Now to create a .Net client to consume a web service, first step is to add the wsdl as reference. In Visual Studio, right click the project folder in Solution explorer and select “Add Web Reference”. 

In the URL field, provide the URL of the wsdl. If any authentication is to be provided to access the web service, the system will prompt you to enter the credentials also. Click on “Add Reference” button after filling in the web reference name. Once you have added the reference, it will appear under the App_webReferences folder in solution explorer (VS2008).

Now that we have added the web reference, next step is to create an object of the web service. First add the namespace and then create an object to access the web service methods. Eg: If the reference name added was “example”, then the object should be created as:

   Example client = new Example ();

Once the object is created, accessing the methods of the web service is straight forward. You can access the web service methods like you access any other class.

Sometimes, the web service may prompt you to enter the login credentials to access the service. In this case, we will have to supply the user name and password. This can be done using the following steps:

NetworkCredential netCredential = new NetworkCredential(“username”, “password”);

client.UseDefaultCredentials = false;

client.Credentials = netCredential;

Read more about the Network credential class in msdn: http://msdn.microsoft.com/en-us/library/system.net.networkcredential(v=VS.90).aspx

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
<Columns>
<asp:BoundField HeaderText="ProductID" />
<asp:TemplateField HeaderText="Image">
<ItemTemplate>
<asp:Image ID="Image1" runat="server" />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>

Now to display images. Here in the database,only the file names is there and hence if the images are in some directory, you have to somehow pre pend it with the filename.Here i am using the appsettings in web.config to provide the path of the images directory.

<appSettings>
<add key="IMG" value="http://your full path"/>
</appSettings>

Now to the C# code for populating the GridView. Here is the entire method i created for binding this GridView.

private void bindGrid()
{
string strconn= ConfigurationManager.ConnectionStrings["YourConnectionString"].ConnectionString;
SqlConnection con = new SqlConnection(strconn);
con.Open();
string cmdText = "Select productId,Filename from Images"
SqlCommand cmd = new SqlCommand(cmdText, con);
cmd.CommandType = CommandType.Text;
DataTable dt = new DataTable();
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dt);
GridView1.DataSource = dt;
GridView1.DataBind();

for (int i = 0; i < dt.Rows.Count; i++)
{
GridView1.Rows[i].Cells[0].Text = dt.Rows[i]["ProductId"].ToString();
GridView1.Rows[i].Cells[2].Text = dt.Rows[i]["Filename"].ToString();
Image PImage = (Image)GridView1.Rows[i].FindControl("Image1");
PImage.ImageUrl = ConfigurationManager.AppSettings["IMG"].ToString() + dt.Rows[i]["FileName"].ToString();
}
con.Close();
}

Though this method will be slow if you want to populate huge amount of data, it is quite effective. Now here in the first line, i am taking the connection string from the web.config.The next few steps are self explanatory as you can see.You may be wondering why i have binded the Grid and after that i am populating it again. That is because, when the for loop runs, if the GridView is not binded, the Index was out of range index error will be shown.
Now in the for loop, the first cell, which contains the bound field, text is set to the ImageId. The second line in the loop, we are finding the image control we had added before as the template field in the GridView.”Image1″ is the ID of the Image Control.Now all that is remaining is setting the ImageUrl property of the found image control. Before that we prepend the FileName with the directory path.

Hope this helps.As i said, this method may be slow if you have many images to be populated.

Suppose we have Data in the Table named Category as follows

Now to bind this to the tree,we will use a recursive function.Also for better performance,we will bind the database results into a global DataTable first and then apply filtering.

Here is the Code to bind to the DataTable.

 private void bindDataTable()
    {
       
        string strConn = ConfigurationManager.ConnectionStrings["yourConnectionName"].ConnectionString;
        SqlConnection conn = new SqlConnection(strConn);
        SqlCommand cmd = new SqlCommand("Select * from Category", conn);
        cmd.CommandType = CommandType.Text;
       
        SqlDataAdapter sqlDa = new SqlDataAdapter();
        sqlDa.SelectCommand = cmd;
        sqlDa.Fill(dt);
        conn.Close();

    }

Now we will add a recursive method that will make use of this DataTable to build the TreeView.

private void buildNodes(TreeNode n, int? categoryId)
    {
        DataRow[] drCategories;
        if (categoryId == null)
            drCategories = dt.Select("NodeLevel=0"); // This will get the Root Node
        else
            drCategories = dt.Select("ParentIdFK='" + categoryId + "'");

        foreach (DataRow dr in drCategories)
        {
            TreeNode t = new TreeNode();
            t.Text = dr["CategoryName"].ToString();
            t.Value = dr["CategoryId"].ToString();    
           
            buildNodes(t, Convert.ToInt32(dr["CategoryId"].ToString()));// Calling the function resursively
            if (n == null)// If it is Root Node
                TreeView1.Nodes.Add(t);
            else
                n.ChildNodes.Add(t);

        }

Above we are using int? so that int type can accept null values.

