In early .NET versions if someone asked, can we implement caching in a Console Application, Windows Presentation Foundation Application and other .NET Applications other than ASP.NET application then people would laugh at this question but now with .NET 4.0 and above framework we can cache data in all types of .NET applications such as Console Applications, Windows Forms and Windows Presentation Application etc.

Let's see what is a new thing in the .NET 4.0 framework. They introduce a new library System.Runtime.Caching that implements caching for all types of .NET Applications.

Reference: http://msdn.microsoft.com/en-us/library/dd985642

Let's try to implement caching in a Console Application.

Step 1: First of all we will create a new Console Application. I have given it the name SystemRuntimeCachingSample40.

Step 2: Now we will try to add a System.Runtime.Caching assembly to our project but unfortunately you will not find that assembly because by default your target framework is .NET Framework 4 Client Profile.





You must change it from client profile to .NET famework 4.



Now you can find the assembly; see the following image:



Step 3: Now everything is set up.

This is the code for caching

static void Main(string[] args)
{  

    for (int i = 0; i < 2; i++)
    {
        ObjectCache cache = MemoryCache.Default;
        CacheItem fileContents = cache.GetCacheItem("filecontents");
        if (fileContents == null)
        {
            CacheItemPolicy policy = new CacheItemPolicy();
            List<string> filePaths = new List<string>();
            string cachedFilePath =
@"C:\Users\amitpat\Documents\cacheText.txt";
            filePaths.Add(cachedFilePath);
            policy.ChangeMonitors.Add(new HostFileChangeMonitor(filePaths));
            string fileData = File.ReadAllText(cachedFilePath);
            fileContents = new CacheItem("filecontents", fileData);
            cache.Set(fileContents, policy);
       }
         Console.WriteLine(fileContents.Value as string);
     }
    Console.Read();
}

When you run your application you will see that for the second time it will not go into the IF block.

Happy Coding.

In an effort to start blogging more about the "helpful" items that I have encountered over the years this is one of my first "Quick Tips" related to improving the life of the developer. We all have had those times where we are tracking down a complex problem within an application and all along the way we have to spend endless time mousing over individual classes to find out what their values are when most commonly we just want to know about one or two key values. Well in this post, I'll show you a neat trick using the "DebuggerDisplay" attribute to help make this process easier.

The Code

To get us started I'm going to just dive into the code, consider the following super condensed code sample.

   1:  static void Main(string[] args)
   2:  {
   3:      var badSampleInstance = new BadSample()
   4:                              { Name = "John Smith",
   5:                                  Address = "123 Main Street",
   6:                                  Phone = "515-555-1212" };
   7:      var goodSampleInstance = new GoodSample()
   8:                              { Name = "John Smith",
   9:                                  Address = "123 Main Street",
  10:                                  Phone = "515-555-1212" };
  11:      Console.ReadLine();
  12:  }
  13:   
  14:  public class BadSample
  15:  {
  16:      public string Name { get; set; }
  17:      public string Address { get; set; }
  18:      public string Phone { get; set; }
  19:  }
  20:   
  21:  [DebuggerDisplay("{Name} ({Phone})")]
  22:  public class GoodSample
  23:  {
  24:      public string Name { get; set; }
  25:      public string Address { get; set; }
  26:      public string Phone { get; set; }
  27:  }

From here we can see a very simple set of code with two classes. If you notice I have added an attribute "DebuggerDisplay" to the top of the GoodSample class. The value used for the display contains a few substitutions "{Name}" and "{Phone}". What this does is update all of the display areas in the debugger, that would typically show the type name for the value which isn't helpful to show the formatted value we supplied. An example of this can be seen here.



So as you can see this can help to get a good glance into your custom objects, and reduce a lot of the "mouseover" action that is common while debugging.

I hope that this content was helpful.

This article Illustrate How to read mails from ASP.Net. Using POP commands you can access you email inbox from ASP.Net. Basic POP commands are USER, PASS, LIST, QUIT, RETR.
More details POP command help you can check these links

//Creating Object for POPHelper
//Parameters are Gmail,Yahoo or MSN Pop Server,
//Port number
//bool isSSL
POPHelper objPopHelper = new POPHelper("pop.gmail.com", 995, true);
objPopHelper.UserName = "Your Gmail Username eg:[email protected]";
objPopHelper.Password = "GmailPassword";
objPopHelper.Connect();
GridView1.DataSource = p.DataSource;
GridView1.DataBind();



