ASP.NET

A Simple implementation of the Proxy Design Pattern using C#

amaniar — Tue, 07 Feb 2012 21:02:57 GMT

A proxy is an object that can be used to control creation and access of a more complex object thereby deferring the cost of
creating it until the time its needed.

Below is a simple implementation of the proxy pattern in C#. The ComplexProtectedExpensiveResource is private to the
ProxyContainer and cannot be instantiated by a client. The client creates an instance of the SimpleProxy class which controls
its access to the more complex and expensive to create ComplexProtectedExpensiveResource class.

Note that the ComplexProtectedExpensiveResource is created by the SimpleProxy instance only when needed and after
verifying that the client indeed has access to it.

namespace Patterns
{
    class ProxyContainer
    {
        private class ComplexProtectedExpensiveResource
        {
            internal void DoWork()
            {
                //do some heavy lifting
            }
        }

        // The Proxy
        public class SimpleProxy
        {
            ComplexProtectedExpensiveResource _complexProtectedResource;
            private string _password;

            public SimpleProxy(string password)
            {
                _password = password;
            }

            public void DoWork()
            {
                if (Authenticate())
                {
                    _complexProtectedResource.DoWork();    
                }
            }

            bool Authenticate()
            {
                //authenticate request
                if (_password == "password")
                {
                    //create expensive object if authenticated
                    if (_complexProtectedResource == null)
                        _complexProtectedResource = new ComplexProtectedExpensiveResource();
                    return true;
                }
                return false;
            }
        }
    }

    // The Client
    class ProxyPattern : ProxyContainer
    {
        static void DoWork()
        {
           var simpleProxy = new SimpleProxy("password");
           simpleProxy.DoWork();
        }
    }
}

Using Sitecores pipeline to pre-populate item in current language

amaniar — Mon, 12 Dec 2011 22:41:10 GMT

Sitecore has a powerful event pipeline infrastructure that you can leverage to plugin commands into various item creation, change, move, publish etc events.

Recently I had to add functionality to Sitecore so that when an items version is created all fields from a target language are copied into the newly created version to ease editing.

To do this first we add an event handler in the Web.Config file for the versionAdded event.

 <event name="item:versionAdded">
        <handler type="MyNamespace.MyClass, MyAssembly" method="OnVersionAdded" />
      </event>

Then add the OnVersionAdded event to the class added to the type attribute above.

The Method is as shown:

namespace MyNameSpace{
    public class MyClass
    {
        public void OnVersionAdded(object sender, EventArgs args)
        {
           //get item
            var item = Event.ExtractParameter(args, 0) as Item;
            try
            {
                if (item != null && item.Version.Number == 1)
                { 
                        //copy fields from fallback item
                        //we were using Language Fallback as explained below. Get whatever sourceItem you want to use 
                        var fallbackItem = FallbackLanguageManager.GetFallbackItem(item, false);

                        item.Editing.BeginEdit();
                        fallbackItem.Fields.ReadAll();
                        //copy over all fields from source to target language
                        foreach (Sitecore.Data.Fields.Field field in fallbackItem.Fields)
                        {
                            if (!field.Shared && !field.Name.StartsWith("__") && field.Name.Trim() != "")
                            {
                                item.Fields[field.Name].SetValue(field.Value, true);
                            }
                        }
                        item.Editing.EndEdit();
                        item.Editing.AcceptChanges();
                    }
                }
            }
            catch (Exception exception)
            {
                Sitecore.Diagnostics.Log.Error("Application Error", exception, this);
                if (item != null)
                { 
                    item.Editing.CancelEdit(); 
                }
            }
    }
}

Note that above code uses a FallbackLanguageManager to get the fallback item.

This is basically the current item in the fallback language configured for the current language.