So now all we have to do is call these methods.

  protected void Page_Load(object sender, EventArgs e)
     {
         if (!IsPostBack)
         {
              bindDataTable();
              buildNodes(null, null);//CategoryId=null is passed which is the ParentId of the Root Node
         }
     }

Now you can add some formatting and Css as you may please to get a better looking Treeview.Happy Coding Folks!!!

Response.Redirect("~/Default.aspx",false);

This error also happens when Server.Transfer method is called.Just use Server.Execute method instead.

Another new feature in the core services is the extensible Output Caching which allows you to configure one or more custom output-cache providers.These providers may be local or remote disks,cloud storages or distributed cache engines.This would mean that the caching ,which was making servers with heavy traffic inefficient, will not have to worry much about the memory.The .Net 4.0 comes with a new System.web.OutputProvider class which allows you to create custom output cache providers.

The new Auto-Start feature for Web applications provides a controlled approach to start an application pool,thus making the process of ‘waking-up’ the application for its first request much faster.

The RedirectPermanent helper class makes it easy to issue HTTP 301 moved Permanently responses,just reducing the number of HTTP round trips that was needed when Response.Redirect() method was used.

The storage of session states could sometimes take up large amount of memory for storing the serialized data..Net 4.0 introduces a new compression option which uses the System.IO.Compression.GZipStream  class.

These are some of the many new core services features available in the .Net 4.0.The web forms also has many new features like

The ability to set meta tags.
More control over view state.
Easier ways to work with browser capabilities.
Support for using ASP.NET routing with Web Forms.
More control over generated IDs.
The ability to persist selected rows in data controls.
More control over rendered HTML in the FormView and ListView controls.
Filtering support for data source controls.

For all the new features and explanation about them,visit asp.net

First Step: Open Visual Studio.Click on File and then select “New WebSite”.From the Next Window that appears,click ASP>NET Web Service.Select your language and then click OK.

By Default,VS 2008 will automatically create your first WebService “Hello World”.Notice that the Class inherits the System.Web.Services.WebService Class.

public class Service : System.Web.Services.WebService

Also,before the method “Hello World”,a [WebMethod] attributed has been specified.This basically tells the compiller to expose the method.

    [WebMethod]
    public string HelloWorld() {
        return "Hello World";
    }

Attaching the WebMethod attribute to the method indicates that you want to expose this method as part of the XML Web Service.To further configure the behavior of the method,we can make use of the properties in the WebMethod attribute.See the different properties of the WebMethod Attribute

 Now if you run the project,you will get the following.

Now if we select the HelloWorld method,ypu will get the next screen that allows you to invoke the method.On invoking the method,you will get the XML output of the method ‘HelloWorld’.

Now lets just create a more meaningful Method to be exposed and make use of the properties of the WebMethod attribute I am creating a Class named Product and i will output the Product Class object.Here is the Class

public class Product
{
 public Product()
 {
  //
  // TODO: Add constructor logic here
  //
 }  
    public string productName;
    public string productPrice;
}

Now the Web Service Method for getting ProductDetails.I have added the EnableSession and Description Properties to the WebMethod attribute.

[WebMethod(EnableSession=true,Description="Gets the Product Details")]
    public Product getProductDetails()
    {
        Product p = new Product();
        p.productName = "xxx";
        p.productPrice = "$12.00";
        return p;
    }

The Output on invoking this method will be

Now suppose you want to change the display Xml node to something other than productName and productPrice.For that use the System.Xml.Serialization namespace and do the following.

public class Product
{
 public Product()
 {
  //
  // TODO: Add constructor logic here
  //
 }
    [XmlElement(ElementName="Name")]
    public string productName;
    [XmlElement(ElementName="Price")]
    public string productPrice;
}

Now,instead of showing the node name as productName and productPrice,it will be shown as Name and Price.

Like this there are many Classes in the Xml.Serialization namespace that can be used to enhance the output of your Webservice.

