Web Dev And Stuff

Make your site run only in ONE Browser window(single instance)!

djsolid — Sun, 15 Nov 2009 10:49:00 GMT

While a was at Teched2009 and watching Tim Heuer presenting Silverlight 3 I noticed a new cool feature named Local Messaging!

When I saw this new feature, a crazy idea crossed my mind. Could this be used in order to allow the user to open my website in only one browser window?

The answer is yes! But not the way I first thought. Here is how (code in MainPage.xaml.cs):

string _localName = "SL App";
bool _Close = false;

public MainPage()
{
   InitializeComponent();

   Loaded += new RoutedEventHandler(MainPage_Loaded);
   try
   {
       LocalMessageReceiver incomingMessage = new LocalMessageReceiver(_localName);
       //Start listening
       incomingMessage.Listen();
   }
   catch (ListenFailedException)
   {
       _Close = true;
   }            
}

protected void MainPage_Loaded(object sender, RoutedEventArgs e)
{
   if (_Close)
   {
       HtmlPage.Window.SetProperty("location", "/InfoMessage.aspx");
   }
   else
   {
       LocalMessageSender msgSender = new LocalMessageSender(_localName);
       msgSender.SendAsync("New instance loaded");
   }
}

Loading Default.aspx

Clicking on the first link

Then on the second link

Those are the files in the solution

That’s an exception driven solution but works for me! :)

This works also across different browsers but if you want you can changed to allow one instance per browser.

Here are the solution files.

Enjoy!

ASP.NET Membership - Change password without asking the old

djsolid — Mon, 28 Sep 2009 03:25:26 GMT

Recently I was in a situation where a user was required to change the password upon first login.

But MembershipUser’s ChangePassword requires 2 arguments. Old and new password. In my case the password was hashed and I couldn’t retrieve it unless the user enter it.

So I wanted to change the password without asking the old one. The solution was :

Reset the password
Keep the generated password in a var
Call MembershipUser.ChangePassword using the generated password as the old one!

It does an extra query to the database but does the job! If the password was stored in Clear or Encrypted form it could be retrieved.

Anonymous user access in N2 CMS

djsolid — Tue, 14 Apr 2009 01:31:19 GMT

N2 CMS

First of all i have to say that N2 CMS i a great Content Management System and really extensible! I discovered it a while ago and i decided to re-develop projects that were built with DotNetNuke with N2.

What do i want?

I want to show a page or a content only to anonymous users. I am using the default ASP.NET Role Provider for Sql Server.

Implementation

So first of all i had to extend that provider. This is how :

public class MyCustomSqlRoleProvider : System.Web.Security.SqlRoleProvider

    public override void AddUsersToRoles(string[] usernames, string[] roleNames)

        if (roleNames.Any(x => x == "Anonymous"))

            throw new InvalidOperationException("Cannot add \"Anonymous\" role

 to user(s). Role is automaticaly assigned.");

        base.AddUsersToRoles(usernames, roleNames);

    public override string[] GetAllRoles()

        List<string> roles = base.GetAllRoles().ToList();

        roles.Add("Anonymous");

        return roles.ToArray();

    public override bool IsUserInRole(string username, string roleName)

        if (HttpContext.Current != null &&

                   !HttpContext.Current.User.Identity.IsAuthenticated &&

                   HttpContext.Current.User.Identity.Name == username)

            return roleName == "Anonymous";

        else

            return base.IsUserInRole(username, roleName);

Nothing fancy here. Just adding the Anonymous Role and checking if user is not logged in and the role being checked is “Anoynoumous” to return true. Also i try to ensure that no one will try to add the '”Anonoymous” role to a registered user.

Next i had to implement an ISecurityManager to do the Authorization. This is how :

public class MyCustomSecurityManager : N2.Security.SecurityManager

    public MyCustomSecurityManager(IWebContext webContext) : base(webContext) { }

    public MyCustomSecurityManager(IWebContext webContext, 
          N2.Configuration.EditSection config) : base(webContext, config) { }

    public override bool IsAuthorized(ContentItem item, IPrincipal principal)

        bool isAuthorized = base.IsAuthorized(item, principal);

        if (!isAuthorized && !principal.Identity.IsAuthenticated &&

                      item.AuthorizedRoles.Count > 0)

            isAuthorized = item.AuthorizedRoles.Any(x => x.Role == "Anonymous");

        return isAuthorized;

Inheriting from N2.Security.SecurityManager i had to override only the IsAuthorized method to work the way i intended to.

And last but not least i had to add to the web.config the following

<n2>

 <engine>

  <components>

   <add service="N2.Security.ISecurityManager, N2"

     implementation="MyCustomSecurityManager, AssemblyName" />

  </components>

 </engine>

</n2>

Conclusion

I hope to find this post useful. If you have any suggestions or questions please let me know. And i case you haven’t checked N2 CMS just take a quick look.

