SaveChanges();
        }
    }

    [Test]
    public void Select_child_using_ByName_index()
    {
        using (var session = store.OpenSession())
        {
            var results = session.Advanced.LuceneQuery<Child>("Child/ByName").WhereEquals("Name", "two").WaitForNonStaleResults().ToList();
            results.Count().ShouldEqual(1);
            results[0].Name.ShouldEqual("two");
        }
    }

    [Test]
    public void Select_child_using_ByPendingSchedule()
    {
        using (var session = store.OpenSession())
        {
            var results = session.Advanced
                .LuceneQuery<Child>("Child/ByPendingSchedule")
                .WhereLessThan("NextRun", now)
                .WaitForNonStaleResults().ToList();

            results.Count().ShouldEqual(2);
            results[0].Name.ShouldEqual("one");
            results[1].Name.ShouldEqual("two");
        }
    }

    Child CreateChildWithSchedule(string name, decimal amount, DateTime startDate)
    {
        var child = parent.CreateChild(name, name, "xxx");
        child.Account.AddPaymentSchedule(startDate, Interval.Week, amount, "Pocket Money");
        return child;
    }
    
}

This is some spike code from Tardis Bank. You can checkout the complete project here:

http://github.com/mikehadlow/Suteki.TardisBank

Thursday, October 28, 2010

Tardis Bank – online pocket money banking for parents and kids

tardisbank_frontpage

meandleo My son Leo (age 8) and I, that us on the right, have a bit of a pocket money problem. He’s supposed to get £2.00 every week, paid on Sunday. He has a Tardis shaped piggy bank, into which he’s supposed to put the £2.00. When he wants to buy something, he’s supposed to get the cash and take it to the shop.

The thing is, I’m a complete scatter brain and often forget to pay the weekly £2.00. Leo is also very spontaneous in his purchasing habits and will often decide he wants to buy something, but has forgotten to bring along his pocket money. In that situation, I buy whatever it is he wants and tell him that I will deduct it from next week’s pocket money…. which I then promptly forget.

We frequently have long discussions about how many weeks have gone past since his last payment and what I’ve bought on his behalf in the meantime. We loose all track of his real pocket money balance.

Regular pocket money is an important financial education for Leo. He needs to learn how to manage money, but without any proper accounting it just ends up being an arbitrary and irregular hand-over of cash and he learns nothing, except how to beg effectively.

These days most people don’t keep their money under the mattress. I use my bank’s online banking web site to manage my finances. What Leo needs is something similar for his pocket money. Once I started to think about our requirements I realised that it would be pretty straightforward to put together a simple web application. There’s also no reason why I couldn’t offer it to anyone who wanted something similar. A simple sign-on system, an account with a list of transactions and a simple payment schedule is all it needs.

Putting Tardis Bank together has been a great opportunity to play with some new technology. I’ve been wanting to have an experiment with the whole NoSQL thing, and RavenDb in particular for quite a while now, not to mention MVC3 Beta. So far the Raven experience has been very nice. Everything works out of the box, and it really makes putting together this kind of site friction free. Not having to worry about database schemas and the whole object-relational thing is very liberating.

I’m planning to present Tardis Bank at £5App here in Brighton next Tuesday, so it’s got to be live and working by then. In the meantime, there’s a holding page:

http://tardisbank.com/

And a GitHub repository for the code:

http://github.com/mikehadlow/Suteki.TardisBank

If you’ve got a spare minute, please check it out and let me know what you think. Any help, especially with the RavenDb usage patterns and the design stuff which I am awful at, would be much appreciated.

Wednesday, October 27, 2010

RavenDb, ASP.NET MVC and Windsor working together

I’m putting together a new project, TardisBank.com, using RavenDb, ASP.NET MVC and Windsor. It’s up on github here:

http://github.com/mikehadlow/Suteki.TardisBank

Here’s how I wire up Windsor and RavenDb.

