.Net : Johan de Koning

Turing machine implementation with WF4 and FlowChart

Written on April 7, 2010 by Johan de Koning | Comment

A couple of days ago I received a tweet about a real hardware implementation of the Turing Machine (http://www.aturingmachine.com/). Impressed about this implementation, I was thinking about how to implement a simple Turing Machine counting program with the use of Workflow Foundation 4. And that’s where the story starts about my first experience with WF4.

Turing machine definition

At Wikipedia a definition of the Turing machine can be found: http://en.wikipedia.org/wiki/Turing_machine. To keep it short, a Turing machine consists of two parts

A tape of unlimited length which is separated in cells
A machine that can read/write on the tape

The machine is a finite state machine. The machine is in one state and with the use of a set of rules the machine can transfer to a different state. A rule contains the following parts

current state
symbol read
next state
symbol to write
move direction

The following rule [state: 0, read: blank, new state: 1, write: blank, move: left] will be executed by the machine when the current state is 0 and the value of the cell on the tape is blank. When the rule is executed, the machine will transfer to state 1, keeps the cell blank and will move the tape one cell to the left. A next rule for state 1 will be executed based on the new cell value read on the new tape position.

The machine part will be written with the use of a workflow diagram. This diagram will contain the different states and rule actions.

Counting rules

The rules for making counting possible (as taken from the aturingmachine.com website)

[state: 0, read: 1, new state: 0 write: 1, move: right]
[state: 0, read: 0, new state: 0, write: 0, move: right]
[state: 0, read: blank, new state: 1, write: blank, move: left]

[state: 1, read: 0, new state: 0, write: 0, move: right]
[state: 1, read: 1, new state: 1, write: 0, move: left]
[state: 1, read: blank, new state: 0, write: 1, move: right]

Tape implementation

The tape is a collection of cells which has an unlimited length. New cells can be added at the start or end of the written tape part. To support this functionality, an implementation is made based on a List collection making it possible to not only add new values at the end of the tape but also at the beginning.

public class Tape : ITape
    {
        public int Position { get; private set; }
        public int Length { get { return _internalCollection.Count; } }

        private List<int?> _internalCollection;

        public Tape()
        {
            Position = 0;
            _internalCollection = new List<int?>(){null};
        }

        public int? ReadCell()
        {
            return _internalCollection[Position];
        }

        public void WriteCell(int? cellValue)
        {
            _internalCollection[Position] = cellValue;
        }

        public void MoveCell(MoveDirection direction)
        {
            switch(direction){
                case MoveDirection.Left:
                    if (Position == 0)
                    {
                        _internalCollection.Insert(0, null);
                    }
                    else
                    {
                        Position--;
                    }
                    break;
                case MoveDirection.Right:
                    Position++;
                    if (Position == _internalCollection.Count)
                    {
                        _internalCollection.Add(null);
                    }
                    break;
            }
        }

        public override string ToString()
        {
            StringBuilder tapeValue = new StringBuilder("[");
            foreach (var cell in _internalCollection)
            {
                if (cell == null) { tapeValue.Append(" "); } else { tapeValue.Append(cell.ToString()); }
            }
            tapeValue.Append("] ");
            return tapeValue.ToString();
        }
    }

Flowchart

The state workflow of Workflow Foundation 3 is not part of version 4. The alternative given is the flowchart. With the flow chart certain types of state machine workflows can be implemented (but not all of them). A flowchart is powerful and simple to use, making it possible to loop back to previous executed activities. This is very useful for moving between the different states.

Together with the Flowchart, two activities are introducted: FlowDecision and FlowSwitch. A FlowDecision can be seen as an if condition while the FlowSwitch is like a switch statement in code. The FlowSwitch will be the central decision node for each state within the turing machine counting implementation

Workflow implementation with standard activities

A console workflow application is used for this implementation. An instance of the Tape is set as variable on the FlowChart.

The counting program can be developed with the use of the standard activities provided by WF4. The following activities are used

FlowSwitch: based on the cell value an execution path is chosen
InvokeMethod: used for executing the WriteCell and MoveCell methods
WriteLine: write the value of all cell values to the console.
Delay: this activiity is optional. Some delay to make output more readable during execution

The default path of the FlowSwitch activity is used for supporting the blank values. This is because of the fact that FlowSwitch works with string values, making it impossible to define a path for a null value.

Custom activities

The InvokeMethod activity is a generic activity to make execution of a method possible. It takes some time to configure each activity. The method parameters (for example the cell value which should be written) are implemented as a Parameter collection, which are not directly visible from the property editor within Visual Studio. To simplify/fasten this assignment process, custom activities will be developed to support the specific methods on the Tape instance.

Custom code activities are based on the CodeActivity or NativeActivity class. The CodeActivity is for creating simple synchronous custom activities. This model is suitable for the custom activities needed by the turing machine workflow. When you want to use all of the functionality exposed by the WF4 runtime, you should use the NativeActivity base class.

Two custom activities are developed

MoveCell activity: for moving the position on the tape one cell. The Direction property holds the move direction
WriteCell activity: for writing a cell value on the current position. The CellValue property holds the value which should be written

namespace TuringMachine.Activities
{
    [Designer(typeof(MoveCellDesigner))]
    public sealed class MoveCell : CodeActivity
    {
        [RequiredArgument()]
        public InArgument<ITape> Tape { get; set; }

        public MoveDirection Direction { get; set; }

        protected override void Execute(CodeActivityContext context)
        {
            var tape = context.GetValue(Tape);
            tape.MoveCell(Direction);
        }
    }
}

namespace TuringMachine.Activities
{
    [Designer(typeof(WriteCellDesigner))]
    public sealed class WriteCell : CodeActivity
    {
        [RequiredArgument()]
        public InArgument<Nullable<int>> CellValue { get; set; }

        [RequiredArgument()]
        public InArgument<ITape> Tape { get; set; }

        protected override void Execute(CodeActivityContext context)
        {
            var tape = context.GetValue(Tape);
            var cellValue = context.GetValue(CellValue);

            tape.WriteCell(cellValue);
        }
    }
}

The InArgument type used for the properties can hold (besides a value like a normal property) an expression. Those expression are defined using the VB.Net language (so null should be defined as Nothing)

The custom activities are added to the Workflow Toolbox making it possible to drag them into the workflow. You can change the property values from within the Property editor

Custom design

When viewing the diagram, it is still not directly clear which values are written and to which direction the position on the tape is moved. WF4 makes it possible to assign a design to a custom activity. The design of the activity is developed with XAML. Assignment is done with the use of the Designer attribute (as shown in the code above)

The XAML used for the MoveCell activity makes it possible to directly select the move direction from within the diagram

<sap:ActivityDesigner x:Class="TuringMachine.Activities.Designer.MoveCellDesigner"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:sap="clr-namespace:System.Activities.Presentation;assembly=System.Activities.Presentation"
    xmlns:sapv="clr-namespace:System.Activities.Presentation.View;assembly=System.Activities.Presentation"
    xmlns:sys="clr-namespace:System;assembly=mscorlib"
    xmlns:tm="clr-namespace:TuringMachine.Classes;assembly=TuringMachine.Classes">
    <sap:ActivityDesigner.Resources>
        <ObjectDataProvider MethodName="GetValues" ObjectType="{x:Type sys:Enum}" x:Key="MoveDirectionValues">
            <ObjectDataProvider.MethodParameters>
                <x:TypeExtension TypeName="tm:MoveDirection"/>
            </ObjectDataProvider.MethodParameters>
        </ObjectDataProvider>
    </sap:ActivityDesigner.Resources>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="auto"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <TextBlock VerticalAlignment="Center">Direction:</TextBlock>
        <ComboBox Grid.Column="1" ItemsSource="{Binding Source={StaticResource MoveDirectionValues}}" SelectedValue="{Binding ModelItem.Direction, Mode=TwoWay}"></ComboBox>
    </Grid>
</sap:ActivityDesigner>

And the WriteCell Activity makes the cell value assignment possible from within the workflow diagram. For the WriteCell activity an ExpressionTextBox is used, supporting the InArgument expression possibilities.

