Advanced Computer Programming : February 2014

Tuesday, February 25, 2014

In Memory Search using Lamda Expression: Realtime Chat application on web in ASP.Net: Step 4

Welcome at Realtime Chat application on web in ASP.Net using SignalR technology. This is step 4 and now we will learn how we can search in memory array without any loop like for, while etc. We will use Lamda expression to search an element in array list with generics. I shall not describe about these technologies from theoretical perspective, here I shall show some application of these. You can read theory of these things from MSDN site.

You may think why this is require for our chat application, really good question. We shall use this technique to find an online user in server. However we can take database help to find online users but to minimize database operation I have used this technique. In chat application I have used a public static list (array) to hold online users, and from here I am searching users to generate online friend lists. By that way I have minimize a lot database operation and this technique can improve your chat application.

Lets check the code first then shall describe the codes.

HTML/ASP.Net part

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <h1>In memory search using Lamda Expression in C#.Net</h1>
        <h3>Search country calling code</h3>
        <p>
            Country Name:
            <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
 <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Find Calling Code" />
        </p>
        <p>
            <asp:Label ID="Label1" runat="server" Text=""></asp:Label>
        </p>
        <a href="http://en.wikipedia.org/wiki/List_of_country_calling_codes" target="_blank">Full list is available here</a>
    </form>
</body>
</html>

and the C# code as below:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{

    protected void Page_Load(object sender, EventArgs e)
    {
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        FindCallingCode();
    }
    private void FindCallingCode()
    {
        //In real use databind before searching, using by that way as demo
        List<Country> countries = new List<Country>();
        countries.Add(new Country { callingCode = "+91", name = "India" });
        countries.Add(new Country { callingCode = "+44", name = "UK" });
        countries.Add(new Country { callingCode = "+1", name = "USA" });
        countries.Add(new Country { callingCode = "+88", name = "Bangladesh" });
        countries.Add(new Country { callingCode = "+49", name = "Germany" });
        countries.Add(new Country { callingCode = "+33", name = "France" });
        countries.Add(new Country { callingCode = "+55", name = "Brazil" });

        Country country = countries.FirstOrDefault(x => x.name.ToLower() == TextBox1.Text.Trim().ToLower());
        if (country != null)
            Label1.Text = "Calling code of " + country.name + " is " + country.callingCode;
        else
            Label1.Text = TextBox1.Text + " Not Found in our Country List";
    }
}
public class Country {
    public string callingCode { get; set; }
    public string name { get; set; }
}

Here is main method is "FindCallingCode()" and class "Country". Here I am doing all operations. Lets look at some important code.

Country class: This class I have defined to create country objects which will store country name and calling code. If you need extra properties you can add these easily.

List<Country> countries = new List<Country>();

In the above code I have defined a list (array) of county objects with name countries. Naming convention using as this variable holding multiple country hence its plural name of country.

countries.Add(new Country { callingCode = "+91", name = "India" });

In the above line of code I have adding element of array by creating country class object.

Country country = countries.FirstOrDefault(x => x.name.ToLower() == TextBox1.Text.Trim().ToLower());

This is actually Lamda expression "x=>x.name" this is doing searching operation with method "FirstOrDefault". This line searching all element and doing comparison with user entered country name and stored country name. When matched it will return the country object.

Label1.Text = "Calling code of " + country.name + " is " + country.callingCode;

In previous line of code we have found country object from array of countries and now getting calling code and name from the found object.

In my chat application I have used mainly this (FirstOrDefault) method and for some cases have used "Count", "Find" methods/properties. "Find" and "FirstOrDefault" both can do a bit similar work but "Find" is very fast (in a blog I found 1000 times) than "FirstOrDefault", hence I am using as and when these are suitable.
For your knowledge you can check other methods as well.

Thanks for reading my blog please visit again for next article.

Source code is available here.