First, in Global.asax.cs I initialise the container and ask it to load and run installers from all the application assemblies:

public class MvcApplication : System.Web.HttpApplication, IContainerAccessor
{
    ...

    protected void Application_Start()
    {
        AreaRegistration.RegisterAllAreas();

        RegisterGlobalFilters(GlobalFilters.Filters);
        RegisterRoutes(RouteTable.Routes);
        InitialiseContainer();
        InitialiseControllerFactory();
    }

    protected void InitialiseContainer()
    {
        if (container == null)
        {
            container = new WindsorContainer()
                .Install(
                    FromAssembly.InDirectory(new AssemblyFilter(HttpRuntime.BinDirectory, "Suteki.*.dll")));
        }
    }

    protected void InitialiseControllerFactory()
    {
        var controllerFactory = container.Resolve<IControllerFactory>();
        ControllerBuilder.Current.SetControllerFactory(controllerFactory);
    }

    static IWindsorContainer container;
    public IWindsorContainer Container
    {
        get { return container; }
    }
}

One of the installers it runs is my RavenInstaller:

public class RavenInstaller : IWindsorInstaller
{
    public void Install(IWindsorContainer container, IConfigurationStore store)
    {
        container.Register(
            Component.For<IDocumentStore>().Instance(CreateDocumentStore()).LifeStyle.Singleton,
            Component.For<IDocumentSession>().UsingFactoryMethod(GetDocumentSesssion).LifeStyle.PerWebRequest
            );
    }

    static IDocumentStore CreateDocumentStore()
    {
        var store = new DocumentStore
        {
            ConnectionStringName = "tardisConnection"
        };
        store.Initialize();
        return store;
    }

    static IDocumentSession GetDocumentSesssion(IKernel kernel)
    {
        var store = kernel.Resolve<IDocumentStore>();
        return store.OpenSession();
    }
}

Because Windsor already provides a global application store for both singleton and per-request components, we can give it the responsibility of handling the instantiation and lifecycle of the DocumentStore and DocumentSesssion. The DocumentStore is created and initialised once the first time it is requested. The DocumentSession has a PerWebRequest lifestyle and is created using a factory method the first time it is requested.

Don’t forget to register the PerRequestLifestyleModule in Web.config:

<system.webServer>
  <validation validateIntegratedModeConfiguration="false"/>
  
  <modules runAllManagedModulesForAllRequests="true">
    <add name="PerRequestLifestyle" type="Castle.MicroKernel.Lifestyle.PerWebRequestLifestyleModule, Castle.Windsor" />
  </modules>
</system.webServer>

Windsor will properly dispose both the DocumentStore when the application closes and the DocumentSession at the end of each request.

Tuesday, October 26, 2010

RavenDb: Playing with Inheritance and Polymorphism

Over the last couple of days I’ve been playing with RavenDb. So far it’s been a very nice experience. I love the way POCO objects get persisted as complete graphs. You can have nicely encapsulated models too, with private setters, and the client API is a joy to use.

I’m putting together a little project as an excuse to play with Raven, MVC3 and NuPack. I’ll put it up on github soon, but simply put it’s a virtual pocket money bank account for parents and their kids. The model has a concept of Parent and Child both of which inherit a User abstract base class. One of the first things I wanted to check was that the Raven can return a polymorphic collections of Users.

Here’s a test that shows that it can:

[Test]
public void Should_be_able_to_treat_Parents_and_Children_Polymorphically()
{
    using (var session = store.OpenSession())
    {
        var mike = new Parent("Mike Hadlow", "mike@yahoo.com");
        var leo = mike.CreateChild("Leo", "leohadlow", "xxx");
        var yuna = mike.CreateChild("Yuna", "yunahadlow", "xxx");
        var john = new Parent("John Robinson", "john@gmail.com");
        var jim = john.CreateChild("Jim", "jimrobinson", "xxx");

        session.Store(mike);
        session.Store(leo);
        session.Store(yuna);
        session.Store(john);
        session.Store(jim);
        session.SaveChanges();
    }

    using (var session = store.OpenSession())
    {
        var users = session.LuceneQuery<User>().WaitForNonStaleResults().ToArray();

        users.Length.ShouldEqual(5);

        users[0].Id.ShouldEqual("users/mike@yahoo.com");
        users[1].Id.ShouldEqual("users/leohadlow");
        users[2].Id.ShouldEqual("users/yunahadlow");
        users[3].Id.ShouldEqual("users/john@gmail.com");
        users[4].Id.ShouldEqual("users/jimrobinson");

        users[0].GetType().Name.ShouldEqual("Parent");
        users[1].GetType().Name.ShouldEqual("Child");
        users[2].GetType().Name.ShouldEqual("Child");
        users[3].GetType().Name.ShouldEqual("Parent");
        users[4].GetType().Name.ShouldEqual("Child");
    }
}