Code Of Connect Method

public void Connect()
        {
            string response = string.Empty;
            ArrayList arrList = new ArrayList();
            try
            {
                //Connect to Host server
                #region Connect Host
                TcpClient _tcpClient = new TcpClient();
                try
                {
                    _tcpClient.Connect(_hostname, _port);
                    //if login is ssl
                    if (_isSsl)
                    {
                        _stream = new SslStream(_tcpClient.GetStream());
                        ((SslStream)_stream).AuthenticateAsClient(_hostname);
                    }
                    else
                    {
                        _stream = _tcpClient.GetStream();
                    }
                }
                catch (Exception ex)
                {
                    throw new POPCommandException("Connection to " + _hostname + " Port: " + _port + " failed. Error Details"+ex.Message);
                }
                #endregion
                // Send POP Commands (USER, PASS, LIST) to Host
                #region POP Commands
                _streamWriter = new StreamWriter(_stream, Encoding.ASCII);
                _streamReader = new StreamReader(_stream, Encoding.ASCII);

                //POP command for send Username
                _streamWriter.WriteLine(POPCommands.USER.ToString()+" "+ UserName);
                //send to server
                _streamWriter.Flush();

                //POP command for send  Password
                _streamWriter.WriteLine(POPCommands.PASS.ToString() + " " + Password);
                //send to server
                _streamWriter.Flush();

                //POP command for List mails
                _streamWriter.WriteLine(POPCommands.LIST.ToString());
                //send to server
                _streamWriter.Flush();
                #endregion
                //Read Response Stream from Host
                #region Read Response Srteam
                //Read Response Stream
                response = null;
                string resText = string.Empty;
                while ((resText = _streamReader.ReadLine()) != null)
                {
                    if (resText == ".")
                    { break; }
                    if (resText.IndexOf("-ERR") != -1)
                    { break; }
                    response += resText;
                    arrList.Add(resText);
                }
                #endregion
                //Binding Properties
                #region Bindings
                //Bind Message count
                BindMailCount(arrList);
                //mails returns List
                _mail = ReadMail(messagecount);
                //get  mails Subjects returns List
                _mailsub = FilterContent(_mail,FiltersOption.Subject);
                _from = FilterContent(_mail, FiltersOption.From);
                _to = FilterContent(_mail, FiltersOption.To);
                SetDataSource(_mailsub, _from);
                #endregion
            }
            catch (Exception ex)
            {
                errors.Add(ex.Message);
            }
        }

Class Diagram of POPHelper



Reading Mails Using POP Command RETR from ASP.NET

private List ReadMail(int Count)
        {
            List lst = new List();
            try
            {
                for (int i = 1; i <= Count; i++)
                {
                    _streamWriter.WriteLine(POPCommands.RETR+" " + i.ToString());
                    _streamWriter.Flush();
                    string resText = string.Empty;
                    while ((resText = _streamReader.ReadLine()) != null)
                    {
                        if (resText == ".")
                        { break; }
                        if (resText.IndexOf("-ERR") != -1)
                        { break; }
                        lst.Add(resText);
                    }
                }               

            }
            catch(Exception ex)
            {
                errors.Add(ex.Message);
            }
            return lst;
        }

Enumerates for Filer message subject and From Address and ToAddress



Method for Filer Content

private List FilterContent(List Mails,FiltersOption filter)
        {
            List filterItems = new List();
            try
            {
                for (int i = 0; i < Mails.Count; i++)
                {
                    if (Mails[i].StartsWith(filter.ToString() + ":"))
                    {
                        string sub = Mails[i].Replace(filter.ToString() + ":", "");
                        filterItems.Add(sub);
                    }
                }
            }
            catch (Exception ex)
            {
                errors.Add(ex.Message);
            }
            return filterItems;
        }

Creating DataSource for GridView

private DataTable SetDataSource(Listsubject,Listsender)
        {
            int messageCount = messagecount;
            dataTab = new DataTable();
            DataRow drow;
            DataColumn Sender = new DataColumn("Sender", typeof(string));
            DataColumn Subject = new DataColumn("Subject", typeof(string));
            dataTab.Columns.Add(Sender);
            dataTab.Columns.Add(Subject);
            for (int i = 0; i < subject.Count; i++)
            {
                drow = dataTab.NewRow();
                dataTab.Rows.Add(drow);
                dataTab.Rows[i][Sender] = sender[i].ToString();
                dataTab.Rows[i][Subject] = subject[i].ToString();
            }
            return dataTab;
        }

In this article I will explain how to read or write connection strings in web.config file using asp.net.