LiteralControl in Markup!!!

djsolid — Sun, 19 Oct 2008 10:25:24 GMT

I always had the question if I could add a LiteralControl via Markup code. Let's say something like that :

<div class="header">
    <asp:LiteralControl runat="server" ID="ltrHeader"></asp:LiteralControl>
</div>
<div class="sub-header">
    <asp:LiteralControl runat="server" ID="ltrSubHeader" Text="Some Text" ></asp:LiteralControl>
</div>

Well It IS possible and simple to be honest. Just Register the control at the top of the page like that :

<%@ Register Assembly="System.Web" Namespace="System.Web.UI" TagPrefix="asp" %>

You might have a warning that "Element 'LiteralControl' is not a known element." but it will compile just fine and you can set the Text programmatically!

Hope that helps anyone who wants to use a LiteralControl over Literal!

Enjoy!

.NET Framework 4.0 and “Dublin”

djsolid — Wed, 01 Oct 2008 17:07:18 GMT

How about a sneak peek into the .NET Framework 4.0?

At Steven Martin's blog you can see about WCF και WF improvements, Dublin etc...

More to come of course at PDC..

Yeaaaaah...!

Silverlight and Shoutcast!

djsolid — Wed, 01 Oct 2008 12:26:52 GMT

Finally a solution!!!!!!!! How can we stream a shoutcast radio via a Silverlight application?

Well in 6 steps...

1. Open Expression Blend

2. Create a Project

3. Add a media element

4. Add the code below at the cs (or vb) file

public Page()
{
	// Required to initialize variables
	InitializeComponent();
	this.Loaded += new RoutedEventHandler(Page_Loaded);
}

void Page_Loaded(object sender, RoutedEventArgs e)
{
	try
      {
      
      myElem.Source = new Uri("http://mystation:port/;");
      myElem.Play();
      }
      catch (Exception ex)
      {
      
	}
}

5. We put ~~mms instead of http and~~ at the end "/;" without the quotes

6. We hit F5 and listen our radio!!!

Enjoy!

Edit : it works with http really good but i never tried until now... So no need for mms at the beginning of the URL.

Set default value for Properties

djsolid — Thu, 18 Sep 2008 09:25:00 GMT

Many times I needed to set a default value for a property.

For example at the property below

public string Property1 {get; set;}

I wanted a default value "Value1". The only way was to create a private field or to set it in code like Property1 = "Value1" somewhere.

What if I wanted to do this for all my properties ?

For this case i decided to create a custom attribute which does that thing. Takes a value and if the value of the current property is null sets it to the given value.

To be more specific let's begin with the custom attribute class:

 [global::System.AttributeUsage(AttributeTargets.Property, Inherited = false, AllowMultiple = false)]
    sealed class DefaultValueAttribute : Attribute
    {
        readonly object defaultValue;
        readonly Type valueType;

        public DefaultValueAttribute(object defaultValue, Type valueType)
        {
            this.valueType = valueType;
            this.defaultValue = Convert.ChangeType(defaultValue, valueType);
        }
        public Type ValueType { get { return valueType; } }
        public object DefaultValue
        {
            get { return defaultValue; }
        }
    }

Then we have a helper class with an extension method :

public static class DefaultValueAttributeHelper
    {
        public static void SetDefaultValues(this object obj)
        {
            Type t = obj.GetType();
            foreach (var item in t.GetProperties())
            {
                foreach (var attr in item.GetCustomAttributes(typeof(DefaultValueAttribute), true))
                {
                    DefaultValueAttribute val = ((DefaultValueAttribute)attr);
                    if (item.GetValue(obj, null) == null ||
                        ((item.GetValue(obj, null).ToString() == "0") && 
                                       (val.ValueType != typeof(string))))
                        item.SetValue(obj, val.DefaultValue, null);
                }
            }

        }
    }

And finally how this can be used for example at an ASP.NET Page:

public partial class UserDetails : System.Web.UI.Page
    {
        public UserDetails()
        {
            this.SetDefaultValues();
        }
        protected void Page_Load(object sender, EventArgs e)
        {
            Response.Write(StringProp + "<br>" + IntProp + "<br>" + (DoubleProp + 1));
        }

        [DefaultValueAttribute("6.11354", typeof(double))]
        public double DoubleProp { get; set; }

        [DefaultValueAttribute("6", typeof(int))]
        public int IntProp { get; set; }

        [DefaultValueAttribute("String1", typeof(string))]
        public string StringProp { get; set; }


    }

Well that's all ... This is really simple. Next step is to create an interface so the above attirbute can be used with custom objects.