For this to work, you have to configure Raven to understand that the type ‘User’ is represented by documents with ids that look like ‘users/xxx’:

var documentStore = new DocumentStore
{
    Configuration = new RavenConfiguration
    {
        DataDirectory = path,
        RunInUnreliableYetFastModeThatIsNotSuitableForProduction = true
    },
    Conventions =
    {
        FindTypeTagName = type => typeof(User).IsAssignableFrom(type) ? "users" : null
    }
};

Other than that it just works.

Here’s my User class:

public abstract class User
{
    public string Id { get; private set; }
    public string Name { get; private set; }
    public string UserName { get; private set; }

    protected User(string name, string userName)
    {
        Id = string.Format("users/{0}", userName);
        Name = name;
        UserName = userName;
    }
}

Note the way that the User.Id gets created in the form ‘users/userName’.

Thursday, October 21, 2010

A Powershell Script for Monitoring Web Site Status

I’ve been having some problems with my server recently. If it restarts, because of windows update or for whatever reason, some of my websites can fail to start. I think it might be because WAS was configured as a manually started service, but I’m not sure. I wanted to be warned if any of the sites on my machine were down, and for an automatic restart to be attempted if they were.

I’ve written a little Powershell script to do this. It was an interesting exercise because one of the things that I wanted to do was get an email via my Google Apps account.

Am I insane? Is there a far easier and more obvious way of doing this? Let me know in the comments.

Here’s the script (and yes, I’m a total Powershell Noob :)

$fromAddress = "someServer@suteki.co.uk"
$toAddress = "mike.hadlow@suteki.co.uk"
$subject = "One or more websites are not responding"
$port = 587
$monitorPassword = "s0meN1cePa33w0rd"

$sites = @{
    "suteki.shop" = "http://suteki.shop/"; 
    "blue.shop" = "http://green.shop/"
    }

# send an email message via gmail
function SendMessage([string]$body)
{
    $message = new-object System.Net.Mail.MailMessage($fromAddress, $toAddress, $subject, $body)
    $smtpServer = "smtp.gmail.com"
    $client = new-object System.Net.Mail.SmtpClient($smtpServer)
    $client.EnableSsl = $TRUE
    $client.Port = 587
    $client.Credentials = new-object System.Net.NetworkCredential($fromAddress, $monitorPassword)
    $client.Send($message)
}

# make a request to the site and return the status code. Return 'Failed' if anything goes wrong
function CheckSiteStatus([string]$url)
{
    $req = [System.Net.HttpWebRequest]::Create($url)
    try
    {
        $res = $req.GetResponse()
        $res.StatusCode
    }
    catch
    {
        "Failed"
    }
}

function RestartSite([string]$site)
{
    C:\Windows\system32\inetsrv\appcmd stop site $site
    C:\Windows\system32\inetsrv\appcmd start site $site
}

function CheckSite([string]$url, [string]$site)
{
    $status = CheckSiteStatus $url
    if ($status -eq "OK")
    {
        ""
    }
    else
    {
        # attempt to restart site
        RestartSite $site
        "site '$site' failed to respond`n"
    }
}

function CheckSites()
{
    $body = ""
    foreach($site in $sites.Keys)
    {
        $url = $sites[$site]
        $body += CheckSite $url $site
    }
    if($body -ne "")
    {
        SendMessage $body
        $body
    }
    else
    {
        "OK"
    }
}

CheckSites

I’ve set it up with Task Scheduler to run every 10 minutes. One of the things I discovered when doing this is that if you say your task action is ‘C:\Scripts\Monitor.ps1’, you will just get notepad.exe executing You have to explicitly launch powershell and invoke: ‘powershell C:\Scripts\Monitor.ps1’.

