I made a exhaustive research and figured out that each Who is server maintains a list of certain domain types. For example,  Whois.net can whois only .COM, .NET and .ORG domains.

Many posts over the internet, including blogs.msdn.com,  also says that to query a who is database one should connect to the whois server through a TCP/IP conenction (usually via port 43).

All the above issues make Whois action fairly difficult to perform. Luckily, today I came across a very nice web site which provides a Whois SOAP web service.  To see the details of the service check this link:

http://www.webservicex.net/whois.asmx?op=GetWhoIS

This web service searches all the who is databases to look up the domain name you provide. Therefore, you will not need to search several who is databases.

To Whois a domain name, you should pass a 'hostname' parameter to the service:

http://www.webservicex.net/whois.asmx?Hostname=Microsoft.com

You can use this web service simply via a GET or a POST method as well as making a reference to it via Visual Studio and call its GetWhoIS metho. As I mentioned in the previous post (about REST web services), I prefer to get the who is answer using XElement.Load method. For example we may write the following method for whoising:

public static string WhoIs(string hostname)
{
XElement WhoisResult = XElement.Load(

"http://www.webservicex.net/whois.asmx/GetWhoIS?HostName=microsoft.com");
return WhoisResult.ToString();
}

Each Who is server returns a different response. Therefore, to develop a method which indicates wheather a domain name exits or not, we should look for a common string value in the WhoIS response. For example the 'NAME SERVER' seems to be a common string. There fore, a domain lookup function can be written this way:

public static bool IsDomainTaken(string hostname)
{
return WhoIs(hostname).ToUpper().Contains("NAME SERVER");
}

As I told you, this web service seems to query several WhoIS server, thus the GetWhoIS method is a little bit time consuming.

P.S. Try to Whois Microsoft.com, the result is pretty funny:

Whois Server Version 2.0

Domain names in the .com and .net domains can now be registered
with many different competing registrars. Go to http://www.internic.net
for detailed information.

MICROSOFT.COM.ZZZZZZ.MORE.DETAILS.AT.WWW.BEYONDWHOIS.COM
MICROSOFT.COM.ZZZZZ.GET.LAID.AT.WWW.SWINGINGCOMMUNITY.COM
MICROSOFT.COM.ZZZZZ.DOWNLOAD.MOVIE.ONLINE.ZML2.COM
MICROSOFT.COM.ZZZOMBIED.AND.HACKED.BY.WWW.WEB-HACK.COM
MICROSOFT.COM.ZZZ.IS.0WNED.AND.HAX0RED.BY.SUB7.NET
MICROSOFT.COM.WILL.LIVE.FOREVER.BECOUSE.UNIXSUCKS.COM
MICROSOFT.COM.WILL.BE.SLAPPED.IN.THE.FACE.BY.MY.BLUE.VEINED.SPANNER.NET
MICROSOFT.COM.WILL.BE.BEATEN.WITH.MY.SPANNER.NET
MICROSOFT.COM.WAREZ.AT.TOPLIST.GULLI.COM
MICROSOFT.COM.TOTALLY.SUCKS.S3U.NET
MICROSOFT.COM.SOFTWARE.IS.NOT.USED.AT.REG.RU
MICROSOFT.COM.SHOULD.GIVE.UP.BECAUSE.LINUXISGOD.COM
MICROSOFT.COM.RAWKZ.MUH.WERLD.MENTALFLOSS.CA
MICROSOFT.COM.OHMYGODITBURNS.COM
MICROSOFT.COM.MORE.INFO.AT.WWW.BEYONDWHOIS.COM
MICROSOFT.COM.LOVES.ME.KOSMAL.NET
MICROSOFT.COM.LIVES.AT.SHAUNEWING.COM
MICROSOFT.COM.IS.NOT.YEPPA.ORG
MICROSOFT.COM.IS.NOT.HOSTED.BY.ACTIVEDOMAINDNS.NET
MICROSOFT.COM.IS.IN.BED.WITH.CURTYV.COM
MICROSOFT.COM.IS.HOSTED.ON.PROFITHOSTING.NET
MICROSOFT.COM.IS.GOD.BECOUSE.UNIXSUCKS.COM
MICROSOFT.COM.IS.A.STEAMING.HEAP.OF.FUCKING-BULLSHIT.NET
MICROSOFT.COM.IS.A.MESS.TIMPORTER.CO.UK
MICROSOFT.COM.HAS.ITS.OWN.CRACKLAB.COM
MICROSOFT.COM.HAS.A.PRESENT.COMING.FROM.HUGHESMISSILES.COM
MICROSOFT.COM.FILLS.ME.WITH.BELLIGERENCE.NET
MICROSOFT.COM.CAN.GO.FUCK.ITSELF.AT.SECZY.COM


Bye for now.

web.config file is case sensative as like other xml files.

