MiniBuss is a micro service bus framework over msmq which consists of less than 400 lines of code, sitting inside one single source file. The project is hosted over at http://minibuss.codeplex.com and the source code is maintained at https://github.com/johandanforth/MiniBuss

I’ve been a fan of the Sinatra inspired web framework called Nancy, especially the neat way of setting up handlers for routes. The simplest sample on their site is this:

public class Module : NancyModule
{
    public Module()
    {
        Get["/greet/{name}"] = x => {
            return string.Concat("Hello ", x.name);
        };
    }
}

So, I shamelessly dug into the Nancy code and borrowed some 20-30 lines of code and came up with something like this for registering handlers for certain incoming commands on the minibus, what do you think?

public class CommandHandler : MessageHandler
{
    public CommandHandler()
    {
        WhenReceiving[typeof(SampleMessage1)] = x =>
        {
            Console.WriteLine("sample 1 message: " + x.Text);
        };

        WhenReceiving[typeof(SampleMessage2)] = x =>
        {
            Console.WriteLine("sample 2 message: " + x.Text);
        };
    }
}

It’s a bit more code but it helps/enforces you to move the handlers off to a certain module. Thoughts?

I made a small update to MiniBuss, the micro service bus framework. The messages you send, Commands and Events, are no longer dependent on IMessage. The messages sent on the bus can now be any .NET class which can be safely serialized.

The MiniBuss package on NuGet has been updated (version 1.1.0.1).

I’m looking for testers, reviewers and co-authors. Areas I want to look more at are multithreading/concurrency and the reply-feature (especially being able to reply to current message in multithreaded scenarios.

This last year our company has invested quite some time in looking at CQRS, which led to looking at great looking service-buses like nServiceBus, Rhino Service Bus and Mass Transit, which led me to do some bus-coding on my own, mostly for fun and for learning MSMQ.

Inspired by the service buses mentioned above, the result became a bare-bones-one-file “micro service bus” that I call MiniBuss which sits on top of MSMQ. The file itself is only some 400 lines of code and supports send, receive, reply, publish and subscribe/unsubscribe.

Setting up a sender may look something like this:

Create the bus, register a message and tell it where messages of this type should go, start the bus and send the message.

Setting up a receiver may look something like this:

Create the bus and tell it which endpoint to listen to (which creates a local MSMQ queue if necessary) and tell it which message type to listen for and which delegate to kick off when such a message is received.

Similarly, when doing a receive/reply, you would have to create the bus on the sender side with a local endpoint and register a message-handler for replies, like this:

The receiver would do a bus.reply() like this:

The MiniBus also supports publish to multiple subscribers. A simple publisher would create a bus with a local endpoint (to receive subscribe/unsubscribe commands), tell it to handle subscriptions for a certain event, then start publishing something every 5 seconds (as an example):

Any clients interesting in subscribing to events from the publisher would create a bus with a local endpoint, start the bus and then send a subscribe command to the publisher, telling it you’re interested in subscribing to a certain type of event and which delegate to handle it:

Now, the question is, what do you think? I know there are issues with the code, like how to make message-handlers multi-threaded/concurrent without messing things up (it’s single threaded right now), and how to best handle exceptions, rollbacks and re-tries . Right now handling exceptions in send and receive works pretty well within a TransactionScope() together with ADO.NET, and if there’s an exception, the message is moved the an error-queue. No re-try or anything, only rollback and move to xxx_error. Also, the publisher doesn’t persist subscriptions, so if it is restarted subscribers wouldn’t know. You know, things like that.

I’m a user of the micro-orm called Dapper and like it a lot, so I’m thinking that maybe I should release this micro-bus as open source and see where people may take it, if anywhere? Maybe just down the drain because they figure out this service bus is dangerous to use and risk loosing messages or something (which would be extremely good to know :)

Or maybe this code is useless because you already got nServiceBus and Rhino out there and coders don’t need another service bus?

What do you say?