Tuesday, October 19, 2010

Populating Drop Down Lists in ASP.NET MVC

Here’s the shopping basket in Suteki Shop:

suteki_shop_basket

As you can see, there’s a drop-down-list of countries. The standard way of populating a drop-down-list is to pass the collection of countries as part of the view model from the controller action. This can get very tedious when you have multiple drop-downs on a form, the controller action soon gets bloated with data access for all that lookup data. It also violates the thunderdome principle: one model in, one model out.

This lookup data is not something that the controller should really have to care about. I would much rather the data just appeared in the drop-down by convention. In the case above, the basket has a property of type Country, so why couldn’t convention just say: if you want to set the country then you need a list of all the countries?

With this in mind, I’ve put together an HtmlHelper extension method, ComboFor which can create a drop-down list for any entity type that implements my INamedEntity interface, so now I just have to write:

<%= Html.ComboFor(x => x.Country) %>

Which produces this HTML:

<select id="Country_Id" name="Country.Id">
    <option selected="selected" value="1">United Kingdom</option> 
    <option value="2">France</option> 
</select>

The extension method itself looks like this:

public static string ComboFor<TModel, TLookup>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TLookup>> propertyExpression)
    where TLookup : INamedEntity
{
    return htmlHelper.With<IComboFor<TLookup, TModel>, TModel>(combo => combo.BoundTo(propertyExpression));
}

My ‘With’ extension method looks up services in the IoC container so that I can do dependency injection in HtmlHelper extension methods.

The implementation of IComboFor looks like this:

public class ComboFor<TEntity, TModel> : IComboFor<TEntity, TModel>, IRequireHtmlHelper<TModel> where TEntity : class, INamedEntity
{
    readonly IRepository<TEntity> repository;
    protected Expression<Func<TEntity, bool>> WhereClause { get; set; }
    protected string PropertyNamePrefix { get; set; }

    public ComboFor(IRepository<TEntity> repository)
    {
        this.repository = repository;
    }
    public string BoundTo(Expression<Func<TModel, TEntity>> propertyExpression, Expression<Func<TEntity, bool>> whereClause, string propertyNamePrefix)
    {
        WhereClause = whereClause;
        PropertyNamePrefix = propertyNamePrefix;
        return BoundTo(propertyExpression);
    }

    public string BoundTo(Expression<Func<TModel, TEntity>> propertyExpression, Expression<Func<TEntity, bool>> whereClause)
    {
        WhereClause = whereClause;
        return BoundTo(propertyExpression);
    }

    public string BoundTo(Expression<Func<TModel, TEntity>> propertyExpression, string propertyNamePrefix)
    {
        PropertyNamePrefix = propertyNamePrefix;
        return BoundTo(propertyExpression);
    }

    public string BoundTo(Expression<Func<TModel, TEntity>> propertyExpression)
    {
        var getPropertyValue = propertyExpression.Compile();
        var propertyName = (!String.IsNullOrEmpty(PropertyNamePrefix) ? PropertyNamePrefix : "")
            + Utils.ExpressionHelper.GetDottedPropertyNameFromExpression(propertyExpression) + ".Id";

        var viewDataModelIsNull = (!typeof(TModel).IsValueType) && HtmlHelper.ViewData.Model == null;
        var selectedId = viewDataModelIsNull ? 0 : getPropertyValue(HtmlHelper.ViewData.Model).Id;
        return BuildCombo(selectedId, propertyName);
    }


    public override string ToString()
    {
        return BuildCombo(0, typeof(TEntity).Name + "Id");
    }

    protected virtual string BuildCombo(int selectedId, string htmlId)
    {
        if (string.IsNullOrEmpty(htmlId))
        {
            throw new ArgumentException("htmlId can not be null or empty");
        }

        if (HtmlHelper == null)
        {
            throw new SutekiCommonException("HtmlHelper is null");
        }
        return HtmlHelper.DropDownList(htmlId, GetSelectListItems(selectedId)).ToString();
    }

    protected IEnumerable<SelectListItem> GetSelectListItems(int selectedId)
    {
        var queryable = repository.GetAll();
        if (WhereClause != null)
        {
            queryable = queryable.Where(WhereClause);
        }
        var enumerable = queryable.AsEnumerable();