Now having created the WebService,lets build a simple client application that uses this WebService.The easiest way is to add a Web Reference to your project.So create a new WebSite or any application.Right click the Solution Explorer and select Add Web Reference. Now on the next dialog box,you will be asked to provide the URL of the WebService.Provide that and also give a name for the reference.Suppose you name ws.3 files will be created.A discoveryfile disco,discovery map file .discoMap and a wsdl file.
Now to access the webservice you will have to create an object of the same.

ws.Service obj=new ws.Service();

To access the method getProductDetails(),create an object of Product and call the method,just like calling a simple method

ws.Product p=new ws.Product();
p=obj.getProductDetails();

That completes our first Tutorial to build a simple XML WebService using .Net.I will come up with more on Web Services in the future.Hope you will enjoy Web Service Programming.

What is WSDL?
WSDL stands for Web Services Description Language, an XML-based language that describes Web services and how to access and locate them.

What is UDDI?
UDDI stands for Universal Description, Discovery and Integration. It is an open, Internet-based specification that offers directory service for storing information about web services.

What are the protocols a .Net Web Service uses.
In .Net, a web service is bind with three different protocols such as HTTP/POST, HTTP/GET, and SOAP,allowing client with three options to choose for communication. These protocols are included in the WSDL file that is automatically generated in .NET.

There are two methods to store the connection string or any other value in the web.config file.Either you can add a key and value pair inside the <appSetting> element or make a custom section of your own in the web.config.To retrieve the values in the custom section defined,ASP.NET 2.0 provides you with the ConfigurationManager Class.

Let’s see both the methods of defining a connection string.
First in the <appSetting> element

<appSettings>
<add key="connectionString" value="connection string value" />
</appSettings>

Now to retrieve this,we can use the following code in the application

string strConn=ConfigurationSettings.AppSettings("connectionString");
SqlConnection conn=new SqlConnection(strconn);

Here the connection string is stored as key and value pair in the <appSettings> element of the web.config file.

Instead of using the <appSettings> section you can also add your own sections in the web.config file to have all your string value that you will be using in your application.
ASP.Net 2.0 provides with a special class for retrieving those customized string values. This class is called the ConfigurationManager class.

Now here we are using a custom section to store the connection string

Now to use the ConnectionStrings section of the web.config file, you can use code like

ConfigurationManager.ConnectionStrings["connection_name"].ConnectionString

The namespace to be added is System.Configuration

Here is another use of the class.

In the web.config,you add the following code,which gives an URL,which is used in many files and may change in the future.

<appSettings>
<add key="URL" value="http://www.three2tango.com/"/>
</appSettings>

Nowto use it  ,you can make use of the ConfigurationManager class

string URL=ConfigurationManager.AppSettings.Get("URL");

Here is the code to  convert a string in CSV format ot an integer array.

 
public int[] StringToArray(string input)
        {
            string[] stringList = input.Split(",".ToCharArray(),
                                              StringSplitOptions.RemoveEmptyEntries);
           
            int[] ids = new int[stringList.Length];

            for (int i = 0; i < stringList.Length; i++)
            {
                ids[i] = (int)Convert.ChangeType(stringList[i], typeof(int));
            }

            return ids;  
        }

 
Here instead of the “,” delimiter you can make use of the delimiter used in your format

Public Class Product()
{
public product(){ }
public string productName;
public float productPrice;
}

Now to create an XML representation of the object of class Product,we can make use of the XmlSerializer class in .Net.Here is the C# code for implementing serialization.

Product p=new Product();
p.productName="product1";
p.productPrice=12.00;
XmlSerializer serializer=new XmlSerializer(typeOf(Product));
StringWriter sw=new StringWriter();
serializer.Serialize(sw,p);
sw.Close(); 

 
Here is another example.In the below code,i have an object of class Product,which contains Product Information.when i run the webservice,i have to pass the ProductId(second line) to get the information and the webservice will automatically generate an XML file containing the details.Now what do we do if we have to save this information to another XML file so that we have the information even after the web service is stopped or in more technical terms we want the data to be persistent.

Namespace used: System.Xml.Serialization;      

Product productXml = new Product();
productXml = application.getProducts().getProductInfo(id);//build the product object
XmlSerializer serialize = new XmlSerializer(typeof(Product));
TextWriter tw = new StreamWriter(Server.MapPath("Products.xml"));
serialize.Serialize(tw, productXml);
tw.Close();

Dont forget to include System.IO,else you wont be able to use TextWriter and StreamWriter.