Thursday, February 20, 2014

Send client message to server using SignalR method - Realtime Chat application on web in ASP.Net: Step 3

This will be my 3rd post on SignalR technology. In previous post I shown how to get server time using SignalR client method, which will be called from server side. Now I shall show how to transfer data between server and client.

This is very simple solution and it can do as same way as normal .Net method calling with parameter.

I am not explaining these code again as I did it last time.

Startup.cs

using Microsoft.Owin;
using Owin;
[assembly: OwinStartup(typeof(SignalRChat.Startup))]
namespace SignalRChat
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            // Any connection or hub wire up and configuration should go here
            app.MapSignalR();
        }
    }
}

ChatHub.cs file code:

using System;
using System.Web;
using Microsoft.AspNet.SignalR;
namespace SignalRChat
{
    public class ChatHub : Hub
    {
        /// <summary>
        /// getservertime
        /// </summary>
        public void getservertime()
        {
            Clients.Caller.serverresponse("This is server response. Server is calling client method from server. <br/> Server time is: " + DateTime.Now.ToShortTimeString());
        }

        public void sendmessage(string usermessage)
        {
            Clients.Caller.serverresponse(usermessage + " :This is server message <br/>");
        }
    }
}

In this code I have added new method "sendmessage(parameter1)" and it will call same client method to return data to client. This is very simple code.

Next will come HTML part, which is as below:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">

    <title>SignalR Simple Chat</title>
    <style type="text/css">
        .container {
            background-color: #99CCFF;
            border: thick solid #808080;
            padding: 20px;
            margin: 20px;
        }
    </style>
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />

    
    <script src="Scripts/json2.js"></script>
    <script src="Scripts/jquery-1.10.2.js"></script>
    <script src="Scripts/jquery-1.10.2.min.js"></script>

    
    <script src="Scripts/jquery.signalR-2.0.0.js"></script>
    <script src="Scripts/jquery.signalR-2.0.0.min.js"></script>

    
    <script src="/signalr/hubs"></script>
    

    <script type="text/javascript">
$(function () {
    // Declare a proxy to reference the hub.
    var chat = $.connection.chatHub;

    //Write your server response related code here
    chat.client.serverresponse = function (message) {
        $('#dvServerResponse').append(message);
    };

    // Start the connection.
    $.connection.hub.start().done(function () {
        //Write your server invoke related code here
        $('#btnHello').click(function () {
            console.log('call server');
            chat.server.sendmessage($('#txt').val());
        });
    });
});
    </script>

</head>
<body>
    <form id="form1" runat="server">
    <div>
<div>
    Enter your message: <input type="text" id="txt" /><br />
    <input type="button" id="btnHello" value="Send message to server" />

    <div id="dvServerResponse"></div>

</div>
    </div>
    </form>
</body>
</html>

When you will run this in browser it will show as below:

Hope you have enjoyed this post and please visit my blog again.

Next will show something about Lamda Expression which I shall use in my chat application.

Wednesday, February 19, 2014

Get Server time - Realtime Chat application on web in ASP.Net using SignalR Technology: Step 2

In previous post I have describe how to set up your project for SignalR with require software. Now I shall show to get server time and how can invoke a server method as request and how can get response with server time by calling client javascript method from server end.
Again here will be these main part of coding and here I am not changing anything in Startup.cs file. This code as it is.

using Microsoft.Owin;
using Owin;
[assembly: OwinStartup(typeof(SignalRChat.Startup))]
namespace SignalRChat
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            // Any connection or hub wire up and configuration should go here
            app.MapSignalR();
        }
    }
}

Next is ChatHub.cs and here is very small code as below:

using System;
using System.Web;
using Microsoft.AspNet.SignalR;
namespace SignalRChat
{
    public class ChatHub : Hub
    {
        public void getservertime()        {
            Clients.Caller.serverresponse("This is server response. Server is calling client method from server.
Server time is: " + DateTime.Now.ToShortTimeString());
        }
    }
}

Here I have added on public method "getservertime()". Note here I have written all method in small letters and shall call this from client javascript in small letters only. Previously I have tested by writing in capital letters and have seen this is not working. So I would suggest to write these methods always in small letters only, to avoid difficulties.

