ASP.NET 4.0 In - Depth Session PART 2 On 10th OCT

Guys, after completing the Part 1 of the Session, its time to go beyond it and show you a few more advanced concepts from ASP.NET 4.0.  The remaining part of the Session includes :

Grayed Portion is already covered in PART 1

1. State Management Enhancements
2. Client side Enhancements
3. Deployment
4. Overview of Dynamic Data

I will present this Session  with Abhijit Jana on 10th October (the next Sunday) from 2 P.M IST. Please visit http://www.dotnetfunda.com/misc/onlinesession.aspx for more details.


If you missed out the Previous Session, you can follow the link to download PPT, the Video and the Source codes :

Download PPT, Sample Code & Video1
Download PPT, Sample Code & Video1

I hope the next session would be as good as this one. Nominate yourself for the same.(You need to register before you nominate yourself) Thank you all for your support.

Be there.

Note : If you have already nominated for the Session you do not need to Renominate yourself.

Lazy Load XAML content from External File and Vice Versa

XAML is the most flexible language built ever. More I see XAML, more I know about it. Today while tweaking around with XAML code, I found XAML could be loaded dynamically from any XML string. That means if you have a xaml in a xml file you can probably load the part of the XAML into your ContentControl or to any control element you want and the UI will appear instantly.

Once you compile a XAML it produces BAML. BAML is in binary format for the XML, so if you can pass a BAML into the UI separately somehow during runtime,you would be seeing the content instantly in the Window. In this post I am going to discuss how easily you could load a Dynamic content of XAML file into a normal WPF ContentControl just like what we do for normal htmls.

What is XamlReader and XamlWriter? 

If you look into the implementation of these classes you could wonder how flexible these are. They are highly capable of parsing the whole content of the file. It uses a XAMLDictionary which holds all the XAML elements that a XAML can see. The Reader parses the Xml content very cautiously to ensure it makes the XAML file to contain no reference of outside. Thus the class is used to Refactor the XAML from outside and hence allows you to put the content anywhere such that everything will be applied on that instantly.

XamlReader exposes methods like Load / Parse which allows you to parse a file content into BAML. Hence each of them returns an binary object which you can put into the Content.

Download Sample Application - 56 KB

Building a CRUD in RESTful Services of WCF

WCF is being popular day by day. Many of us is building services using WCF and want other application made on different architecture to communicate or inter operate with each other. REST or Representational State Transfer is a Design Pattern to build a service so that it works the same way as service works but it will eventually use Web Request - Response mechanism to communicate between clients rather than using SOAP messages.  In this post, I will give you a step by step approach how you could build your own WCF service using REST.

What is REST ?

REST abbreviated as Representational State Transfer is coined by Roy Fielding is a Design pattern for Networked system. In this pattern the Client invokes a Web request using an URL, so the basic of REST pattern is to generate unique URI to represent data.

If you look into Roy Fielding's quote on REST it says :
"Representational State Transfer is intended to evoke an image of how a well-designed Web application behaves: a network of web pages (a virtual state-machine), where the user progresses through an application by selecting links (state transitions), resulting in the next page (representing the next state of the application) being transferred to the user and rendered for their use."

That means REST is intended for Web applications where the browser invokes each request by specifying unique Uri.

REST Based Services

Download Sample Application - 200KB

5 things I would like to see in C# 5.0

C# 4.0 is out with a lots of new specs this year. Few of them are really good, like the support of Task level Parallelism, Dynamic behavior of objects etc. So C# is very rich now in all respect. But this is not the end of everything. As I did introduced few old but Unknown C# topics, I would also love to explore new things that comes up with C#. So lets discuss a few things which I would love to have.

There is already a buzz around on C# 5.0 specifications in forums. A notable discussion around should be some threads like

What features you want to see in C# 5.0
C# language speculation 4.5 /5.0

etc. These community links are really great where a lots of people voted for new language specs, while quite a few things are already would be in process like :

Binding Operators

Binding Operators may be C# 5.0. The support for Binding on .net objects are awesome. I came to know this from Chris on his post where he speaks how Binding operators looks like long ago. The delphi assignment operator := is now been used in this purpose. :=:  would be used for two way binding.  Thus

comboBox1.Text :=: textBox1.Text; 

means there would be two way binding between the properties so that when ComboBox1.Text changes its Text it will automatically change the value of Textbox1.Text.
Binding is actually not a new thing to the system. In WPF we already have Binding in place, but for that we need the properties to have implemented from INotifyPropertyChanged. So it is not in the language, the WPF objects are doing this internally by handling the PropertyChanged event on the object. But if that is included as an operator it would be a cool feature to add on.