This is based on the Fallback provider released by Alex Shyba at Sitecore:

http://sitecoreblog.alexshyba.com/2010/11/approaching-language-fallback-with.html

If you are not using the fallback simply change the line to get the Item from the desired source language like:

var fallbackItem = item.Database.GetItem(item.ID, Language.Parse("en"));

Code for the FallbackLanguageManager (borrowed from Alex’s fallback provider source)

public class FallbackLanguageManager
    {
        public static Item GetFallbackItem(Item item, bool forceFallback)
        {
            var fallbackLanguage = GetFallbackLanguage(item.Language, item.Database);
            var enforcedFallbackLanguage = Language.Parse("en");

            if (fallbackLanguage != null && !String.IsNullOrEmpty(fallbackLanguage.Name) && !fallbackLanguage.Equals(item.Language))
            {
                return item.Database.GetItem(item.ID, fallbackLanguage, Version.Latest);
            }

            if (forceFallback && !item.Language.Equals(enforcedFallbackLanguage))
            {
                return item.Database.GetItem(item.ID, enforcedFallbackLanguage, Version.Latest);
            }

            return null;
        }

        public static Language GetFallbackLanguage(Language language, Database database)
        {
            var sourceLangItem = GetLanguageDefinitionItem(language, database);
            return sourceLangItem != null ? GetFallbackLanguage(sourceLangItem) : null;
        }

        public static Item GetLanguageDefinitionItem(Language language, Database database)
        {
            var sourceLanguageItemId = LanguageManager.GetLanguageItemId(language, database);
            return ID.IsNullOrEmpty(sourceLanguageItemId) ? null : ItemManager.GetItem(sourceLanguageItemId, Language.Parse("en"), Version.Latest, database, SecurityCheck.Disable);
        }

        protected static Language GetFallbackLanguage(Item langItem)
        {
            var fallbackLangName = langItem[SitecoreFields.FallbackLanguage];
            Language fallbackLang;
            return Language.TryParse(fallbackLangName, out fallbackLang) ? fallbackLang : null;
        }
    }

Hope this helps!

Removing / Restricting Access to Sitecores Interface on Content Delivery Environments

amaniar — Mon, 24 Oct 2011 21:40:32 GMT

Here are a few steps you can follow if you want to restrict access to Sitecore’s Interface on content delivery environments.

1) Open Internet Information Services (IIS) Manager

2) Expand your Content Delivery website

3) Click on the Sitecore folder

4) Double Click on Authentication in the middle content pane

5) In the Authentication Pane right click Anonymous Authentication and click Disable

6) Try visiting the Sitecore login page on the Content Delivery site and verify that you get an access denied exception

7) You might also want to copy the yourwebroot/sitecore/service folder into the webroot and update the paths in the web.config file for the various error pages.

Hope this helps.

Copying Sitecore Items across Languages

amaniar — Mon, 25 Oct 2010 21:20:53 GMT

When using multiple languages/cultures in the Sitecore CMS the content of an item isn’t usually copied over from an existing language to a new language version.

While working on a multi lingual website after content was added to the primary language (en-US) I had to write a script to copy all fields from the primary language into other languages (Example en-GB).

Here is some code that I used for Sitecore 6.2.

The following method copies an item from the Source Language to a Target Language provided that the source item has at least one version. Note that if the Target Item lacks a version one is created and only the custom fields (ones not starting with a __) are copied over.

void Copy(Sitecore.Data.Items.Item item, Sitecore.Globalization.Language sourceLanguage,

Sitecore.Globalization.Language targetLanguage)

{

//get a reference to the master DB

Sitecore.Data.Database masterDB = Sitecore.Configuration.Factory.GetDatabase("master");

Sitecore.Data.Items.Item targetItem = masterDB.Items[item.ID, targetLanguage];

Sitecore.Data.Items.Item sourceItem = masterDB.Items[item.ID, sourceLanguage];

if (targetItem == null || sourceItem == null || sourceItem.Versions.Count == 0)

return;

//Disable the security context

using (new Sitecore.SecurityModel.SecurityDisabler())

{

try

{

if (targetItem.Versions.Count == 0)

{

//add a version if none exist

targetItem = targetItem.Versions.AddVersion();

}

//edit item in target language

targetItem.Editing.BeginEdit();

sourceItem.Fields.ReadAll();

//copy over all fields from source to target language

//we omit internal fields which start with __

foreach (Sitecore.Data.Fields.Field field in sourceItem.Fields)

{

if (!field.Shared && !field.Name.StartsWith("__") && field.Name.Trim() != "")

{

targetItem.Fields[field.Name].SetValue(field.Value, true);

}

targetItem.Editing.EndEdit();

targetItem.Editing.AcceptChanges();