Say you want to generate your own tag-cloud from a list of categories or tags you pull from an RSS-feed or similar. This is one way to do it. I’m using ASP.NET MVC for this sample which creates a simple tag-cloud in a Razor-view with HTML looking something like this:

The controller-code to start out with looks like this, where you read in the RSS-feed into a SyndicationFeed class, then pull out and flatten all the categories you have in that feed. Then group all those categories and count them to build up this simple view-model which is a Dictionary of category and percentage:

So now we got this view-model which is a Dictionary<string,int> and contains category/percentage data like this:

So all we need to do is create some kind of cloud in HTML or similar in the view. One way of doing it is this, which creates the output shown at the top:

Obviously, to be able to click on a tag and so on you need to create a richer view-model, I just wanted to show how I grab and count the tags from the feed

Making extensions for Dapper-dot-net was so fun and I needed a few more simple ones so I refactored a bit and made a few Update() and Delete() extensions as well. I’m also looking for Id-properties with the [Key] attribute on them. The class grew a bit, but it now supports the functions below. Note that this will only work for very simple objects and tables, but it might be helpful for some of you

I’m trying to follow the overall Dapper syntax as much as I can. If you done specify the table name with the input parameter, I’m using the name of the class/entity as table name, except where anonymous types are used.

The object I’m using for testing

    public class Test
    {
        [Key]
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

Insert typed object

                var entity = new Test() { Name = "Johan", Age = 44 };
                connection.Insert(entity);

.csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }

Insert anonymous object

                connection.Insert("insert into test", new { Name = "Johan", Age = 20 });

.csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }

Update typed object (where-clause built up from Id-properties)

                var entity = new Test() { Id = 16, Name = "Johan", Age = 50 };
                connection.Update(entity);

.csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }

Delete typed object (where-clause built up from Id-properties)

                var entity = new Test() { Id = 4, Name = "Johan", Age = 44 };
                var deletedCount = connection.Delete(entity);

Delete anonymous object (where-clause built up from anonymous object)

                var deletedCount = connection.Delete("delete from test", new { Name = "Johan" });

The Code:

public static class DapperExtensions
{
    public static void Insert(this IDbConnection connection, object entityToInsert)
    {
        Insert(connection, null, entityToInsert);
    }

    public static void Insert(this IDbConnection connection, string sql, object entityToInsert)
    {
        var name = entityToInsert.GetType().Name;
        var sb = new StringBuilder(sql);
        if (sql == null)
            sb.AppendFormat("insert into {0}", name);
        sb.Append(" (");
        BuildInsertParameters(entityToInsert, sb);
        sb.Append(") values (");
        BuildInsertValues(entityToInsert, sb);
        sb.Append(")");
        connection.Execute(sb.ToString(), entityToInsert);
    }

    public static int Update(this IDbConnection connection, object entityToUpdate)
    {
        return Update(connection, null, entityToUpdate);
    }

    public static int Update(this IDbConnection connection, string sql, object entityToUpdate)
    {
        var idProps = GetIdProperties(entityToUpdate);
        if (idProps.Count() == 0)
            throw new ArgumentException("Entity must have at least one [Key] property");

        var name = entityToUpdate.GetType().Name;

        var sb = new StringBuilder(sql);
        if (sql == null)
            sb.AppendFormat("update {0}", name);

        sb.AppendFormat(" set ");
        BuildUpdateSet(entityToUpdate, sb);
        sb.Append(" where ");
        BuildWhere(sb, idProps.ToArray());

        return connection.Execute(sb.ToString(), entityToUpdate);
    }

    public static int Delete<T>(this IDbConnection connection, T entityToDelete)
    {
        return Delete(connection, null, entityToDelete);
    }

    public static int Delete<T>(this IDbConnection connection, string sql, T entityToDelete)
    {
        var idProps = typeof (T).IsAnonymousType() ? 
            GetAllProperties(entityToDelete) : 
            GetIdProperties(entityToDelete);

        if (idProps.Count() == 0)
            throw new ArgumentException("Entity must have at least one [Key] property");

        var name = entityToDelete.GetType().Name;

        var sb = new StringBuilder(sql);
        if (sql == null)
            sb.AppendFormat("delete from {0}", name);

        sb.Append(" where ");
        BuildWhere(sb, idProps);

        return connection.Execute(sb.ToString(), entityToDelete);
    }

    private static void BuildUpdateSet(object entityToUpdate, StringBuilder sb)
    {
        var nonIdProps = GetNonIdProperties(entityToUpdate).ToArray();