If anyone has any improvements please let me know!

ASP.NET Messagebox - Server and Client

djsolid — Sun, 14 Sep 2008 10:15:00 GMT

Today I ran into an excellent post of Bill Beckelman about a server side asp.net message box.

More info you can find on this post. And I thought what if I wanted to use it via the client ? So I decided to extended a little further and to add a client-side behavior.

How can be used via the client?

To use the MessageBox via client you should call the
ShowMessageBox(type,Header,Text,Width,Height) function.

The first argument is the type. At the moment possible values are info,error,success and warning.
The second is the the header of the messagebox and the third is the text. You can also use html...!
The other two are width and height of the message box.

Example : ShowMessageBox('info','A Simple Header','Just some text',400,125);

So simple :)

You can view a demo or you can download the updated version.

Again credits to Bill Beckelman!

Screenshots

Firebug 1.2 - New Version

djsolid — Mon, 25 Aug 2008 22:28:00 GMT

Just a few hours ago the 1.2 version of the ultimate web development tool, Firebug , has been released. Several improvements and bug fixes come with this release. You can find more at John's post.

Update NOW!!!!

The @Reference Directive

djsolid — Wed, 13 Aug 2008 10:01:53 GMT

When I want to add a user control to a page I use the @Register directive at the top of the page. and the I add the control to the markup. But what if I want to add a user control programmatically but I have no reference of it via the markup? That is where the @Reference directive comes to action.

What's the story?

We have a user control with the name myUserControl.aspx

We add at the top of the page the control we want to programmatically add like this...

And finally the controls is being added to the page like this...

In general, when we declare a control in the page layout we use @Register and when we create the control programmatically we use @Reference.

That's it ...

ASP.NET Browsers Filter!!

djsolid — Tue, 12 Aug 2008 06:49:00 GMT

Yesterday .NET SP1 released and many new features for ASP.NET where added. But yesterday i also discovered a feature that ASP.NET has from version 2.0

Let's say we have a button. We can decide what value will the properties have for different browsers!!! And we can do that with this way...

<asp:Button ie:Text="IEText" runat="server" mozilla:Text="FFText" />

The result in IE will be a button with IEText and in Firefox FFText.

The above works with all properties like OnClientClick!

This could be useful i.e. at file upload control where each browser handles different the rendering of the tag.

Cool eh?

Add scripts to head dynamically

djsolid — Fri, 08 Aug 2008 08:14:00 GMT

Many times when i develop a user control i have the need to add some javascript to the header of the page. But the header doesn't have a method where you can add script and RegisterStartupScript inserts the script at the bottom of the page.

So i thought let's create an extension method...

public static void AddScriptToHead(this HtmlHead h, string script, bool AddScriptTags) { Literal l = new Literal() if (AddScriptTags) l.Text = @"<script type=""text/javascript""> //<![CDATA[" + script + @"//]]> </script>"; else l.Text = script; h.Controls.Add(l); }

This is how this method can be used for inserting javascript tags to a page's header...

Without the script tags....

Page.Header.AddScriptToHead(@" function someFunction() { //Do Something } ", true);

And not only javascript but custom css files, meta tags etc...

Page.Header.AddScriptToHead( @"<link type=""text/css"" rel=""stylesheet"" href=""some.css""></link>" , false);

That's it! Javascript, css files, meta tags and anything else can be inserted to the header dynamically!!

Enjoy...

ASP.NET AJAX 4.0 Template Example

djsolid — Wed, 23 Jul 2008 12:32:00 GMT

Yesterday was released the first preview of ASP.NET 4.0. Lot's of cool stuff come with this release and with this article i will try to demonstrate the use of templates. The example is available for download

Let's start...

First we have to download MicrosoftAjaxTemplates.js available from Codeplex and and add it to our project. Then we have to add a reference to our page.
We will do it via the ScriptManager like this.

<asp:ScriptManager runat="server" ID="sm" EnablePageMethods="true">
            <Scripts>
                <asp:ScriptReference Path="~/MicrosoftAjaxTemplates.js" />
            </Scripts>
</asp:ScriptManager>

We also enable PageMethods. Then we add a button that will get data from the server, the template that we want to use and a div to show the data...

<input type="button" id="btn" value="Show Data" onclick="exec()" />
<div id="myTemplate" class="sys-template">
            <h3>
                {{ Title }}</h3>
            Name:
            <input type="text" value="{{ FirstName + ' ' + LastName}}" />  Date:
            <input type="text" value="{{ DateNow.format('dd/MM/yyyy hh:mm:ss') }}" /> 
            
            BirthDate:  <input type="text" value="{{ BirthDate.format('dd/MM/yyyy') }}" />
            
            
            BirthDate is unkown
            
</div>
<div id="data">
</div>

Then we add a WebMethod to our code-behind file and a custom class with 4 properties. This method will be used via PageMethods so it has to be public and static.