}

catch (Exception ex)

{

targetItem.Editing.CancelEdit();

Response.Write(ex.Message);

}

The following method copies an item from a Source Language to a Target language. In this case two items can be different but are expected to have the same Fields.

void Copy(Sitecore.Data.Items.Item sourceItem, Sitecore.Globalization.Language sourceLanguage,

Sitecore.Data.Items.Item targetItem, Sitecore.Globalization.Language targetLanguage)

{

Sitecore.Data.Database masterDB = Sitecore.Configuration.Factory.GetDatabase("master");

targetItem = masterDB.Items[targetItem.ID, targetLanguage];

sourceItem = masterDB.Items[sourceItem.ID, sourceLanguage];

if (targetItem == null || sourceItem == null || sourceItem.Versions.Count == 0)

return;

using (new Sitecore.SecurityModel.SecurityDisabler())

{

try

{

if (targetItem.Versions.Count == 0)

{

targetItem = targetItem.Versions.AddVersion();

}

targetItem.Editing.BeginEdit();

sourceItem.Fields.ReadAll();

foreach (Sitecore.Data.Fields.Field field in sourceItem.Fields)

{

if (!field.Shared && !field.Name.StartsWith("__") && field.Name.Trim() != "")

{

targetItem.Fields[field.Name].SetValue(field.Value, true);

}

targetItem.Editing.EndEdit();

targetItem.Editing.AcceptChanges();

}

catch (Exception ex)

{

targetItem.Editing.CancelEdit();

Response.Write(ex.Message);

}

You can call the above methods after querying Sitecore’s Master DB for items you would like to clone.

protected void Import(object sender, EventArgs e)

{

try

{

Sitecore.Data.Database masterDB = Sitecore.Configuration.Factory.GetDatabase("master");

Sitecore.Data.Items.Item[] items = Sitecore.Context.Database.SelectItems

("/sitecore/content/Home/MySectionToCopy//*");

//get source and target language for the copy

Sitecore.Globalization.Language sourceLanguage = Sitecore.Data.Managers.LanguageManager.GetLanguage("en-US", masterDB);

Sitecore.Globalization.Language targetLanguage = Sitecore.Data.Managers.LanguageManager.GetLanguage("en-GB", masterDB);

if (sourceLanguage == null || targetLanguage == null)

return;

foreach (Item item in items)

{

//copy item from source to target language

Copy(item, sourceLanguage, targetLanguage);

}

catch (Exception ex)

{

Response.Write(ex.Message);

}

Note: You also have the option to plug into Sitecore’s event pipeline and automatically copy a source language into the target language when a version is added.

More on Event Handling in Sitecore here: http://sdn.sitecore.net/Articles/API/Using%20Events/Handling%20Events.aspx

Enabling HTTP Redirect in IIS7

amaniar — Tue, 12 Oct 2010 20:00:11 GMT

If you want a virtual directory or a site in IIS7.x to redirect to another url you first have to make sure you have installed http redirect for IIS.

To do that goto Control Panel > Program and Features and select Turn Windows features on or off

Choose IIS and click on Add Role Services and make sure you check HTTP Redirection

Let the feature be installed and configured.

Now you will see the HTTP Redirect option in the Features View of IIS.

Click HTTP Redirect and add the necessary redirect information to add a redirect for a virtual directory or an entire site.

WCF and IIS7: 404 - File or Directory not found

amaniar — Tue, 31 Aug 2010 20:48:41 GMT

Ever been puzzled by the 404 - File or Directory not found error message when deploying a WCF service to a new .NET/IIS7 installation?

The error seems to indicate that the .svc file could not be located even though it’s present in the website.

This usually is a side effect of the server not having WCF Activation feature turned on. As soon as you turn it on in the Add features wizard your WCF service will be served correctly by IIS.

Cleaner ClientID's with ASP.NET 4.0

amaniar — Tue, 27 Apr 2010 14:40:07 GMT

A common complain we have had when using ASP.NET web forms is the inability to control the ID attributes being rendered in the HTML markup when using server controls.

Our Interface Engineers want to be able to predict the ID’s of controls thereby having more control over their client side code for selecting/manipulating elements by ID or using CSS to target them.