        for (var i = 0; i < nonIdProps.Length; i++)
        {
            var property = nonIdProps;

            sb.AppendFormat("{0} = @{1}", property.Name, property.Name);
            if (i < nonIdProps.Length - 1)
                sb.AppendFormat(", ");
        }
    }

    private static void BuildWhere(StringBuilder sb, IEnumerable<PropertyInfo> idProps)
    {
        for (var i = 0; i < idProps.Count(); i++)
        {
            sb.AppendFormat("{0} = @{1}", idProps.ElementAt(i).Name, idProps.ElementAt(i).Name);
            if (i < idProps.Count() - 1)
                sb.AppendFormat(" and ");
        }
    }

    private static void BuildInsertValues(object entityToInsert, StringBuilder sb)
    {
        var props = GetAllProperties(entityToInsert);

        for (var i = 0; i < props.Count(); i++)
        {
            var property = props.ElementAt(i);
            if (property.GetCustomAttributes(true).Where(a => a is KeyAttribute).Any()) continue;
            sb.AppendFormat("@{0}", property.Name);
            if (i < props.Count() - 1)
                sb.Append(", ");
        }
    }

    private static void BuildInsertParameters(object entityToInsert, StringBuilder sb)
    {
        var props = GetAllProperties(entityToInsert);

        for (var i = 0; i < props.Count(); i++)
        {
            var property = props.ElementAt(i);
            if (property.GetCustomAttributes(true).Where(a => a is KeyAttribute).Any()) continue;
            sb.Append(property.Name);
            if (i < props.Count() - 1)
                sb.Append(", ");
        }
    }

    private static IEnumerable<PropertyInfo> GetAllProperties(object entity)
    {
        return entity.GetType().GetProperties();
    }

    private static IEnumerable<PropertyInfo> GetNonIdProperties(object entity)
    {
        return GetAllProperties(entity).Where(p => p.GetCustomAttributes(true).Any(a => a is KeyAttribute) == false);
    }

    private static IEnumerable<PropertyInfo> GetIdProperties(object entity)
    {
        return GetAllProperties(entity).Where( p => p.GetCustomAttributes(true).Any(a => a is KeyAttribute));
    }
}

public static class TypeExtension
{
    public static Boolean IsAnonymousType(this Type type)
    {
        if (type == null) return false;

        var hasCompilerGeneratedAttribute = type.GetCustomAttributes(typeof(CompilerGeneratedAttribute), false).Count() > 0;
        var nameContainsAnonymousType = type.FullName.Contains("AnonymousType");
        var isAnonymousType = hasCompilerGeneratedAttribute && nameContainsAnonymousType;

        return isAnonymousType;
    }
}

Feel free to fork the code as much as you can, I’m too tired to stay up longer. Dapper is getting really useful 

Years and years ago I wrote this blog post about detecting if the user was idle or active at the keyboard (and mouse) using a global hook. Well that code was for .NET 2.0 and Windows Forms and for some reason I wanted to try the same in WPF and noticed that a few things around the keyboard and mouse hooks didn’t work as expected in the WPF environment. So I had to change a few things and here’s the code for it, working in .NET 4.

I took the liberty and refactored a few things while at it and here’s the code now. I’m sure I will need it in the far future as well.

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace Irm.Tim.Snapper.Util
{
    public class ClientIdleHandler : IDisposable
    {
        public bool IsActive { get; set; }

        int _hHookKbd;
        int _hHookMouse;

        public delegate int HookProc(int nCode, IntPtr wParam, IntPtr lParam);
        public event HookProc MouseHookProcedure;
        public event HookProc KbdHookProcedure;

        //Use this function to install thread-specific hook.
        [DllImport("user32.dll", CharSet = CharSet.Auto,
             CallingConvention = CallingConvention.StdCall)]
        public static extern int SetWindowsHookEx(int idHook, HookProc lpfn,
            IntPtr hInstance, int threadId);

        //Call this function to uninstall the hook.
        [DllImport("user32.dll", CharSet = CharSet.Auto,
             CallingConvention = CallingConvention.StdCall)]
        public static extern bool UnhookWindowsHookEx(int idHook);