I have one web application that contains many pages and each page contains relationship with database connection to get data from database and display it on page because of that I need to write database connections for each page to interact with database. Now the server name or credentials of database server has changed in that situation it will create problem because we need to modify the database connections of each page using asp.net.

To avoid this situation it would be better if we place connection string in one place and reuse it in every page wherever we need to connect to SQL Server. Web.config is the best place to store the connection strings in asp.net and it would be safer place to store the connection strings instead of writing connection strings in every web page.

Now we want to add connection string in web.config file for that first create new website using visual studio after that create new website open web.config file and search for “connectionStrings” and add new item in connectionStrings section

After open web.config file in application and add sample db connection in connectionStrings section like this

< connectionStrings>
< add name="yourconnectinstringName" connectionString="Data Source= DatabaseServerName; Integrated Security=true;Initial Catalog= YourDatabaseName; uid=YourUserName; Password=yourpassword; "
providerName="System.Data.SqlClient"/>
</ connectionStrings >

Example of declaring connectionStrings in web.config file like this

< connectionStrings>
< add name="dbconnection" connectionString="Data Source=Scott;Integrated Security=true;Initial Catalog=MySampleDB" providerName="System.Data.SqlClient"/>
</ connectionStrings >

Here to access my database server there is no need of username and password for that reason I didn’t enter username and password in connection string.

After add dbconnection in connectionString we need to write the some code in our codebehind file to get connection string from web.config file for that add following namespace in codebehind file and write the following code

using System.Configuration;

This namespace is used to get configuration section details from web.config file.

After add namespaces write the following code in code behind

C# code

using System;
using System.Data.SqlClient;
using System.Configuration;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
//Get connection string from web.config file
string strcon = ConfigurationManager.ConnectionStrings["dbconnection"].ConnectionString;
//create new sqlconnection and connection to database by using connection string from web.config file
SqlConnection con = new SqlConnection(strcon);
con.Open();
}
}

VB.NET

Imports System.Data.SqlClient
Imports System.Configuration
Partial Public Class _Default
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
'Get connection string from web.config file
Dim strcon As String =
ConfigurationManager.ConnectionStrings("dbconnection").ConnectionString
'create new sqlconnection and connection to database by using connection string from web.config file
Dim con As New SqlConnection(strcon)
con.Open()
End Sub
End Class

OK, finish.

The above error message indicate that you haven’t configured your ASP.NET 4 on your IIS. To configure IIS7.0 to use ASP.NET 4, please follow this steps:

- Open command prompt under Administrative privileges.
- Navigate to this location C:\Windows\Microsoft.NET\Framework\v4.0.30319.
- Locate aspnet_regiis.exe file.
- Run the utility with –i switch to register ASP.NET 4.0 with IIS7



And you can see it will work now.

You may receive the following error message while browsing an asp.net application

"Server Error in '/application name' Application
--------------------------------------------------------------------------------

Runtime Error
Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.

Details: To enable the details of this specific error message to be viewable on remote machines, please create a tag within a "web.config" configuration file located in the root directory of the current web application. This tag should then have its "mode" attribute set to "Off". "

This error might occur due to two scenarios.

1. There is an error in the application's logic with the inputformat, Type etc., and you have set the Custom Error Mode in the web.config to "On" and not specified a default redirect error page.

2. The web.config file is not well formed or having invalid characters and the application is not able to pick up the settings from the same.

Solution

1. Set the custom error mode to "Off" to view the error. After rectifying it and before deployment, change it to "On" and specify a default error page, as follows:-

<customErrors defaultRedirect="ErrorPage.aspx" mode="On">
</customErrors>

such that your users will not be able to see the actual error and get your friendly error page where you can politely say "An error has occured! Sorry for the inconvenience ..." .

2. If the above solution is not working (i.e. even after setting the custom error mode to On, the same "Server Error" occurs, then the likely chance is that your web.config file is not well formed and has invalid characters etc.,

To resolve, it copy paste the contents of the file to a notepad, save it as an xml file and try to browse the xml file in the browser. If the xml file is unable to be rendered by the browser and throws error, then you can find the place where the tags are not well formed or invalid character(s) exist and rectify them.

Things worth noting is Web.config is case sensitive and even trailing / leading spaces can cause the above error.

This article applies to .NET - ASP.NET 1.0, 1.1 Versions. Hope it help

Sometime when you try to setup a application for your website on IIS7 you get following error when you load your website.