        if (typeof(TEntity).IsOrderable())
        {
            enumerable = enumerable.Select(x => (IOrderable)x).InOrder().Select(x => (TEntity)x);
        }
        
        if (typeof(TEntity).IsActivatable())
        {
            enumerable = enumerable.Select(x => (IActivatable)x).Where(a => a.IsActive).Select(x => (TEntity)x);
        }
        
        var items = enumerable
            .Select(e => new SelectListItem { Selected = e.Id == selectedId, Text = e.Name, Value = e.Id.ToString() });

        return items;
    }

    public HtmlHelper<TModel> HtmlHelper { get; set; }
}

The interesting bit is the ‘GetSelectListItems’ method which gets the select list items from the repository. You have a chance here to provide a Linq where clause to filter the items. It also understands my IOrderable and IActivatable interfaces, so any entity that implements IOrderable will be shown in the correct order in the drop down, and any that implement IActivatable will only appear if they are active.

All this works because of conventions and polymorphism. Now I have much simpler controller actions that usually have a model as the argument and return a model in the ViewResult. Nice!

Friday, October 15, 2010

ASP.NET MVC Controller Action Unit Test Extension Methods

Testing the ActionResult returned by a controller action can be a PITA. You have to get the view name, check that it's correct, get the model, make sure it’s the right type and then do various asserts against it.

We’ve put together a set of extension methods that make writing controller action tests a breeze. Here’s are some examples:

[Test]
public void Show_should_get_reviews_for_product()
{
    controller.Show(1)
        .ReturnsViewResult()
        .WithModel<Product>()
        .AssertAreSame(productRepository.GetById(1), x => x)
        .AssertAreEqual(2, x => x.Reviews.Count());
}

[Test]
public void New_renders_view()
{
    controller.New(5)
        .ReturnsViewResult()
        .WithModel<Review>()
        .AssertAreSame(product, x => x.Product);
}

[Test]
public void NewWithPost_saves_review()
{
    var review = new Review { Product = new Product { Id = 5 } };
    
    controller.New(review)
        .ReturnsRedirectToRouteResult()
        .ToAction("Submitted")
        .WithRouteValue("Id", "5");

    reviewRepository.AssertWasCalled(x => x.SaveOrUpdate(review));
}

You can grab the latest version of the extension methods here:

http://code.google.com/p/sutekishop/source/browse/trunk/Suteki.Shop/Suteki.Common/TestHelpers/ActionResultExtensions.cs

Happy testing!

Update: Jeremy Skinner tells me that the same or similar extension methods are also available in MvcContrib.

Thursday, October 14, 2010

Use a Single Version File For All Projects in a Solution

It’s a good idea for all the assemblies in a single solution to have the same version number, but the default in Visual Studio is for each project to have it’s own AssemblyInfo.cs file, each with it’s own version number. However it’s easy to share a single Version.cs file between all the projects.

First create the Version.cs file as a solution item (right click on the solution, Add, New Item). It should look something like this:

using System.Reflection;

[assembly: AssemblyVersion("2.0.1.442")]
[assembly: AssemblyFileVersion("2.0.1.442")]

version_file_solution_explorer

Now remove those same lines (AssemblyVersion and AssemblyFileVersion) from the AssemblyInfo.cs file in each project in the solution.

The next step to add a link to the Version.cs file to each project. Right click on the project and choose ‘Add New Item’ and then ‘Existing Item’. Browse to the Version.cs file in the solution root directory and add it as a link (click on the little drop down arrow on the ‘Add’ button in the file dialogue):

version_add_link

Do this to all your projects. Now you only have to maintain the version number for the whole solution in one place. Nice!

It’s common practice to integrate version numbering with continuous integration. This usually works by having the CI build process update the version number with the build number before each build. Having the number represented in one place makes that much easier.