WPF Tutorial : Styles, Triggers and Animations : 7

Introduction

Perhaps the most interesting and most important feature for any WPF application is Styling. Styling means defining styles for controls, and store in reusable ResourceDictionaries and hence forth, it could be used later on by calling its name. Styles in WPF could be well compared with CSS styles. They are both similar in most of the cases, while the former extends the feature allowing most of the features which WPF have. In this article I will discuss mostly how you could use Style in your WPF application to enhance the Rich experience of your UI.

Style

WPF exposes a property Style for every Control. If you look into the object Hierarchy, the Style is basically a property which exposes an object of Style in FrameworkElement. So each object can associate it and define custom setters to manipulate the basic look and feel of a control.

Clearly, the above diagram shows the association of Style in FrameworkElement and from the object hierarchy every control somehow inherits from FrameworkElement and hence style will be available to it. Style is also a WPF object which is inherited form DispatcherObject which helps in setting different properties of your UI Element.

How Style differs from Theme  ?

Before we move further into Styles lets talk about Themes. Theme is totally different from Styles. Themes are defined at OS level, or more precisely a Theme can take part of delivering styles all over the Desktop while Styles are restricted to the contextual area of a WPF window. WPF are capable of retrieving the color scheme which is defined in OS level. Say for instance, if you do not define style for your application, the elements in the screen will automatically get styles from external environment. Say for instance, in XP if you change the theme to something else you would see that the buttons, TextBox on your WPF window will change its color instantly. You can even set the Theme which the application would use programmatically from your code.

What about Templates ?

Every control defines a ControlTemplate. A ControlTemplate defines the overall structure of the control. As I have already told you, say for instance you have a Button. Button is a control that is made up of more than one control. It would have a ContentPresenter which writes the Text over the control, it would have a Rectangle which keeps the boundary of the Button etc. So Template is a special property associated with a Control which specifies how the control will look like structurally. We can easily define our Template and change the overall structure of a control.

Templates are basically of 2 types :

1. ControlTemplate
2. DataTemplate

ControlTemplate defines the structure of the Control. It means say for instance, you define the ControlTemplate for a ComboBox. So from ControlTemplate you can easily change the Button associated with the ComboBox which opens the DropDown, you can change the structure of the TextBox, the Popup etc. So ControlTemplate allows you to change the overall structure of the Control.



Click To Read Entire Article

Progress Streamed File download and Upload with Resume facility

For distributed applications, WCF is the most easy and rich component.I like to use WCF as it is very easy to implement and also provides built in functions to handle with Complex problems. One of such interesting thing that I found in WCF is the support for Streaming while sending data from the service.

WCF allows you to send Byte streams through the communication channel or even allows you to implement a service that might take the stream start location from the service call and send the stream from a certain location. It allows you to use normal HttpBinding to support streams which is capable download or upload in connected Client - Server architecture. Hence there will be not timeouts for sending or receiving large files. In this article I will show you how you could use Streaming to ensure your files are downloaded or uploaded correctly.

Once I read Demitris solution for File upload and download it made me very easy to adjust the code and enhance it further with more flexibilities.

Lets first create the service step by step :

Service

1. Create a Service Application and name it as WCFCommunicationService
2. The first thing that you need to do in order to create a service is ServiceContract. So once you create a Service Library, you need to delete the existing Service1 and IService1 files from the solution and add a new Interface. 
3. Create Two method, one for FileDownload and another for FileUpload. Lets see how the service definition looks like :

Contract

[ServiceContract]
public interface IFileTransferLibrary
{

    [OperationContract()]
    void UploadFile(ResponseFile request);

    [OperationContract]
    ResponseFile DownloadFile(RequestFile request);
}

The Contract defines the methods that are exposed to outside. The ServiceContract defines the interface which will have the members which are available to outside. The OperationContract identifies the exposed members. In the above contract the IFileTransferLibrary has two methods, UploadFile which takes an object of ResponseFile and DownloadFile which returns an object of ResponseFile.