        //Use this function to pass the hook information to next hook procedure in chain.
        [DllImport("user32.dll", CharSet = CharSet.Auto,
             CallingConvention = CallingConvention.StdCall)]
        public static extern int CallNextHookEx(int idHook, int nCode,
            IntPtr wParam, IntPtr lParam);

        //Use this hook to get the module handle, needed for WPF environment
        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        public static extern IntPtr GetModuleHandle(string lpModuleName);

        public enum HookType : int
        {
            GlobalKeyboard = 13,
            GlobalMouse = 14
        }

        public int MouseHookProc(int nCode, IntPtr wParam, IntPtr lParam)
        {
            //user is active, at least with the mouse
            IsActive = true;
            Debug.Print("Mouse active");

            //just return the next hook
            return CallNextHookEx(_hHookMouse, nCode, wParam, lParam);
        }

        public int KbdHookProc(int nCode, IntPtr wParam, IntPtr lParam)
        {
            //user is active, at least with the keyboard
            IsActive = true;
            Debug.Print("Keyboard active");

            //just return the next hook
            return CallNextHookEx(_hHookKbd, nCode, wParam, lParam);
        }

        public void Start()
        {
            using (var currentProcess = Process.GetCurrentProcess())
            using (var mainModule = currentProcess.MainModule)
            {

                if (_hHookMouse == 0)
                {
                    // Create an instance of HookProc.
                    MouseHookProcedure = new HookProc(MouseHookProc);
                    // Create an instance of HookProc.
                    KbdHookProcedure = new HookProc(KbdHookProc);

                    //register a global hook
                    _hHookMouse = SetWindowsHookEx((int)HookType.GlobalMouse,
                                                  MouseHookProcedure,
                                                  GetModuleHandle(mainModule.ModuleName),
                                                  0);
                    if (_hHookMouse == 0)
                    {
                        Close();
                        throw new ApplicationException("SetWindowsHookEx() failed for the mouse");
                    }
                }

                if (_hHookKbd == 0)
                {
                    //register a global hook
                    _hHookKbd = SetWindowsHookEx((int)HookType.GlobalKeyboard,
                                                KbdHookProcedure,
                                                GetModuleHandle(mainModule.ModuleName),
                                                0);
                    if (_hHookKbd == 0)
                    {
                        Close();
                        throw new ApplicationException("SetWindowsHookEx() failed for the keyboard");
                    }
                }
            }
        }

        public void Close()
        {
            if (_hHookMouse != 0)
            {
                bool ret = UnhookWindowsHookEx(_hHookMouse);
                if (ret == false)
                {
                    throw new ApplicationException("UnhookWindowsHookEx() failed for the mouse");
                }
                _hHookMouse = 0;
            }

            if (_hHookKbd != 0)
            {
                bool ret = UnhookWindowsHookEx(_hHookKbd);
                if (ret == false)
                {
                    throw new ApplicationException("UnhookWindowsHookEx() failed for the keyboard");
                }
                _hHookKbd = 0;
            }
        }

        #region IDisposable Members

        public void Dispose()
        {
            if (_hHookMouse != 0 || _hHookKbd != 0)
                Close();
        }

        #endregion
    }
}

The way you use it is quite simple, for example in a WPF application with a simple Window and a TextBlock:

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <TextBlock Name="IdleTextBox"/>
    </Grid>
</Window>

And in the code behind we wire up the ClientIdleHandler and a DispatcherTimer that ticks every second:

public partial class MainWindow : Window
{
    private DispatcherTimer _dispatcherTimer;
    private ClientIdleHandler _clientIdleHandler;

    public MainWindow()
    {
        InitializeComponent();
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        //start client idle hook
        _clientIdleHandler = new ClientIdleHandler();
        _clientIdleHandler.Start();
        
        //start timer
        _dispatcherTimer = new DispatcherTimer();
        _dispatcherTimer.Tick += TimerTick;
        _dispatcherTimer.Interval = new TimeSpan(0, 0, 0, 1);
        _dispatcherTimer.Start();
    }

    private void TimerTick(object sender, EventArgs e)
    {
        if (_clientIdleHandler.IsActive)
        {
            IdleTextBox.Text = "Active";
            //reset IsActive flag
            _clientIdleHandler.IsActive = false;    
        }
        else IdleTextBox.Text = "Idle";
    }
}

Remember to reset the ClientIdleHandle IsActive flag after a check.