While playing with the just released VS2010 and .NET 4.0 I discovered some real cool improvements. One of them is the ability to now have full control over the ID being rendered for server controls.

ASP.NET 4.0 controls now have a new ClientIDMode property which gives the developer complete control over the ID’s being rendered making it easy to write JavaScript and CSS against the rendered html.

By default the ClientIDMode is set to Predictable which results in clean and predictable ID’s by concatenating the ID’s of the Parent and child controls. So the following markup:

<asp:Content ID="ParentContainer" ContentPlaceHolderID="MainContentPlaceHolder" runat="server">

<asp:Label runat="server" ID="MyLabel">My Label</asp:Label>

</asp:Content>

Will render:

<span id="ParentContainer_MyLabel">My Label</span>

Instead of something like this: (current)

<span id="ct100_ParentContainer_MyLabel">My Label</span>

Other modes include AutoID (renders ID’s like it currently does in .NET 3.5), Static (renders the ID exactly as specified in the code) and Inherit (defers the mode to the parent control).

So now I can write my jQuery selector as:

$(“ParentContainer_MyLabel”).text(“My new Text”);

Instead of:

$(‘<%=this. MyLabel.ClientID%>’).text(“My new Text”);

Scott Mitchell has a great article about this new feature:

http://bit.ly/ailEJ2

Am excited about this and some other improvements. Many thanks to the ASP.NET team for Listening!

IIS7 Shared Configuration with Offline Files

amaniar — Wed, 13 Jan 2010 23:09:37 GMT

Recently I was working on a hardware architecture project for a client. The final architecture for one of the websites consisted of 3 web servers hosting windows 2008 and IIS 7 being load balanced.
When setting up the websites we decided to use the Shared Configuration hosting built into IIS7. Shared configuration allows you to deploy and propagate IIS configuration changes to all servers by changing one configuration file.
This post explains it in more detail:
http://learn.iis.net/page.aspx/264/shared-configuration/

We decided to create a network share for the shared configuration files and use the Offline files feature to make sure that the config files were available to IIS even if the share wasn’t temporarily unavailable.
A good post about how to user Offline sharing is here:
http://learn.iis.net/page.aspx/212/offline-files-for-shared-configuration

After following all steps all app pools seemed to crash with a strange exception in the event logs:
The worker process for application pool 'MyAppPool' encountered an error 'Cannot read configuration file
' trying to read global module configuration data from file '\\?\<EMPTY>', line number '0'. Worker process startup aborted.

After some researching we realized that although the Offline file functionality seems to be available it doesn’t really do anything unless you have the Desktop Experience installed. Otherwise anytime the network shared becomes unavailable the WAS fails to start your worker process and after a set number of times, it goes into Rapid Fail Protection Mode and stops the application pool.

Good IIS resources:

http://mvolo.com/blogs/serverside/default.aspx

http://learn.iis.net/

Building a Silverlight Flickr Application using Windows Communication Foundation

amaniar — Wed, 30 Sep 2009 20:08:32 GMT

Flickr is a popular photo-sharing website. It’s primarily used by people to store, organize and share their photos. Flickr allows both public and private photos and the ability of people being able to comment on them.

Like many other social websites Flickr has a public API that can be used to get access to their data via low level web service calls. We shall use an open source Flickr API library called FlickrNet to take care of the low level web service calls for us.

In this post we shall be using the FlickrAPI to build a simple Silverlight based application. The completed application will display 10 random public photos for any Flickr username/email with the ability to view a larger photo along with any comments.

The Flickr API provides a means for application developers to interface with Flickr assets - photos, users, comments, blogs, groups, and so forth. In order to use the Flickr API you must have an API key, which you can get for free from the Flickr API Keys page at http://www.flickr.com/services/api/keys.

After downloading the FlickrNet.dll we create a web application and a silverlight application. We add the FlickrNet.dll as a reference into the web app and add a Silverlight enabled - WCF service for transmitting data to the Silverlight application.

Next we add flickrNet config section to our web application and populate it with our API key.

Note: You might want to disable caching by adding disableCache="true" to the config section if you get permission exceptions in production.

…

</configSections>

We also add a FlickrPhoto and FlickrComment classes to represent a Flickr photo and comment respectively.