<sap:ActivityDesigner x:Class="TuringMachine.Activities.Designer.WriteCellDesigner"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:sap="clr-namespace:System.Activities.Presentation;assembly=System.Activities.Presentation"
    xmlns:sapv="clr-namespace:System.Activities.Presentation.View;assembly=System.Activities.Presentation"
    xmlns:conv="clr-namespace:System.Activities.Presentation.Converters;assembly=System.Activities.Presentation"
    xmlns:local="clr-namespace:TuringMachine.Activities.Designer"
    xmlns:sys="clr-namespace:System;assembly=mscorlib">
  <sap:ActivityDesigner.Resources>
    <conv:ArgumentToExpressionConverter x:Key="expressionConverter"/>
  </sap:ActivityDesigner.Resources>
  <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="auto"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <TextBlock VerticalAlignment="Center">Cell value</TextBlock>
        <sapv:ExpressionTextBox Grid.Column="1" Expression="{Binding Path=ModelItem.CellValue, Mode=TwoWay, ConverterParameter=In, Converter={StaticResource expressionConverter}}" ExpressionType="{local:NullableExtension sys:Int32}" OwnerActivity="{Binding Path=ModelItem}"></sapv:ExpressionTextBox>
    </Grid>
</sap:ActivityDesigner>

Workflow implementation with custom activities

With the use of the developed custom activities together with their design, the diagram of the workflow will give us directly more information related to the execution of the program

What’s next?

My first impression about WF4 is that the usage is more simplified. Within the previous version of WF you had to write a lot of code to execute external methods. With the use of the CodeActivity (or NativeActivity) class it is easy to implement custom activities. The possibility to use XAML to layout your custom activities is very powerful. It makes it possible to implement diagrams which are visual more meaningful (especially useful when hosting the WF designer within your own application). While the FlowChart is not a real State Workflow, it is suitable for the implementation written above. The usage feels more natural, just like developing a sequence workflow.

While developing the counting workflow I had some issues with the support of Nullable types and the ExpressionTextBox. I needed to implement an TypeExtension to make it possible to define the ExpressionType as a Nullable. This was not what I expected because XAML 2009 (XAML version of .Net 4) should make it possible to define the type as {x:Type TypeName=System:Nullable`1[[System.Int32]]}. But this syntax is not accepted as valid.

Source code

The visual studio 2010 solution including the workflows and source code files can be found at (http://johandekoning.codeplex.com -> browse to WF/TuringMachine)

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Top2OneNote Addin – Making my digital notepad notes searchable

Written on December 8, 2009 by Johan de Koning | 11 Comments

Last week I bought a nice gadget at our discount supermarket (Aldi). The gadget is called a Digital notepad and makes it possible to record your notes while writing them down on paper. Your writing is stored on the internal memory as vector data. There is a lot of software supplied, but using them is not that straightforward.

Most of the software supplied with this gadget wants to convert the note to clear text. But because of my bad handwriting, most of the time the converted text makes no sense. I also want to keep the drawing which I added to my notes. So instead of converting it to text, I would be happy if I can archive the notes and make them searchable.

Microsoft OneNote gives Tablet PC users the option to add handwritten notes to there OneNote notebook. Those notes are made searchable, while the handwritten note still exists. Instead of using a Tablet PC I want to convert my Digital Notepad content to OneNote handwritten notes. And therefore I developed a small OneNote addin which makes this possible. The source code together with the installer can be found at http://top2onenote.codeplex.com. Within this blogpost, I will explain some of the steps I took to make this addin possible.

Reading a TOP file

There is less information available about the file format that is generated by the Digital Notepad. The file extension is called .Top and it looks like it is a format invented by Waltop International Corp. When searching on the Internet for more information I found this blogpost together with some perl and python scripts to convert a Top file to SVG. I will use the logic of these scripts to convert my notes to OneNote.

Develop an OneNote AddIn

Visual Studio 2008 gives you the possiblity to develop Office Add Ins. There are different project templates supplied for Word, Excel and Outlook… but not for OneNote. There are no Visual Studio templates available for OneNote, so developing a AddIn is not that easy. Again Google gives me a nice search result, a blogpost about creating a toolbar addin for OneNote 2007: http://blogs.msdn.com/descapa/archive/2006/08/31/734298.aspx. There is a step by step tutorial supplied which will explain the different steps to develop a toolbar Addin which will popup a Hello world message. The AddIn will make use of COM Interop, which makes it possible to use C#.

The interface which should be implemented does only contains two methods. I found out that using this interface will only gives you the active OneNote page. With the OneNote.ApplicationClass (part of the Microsoft.Office.OneNote.Interop assembly) you will update the OneNote page outside OneNote. This means that the functionality of your addin does not run within OneNote, but inside a DllHost container.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using OneNote = Microsoft.Office.Interop.OneNote;

namespace Top2OneNoteAddIn
{
   [ComImport, Guid("C9590FA7-2132-47fb-9A78-AF0BF19AF4E6")]
   public interface IOneNoteAddIn
   {
      bool OnClick([In] String strActivePageID);

      bool OnEvent([In] OneNote.OneNoteAddIn_Event evt, [In] String strParameter);
   }
}

Note: together with OneNote 2007 I also installed the OneNote 2010 Beta. It seems like the AddIn functionality will change, because the addin is shown on the toolbar but clicking on it does not trigger the functionality. I think that with the release of OneNote 2010 that I will be easier to develop OneNote Addins, probably with the use of a Visual Studio template.

OpenFileDialog issue

The AddIn should, when clicked, open up a file dialog where the user can select the .top file which should be imported. Because the plugin does not run for within OneNote, the OpenFileDialog was shown below the OneNote window. I found a solution by supplying the Windows handler of OneNote as owner of the OpenFileDialog. This way the dialog is shown on top of OneNote

Process[] procs = Process.GetProcessesByName("OneNote");
IntPtr hwnd = procs[0].MainWindowHandle;

OpenFileDialog dialog = new OpenFileDialog();
dialog.Filter = "top files (*.top)|*.top|All files (*.*)|*.*";
dialog.Title = "Select a top file";
dialog.ShowDialog(new WindowWrapper(hwnd));

A little WindowWrapper class is added to the solution, which implements the IWin32Window interface making it possible to supply the window handler as argument to the ShowDialog method.

public class WindowWrapper : System.Windows.Forms.IWin32Window
{
        private IntPtr _hwnd;

        public WindowWrapper(IntPtr handle)
        {
            _hwnd = handle;
        }

        #region IWin32Window Members

        public IntPtr Handle
        {
            get { return _hwnd; }
        }

        #endregion
}

InkAnalyzer

The vector data from the top file is converted to a collection of Stroke objects (for which the constructor gets a StylusPointCollection as argument). Those stoke objects are set to the InkAnalyzer. The Analyze method performs layout analysis, writing and drawing classification, and handwriting recognition. The result is given back as an AnalysisStatus object which will be used for building the XML structure used to update the OneNote page.