"getservertime()" is very small method which will invoked by client on button press and this method will invoke a client's javascript method to send response to client. Note here I am writting 'Clients.Caller' to find out the client from where server method has invoked. If I need to call any different client's method (usually for chat application one user will send method to other, so one client will invoke server method and server method will call other client's client method. These things I shall show later) then there will be some different way, which I shall explain later. After 'Client.Caller' method name is coming that is "serverresponse()". This client method is passing argument and this will deliver server message to client.

Next I shall explain about client code and these all are HTML and Javascript only.

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">

    <title>SignalR Simple Chat</title>
    <style type="text/css">
        .container {
            background-color: #99CCFF;
            border: thick solid #808080;
            padding: 20px;
            margin: 20px;
        }
    </style>
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />

    
    <script src="Scripts/json2.js"></script>
    <script src="Scripts/jquery-1.10.2.js"></script>
    <script src="Scripts/jquery-1.10.2.min.js"></script>

    
    <script src="Scripts/jquery.signalR-2.0.0.js"></script>
    <script src="Scripts/jquery.signalR-2.0.0.min.js"></script>

    
    <script src="/signalr/hubs"></script>
    

    <script type="text/javascript">
$(function () {
    // Declare a proxy to reference the hub.
    var chat = $.connection.chatHub;

    //Write your server response related code here
    chat.client.serverresponse = function (message) {
        $('#dvServerResponse').append(message);
    };

    // Start the connection.
    $.connection.hub.start().done(function () {
        //Write your server invoke related code here
        $('#btnHello').click(function () {
            console.log('call server');
            chat.server.getservertime();
        });
    });
});
    </script>

</head>
<body>
    <form id="form1" runat="server">
    <div>
<div>
    <div id="dvServerResponse"></div>
    <input type="button" id="btnHello" value="Get Server Time" />
</div>
    </div>
    </form>
</body>
</html>

These HTML and Javascript code I have written in ASP.Net file however this will work in normal HTML file as well.
Initial part is javascript library file referencing section. Here I am calling files in three steps, first JSON and JQeury files, next SignalR library and finally Hub files. Next starting custom java script codes.

In java script code firstly I have created a proxy of chatHub. Next code is

//Write your server response related code here

    chat.client.serverresponse = function (message) {

        $('#dvServerResponse').append(message);

    };

For time being you can assume this is standard syntax of creating client methods which will be called from server and within this cal implement client activities. For my case I am appending server response at div.

Other part of client codes as below

//Write your server invoke related code here

$('#btnHello').click(function () {

console.log('call server');

chat.server.getservertime();

});

This method will start executing once btnHello clicked and it will invoke server method to get server response. Here to invoke server method syntax like "chat.server.getservertime()" or "proxy-object.server.server-method()".

Finally result will displayed in client browser.

Here is the full code.

Thanks for reading my blog.

Tuesday, February 18, 2014

SignalR - Hello World: Real time chat application on Web in ASP.Net using SignalR technology : Step 1

Programming
 with distributed technology is my passion. Earlier I have worked with 
Remoting, Socket, Web Service and a bit with WCF. So when I first came 
to know about SignalR technolog, really I can not wait to start coding 
on it. Now I can able to write own chat application for AlapMe
 and really its working fine. Most of all by using SignalR I can use 
socket of HTML5. I shall write multiple posts on SignalR as tutorial as I
 did in past with C# Socket programming. I shall publish these posts on 
this blog and on my socket programming blog as well.
I have started SignalR programming with Visual Studio Express 2013 which is freely downloadable from here.
 Also you can read full documentation from Microsoft from this link. As 
my target to share some practical example with ready to use code hence I
 shall not describe in detail about the technology. You can follow 
Microsoft documentation website for it. 
To start with SignalR first coding you need to follow steps are below.
Lunch
 your VS 2013 and create a blank project and add new item of SignalR Hub
 Class (v2) set its name as you wish, for my case its MyHub.cs. When you
 will add this class Visual Studio automatically add all related 
references and jquery classes. To add these things it may take some time
 may be 2-3 minutes. This new item will come with a sample method 
'Hello()', for now just follow these later I shall describe what is 
these things and why these are. Full code will look like below:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using Microsoft.AspNet.SignalR;

namespace SignalR_Learning

{

    public class MyHub : Hub

    {

        public void Hello()