Following three sections are more important to web developers:

1. <appSettings> - All the custome/miscellaneous pieces of information can be set here.
2. <connectionSettings> - Holds the all connection information for accessing database.
3. <system.web> - Holds every ASP.Net setting that need to be configured for web application. For example it holds major sub sections like <customErrors>, <authorization> and <authentication> etc..

Generally every web server starts with some basic settings. These basic settings are typically stored in two files at following location: C:\Windows\Microsoft.NET\Framework\v####\Config

These two config files are namely machine.config and web.config and these files are locked and not open for editing purpose by any developer. We can override these settings using application level web.config file.

by: omar

Every time I create an IIS website, I do some steps, which I consider as best practice for creating any IIS website for better performance, maintainability, and scalability. Here' re the things I do:

Create a separate application pool for each web application

I always create separate app pool for each web app because I can select different schedule for app pool recycle. Some heavy traffic websites have long recycle schedule where low traffic websites have short recycle schedule to save memory. Moreover, I can choose different number of processes served by the app pool. Applications that are made for web garden mode can benefit from multiple process where applications that use in-process session, in memory cache needs to have single process serving the app pool. Hosting all my application under the DefaultAppPool does not give me the flexibility to control these per site.

The more app pool you create, the more ASP.NET threads you make available to your application. Each w3wp.exe has it's own thread pool. So, if some application is congesting particular w3wp.exe process, other applications can run happily on their separate w3wp.exe instance, running under separate app pool. Each app pool hosts its own w3wp.exe instance.

So, my rule of thumb: Always create new app pool for new web applications and name the app pool based on the site's domain name or some internal name that makes sense. For example, if you are creating a new website alzabir.com, name the app pool alzabir.com to easily identify it.

Another best practice: Disable the DefaultAppPool so that you don't mistakenly keep adding sites to DefaultAppPool.

First you create a new application pool. Then you create a new Website or Virtual Directory, go to Properties -> Home Directory tab -> Select the new app pool.

Customize Website properties for performance, scalability and maintainability

First you map the right host headers to your website. In order to do this, go to WebSite tab and click on "Advanced" button. Add mapping for both domain.com and www.domain.com. Most of the time, people forget to map the domain.com. Thus many visitors skip typing the www prefix and get no page served.

Next turn on some log entries:

These are very handy for analysis. If you want to measure your bandwidth consumption for specific sites, you need the Bytes Sent. If you want to measure the execution time of different pages and find out the slow running pages, you need Time Taken. If you want to measure unique and returning visitors, you need the Cookie. If you need to know who is sending you most traffic - search engines or some websites, you need the Referer. Once these entries are turned on, you can use variety of Log Analysis tools to do the analysis. For example, open source AWStats.

But if you are using Google Analytics or something else, you should have these turned off, especially the Cookie and Referer because they take quite some space on the log. If you are using ASP.NET Forms Authentication, the gigantic cookie coming with every request will produce gigabytes of logs per week if you have a medium traffic website.

This is kinda no brainer. I add Default.aspx as the default content page so that, when visitors hit the site without any .aspx page name, e.g. alzabir.com, they get the default.aspx served.

Things I do here:

• Turn on Content Expiration. This makes static files remain in browser cache for 30 days and browser serves the files from its own cache instead of hitting the server. As a result, when your users revisit, they don't download all the static files like images, javascripts, css files again and again. This one setting significantly improves your site's performance.
• Remove the X-Powered-By: ASP.NET header. You really don't need it unless you want to attach Visual Studio Remote Debugger to your IIS. Otherwise, it's just sending 21 bytes on every response.
• Add "From" header and set the server name. I do this on each webserver and specify different names on each box. It's handy to see from which servers requests are being served. When you are trying to troubleshoot load balancing issues, it comes handy to see if a particular server is sending requests.

I set the 404 handler to some ASPX so that I can show some custom error message. There's a 404.aspx which shows some nice friendly message and suggests some other pages that user can visit. However, another reason to use this custom mapping is to serve extensionless URL from IIS. Read this blog post for details.

Make sure to set ASP.NET 2.0 for your ASP.NET 2.0, 3.0 and 3.5 websites.

Finally, you must, I repeat you "MUST" turn on IIS 6.0 gzip compression. This turns on the Volkswagen V8 engine that is built into IIS to make your site

original  link from:

http://msmvps.com/blogs/omar/archive/2008/10/04/best-practices-for-creating-websites-in-iis-6-0.aspx?

There actually were lots of examples of doing this on the Internet, but it was challenging to find one that worked period or would work in multiple browsers! Finally, after doing extensive searches and tweaks, here is the final function I used to restrict a text box to only accept numbers:

Javascript Function

[sourcecode language='jscript']

// A function that only allows numbers to be typed into a text field.
function NumberValidation(event)
{
var charCode = (event.which) ? event.which : event.keyCode;

return !(charCode > 31 && (charCode < 48 || charCode > 57));
}

[/sourcecode]
ASP.NET Code

[sourcecode language='csharp']

[/sourcecode]

*Note: Even though Visual Studio will indicate you cannot have OnKeyPress in the aspx, you can still put it there and it will work.