This happens when ASP.NET modules and handlers should be specified in the IIS and configuration sections in Integrated mode. This problem can be fixed using following workaround

1) Change application configuration: First way to fix this issue is to migrate the application configuration to work properly in Integrated mode. You can use “ AppCmd“ command to migrate the application configuration:

%windir%/system32/inetsrv/>Appcmd migrate config “<AppPath>

Where “ <AppPath>“ is the virtual path of the application, such as “Default Web Site/virtualapp1“.

2) Modify web.config: You have to manually move the customer entries in the <system.web>/<httpModules> and configuration to the <system.web>/<httpHandlers><system.webServer>/<handlers> and <system.webServer>/<modules> configuration sections, and either remove the <httpHandlers> and <httpModules> configuration OR add the following to your application’s or websites web.config:

<system.webServer>
<validation validateIntegratedModeConfiguration=”false”/>
</system.webServer>

3) Switch to Classic ASP.NET: Switch the website or application to an application pool that is configured to run in Classic ASP.NET mode. To move back to classic mode go to IIS7 Manager >> Select the site (which you want to switch) >> edit settings and you will get following screen



Press “ Select” button which will open a window “Select Application Pool” (check below image); Select “Classic .NET AppPool” from the drop-down and press OK.



Now try to Access your website/application.

This article is continuation of ASP.NET AJAX 4.0 Template Programming Part 1. In this part, I explain the different data binding options in ASP.NET AJAX 4.0 templates. Just a recap that I've consumed an ADO.NET data services to fetch AdventureWorks's Product table records. In this article, I explain how to update/add new record from client side.

Bindings

Template supports the following bindings:

- One-time - The expression is evaluated only once when the template rendering happen
- One-way Live Binding - The expression is evaluated and update the value, if items in the data source changed
- Two-way Live Binding - If the data source value changed, the value in the expression updated. And if the value in the expression is updated, it will update data source also.

The below diagram depicts the binding.



In the above diagram, the red dashed arrow shows one-time data binding. Once the data from data source has been fetched by DataView using AdoNetDataContext. The one-way live binding has been shown as purple shadowed arrow. The purpose shadow here is whenever a data updated at data source, it is being updated to data view through AdoNetDataContext. The two-way live binding has been shown as green shadowed two-head arrow. In this case, data context should have the knowledge about update operation on data source and provide an interface to data view to send the modified values.

The these three bindings, ASP.NET AJAX provides the following expression convention:

- {{ }} - One-time (can be used on any HTML controls for example <p>{{ Name }}</p>)
- { binding } - One-way if other than user input HTML controls for example <td>{ binding Name } </td>
- {binding } - Two-way if INPUT HTML controls for example <input type="text" sys:value="{{ binding Name }}" />

Here, the input controls binds the values using sys:value attribute for two-way binding. Before going into the updatable data source, let us see how can we design master-detail layout to display Product name and Product details.

Master-Detail Layout

<body xmlns:sys="javascript:Sys"
xmlns:dataview="javascript:Sys.UI.DataView"
sys:activate="*">
  <form id="form1" runat="server">
  <div>
      <!--Master View-->
      <ul sys:attach="dataview" class=" sys-template"
          dataview:autofetch="true"
          dataview:dataprovider="{{ dataContext }}"
          dataview:fetchoperation="Products"
          dataview:selecteditemclass="myselected"            
          dataview:fetchparameters="{{ {$top:'5'} }}"
          dataview:sys-key="master"            
      >
          <li sys:command="Select">{binding Name }</li>
      </ul>

      <!--Detail View-->
      <div class="sys-template"
          sys:attach="dataview"
          dataview:autofetch="true"
          dataview:data="{binding selectedData, source={{master}} }">
          <fieldset>
            <legend>{binding Name}</legend>
            <label for="detailsListPrice">List Price:</label>
            <input type="text" id="detailsListPrice"
                sys:value="{binding ListPrice}" />
            <br />
            <label for="detailsWeight">Weight:</label>
            <input type="text" id="detailsWeight" sys:value="{binding Weight}" />
            <br />              
          </fieldset>
          <button onclick="dataContext.saveChanges()">Save Changes</button>
      </div>
  </div>
  </form>
</body>

Selectable And Editable

An unordered list shows the master details, here the product name (line 15). This line also indicates that the list item is selectable using sys:command="Select". For maintaining master-detail or selectable item, primary key needs to be specified. The sys-key property of data view refers that primary key. In this example, I call the primary key as "master" (line 13). Also, you can see that I've passed a filter option using fetchparameter property of data view (line 12). In this example, I request the ADO.NET data service to give only top five records using its filter syntax.