InkAnalyzer analyzer = new InkAnalyzer();
analyzer.AddStroke(stroke);

AnalysisStatus status = analyzer.Analyze();
if (status.Successful)
{
   Console.WriteLine(analyzer.GetRecognizedString());
}

The AddStroke method has overloaded method for which you can specify the languageId of the stroke. By default the locale settings of the active thread will be used. In my case the Dutch language id was used (because of my region settings). I use English as my OS display language. When the Dutch language pack is not installed, the result of the analyzer will not be successful. So keep in mind to check if the correct language packs are installed to make handwritten recognition possible. The method analyzer.GetInkRecognizersByPriority() gives back a list of available InkRecognizers for the different languages.

Building the OneNote XML

You can update OneNote pages by providing a XML structure. Adding or updating depends if objectids are supplied. If this is the case, the object will be updated. An example of the XML used to add the handwritten notes to OneNote

<?xml version="1.0"?>
<one:Page xmlns:one="http://schemas.microsoft.com/office/onenote/2007/onenote"
        ID="{C6CCDE4D-7F47-46FA-9DD6-0A4CEC503E86}{1}{B0}">
	<one:Outline>
		<one:Position x="209.9905395507812" y="126.0"/>
		<one:Size width="245.2818908691406" height="125.3196716308594"/>
		<one:OEChildren>
			<one:OE>
				<one:InkWord recognizedText="hallo">
					<one:Data>AMIGHQSQBOYCAYABKgAaH4tCcEWEdYC+0EXZBFjPVIrml8VPjwb4utLhmyK/
7HHMzCKxQYkOuxMs7nqh3rsTi+Ves0icm6ElWrdREvqHlTLy7BdBuMAWv/Mr9HrEZm2nDbJYSZodTkA0BmwQRVOAL
HoY1USZZUo0BjFbMxSVQJ6SzJhLtWqQHBLFWlUDC0gURSNGI1cNAAAABQcLZU9mZ2hpGRQyCACAHgIh4uJBMwgA
4BICSvPiQRGrqtNBZAMVRgBAShs20YdmzeA0YdmxgA6YdmsBow7GLAB0w7Nm8AAATxMEawMVRgBAahA+gEXPAA
ARXQADggAAIqIAAAqKAW+C/gdb+B19kqxUublEssCwCSiblSgFlABLLFSyypYWLLFlliiC/gR7+BH7ACTZc3LJqblks2W
CzZQ2VNliyklZSMkzVmrKsVKSgNyygAoAESBQIxrXX3TKARMEEgARIKFVgU7sSj5OjNx+XqrpdDQFFEYAQAAABRRGA
QAAAAoAESDcOupAmua8QApiMYL+CJP4IlAAAEoAAEoAgv4BG/gEfKycSbsm5di0qry2bEGy8tUKABEg4IA52V90ygE
TBBIAESCouC8UZctFT6fx0sc+lOXuBRRGAEAAAAUURgFAAAAKP0Aj06oIUjE4DWAKWiGC/gnj+CeQBBZZQACC/gEj
+ARWM5yUt25ddnaFiwAKABEgIH932l90ygETBBIAESAf+viILJADTKojJ+vOFaLHBRRGAEAAAAUURgGAAAAJFiKA30M
Qcv/ZAAp0SYL+BFP4EVAACUALAkJRU3NypSbCwUCC/gDT+ANeJMktzPHc7Le7dtVaNy7WOIgkuJbmpZGrZQAKAB
EgYAtv1V90ygETBBIAESAUVWvkl8H9TbQgjxGuoKlABRRGAEAAAAUURgDAAAAKP0Ai63IF0ksIC+AKggFlgv4MK/gw
25SpYsFlhLAESwlsmybLNypbKAssqWUlllixZYsAgv4EY/gRkAlgZYWWFlEs2WaFUTZVkqJUuUlgAssssVAACgARIGBI
qdtfdMoBEwQSABEgk453gdolgkGItwM1/odLkQUURgBAAAAFFEYBwAAACgARIGLKJkG7kLtA
					</one:Data>
				</one:InkWord>
			</one:OE>
		</one:OEChildren>
	</one:Outline>
	<one:Outline>
		<one:Position x="225.0141754150391" y="461.2535400390625"/>
		<one:Size width="680.25830078125" height="80.7023696899414"/>
		<one:OEChildren>
			<one:OE>
				<one:InkWord recognizedText="dit">...
					</one:Data>
				</one:InkWord>
				<one:InkWord recognizedText="is">
					<one:Data>...
					</one:Data>
				</one:InkWord>
				<one:InkWord recognizedText="een">
					<one:Data>...</one:Data>
				</one:InkWord>
				<one:InkWord recognizedText="test">
					<one:Data>...
					</one:Data>
				</one:InkWord>
			</one:OE>
		</one:OEChildren>
	</one:Outline>
</one:Page>

Only the data for the first word is shown in this example to keep things clear. At the root element (Page) the ID of the existing page (provided as argument of the OnClick method) to define that the content should be inserted to the page.The InkWord data are stored as Ink Serialized Format with BASE64 encoding and placed together with the recognizedText to make searching within the handwritten notes possible.

InkWordNode iwNode = node as InkWordNode;

using (MemoryStream ms = new MemoryStream())
{
   iwNode.Strokes.Save(ms);
   byte[] isfBytes = ms.ToArray();
   dataNode.SetValue(Convert.ToBase64String(isfBytes));
}

Updating OneNote

Updating the OneNote page is done by creating an instance of the OneNote.ApplicationClass. The UpdatePageContent method is used whereby the created XML structure is supplied as argument. There is a little delay between executing the importer and when the page is updated. The cause of this delay is probally that the OneNote page is updated outside OneNote and that it will be triggered to refresh the page content.

OneNote.ApplicationClass onApplication = new OneNote.ApplicationClass();

XNamespace one = "http://schemas.microsoft.com/office/onenote/2007/onenote";
XElement root = new XElement(one + "Page", new XAttribute(XNamespace.Xmlns + "one", one));
root.Add(new XAttribute("ID", strActivePageID));

BuildXML(analyzer.RootNode, root, one);

onApplication.UpdatePageContent(root.ToString(), DateTime.MinValue);

What’s next?

The result of the importer is the same when writing the text directly with the use of a Tablet PC. Probably the results of a Tablet PC are maybe even more secure, but that’s also the reason that I don’t want to convert the handwritten notes to text.