One last thing you should always do is provide a way for anyone to discover the version number of a running instance of your application. With an ASP.NET MVC web application, it’s a simple as this little controller action:

public ActionResult Version()
{
    var version = Assembly.GetExecutingAssembly().GetName().Version;
    var versionMessage = string.Format("Suteki Shop. Version {0}.{1}.{2}.{3}", 
        version.Major, version.Minor, version.Build, version.MinorRevision);
    return Content(versionMessage);
}

Now if ever I need to know the version of a running instance I can just type the …/Version URL:

suteki.shop_versionnumber

NHibernate Schema Export in Suteki Shop

Using the NHibernate Schema Export makes the initial database creation experience for Suteki Shop really slick. All you have to do now is run a little console app:

suteki.shop.createdb

All the initial inserts of static data are also done in code using NHibernate. It makes for a very simple development experience.

No more managing huge SQL scripts :)

Monday, October 11, 2010

A Quick Play With NuPack

For those of you who have been hiding under a rock for the last few days, NuPack is a Microsoft sponsored package management system along the lines of Ruby Gems. As anyone who’s tried to use open source software on a .NET project will know, package management, or lack of it, has been a huge problem. Having a standard system that OSS developers can target and a central recognised repository of software will have a major impact on the adoption of OSS in the .NET world.

Make no mistake, this is revolutionary. It’s the difference between right-clicking on references in VS to install an OSS library and the huge PITA that getting source, building, resolving dependencies, etc has been up to now. It makes it orders of magnitude easier.

So, eager to have a play with this shiny new toy, I quickly installed the CTP and fired it up. Looking at the list of packages, I was initially disappointed to see that the latest Castle Windsor release, 2.5.1, wasn’t there. Never mind, I thought, this is a perfect excuse to dig around and see how it works.

Let’s build a new NuPack package for Windsor 2.51.

Castle Windsor has a dependency on Castle.Core, so I need to create a package for that too. Castle.Core also has dependencies on log4net and NLog. So I created a directory structure like this:

nupack_directory_structure

In the Castle.Core directory goes the Castle.Core.nuspec file. It’s a simple XML file that describes the package. I just copied the version from the NuPack source and changed the version number, note the dependencies list:

<?xml version="1.0" encoding="utf-8"?>
<package>
  <metadata>
    <id>Castle.Core</id>
    <version>2.5.1</version>
    <authors>
      <author>Jonathon Rossi &amp; Krzysztof Kozmic</author>
    </authors>
    <description>Core of the castle project</description>
    <language>en-US</language>
  </metadata>
  <dependencies>
    <dependency id="log4net" />
    <dependency id="NLog" minversion="1.0" />
  </dependencies>
</package>

In the lib directory under Castle.Core we put the Castle.Core.dll downloaded from the Castle project website. We do the same for Castle.Ioc, here’s the Castle.Ioc.nuspec file, including the dependency on our new Castle.Core 2.5.1:

<?xml version="1.0" encoding="utf-8"?>
<package>
  <metadata>
    <id>Castle.Ioc</id>
    <version>2.5.1</version>
    <authors>
      <author>Ayende Rahien</author>
    </authors>
    <description>Castle Project ... </description>
    <language>en-US</language>
  </metadata>
  <dependencies>
    <dependency id="Castle.Core" version="2.5.1" />
  </dependencies>
</package>

We pop the Castle.Windsor.dll assembly in the lib folder. For log4net and NLog I just copied the existing nuspec files and assemblies from the NuPack source.

The next job is to run nupack.exe against the nuspec files. This packs up the assemblies and the nuspec file into a single nupkg binary file:

nupack_console

Open the Package Manager Console in Visual Studio and point it at our local nupkg files rather than the default remote repository:

nupack_package_source

Now we can install our new packages:

nupack_install_packages

Note deliberate mistake :)

When you install the packages, NuPack adds a reference to them to your project:

nupack_project_refs

It also creates a packages.config file:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="NLog" version="1.0" />
  <package id="log4net" version="1.2.1" />
  <package id="Castle.Core" version="2.5.1" />
  <package id="Castle.Ioc" version="2.5.1" />
</packages>

One thing that confused me for a while is that NuPack caches the packages list while your solution is open. When I deleted all the references, the assemblies and the packages.config file it still insisted that: ‘Mike.Spikes already has a reference to 'log4net 1.2.1'’. Closing and opening the solution refreshed the cache and fixed the problem.

So there we have it. NuPack is very cool and the fact that it only took me a couple of hours this afternoon to go from zero to building my own packages shows how easy it is. You need to learn how to use it, it’s going to be ubiquitous in .NET development very soon.