    [WebMethod]
    public static List<Info> GetVal()
    {
        List<Info> l = new List<Info>();
        l.Add(new Info { BirthDate = DateTime.Parse("2/6/2008"), FirstName = "John", LastName = "Katsiotis", DateNow = DateTime.Now, Title = "Cool ASP.NET Developer" });
        l.Add(new Info { BirthDate = null, FirstName = "Foo", LastName = "Bar", DateNow = DateTime.Now, Title = "Common Name Example" });
        System.Threading.Thread.Sleep(2500);
        return l;
    }

    public class Info
    {
        public DateTime? BirthDate { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public DateTime DateNow { get; set; }
        public string Title { get; set; }
    }

In our GetVal method we create two instances of class Info and we return a list that contains those two. We also create a delay of 2.5 secs.

Finally we have add the nessecary javascript to our aspx page which is...

<script type="text/javascript">
    function initTemplateValues(_Title,_FirstName,_LastName,_DateNow,_BirthDate)
    {
        var t = new Sys.Preview.UI.Template.getTemplate($get("myTemplate"));
        t.createInstance($get("data"),
        {
            Title: _Title,
            FirstName: _FirstName,
            LastName: _LastName,
            DateNow: _DateNow,
            BirthDate: _BirthDate
        });
    }
    function exec()
    {

        $get('data').innerHTML='Please wait...';
        PageMethods.GetVal(onComplete,onError);
    }
    function onComplete(args)
    {
        $get('data').innerHTML=''
        for(var i=0;i<args.length;i++)
        {
            initTemplateValues(args[i].Title,args[i].FirstName,args[i].LastName,args[i].DateNow,args[i].BirthDate);
        }
    }
    function onError(args)
    {
        $get('data').innerHTML=args;
    }
    </script>

First we have exec() which calls the server-side method GetVal. Then if the call is sucessful the onComplete methods is called and foreach item in args (which type is Info) we create an area that uses the template defined in our aspx page and we add that template to a div with id results.

Pretty simple don't you think?

Enjoy...!!!

Create a Facebook-like Ajax Image Gallery!

djsolid — Mon, 07 Jul 2008 10:08:00 GMT

A lot of people have been using facebook and i am sure that everyone has noticed the ajax gallery that faecebook has. In this article we will try to make our own gallery that does the same stuff. When the user clicks on the image he navigates to the next and when the user presses the back button of the browser the previous image is displayed.

We are going to use a new feature of the AJAX Framework which is History Support! (available via the property of ScriptManager, EnableHistory)

First create a new "ASP.NET 3.5 Extensions Web Site"

Then at the aspx page we add :

EnableHistory : Enables the new feature of AJAX Framework which allows the user to navigate back and forward in an AJAX page.

EnableStateHash : If true the url responible for AJAX History is encoded. By Default is true.

OnNavigate : This event is fired when the user clicks the back button of the browser and the ScriptManager makes a postback.

At the aspx.cs page we add :

First we read the image folder (it could be from a database). We strip out the full path and we keep only the image name. Then we check if this is not a postback and we display the first image of our list. When the user clicks the Back Button the Navigate Event of the ScriptManager is fired. We get the current image index and we add +1.

When the user clicks on the ImageButton the Click event is fired. The point of interest at this method is the AddHistoryPoint of the ScriptManager. Using this method we add something that can tell us (when the user clicks the back button) what was the page like in order to be able to recreate it.

You can download the source code from here!

You can view a live example here!

That's it! enJoy!

Shoutcast.NET - Get Details From a Shoutcast Server

djsolid — Tue, 17 Jun 2008 18:13:00 GMT

I have been using Shoutcast for a long time. And each and every time had to do the same stuff if i wanted to get details such as song title, current listener etc. So i decided to write a simple class library to make things easier. What you have to do in order to be able to use this library is to find out the exact url of your stream.

Let's say that it is : http://mydomain.com:8000

Then at the end you add /admin.cgi?mode=viewxml&pass=YOURADMINPASS.

So the url becomes http://mydomain.com:8000/admin.cgi?mode=viewxml&pass=YOURADMINPASS

Where YOURADMINPASS is the pass that you use to connect to the server. You pass the url to the constructor and you are ready to get the details! Below is an example. Replace StreamServerURL with yours.

The project is available at Codeplex. Link : Shoutcast.NET

PS Now i am writing an other version which does not requires the password but it gives access to fewer details.