Search within a handwritten note

The importer could be optimized in different ways. Some issues/ideas to improve this add in

Language selection – selected by import or set as a preference
Insert at cursor position – currently the location is set to the top left. It is possible to retrieve the cursor position by requesting the page content (GetPageContent) with the use of the OneNote.ApplicationClass. The location of the cursor is marked as a selection inside the retrieved XML structure
Improve text recognition – the InkAnalyzer has different properties to improve the text recognition. This way better results are achieved
Drag and drop support – instead of using the open file dialog, it would be nice if you can just drag the top file on your OneNote page

Like I mentioned, you can find the source at http://top2onenote.codeplex.com. It is not my goal to put a lot of effort in the development of this AddIn. If you are interested in improving this AddIn, send some feedback and I can add you as contributor to this project. If you have other questions, ask them and I will try to answer them.

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XMPP and WCF .Net – Connecting a XMPP client to Openfire

Written on December 1, 2009 by Johan de Koning | Comment

With Openfire installed (http://www.johandekoning.nl/index.php/2009/11/30/xmpp-and-wcf-net-installation-of-openfire/) it is time to create some users and connect with a XMPP client to the server.

User management

Because of the simple installation, users created on the Openfire server are stored inside the embedded database. To add new users, make sure that the server runs and open the administration console (default address http://localhost:9090).

Note: I already mentioned this in my previous blog. Within my Vista environment I had to make sure that I start the Openfire server as administrator

Within the Administration Console, you will find the Users/Groups section at the top of the page. When you open this section you will get an overview of the users created on the Openfire server

User Summary

Click on the Create New User option on the left, to create a new user. The Create User page needs some information for the new user. Provide this information and click create user to add the user. Or choose Create & Create another if you want to create another user after this user account is added.

Create User

I create two users which are called user1 and user2. I gave the the same password as their username. The overview shows the following user list.

User Summary (users created)

One of the core extensions of the XMPP protocol is the ability to have a user list which is stored on the server (which is called a Roster). Within the Administration Console you can manage those lists, to make it possible that user1 has user2 as a contact and visa versa. This is off course also possible from within a XMPP client where you can add new users.

To manage a contacts list (roster) for a user, click on the username (of the user you want to manage) from the overview. You will get the User Properties screen, with some basic information.

User properties

At the left you will find a Roster option. When you click that option, you get an overview of the roster items. These items can be other users, or groups of users. Click the Add New Item (at the right of the screen) to add user 2 to the roster items of user 1.

Add roster item

When added, the user roster overview will show user 2. Perform the same action for user 2 but this time add user 1 to the roster list.

User Roster

When both users are on both list, the user configuration part is finished. I know it is very basic, but this is jus for development. When can now use a XMPP client to make a connection with our server.

Using Psi (XMPP Client)

There are a lot of XMPP clients available on the Internet. I use Psi because it has a nice XML logging feature, to make the XMPP stream visible. I can use this sample stream for development of a XMPP client in .Net without the use of WCF. You can download the Psi client at http://psi-im.org/download/

When you start the client for the first time, it will show you a message that you need to set up an account. Click on the Use existing account option, because our test accounts are already available on the server.

Account setup

On the first tab (Account) fill in the Jabber ID (JID) and password. The jabber ids for our users are user1@localfire and user2@localfire . The password are user1 and user2.

Account Tab

At the connection tab, we need to specify our server location. This is localhost when it runs on the same machine where you installed this client. For testing purposes we will not use an encrypt connection (Never).

Connection tab

Click save to store the account information. The main screen of Psi will be visible whereby the user status is set to Offline.

Psi main screen

Before we connect to our Openfire server, I want to enable the XML console to get an idea of the stream which is send between client and server. Right click on the first item of the list (openfire) and select Open XML Console… Within the XML Console, mark the enable checbox at the bottem left. To get the client connected, select from the dropdownlist at the bottom of the main screen, the Online status. The client will connect to the server and the stream will be made visible in the XML Console dialog.

XML Console

The XMPP stream

I connected another client to the server as user 2. Between both users i send a message with the text “Hello” (User 1 -> User 2) and “Goodbye” (User 2 -> User 1). The presence of user 1 will be set to Offline and the application will be closed. Below you find the captured XMPP stream.

What’s next?

This blog post explained how to set up the connecting between a XMPP client and server. The captured stream will be used for further analysis. The next step will be the development of a simple XMPP client which will echo back received messages in reverse order. This client will not be written with Windows Communication Foundation to get some feeling how a .Net client with the TcpClient class will work.

If you have questions after reading this post, or have other feedback? Please send in a comment.

<!--client-->
<?xml version="1.0"?>
<stream:stream xmlns:stream="http://etherx.jabber.org/streams" version="1.0" xmlns="jabber:client" to="localfire" xml:lang="en" xmlns:xml="http://www.w3.org/XML/1998/namespace" >

<!--server-->
<?xml version='1.0' encoding='UTF-8'?><stream:stream xmlns:stream="http://etherx.jabber.org/streams" xmlns="jabber:client" from="localfire" id="c035b19c" xml:lang="en" version="1.0">

<stream:features>
<starttls xmlns="urn:ietf:params:xml:ns:xmpp-tls"/>
<mechanisms xmlns="urn:ietf:params:xml:ns:xmpp-sasl">
<mechanism>DIGEST-MD5</mechanism>
<mechanism>PLAIN</mechanism>
<mechanism>ANONYMOUS</mechanism>
<mechanism>CRAM-MD5</mechanism>
</mechanisms>
<compression xmlns="http://jabber.org/features/compress">
<method>zlib</method>
</compression>
<auth xmlns="http://jabber.org/features/iq-auth"/>
<register xmlns="http://jabber.org/features/iq-register"/>
</stream:features>

<!--client-->
<auth xmlns="urn:ietf:params:xml:ns:xmpp-sasl" mechanism="DIGEST-MD5" />

<!--server-->
<challenge xmlns="urn:ietf:params:xml:ns:xmpp-sasl">cmVhbG09ImxvY2FsZmlyZSIsbm9uY2U9IitaQVRkeUZNeWJjV1ZveHJHTXNIV2dxNVR1QWhNUkFoQ08wVWlp
VzciLHFvcD0iYXV0aCIsY2hhcnNldD11dGYtOCxhbGdvcml0aG09bWQ1LXNlc3M=</challenge>

<!--client-->
<response xmlns="urn:ietf:params:xml:ns:xmpp-sasl">dXNlcm5hbWU9InVzZXIxIixyZWFsbT0ibG9jYWxmaXJlIixub25jZT0iK1pBVGR5Rk15YmNXVm94ckdNc0hXZ3E1
VHVBaE1SQWhDTzBVaWlXNyIsY25vbmNlPSJhM0dMY21ra3VFUjEwaVBTMlJzQnpRZWlBY2pzSnIzNVNyTzRkTFNzM
2FnPSIsbmM9MDAwMDAwMDEsZGlnZXN0LXVyaT0ieG1wcC9sb2NhbGZpcmUiLHFvcD1hdXRoLHJlc3BvbnNlPWM1N
TlhMjBhMmFkZGVjYmJjOTFkZTZkNDYwODYyODU5LGNoYXJzZXQ9dXRmLTg=</response>

<!--server-->
<success xmlns="urn:ietf:params:xml:ns:xmpp-sasl">cnNwYXV0aD04NjMxMTIzNDZlM2MxOTUxMGZlNzFmNTA5N2E0MWViMg==</success>