Whenever an item in the master list is selected, the details view needs to be notified. The widget for the details view and binding details should be identified using regular sys:attach="dataview" and dataview's data property. In this example, dataview:data="{binding selectedData, source={{master}} }" specifies that binding with data view with sys-key name "master". The fieldset is used to show set of values for a product. Here, the list price and weight can be editable.

Once an item has been edited, this needs to be notified to the data source through data context. The button with caption "Save Changes" specifies that whenver this button is clicked, save the items in the details view into data source through data context's saveChanges() method. The corresponding data source's update option should be set on data context's set_saveOperation(). The following JavaScript code explains this.

var dataContext = new Sys.Data.AdoNetDataContext();
dataContext.set_serviceUri("AWProductDataService.svc");
dataContext.set_saveOperation("Products(master)");
dataContext.initialize();

The ADO.NET Product data service's Products(id) method is used on set_saveOperation. An item can be updated, when Product service of ADO.NET data service is being invoked with product primary key as argument. Here, again I'm referring master layout's "master" sys-key as primary key of Product.

The output of the above code is



The top one is master view where Sport-100 Helmet, Red is selected and the details has been shown in the bottom page. You can edit and update the data source.

The selecteditemclass property of data view is used to show the selected item in different style.

.myselected  {
        color: white;
        font-weight: bold;
        background-color: Silver;
      }

For those of you who just upgraded your site to the latest ASP.NET 4.0 Framework, you may sometimes see this error message: “A potentially dangerous Request.QueryString value was detected from the client”.

The request validation feature in ASP.NET provides a certain level of default protection against cross-site scripting (XSS) attacks. In previous versions of ASP.NET, request validation was enabled by default. However, it applied only to ASP.NET and only when those pages were executing.

In ASP.NET 4, by default, request validation is enabled for all requests, because it is enabled before the BeginRequest phase of an HTTP request. As a result, request validation applies to requests for all ASP.NET resources, not just .aspx page requests. This includes requests such as Web service calls and custom HTTP handlers. Request validation is also active when custom HTTP modules are reading the contents of an HTTP request.

As a result, request validation errors might now occur for requests that previously did not trigger errors. To revert to the behavior of the ASP.NET 2.0 request validation feature, add the following setting in the Web.Config  file:

<httpRuntime requestValidationMode="2.0" />

However, we recommend that you analyze any request validation errors to determine whether existing handlers, modules, or other custom code accesses potentially unsafe HTTP inputs that could be XSS attack vectors.

If you have problem with this upgrade, you can host your site with us. We are the premier European hosting that support ASP.NET 4 hosting with only €3.00/month. If you don’t like our service, you can just cancel your account.

By default the client-side validation is triggered when submitting forms using buttons. However, sometimes you may want to trigger client-side validation on your ASP page manually from custom Javascript. You can achieve that by calling Javascript validation functions provided by the ASP.Net framework directly from your custom code.

The following page source example displays a TextBox and its validation controls (RequiredFieldValidator & ValidationSummary). The validation controls have the same ValidationGroup defined, which allows us to validate different page elements independently. The page displays also a DIV element that will cause the Validation action when clicked:

<!-- Validation Summary -->
<asp:ValidationSummary ID="ValidationSummary1" runat="server"
            HeaderText="Validation errors:" ValidationGroup="Group1"/> 

<!-- TextBox and its validator -->
Name: <asp:TextBox ID="TextBox1" runat="server" />
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server"
            ErrorMessage="Name is required" Text="*"
            ControlToValidate="TextBox1" ValidationGroup="Group1"> /> 

<!-- Div that causes client-side validation when clicked -->
<div onclick="Validate();" >Validate Form</div>

The code above should should produce smth like that when validation is triggered:



Now let's take a look at the custom JS code that triggers the validation. There are couple ways to do that:

- Easy way - works for all validators from the same ValidationGroup:

function Validate()
{
    // If no group name provided the whole page gets validated
    Page_ClientValidate('Group1');
}

- If you want to validate only specific validators:

function Validate()
{
    // Get the specific validator element
    var validator = document.getElementById('RequiredFieldValidator1');

     // Validate chosen validator
    ValidatorValidate(validator);

    // Update validation summary for chosen validation group
    ValidatorUpdateIsValid();
    ValidationSummaryOnSubmit(validationGroup);
}