The Solution looks like this:

Next we implement a method in the WCF Service that returns the top 10 random pics for a given user name.
For this you can use the PeopleFindByUsername method to find the user and then create a PhotoSearchOptions object and set the PerPage property to 200 so we get the first 200 photos for the user.

We order the returned list randomly and then select the top 10 photos with the help of some linq.

FoundUser userInfo = flickr.PeopleFindByUsername(username);

flickrUserId = userInfo.UserId;PhotoSearchOptions options = new PhotoSearchOptions();

options.UserId = flickrUserId;

options.PerPage = 200;

//get 10 pics randomly

Photos searchResults = flickr.PhotosSearch(options);

pics = (from p in searchResults.PhotoCollection.OrderBy(p=>Guid.NewGuid())

select new FlickrPhoto

{

PhotoId = p.PhotoId,

Title = p.Title,

MediumUrl = p.MediumUrl,

WebUrl = p.WebUrl,

LargeUrl = p.LargeUrl,

ThumbnailUrl = p.ThumbnailUrl,

SmallUrl = p.SmallUrl}).Take(10).ToList();

Next we will add a ServiceReference to this service from our Silverlight project called FlickrServiceReference. Now we have a client side proxy called FlickrServiceReference which we can use to talk to our web service.

In the silverlight application you can then accept a Flickr username/email from the user and call the Web services GetRandomPhotos method and bind the results to an ItemsControl as shown in the following code snippet.

FlickrServiceReference.FlickrServiceClient service = new SilverlightApplication.FlickrServiceReference.FlickrServiceClient();

service.GetRandomPicsCompleted += new EventHandler<SilverlightApplication.FlickrServiceReference.GetRandomPicsCompletedEventArgs>(service_GetRandomPicsCompleted);

service.GetRandomPicsAsync(“FlickrUsername”);

Using a DataTemplate for the ItemsControl to show the Thumbnails inside a ScrollViewer so we can scroll the photos. We use data binding to bind the image source to the ThumbnailUrl property.

Here is a snippet of the scroll viewer that wraps the thumbnails

<ItemsControl x:Name="icPhotos" HorizontalAlignment="Left" VerticalAlignment="Top"

BorderBrush="#FFB83636" BorderThickness="1,1,1,1" RenderTransformOrigin="0.5,0.5" >

<ItemsControl.ItemTemplate>

<StackPanel.Resources>

</Storyboard>

</Storyboard>

</StackPanel.Resources>

<StackPanel.RenderTransform>

</TransformGroup>

</StackPanel.RenderTransform>

<Image Source="{Binding Path=ThumbnailUrl}" MaxWidth="100" MaxHeight="100" Margin="10" MouseLeftButtonDown="Image_MouseLeftButtonDown"/>

</StackPanel>

</DataTemplate>

</ItemsControl.ItemTemplate>

</ItemsControl>

</ScrollViewer>

You will notice we have added two animations called grow and shrink that will fire on MouseEnter and MouseLeave on the stackpanel. As a result the images zoom by 10% every time the cursor is hovered over them.

Next we add some more markup to display a large image along with any comments when a thumbnail is clicked.

OnMouseLeftButtonDown event of the thumbnail is wired to call the GetComments method on the web service and bind the returned Comments to a ItemSource property of the DataGrid. The larger image is bound to the images mediumUrl.

The GetComments Method returns a List of FlickrComments for the Photo ID.

public List<FlickrComment> GetComments(string pid)

{

Flickr flickr = new Flickr();

string flickrUserId = string.Empty;

List<FlickrComment> comments = new List<FlickrComment>();

try

{

Comment[] commentResults = flickr.PhotosCommentsGetList(pid);

comments = (from c in commentResults

select new FlickrComment

{

CommentHtml = c.CommentHtml,

DateCreated = c.DateCreated,

PhotoId = c.PhotoId,

AuthorUserName = c.AuthorUserName,

CommentId = c.CommentId

}).ToList();

}

catch (FlickrApiException)

{

// report error

}

return comments;

}

Check the live demo here.

Download Source code here:

Resources:
http://www.flickr.com/services/api/keys/
http://flickrnet.codeplex.com/
http://www.4guysfromrolla.com/articles/091609-1.aspx
http://www.asifmaniar.com/samples/Flickr-Silverlight-WCF.aspx