<!--client-->
<?xml version="1.0"?>
<stream:stream xmlns:stream="http://etherx.jabber.org/streams" version="1.0" xmlns="jabber:client" to="localfire" xml:lang="en" xmlns:xml="http://www.w3.org/XML/1998/namespace" >

<!--server-->
<?xml version='1.0' encoding='UTF-8'?><stream:stream xmlns:stream="http://etherx.jabber.org/streams" xmlns="jabber:client" from="localfire" id="c035b19c" xml:lang="en" version="1.0">
<stream:features>
<compression xmlns="http://jabber.org/features/compress">
<method>zlib</method>
</compression>
<bind xmlns="urn:ietf:params:xml:ns:xmpp-bind"/>
<session xmlns="urn:ietf:params:xml:ns:xmpp-session"/>
</stream:features>

<!--client-->
<iq type="set" id="bind_1" >
<bind xmlns="urn:ietf:params:xml:ns:xmpp-bind">
<resource>Home</resource>
</bind>
</iq>

<!--server-->
<iq xmlns="jabber:client" type="result" id="bind_1" to="localfire/c035b19c" >
<bind xmlns="urn:ietf:params:xml:ns:xmpp-bind">
<jid>user1@localfire/Home</jid>
</bind>
</iq>

<!--client-->
<iq type="set" id="aab7a" >
<session xmlns="urn:ietf:params:xml:ns:xmpp-session"/>
</iq>

<!--server-->
<iq type="result" id="aab7a" to="user1@localfire/Home" >
<session xmlns="urn:ietf:params:xml:ns:xmpp-session"/>
</iq>

<!--client-->
<iq type="get" id="aab8a" >
<query xmlns="jabber:iq:roster"/>
</iq>

<!--server-->
<iq type="result" id="aab8a" to="user1@localfire/Home" >
<query xmlns="jabber:iq:roster">
<item subscription="both" jid="user2@localfire" />
</query>
</iq>

<!--client-->
<presence>
<priority>5</priority>
<c xmlns="http://jabber.org/protocol/caps" node="http://psi-im.org/caps" ver="0.13-dev-rev2" ext="ca cs ep-notify html" />
</presence>

<iq type="get" to="user1@localfire/Home" id="aabaa" >
<query xmlns="http://jabber.org/protocol/disco#info" node="http://psi-im.org/caps#ca" />
</iq>

<iq type="get" id="aabba" >
<query xmlns="jabber:iq:private">
<storage xmlns="storage:bookmarks"/>
</query>
</iq>

<iq type="get" to="user1@localfire" id="aabca" >
<vCard xmlns="vcard-temp" version="2.0" prodid="-//HandGen//NONSGML vGen v1.0//EN" />
</iq>

<iq type="get" to="localfire" id="aabda" >
<query xmlns="http://jabber.org/protocol/disco#info"/>
</iq>

<!--server-->
<presence from="user2@localfire/Work" to="user1@localfire/Home" >
<c xmlns="http://jabber.org/protocol/caps" node="http://exodus.jabberstudio.org/caps" ext="xhtml-im" ver="0.10.0.0" />
<priority>1</priority>
</presence>

<!--client-->
<iq type="get" to="user2@localfire/Work" id="aabea" >
<query xmlns="http://jabber.org/protocol/disco#info" node="http://exodus.jabberstudio.org/caps#0.10.0.0" />
</iq>

<iq type="get" to="user2@localfire/Work" id="aabfa" >
<query xmlns="http://jabber.org/protocol/disco#info" node="http://exodus.jabberstudio.org/caps#xhtml-im" />
</iq>

<!--server-->
<iq from="user1@localfire/Home" type="get" to="user1@localfire/Home" id="aabaa" >
<query xmlns="http://jabber.org/protocol/disco#info" node="http://psi-im.org/caps#ca" />
</iq>

<!--client-->
<iq type="result" to="user1@localfire/Home" id="aabaa" >
<query xmlns="http://jabber.org/protocol/disco#info" node="http://psi-im.org/caps#ca" >
<identity category="client" type="pc" name="Psi" />
<feature var="urn:xmpp:jingle:1" />
<feature var="urn:xmpp:jingle:transports:ice-udp:1" />
<feature var="urn:xmpp:jingle:apps:rtp:1" />
<feature var="urn:xmpp:jingle:apps:rtp:audio" />
</query>
</iq>

<!--server-->
<iq type="result" id="aabba" to="user1@localfire/Home" >
<query xmlns="jabber:iq:private">

<storage xmlns="storage:bookmarks"/>
</query>
</iq>

<iq from="user1@localfire" type="result" id="aabca" to="user1@localfire/Home" >
<vCard xmlns="vcard-temp" version="2.0" prodid="-//HandGen//NONSGML vGen v1.0//EN" >
<FN>User 1</FN>
</vCard>
</iq>

<iq from="localfire" type="result" id="aabda" to="user1@localfire/Home" >
<query xmlns="http://jabber.org/protocol/disco#info">
<identity category="server" type="im" name="Openfire Server" />
<identity category="pubsub" type="pep" />
<feature var="http://jabber.org/protocol/pubsub#manage-subscriptions" />
<feature var="http://jabber.org/protocol/pubsub#modify-affiliations" />
<feature var="http://jabber.org/protocol/pubsub#retrieve-default" />
<feature var="http://jabber.org/protocol/pubsub#collections" />
<feature var="jabber:iq:private" />
<feature var="http://jabber.org/protocol/disco#items" />
<feature var="vcard-temp" />
<feature var="http://jabber.org/protocol/pubsub#publish" />
<feature var="http://jabber.org/protocol/pubsub#subscribe" />
<feature var="http://jabber.org/protocol/pubsub#retract-items" />
<feature var="http://jabber.org/protocol/offline" />
<feature var="http://jabber.org/protocol/pubsub#meta-data" />
<feature var="jabber:iq:register" />
<feature var="http://jabber.org/protocol/pubsub#retrieve-subscriptions" />
<feature var="http://jabber.org/protocol/pubsub#default_access_model_open" />
<feature var="jabber:iq:roster" />
<feature var="http://jabber.org/protocol/pubsub#config-node" />
<feature var="http://jabber.org/protocol/address" />
<feature var="http://jabber.org/protocol/pubsub#publisher-affiliation" />
<feature var="http://jabber.org/protocol/pubsub#item-ids" />
<feature var="http://jabber.org/protocol/pubsub#instant-nodes" />
<feature var="http://jabber.org/protocol/commands" />
<feature var="http://jabber.org/protocol/pubsub#multi-subscribe" />
<feature var="http://jabber.org/protocol/pubsub#outcast-affiliation" />
<feature var="http://jabber.org/protocol/pubsub#get-pending" />
<feature var="google:jingleinfo" />
<feature var="jabber:iq:privacy" />
<feature var="http://jabber.org/protocol/pubsub#subscription-options" />
<feature var="jabber:iq:last" />
<feature var="http://jabber.org/protocol/pubsub#create-and-configure" />
<feature var="urn:xmpp:ping" />
<feature var="http://jabber.org/protocol/pubsub#retrieve-items" />
<feature var="jabber:iq:time" />
<feature var="http://jabber.org/protocol/pubsub#create-nodes" />
<feature var="http://jabber.org/protocol/pubsub#persistent-items" />
<feature var="jabber:iq:version" />
<feature var="http://jabber.org/protocol/pubsub#presence-notifications" />
<feature var="http://jabber.org/protocol/pubsub" />
<feature var="http://jabber.org/protocol/pubsub#retrieve-affiliations" />
<feature var="http://jabber.org/protocol/pubsub#delete-nodes" />
<feature var="http://jabber.org/protocol/pubsub#purge-nodes" />
<feature var="http://jabber.org/protocol/disco#info" />
<feature var="http://jabber.org/protocol/rsm" />
</query>
</iq>