Thursday, October 07, 2010

Experimental ASP.NET MVC Add-ins : Updated (or why it pays to blog)

Get the code here.

Github is awesome. Yesterday I wrote a post on how to use MEF alongside Windsor to build an add-in framework for a website. Today Krzysztof Ko┼║mic took my MefAreas and removed all the MEF code. Why? Well, it turns out that a new feature in Windsor 2.5 is dynamic assembly loading and registration. It’s really nice, and is a far better solution that my nasty MEF/Windsor hack.

Here’s what the startup code used to look like:

public class MvcApplication : HttpApplication, IContainerAccessor
{
    ...

    protected void Application_Start()
    {
        HostingEnvironment.RegisterVirtualPathProvider(new AssemblyResourceVirtualPathProvider());
        RegisterRoutes(RouteTable.Routes);

        InitializeWindsor();
        InitializeAddins();
    }


    void InitializeAddins()
    {
        using (var mefContainer = new CompositionContainer(new DirectoryCatalog(HttpRuntime.BinDirectory, "*AddIn.dll")))
        {
            var lazyInstallers = mefContainer.GetExports<IAddinInstaller>();
            foreach (var lazyInstaller in lazyInstallers)
            {
                var installer = lazyInstaller.Value;
                Container.Install(new CommonComponentInstaller(installer.GetType().Assembly));
                installer.DoRegistration(Container);
            }
        }
    }

    void InitializeWindsor()
    {
        container = new WindsorContainer()
            .Install(new CoreComponentsInstaller())
            .Install(new AddinInstaller(Assembly.GetExecutingAssembly()));

        var controllerFactory = Container.Resolve<IControllerFactory>();
        ControllerBuilder.Current.SetControllerFactory(controllerFactory);
    }

    static IWindsorContainer container;
    
    public IWindsorContainer Container
    {
        get { return container; }
    }
}

And here’s what it looks like now:

public class MvcApplication : HttpApplication, IContainerAccessor
{
    ...

    protected void Application_Start()
    {
        HostingEnvironment.RegisterVirtualPathProvider(new AssemblyResourceVirtualPathProvider());
        AreaRegistration.RegisterAllAreas();

        RegisterRoutes(RouteTable.Routes);

        InitializeWindsor();
    }

    void InitializeWindsor()
    {
        container = new WindsorContainer()
            .Install(FromAssembly.This(),
                     FromAssembly.InDirectory(new AssemblyFilter(HttpRuntime.BinDirectory, "*AddIn.dll")));

        var controllerFactory = Container.Resolve<IControllerFactory>();
        ControllerBuilder.Current.SetControllerFactory(controllerFactory);
    }

    static IWindsorContainer container;
    
    public IWindsorContainer Container
    {
        get { return container; }
    }
}

Install(FromAssembly.InDirectory(new AssemblyFilter(HttpRuntime.BinDirectory, “*AddIn.dll”)) does the magic of loading all assemblies with file names ending in ‘AddIn.dll’ and grabbing their IWindsorInstallers. No need for MEF, no need for IAddinInstaller.

Once again a real vindication of why it pays to share. Thanks Krzysztof!

Wednesday, October 06, 2010

Experimental ASP.NET MVC Add-ins

Updated: Please read the new post here.

Get the source code.

I’ve been thinking recently about how to provide an ‘add-in’ framework for Suteki Shop. The idea is that you could ‘drop in’ additional functionality without changing the core system. A good example of this would be payment providers, so if I wanted to have a PayPal payment provider I could simply write that as a separate assembly and then simply drop it into the bin directory of the website and it would just work. Suteki Shop is build around the Windsor IoC container, so it is already designed as a collection of components. What I needed was a way for add-in assemblies to be discovered and some mechanism to allow them to register their components in the container.

I found this excellent post by Hammett where he builds a composable website using MEF. I took this as my inspiration and tweaked it so that MEF is only used for the initial assembly discovery and installation.