        {

            Clients.All.hello();

        }

    }

}

Now
 go to next step and add next item in project, that is OWIN Startup 
class. I am giving its default name 'Startup1.cs' for my sample project.
 Visual Studio will create this file with some pre-added code. We will 
extend these code as per your needs. Code as below:

using System;

using System.Threading.Tasks;

using Microsoft.Owin;

using Owin;

[assembly: OwinStartup(typeof(SignalR_Learning.Startup1))]

namespace SignalR_Learning

{

    public class Startup1

    {

        public void Configuration(IAppBuilder app)

        {

            // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=316888

        }

    }

}

In method Configuration I shall add just a line of code 'app.MapSignalR();' so full method will look like:

public void Configuration(IAppBuilder app)

{

    // For more information on how to configure your application, visit      http://go.microsoft.com/fwlink/?LinkID=316888

    app.MapSignalR();

}

 Now
 we will move to front end coding and this part will develop with simple
 HTML page, however you can use ASPX page as well. Now I have added a 
HTML page with name 'index.html'

<! DOC TYPE ht ml >

< ht ml xmlns="http://www.w3.org/1999/xhtml" >

    SignalR Simple Chat

    "X-UA-Compatible" content="IE=edge" / >

     < sc ript src="Scripts/jquery-1.10.2.js">

    < sc ript src="Scripts/jquery-1.10.2.min.js">

    < scri pt src="Scripts/json2.js">

    "Scripts/jquery.signalR-2.0.0.js">

    "Scripts/jquery.signalR-2.0.0.min.js">

    "/signalr/hubs">

    "text/ ">

        var chat;

        $(f unction () {

            // Declare a proxy to reference the hub.

            //chat = $.hubConnection.myhub;

            chat = $.connection.myhub;

            //alert(chat);

            chat.client.hello = function (message) {

                alert(message);

            };

            // Start the connection.

            $.connection.hub.start().done(function () {

                $('#btnhello').click(function () {                    

                    alert(chat);

                });

            });

        });

    "button" value="Hello" id="btn hello" />

Saturday, February 1, 2014

Excel-VBA: Find Last Cell of Active WorkSheet

Hello here is the code

Public Function GetLastCellAddress() As String
    ' Variables
    Dim intCol As Integer
    Dim lngRow As Long
    Dim rUsedRange As Range
    Dim rCell As Range

    ' first unlock all cells
    Cells.Locked = False
    If WorksheetFunction.CountA(Cells) > 0 Then
        lngRow = Cells.Find(what:="*", After:=[A1], _
                            SearchOrder:=xlByRows, SearchDirection:=xlPrevious).Row
        intCol = Cells.Find(what:="*", After:=[A1], _
                            SearchOrder:=xlByColumns, SearchDirection:=xlPrevious).Column
        Set rUsedRange = ActiveSheet.Range("$A$1" & ":" & Cells(lngRow, intCol).Address)

        lngRow = Cells.Find(what:="*", After:=[A1], _
                            SearchOrder:=xlByRows, SearchDirection:=xlPrevious).Row
        intCol = Cells.Find(what:="*", After:=[A1], _
                            SearchOrder:=xlByColumns, SearchDirection:=xlPrevious).Column
        Set rUsedRange = ActiveSheet.Range("$A$1" & ":" & Cells(lngRow, intCol).Address)
        GetLastCellAddress = rUsedRange.Address
    End If
End Function