<iq from="user2@localfire/Work" type="result" id="aabea" to="user1@localfire/Home" >
<query xmlns="http://jabber.org/protocol/disco#info" node="http://exodus.jabberstudio.org/caps#0.10.0.0" >
<feature var="jabber:iq:agents" />
<feature var="jabber:iq:oob" />
<feature var="jabber:iq:browse" />
<feature var="jabber:iq:time" />
<feature var="jabber:iq:version" />
<feature var="jabber:iq:last" />
<feature var="http://jabber.org/protocol/disco#items" />
<feature var="http://jabber.org/protocol/disco#info" />
<feature var="storage:bookmarks" />
<feature var="jabber:x:data" />
<feature var="jabber:x:conference" />
<feature var="jabber:x:event" />
<feature var="http://jabber.org/protocol/muc" />
<feature var="http://jabber.org/protocol/muc#user" />
<feature var="http://jabber.org/protocol/muc#owner" />
<feature var="http://jabber.org/protocol/si" />
<feature var="http://jabber.org/protocol/si/profile/file-transfer" />
<feature var="http://jabber.org/protocol/bytestreams" />
</query>
</iq>

<iq from="user2@localfire/Work" type="result" id="aabfa" to="user1@localfire/Home" >
<query xmlns="http://jabber.org/protocol/disco#info" node="http://exodus.jabberstudio.org/caps#xhtml-im" >
<feature var="http://jabber.org/protocol/xhtml-im" />
</query>
</iq>

<iq from="user1@localfire/Home" type="result" to="user1@localfire/Home" id="aabaa" >
<query xmlns="http://jabber.org/protocol/disco#info" node="http://psi-im.org/caps#ca" >
<identity category="client" type="pc" name="Psi" />
<feature var="urn:xmpp:jingle:1" />
<feature var="urn:xmpp:jingle:transports:ice-udp:1" />
<feature var="urn:xmpp:jingle:apps:rtp:1" />
<feature var="urn:xmpp:jingle:apps:rtp:audio" />
</query>
</iq>

<!--client-->
<message type="chat" to="user2@localfire" id="aac0a" >
<body>Hello</body>
<active xmlns="http://jabber.org/protocol/chatstates"/>
</message>

<!--server-->
<message from="user2@localfire/Work" type="chat" id="jcl_13" to="user1@localfire/Home" >
<body>Goodbye</body>
<x xmlns="jabber:x:event">
<composing/>
</x>
<html xmlns="http://jabber.org/protocol/xhtml-im">
<body xmlns="http://www.w3.org/1999/xhtml">
<p style="font-size:small;font-family:Arial;color:#000000" >Goodbye</p>
</body>
</html>
</message>

<!--client-->
<presence type="unavailable" >
<status>Logged out</status>
</presence>

</stream:stream>

<!--server-->
</stream:stream>

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XMPP and WCF .Net – Installation of OpenFire

Written on November 30, 2009 by Johan de Koning | 1 Comment

In my previous blogpost, I talked about my goal to make an XMPP implementation within .Net based on Windows Communication Foundation. Before I can start, I had to find out how a normal XMPP stream would be send/retrieved between client and server.

In this blogitem, I will explain the steps I took to install the OpenFire server. http://www.igniterealtime.org/projects/openfire/index.jsp Within my other blog I used a seperate environment which is mostly based on Ubuntu. This time I install the OpenFire server within Windows Vista. The reason for this is that it is also the environment of my .Net development tools.

Installation wizard

First download the installation file of OpenFire from the website. I use Openfire 3.6.4 http://www.igniterealtime.org/downloads/index.jsp

The OpenFire website

Download page

The installation wizard is quite straight forward and more like next-next-finish.

Language selection

Welcome step of the wizard

License Agreement

Installation location

Start menu shortcut

Progress of installation

Completing wizard step

On the last step, mark the Run Openfire option (which is marked by default) to launch the Openfire server. This makes it possible to continue the installation from the Admin Console (which runs inside the browser).

Openfire server status

Admin console installation/configuration

To finalize the installation, some setup steps will be shown within the Admin Console. Select the prefered language in the first step

Language selection

You can keep the server settings values the default. Because I will only use the Openfire server locally (or within my own netwerk) it is not important that the right domain is set. The clients will connect to localhost or the ipaddress of the computer.

Server settings

Because I want to keep the installation as simple as possible, I choose for an Embedded database. The performance penalty with the embedded database is for test purposes not an issue.

Database settings

I will create the test users from within the Admin console. This means that I don’t need Active Directory/LDAP or Clearspace integration. I choose for the Default option to store users inside the server database.

Profile settings

To access the admin console after these setup steps, it is important to setup an Administration account. The username of this account will be “admin”

Administrator account

This completes the openfire setup process. You can now login to the real admin console

Note: I had some trouble to log in to the Admin Console on my Vista enviroment. The admin user was not valid. I found out that I had to restart the Openfire server by stopping the server, quit the status dialog and start the Openfire server again for the start menu. It is important to start the Openfire server as administrator (right click on the shortcut and select Run as administrator) otherwise you are still not able to login.

Admin console login

Server information page

What’s next?

As a mentioned the installation of Openfire, with the (default) settings I chose, is easy and straight forward. The next step will be to configure some users and to connect a XMPP client to the server. In the meantime I really like to have you feedback on this blogpost (did you like the images to explain the installation) or on my other blogposts.

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XMPP and WCF .Net – Introduction

Written on November 29, 2009 by Johan de Koning | 1 Comment

Hummm… XMPP and WCF? Is this not a blog page about Android or other Google related stuff. That’s partly true but as a Microsoft .Net developer I am more interested in combining the best of both world. I like Google and Microsoft products. I really like the open source vision of Google. But when it comes to development tools I prefer using Microsoft.

So that’s me, living between both worlds. Using the best of both worlds to develop good implementations. And that is where this new blog post are about.

Some time ago Google launched Google Wave presentation (http://wave.google.com/help/wave/about.html) When I watched the presentation, I was (and still am) impressed.

At my previous job, we developed a real time location aware application. A huge amount of data was collected by the location systems, was processed by the server and was made visible on the clients. The made visible part is a tricky one, because we wanted to make use of protocols which where cross platform like SOAP. The result was a polling mechanism which sends requests on interval basis to the server to get new data.

We knew that this was not the best implementation. At that time (almost 3 years ago) we were also thicking about as a possible solution. XMPP stands for Extensible Messaging and Presence Protocol (http://xmpp.org/). A protocol which was developed already in 1999 and is based on XML. I think that the popularity of this protocol was getting a boost when Google launched their Google Talk client in augustus 2005.