Here’s a snippet of my Global.asax.cs file:

public class MvcApplication : HttpApplication, IContainerAccessor { ... protected void Application_Start() { HostingEnvironment.RegisterVirtualPathProvider(new AssemblyResourceVirtualPathProvider()); RegisterRoutes(RouteTable.Routes); InitializeWindsor(); InitializeAddins(); }

void InitializeAddins() { using (var mefContainer = new CompositionContainer(new DirectoryCatalog(HttpRuntime.BinDirectory, "*AddIn.dll"))) { var lazyInstallers = mefContainer.GetExports<IAddinInstaller>(); foreach (var lazyInstaller in lazyInstallers) { var installer = lazyInstaller.Value; Container.Install(new CommonComponentInstaller(installer.GetType().Assembly)); installer.DoRegistration(Container); } } } void InitializeWindsor() { container = new WindsorContainer() .Install(new CoreComponentsInstaller()) .Install(new AddinInstaller(Assembly.GetExecutingAssembly())); var controllerFactory = Container.Resolve<IControllerFactory>(); ControllerBuilder.Current.SetControllerFactory(controllerFactory); } static IWindsorContainer container; public IWindsorContainer Container { get { return container; } } }

In the InitializeWindsor method we create a new windsor container and do the registration for the core application, this is standard stuff that I’ve put into every MVC/Monorail based app I’ve written in the last 3 years. The InitializeAddins method is where the MEF magic happens. We create a new directory catalogue and look for any assembly in the bin directory that ends with ‘AddIn.dll’. Each add-in must include an implementation of IAddinInstaller attributed as a MEF export. We then do some common windsor registration with an AddinInstaller and allow the add-in itself to do any additional custom registration by calling its DoRegistration method. Note that we only keep the MEF CompositionContainer long enough to set things up, after that it’s disposed.

Note that we also register a custom virtual path provider ‘AssemblyResourceVirtualPathProvider’ so that we can load views that are embedded in assemblies as resource files rather than from the file system. It’s described in this Code Project article.

Here’s a typical implementation of IAddinInstaller, note the MEF export attributes:

[Export(typeof(IAddinInstaller)), PartCreationPolicy(CreationPolicy.NonShared)]
public class Installer : IAddinInstaller
{
    public void DoRegistration(IWindsorContainer container)
    {
        // do any additional registration
    }
}

The CommonComponentInstaller does registration for the components that are common for all add-ins. In this case, controllers and INavigation implementations:

public class CommonComponentInstaller : IWindsorInstaller
{
    readonly Assembly assembly;

    public CommonComponentInstaller(Assembly assembly)
    {
        this.assembly = assembly;
    }

    public void Install(IWindsorContainer container, IConfigurationStore store)
    {
        container.Register(
                AllTypes
                    .FromAssembly(assembly)
                    .BasedOn<IController>()
                    .WithService.Base()
                    .Configure(c => c.LifeStyle.Transient.Named(c.Implementation.Name.ToLower())),
                AllTypes
                    .FromAssembly(assembly)
                    .BasedOn<INavigation>()
                    .WithService.Base()
                    .Configure(c => c.LifeStyle.Transient.Named(c.Implementation.Name.ToLower()))
            );
    }
}

INavigation is just a simple way to provide an extensible menu. Any add-in that wants to add a menu item simply implements it:

public class CustomerNavigation : INavigation
{
    public string Text
    {
        get { return "Customers"; }
    }

    public string Action
    {
        get { return "Index"; }
    }

    public string Controller
    {
        get { return "Customer"; }
    }
}
 
The navigation controller simply has a dependency on all INavigation implementations, and passes them to its view:
 
public class NavigationController : Controller
{
    readonly INavigation[] navigations;

    public NavigationController(INavigation[] navigations)
    {
        this.navigations = navigations;
    }

    public ViewResult Index()
    {
        return View("Index", navigations);
    }
}

Now the ‘Customers’ menu appears as expected:

MefAreas

An add-in itself is just a regular C# library project:

mefaddin_2

Views need to be marked as Embedded Resources rather than Content, and controllers should inherit AddinControllerBase rather than the standard Controller, but other than that they are laid-out and behave just like a regular MVC project.

So far this is working nicely. I should probably also take a look at the MVCContrib portable areas as well.

The complete example is on github: http://github.com/mikehadlow/MefAreas