In our RIA Services application, we’re using the AutoCompleteBox control, but what if you want to select something from the list, press Enter and bind to a Command in a viewmodel? Sort of like the Button Command property.

I decided to extend the control and add a “Command” DependencyProperty for an ICommand which is executed when Enter is pressed and if an item is selected in the AutoCompleteBox. Works for us:

public class AutoCompleteBoxEx : AutoCompleteBox

{

    protected override void OnKeyDown(KeyEventArgs e)

    {

        if (SelectedItem != null && e.Key == Key.Enter)

        {

            if (Command != null)

                Command.Execute(SelectedItem);

        }

        base.OnKeyDown(e);

    }

    public static readonly DependencyProperty CommandProperty =

        DependencyProperty.RegisterAttached("Command",

                    typeof(ICommand),

                    typeof(AutoCompleteBoxEx),

                    null);

    public ICommand Command

    {

        get { return (ICommand)GetValue(CommandProperty); }

        set { SetValue(CommandProperty, value); }

    }

}

In our upcoming Silverlight 4 project there’s a need for a textbox with a mask for entering a Swedish national identification number (personnummer) with either 10 or 12 digits, in the form of yyyymmdd-nnnn. It’s quite simple, I just want to make sure only digits are entered and that the dash (-) is placed automatically and a few other small things that I’d like to tweak.

As far as I can see (correct me if I’m wrong here) there’s no mask feature in SL4 (yet), so I’m simply going to inherit and extend the built in TextBox. Validation of the number is done in the viewmodel instead of built into the control. See upcoming blogpost for that.

So, enough talk already, hope it can be of use:

public class PersonnummerTextBox : TextBox
{
    public bool TwelveDigits { get; set; }
 
    private int _leftPart;
    private Key _lastKey;
 
    public PersonnummerTextBox()
    {
        TextChanged += OnTextChanged;
        Loaded += OnLoaded;
    }
 
    private void OnLoaded(object sender, RoutedEventArgs e)
    {
        _leftPart = TwelveDigits ? 8 : 6;
    }
 
    /// <summary>
    /// Only allow digits and tab, no shifts or ctrl
    /// </summary>
    /// <param name="e"></param>
    protected override void OnKeyDown(KeyEventArgs e)
    {
        _lastKey = e.Key;   //used in OnTextChanged to handle Del key
 
        base.OnKeyDown(e);
 
        if (((e.Key >= Key.NumPad0 && e.Key <= Key.NumPad9) ||
            (e.Key >= Key.D0 && e.Key <= Key.D9) ||
            e.Key == Key.Tab) &&    //so that we can TAB out from the control ;)
            (Keyboard.Modifiers & ModifierKeys.Shift) == 0 &&
            (Keyboard.Modifiers & ModifierKeys.Control) == 0)
        {
            e.Handled = false;
            return;
        }
 
        e.Handled = true;
    }
 
    /// <summary>
    /// Make sure the dash (-) is placed on the correct place automatically
    /// either as yyyymmdd-nnnn or yymmdd-nnnn
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void OnTextChanged(object sender, TextChangedEventArgs e)
    {
        var leftPartPlusDash = (_leftPart + 1);
        var cursorPosition = SelectionStart;
        var strippedText = Text.Replace("-", "");
 
        if (strippedText.Length > _leftPart)
        {
            //move the cursor after the dash
            if (strippedText.Length == leftPartPlusDash &&
                cursorPosition == leftPartPlusDash && 
                _lastKey != Key.Delete) 
                cursorPosition = (_leftPart + 2);
 
            //put a dash in the right place
            Text = string.Format("{0}-{1}", 
                strippedText.Substring(0, _leftPart), 
                strippedText.Substring(_leftPart, Math.Min(4, strippedText.Length - _leftPart)));
        }
        else
            Text = strippedText;
 
        //move cursor to the wanted position
        SelectionStart = cursorPosition;
    }
}