[MessageContract]
public class ResponseFile : IDisposable
{
    [MessageHeader]
    public string FileName;

    [MessageHeader]
    public long Length;

    [MessageBodyMember]
    public System.IO.Stream FileByteStream;

    [MessageHeader]
    public long byteStart = 0;

    public void Dispose()
    {
        if (FileByteStream != null)
        {
            FileByteStream.Close();
            FileByteStream = null;
        }
    }
}

[MessageContract]
public class RequestFile
{
    [MessageBodyMember]
    public string FileName;

    [MessageBodyMember]
    public long byteStart = 0;
}

If you see the classes RequestFile and ResponseFile, you will see that I have used MessageContract instead of DataContract for my complex types. It is important. AS I am going to send the data streamed to the client, I need to send the data into packets. DataContract will send the whole object at a time while Messagecontract sends them into small Messages.It is also important to note that I have used IDisposable for ResponseFile to ensure that the Stream is closed whenever the connection is terminated.

Another important note is you need to use Stream as MessageBodyMember. The stream data will always transferred in MessageBody and you cannot add any other member into it. Thus you can see I have put all other members as MessageHeader.

For Both UploadFile and DownloadFile the Stream is taken from the ResponseFile object. The byteStart element of RequestFile ensures from where the the downloading should start and hence helps in Resuming a half downloaded file.  Lets see how to implement this :

public ResponseFile DownloadFile(RequestFile request)
{
    ResponseFile result = new ResponseFile();

    FileStream stream = this.GetFileStream(Path.GetFullPath(request.FileName));
    stream.Seek(request.byteStart, SeekOrigin.Begin);
    result.FileName = request.FileName;
    result.Length = stream.Length;
    result.FileByteStream = stream;
    return result;

}
private FileStream GetFileStream(string filePath)
{
    FileInfo fileInfo = new FileInfo(filePath);

    if (!fileInfo.Exists)
        throw new FileNotFoundException("File not found");

    return new FileStream(filePath, FileMode.Open, FileAccess.Read);
}
public void UploadFile(ResponseFile request)
{
           
    string filePath = Path.GetFullPath(request.FileName);
            
    int chunkSize = 2048;
    byte[] buffer = new byte[chunkSize];

    using (FileStream stream = new FileStream(filePath, FileMode.Append, FileAccess.Write))
    {
        do
        {
            int readbyte = request.FileByteStream.Read(buffer, 0, chunkSize);
            if (readbyte == 0) break;

            stream.Write(buffer, 0, readbyte);
        } while (true);
        stream.Close();
    }
}

If you see the code, you can see how I have used byteStart to start sending Bytes for the file. This ensures the file download to have resume facility. You can also implement the same for UploadFile too.

Download FileTransfer Sample - 161KB

Online Session on ASP.NET

I have just covered an Online session on "ASP.NET 4.0 in depth features" with Abhijit Jana for DotNetFunda.Com. If you were already there for the session, I hearty congratulate you people for your co-operation and also like you to join us in the concluding part of the session which will be declared later in the day.

In the session :

Things that we have covered already :

1. Basic Introduction of ASP.NET 4.0 Features
2. Visual Studio Enhancement Session
3. Server Control Enhancements
4. Search Engine Optimization

The session is not an end, We have lots of things to cover and probably we will fix a time later in the next week and update you the same. Stay Tune.

You can download Sample Applications that I showed : 

1. Routing Demo Application
2. Meta Tags and Parmanent Redirections

The sample video :

Download PPT, Sample Code & Video1
Download PPT, Sample Code & Video2

You can download the sample application and also run the PPT and Video from the link above. (Let me know if the link goes down.)

The Grayed items are already discussed, while others will be taken in the next session which will be announced shortly.

For reference Reading :

ASP.NET 4.0 WhitePapers

Thanks for being a part of the session.
Hope to see you soon.