I found a presentation on the Web about XMPP (http://www.slideshare.net/kellan/beyond-rest) which has a nice slide (shown in the image below). This reminds me of an episode of the Smurfs (http://en.wikipedia.org/wiki/The_Smurfs) where the Smurfs are on a long trip.

Brainy Smurf: Is it much further, Papa Smurf?
Papa Smurf: Not much further my little smurfs.
Jokey Smurf: (different location) Is it much further, Papa Smurf?
Papa Smurf: Not much further my little smurfs.
Grouchy Smurf: (third location) Is it much further, Papa Smurf?
Papa Smurf: (exasperated) Yes…it is!

Are we there yet?

So when all Smurfs are requesting data from Papa Smurf, Papa Smurf becomes overloaded. A better solution would be a Publish Subscribe implementation (http://en.wikipedia.org/wiki/Publish/subscribe). XMPP has such extension: http://xmpp.org/extensions/xep-0060.html. This way the clients (little smurfs) don’t become bored (they can do other things) and Papa Smurfs don’t get distracted or even overloaded.

Tell me when I get there

The protocol of Google Wave is based on this model. The protocol makes use of the XMPP protocol together with some extensions. Installation document of the Google Wave Federation Prototype server can be found at http://code.google.com/p/wave-protocol/wiki/Installation Of course Google is using Java or Phyton for the example clients, and that is exactly the part where my love for Microsoft fits in. I am really interested in building a Google Wave protocol client within .Net

Because XMPP is involved, the first step would be to develop a XMPP client in .Net. There are some XMPP libraries available for .Net but those don’t have a flexible extension model. And when looking at Windows Communication Foundation, there are already some parts available for setting up the connection and send/retrieve messages. Developing an XMPP library based on the WCF technology is the first goal of these new blog posts.

What’s next?

Before looking at a WCF implemtation, it is good to know how XMPP works. Therefore I will develop a sample client which makes use of the .Net TcpClient to initiate and send/retrieve messages (no WCF involved). To test this client I will install a XMPP server called OpenFire (http://www.igniterealtime.org/projects/openfire/index.jsp). Check this blog often for new updates… and remember Papa Smurf, we are not there yet!

BTW I love to retrieve comments on this (or my other blogposts). Your feedback is really important!

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WBXML .Net release 1.0

Written on April 5, 2009 by Johan de Koning | 3 Comments

Today I released the first version of the WBXML .Net 1.0 library. With this library you can encode and decode WBXML messages.

More information can be found at http://wbxml.codeplex.com

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WBXML for .Net

Written on February 2, 2009 by Johan de Koning | Comment

Synchronisation of data between multiple devices is important to have information at every place at every time. For example, I want to have my work agenda items on my mobile phone so that I have a quick overview (and get a notification) when I have a meeting.

There are different protocols for data synchronization. To synchronize my mobile agenda with work (which makes use of Oracle Collaboration Suite) I have to use SyncML. There are some commercial products available (I used the SyncML client of Synthesis AG on my Windows Mobile Device, which is very good) but I am a developer and I wanted to know how SyncML works.

When reading the SyncML specification I tried to initiate a fresh synchronisation (from the server to a mobile which has an empty agenda). Sending message to the Oracle server was working, but the response I got back was not correct (the SyncML messages where accepted but the agenda items where not send back). I wanted to compare those messages to the ones (commercial) SyncML applications where sending… but I found out that these where using WBXML.

What is WBXML?

WBXML stands for WAP Binary XML. It is used to send XML in a compact way to reduce bandwidth (which is limited for a mobile device when using GPRS). For example the content of the following XML (as defined in the WBXML specification as an example)

<br />
<XYZ><CARD><br />
     X &amp; Y<BR /><br />
     X=1<br />
</CARD></XYZ><br />

will be in WBXML (hex notation):

03 01 03 00 47 46 03 0D 0A 20 20 20 20 20 58 20 26 20 59 00 05 03 0D 0A 20 20 20 20 20 58 00 02 81 20 03 3D 00 02 81 20 03 31 20 0D 0A 20 20 00 01 01

Interested by the use of this encryption I started reading the WBXML specification. I searched on the Internet if there where any WBXML libraries for .Net but couldn’t find one. So i decided to write my own.

At CodeProject I found a blog written by Tamir Khason about a WBXML parser for C#. Comparing it to the WBXML specification (and also referencing to his own remarks on the blog) the parser is not following the specification. I liked the idea of extending the XMLDocument of .Net and used that as a base of the WBXMLDocument class.

The code of the WBXML .Net library can be found at http://www.codeplex.com/wbxml. I will finalize this library so that it can be used for WBXML message which are used for SyncML.

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HttpWebRequest on Compact Framework: The operation has timed-out

Written on August 14, 2008 by Johan de Koning | 5 Comments

With .Net Compact Framework I developed an application that is doing a webrequest on interval bases. With the webrequest I sent data by providing some arguments inside the querystring. I am not interested in the response and therefore I did not assign the GetResponse() return value. I use the following code:

<br />
HttpWebRequest webRequest;</p>
<p>try<br />
{<br />
   webRequest = WebRequest.Create("http://someurl.com/with.aspx?querystring=value");<br />
   webRequest.Method = "GET";<br />
   webRequest.KeepAlive = false;<br />
   webRequest.GetResponse();<br />
}<br />
catch (Exception e){<br />
    //Something goes wrong. Implement handling of this exception<br />
}<br />
finally {<br />
   webRequest = null; //To clear up the webrequest<br />
}<br />

This code works… for only 2 times. The third time it is executed I get a: The operation has timed-out exception. It looks like the GetResponse() method keeps a connection (or socket) open which make it not possible to make new connection at the third time the method is executed. I solved this problem by assigning the GetResponse() value to a WebRequest variable and execute the Close() method inside the finally part of the try catch:

<br />
HttpWebRequest webRequest;<br />
WebResponse webResponse = null; //Need to assign this as null otherwise it does not compile<br />
try<br />
{<br />
   webRequest = WebRequest.Create("http://someurl.com/with.aspx?querystring=value");<br />
   webRequest.Method = "GET";<br />
   webRequest.KeepAlive = false;<br />
   webResponse = webRequest.GetResponse(); //Assign to webResponse<br />
}<br />
catch (Exception e){<br />
    //Something goes wrong. Implement handling of this exception<br />
}<br />
finally {<br />
   if(webResponse != null)<br />
   {<br />
      webResponse.Close(); //Close webresponse connection<br />
   }</p>
<p>   webResponse = null; //To clear up the webresponse<br />
   webRequest = null; //To clear up the webrequest<br />
}<br />

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Command-line arguments Windows Mobile

Written on August 4, 2008 by Johan de Koning | 2 Comments

In September I will go on holiday to the United States for 3 weeks. It would be nice to send updates to family and friends by placing images on Picasa. These web images will be taken with the photocamera from my mobile (which is Windows Mobile 6 based). I will upload the pictures when a free WiFi access point is available.

The program will place taken photos in a queue. When I have an internet connection available I can upload all the pictures from this queue to Picasa. This results in an application that can be seperated in two parts: the take a photo functionality and the upload photo-queue functionality.

Use cases explaining functionality

My mobile has a photo camera button which will trigger the default photo camera application. This default camera application can be replaced by changing the button settings on the mobile phone. When replaced (and when clicking the camera button) I want my application to start up ready to take a picture (so it will behave the same as the default camera application). After taking a picture you can type in some comment and add it to the queue.

When arriving at the hotel (or some other connective place) I want to upload the taken images. I can off course push the photo camera button again, but this time it is not my intention to take a new picture. In this case I want to start the application from the Start -> Programs menu and see the state of the queue with the option to upload the photos. The same application but with a different startup state.

The use of command-line arguments should solve this problem. But is this also possible with the Compact .Net Framework

Not a solution: Environment.GetCommandLineArgs

For Windows Form based application (which my mobile application is) the use of the Environment class is suggested to get the command-line arguments. The static method

<br />
public static string[] GetCommandLineArgs()<br />

The problem is that this method is not implemented inside the .Net Compact Framework and can’t therefore not been used.

Solution: static void Main(String[] args)

Just like console application (written in .Net) you have a Main method for your Windows Forms application. Besides the files created for the Form (by default Form1.cs and Form1.Designer.cs) a Program.cs file is created which contains a Main method. By adding a String[] args to the Main method, you can work with command-line arguments. An example of the new Main method

<br />
[MTAThread]<br />
static void Main(String[] args)<br />
   {<br />
      if (args != null &#038;&#038; args.Length > 0)<br />
     {<br />
         foreach (String arg in args)<br />
         {<br />
            MessageBox.Show(arg);<br />
         }<br />
     }<br />
     else<br />
     {<br />
         MessageBox.Show("No program arguments");<br />
     }<br />
     Application.Run(new Form1());<br />
}<br />

The arguments can be given to the form (Form1 in this example) by changing the constructor.

Creating a shortcut

The easiest way to create a shortcut is by using the Windows Explorer on your mobile phone. Navigate to the executable file of the application. Tap and hold the file selected with your styles to get the context menu. Select copy.

At the same location (or on a different location) tap (and hold) on an empty space to get the context menu. This context menu will give you the option to paste as a shortcut.

To add the command line argument inside the shortcut, i copied the shortcut (.lnk file) with ActiveSync to my desktop pc and edit the content with notepad. The file will now look like this:

59#”\Programmabestanden\ProgramArguments\ProgramArguments.exe” this_is_a_program_argument

My Windows Mobile OS is Dutch. On an English based OS the Programmabestanden part will be replaced by something like Program files. I don’t know if the number 59 before the line is mandatory. The number of characters with quotes is 59 long. So maybe it is used for reading optimalization. I really don’t know. I just added the this_is_a_program_argument at the end of the shortcut, saved the file and copied it back to my pocket pc.

Starting the application with the shortcut will show a messagebox with the text this_is_a_program_argument. When starting the application from the normal executable you will get a messagebox saving No program arguments.

Attachment: example project

You can download the example application from here

Special thanks

I want to thank Paul for discussing this problem and finding a solution.

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LINQ to XSD versus XSD.exe (part 1)

Written on July 19, 2008 by Johan de Koning | Comment

While LINQ to XSD is still in alpha, it is always a good idea to look at the (new) possibilities of this new technology. Before LINQ to XSD I used the XSD.exe to generate source files based on a XML schema. By generating this code you can work with XML files on a typed safe manner.

I will try to compare the differents between LINQ to XSD and the XSD tool. I will look at the (generated) code needed to work with XML files and try to compare the performances of both techniques. Based on the Linq to XSD overview document I will use the following XML schema:

<xs:schema
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  targetNamespace="http://www.example.com/Orders"
  xmlns="http://www.example.com/Orders"
  elementFormDefault="qualified">
   <xs:element name="Batch">
      <xs:complexType>
         <xs:sequence>
           <xs:element ref="PurchaseOrder" minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
       </xs:complexType>
     </xs:element>
   <xs:element name="PurchaseOrder">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="CustId" type="xs:string"/>
        <xs:element ref="Item" minOccurs="0" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
<xs:element name="Item">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="ProdId" type="xs:string"/>
        <xs:element name="Price" type="xs:double"/>
        <xs:element name="Quantity" type="xs:int"/>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

Code generation difficulties

The XML Schema placed above is different than the one I start using by default (for the PageType XML Schema of the Aincha Web Framework). Because the Purchase orders schema is not that complex I would have implemented it this way:

<xs:schema
  xmlns:xs="http://www.w3.org/2001/XMLSchema"
  targetNamespace="http://www.example.com/Orders"
  xmlns="http://www.example.com/Orders"
  elementFormDefault="qualified">
<xs:element name="Batch">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="PurchaseOrder" minOccurs="0" maxOccurs="unbounded">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="CustId" type="xs:string"/>
              <xs:element name="Item" minOccurs="0" maxOccurs="unbounded">
                <xs:complexType>
                  <xs:sequence>
                    <xs:element name="ProdId" type="xs:string"/>
                    <xs:element name="Price" type="xs:double"/>
                    <xs:element name="Quantity" type="xs:int"/>
                  </xs:sequence>
                </xs:complexType>
              </xs:element>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

This schema has the same definition as the previous one only the PurchaseOrder and Item are part of the complexType parts. Although this schema’s are both valid and they look the same, when using this schema with the XSD tool, different code is generated.

The first schema will generate the classes:

Batch
PurchaseOrder
OrderItem

While the second schema will generate classes:

Batch
BatchPurchaseOrder
BatchPurchaseOrderItem

Which is in my opinion not the names you would expect. If the schema is way more complex, you get even bigger names. And I know for sure that programmers don’t want to work with this unusual names.

At first, I though that this was a limitation of the XSD tool. But using the second schema within LINQ to XSD, the class names are also different and generated as private classes of the Batch object. With LINQ to XSD you get the following:

Batch
Batch.PurchaseOrderLocalType
Batch.PurchaseOrderLocalType.ItemLocalType

So it is important to keep it mind that different code will be generated bases on the structure of the XSD. Even when both schemas are valid.

What’s next?

In the next part of this comparison research I will investigate the following things:

amount of code used to work with XML data (based on the generated schema code);
time to load/parse the XML data (with different sizes);
time to print all the items inside the purchase orders to the console;
time to calculate the total purchase orders batch value and time to calculate the purchase order value for each customer;
CPU and Memory consumptions;

If you have other suggestions? Don’t hesitate to post them as a comment to this blog item.

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During the day he is a Microsoft .Net Developer, at night he is looking at Google

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Tape implementation

Flowchart

Workflow implementation with standard activities

Custom activities

Custom design

Workflow implementation with custom activities

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Source code

Reading a TOP file

Develop an OneNote AddIn

OpenFileDialog issue

InkAnalyzer

Building the OneNote XML

Updating OneNote

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User management

Using Psi (XMPP Client)

The XMPP stream

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Installation wizard

Admin console installation/configuration

What’s next?

What’s next?

Use cases explaining functionality

Not a solution: Environment.GetCommandLineArgs

Solution: static void Main(String[] args)

Creating a shortcut

Attachment: example project

Special thanks

Code generation difficulties

What’s next?

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