Response.Redirect("Form2.aspx")

or

Response.Redirect("http://www.yahoo.com/")

to send the user to another page.

Server.Transfer is similar in that it sends the user to another page with a statement such as Server.Transfer("Form2.aspx"). However, the statement has a number of distinct advantages and disadvantages.

Firstly, transferring to another page using Server.Transfer conserves server resources. Instead of telling the browser to redirect, it simply changes the "focus" on the Web server and transfers the request. This means you don't get quite as many HTTP requests coming through, which therefore eases the pressure on your Web server and makes your applications run faster.

But watch out: because the "transfer" process can work on only those sites running on the server, you can't use Server.Transfer to send the user to an external site. Only Response.Redirect can do that.

Secondly, Server.Transfer maintains the original URL in the browser. This can really help streamline data entry techniques, although it may make for confusion when debugging.

That's not all: The Server.Transfer method also has a second parameter—"preserveForm". If you set this to True, using a statement such as Server.Transfer("Form2.aspx", True), the existing query string and any form variables will still be available to the page you are transferring to.

For example, if your WebForm1.aspx has a TextBox control called TextBox1 and you transferred to WebForm2.aspx with the preserveForm parameter set to True, you'd be able to retrieve the value of the original page TextBox control by referencing Request.Form("TextBox1").

This technique is great for wizard-style input forms split over multiple pages. But there's another thing you'll want to watch out for when using the preserveForm parameter. ASP.NET has a bug whereby, in certain situations, an error will occur when attempting to transfer the form and query string values. You'll find this documented at http://support.microsoft.com/default.aspx?id=kb;en-us;Q316920.

The unofficial solution is to set the enableViewStateMac property to True on the page you'll be transferring to, then set it back to False. This records that you want a definitive False value for this property and resolves the bug.

So, in brief: Response.Redirect simply tells the browser to visit another page. Server.Transfer helps reduce server requests, keeps the URL the same and, with a little bug-bashing, allows you to transfer the query string and form variables.

"code with no comment rox!" - Alex

[]'s

protected void Page_Load(object sender, EventArgs e)
{
    loadFolder(GridView1, Server.MapPath("."));
}

public void loadFolder(GridView gv_arquivos, String folder)
{

    DirectoryInfo pasta = new DirectoryInfo(folder);
    DirectoryInfo[] subPastas = pasta.GetDirectories();
    FileInfo[] arquivos = pasta.GetFiles();

    DataTable dt = new DataTable();

    dt.Columns.Add("Nome");
    dt.Columns.Add("Tamanho");
    dt.Columns.Add("Tipo");
    dt.Columns.Add("Modificado");
    dt.Columns.Add("Action");

    if (folder != "")
    {
        DataRow dr1 = dt.NewRow();
        dr1["Nome"] = "../";

        dr1["Tamanho"] = "";
        dr1["Tipo"] = "";
        dr1["Modificado"] = "";
        dr1["Action"] = "";

        dt.Rows.Add(dr1);
    }
    foreach (DirectoryInfo dir in subPastas)
    {
        DataRow dr = dt.NewRow();
        dr["Nome"] = "/" + dir.Name;
        dr["Tamanho"] = "-";
        dr["Tipo"] = "Diretório";
        dr["Modificado"] = dir.LastWriteTime.ToString("dd/MM/yyyy");
        dr["Action"] = "";

        dt.Rows.Add(dr);
    }

    foreach (FileInfo file in arquivos)
    {
        DataRow dr = dt.NewRow();
        dr["Nome"] = file.Name;
        dr["Tamanho"] = Convert.ToString(file.Length / 1024) + " kb";
        dr["Tipo"] = file.Extension;
        dr["Modificado"] = file.LastWriteTime.ToString("dd/MM/yyyy");
        dr["Action"] = "";

        dt.Rows.Add(dr);
    }

    gv_arquivos.DataSource = dt;
    gv_arquivos.DataBind();

}

The following article from MSDN explains that

the hex number within the file name (here cdcab7d2) is a hash code that represents the directory that the original file was in. So all files at the root of your source app will use cdcab7d2, while files in other folders will use different numbers. This is used to avoid naming conflicts in case you have files with the same name in different directories (which is very common for default.aspx!).

Source: http://msdn.microsoft.com/en-us/library/aa479318.aspx

If you create a WEB APPLICATION there is no such a option, you can only build the project and all the aspx files will be open to changed with no protection, also the web site will be slow on the first run. The answer to this problem is the Web Deployment add-on for Visual Studio. This add-on let you to add a new type of project to your web site solution which provide lots of customizations on the build process including pre-compile the web site.

Download Visual Studio® 2008 Web Deployment Projects - RTW from:
http://www.microsoft.com/downloads/details.aspx?familyid=0AA30AE8-C73B-4BDD-BB1B-FE697256C459&displaylang=en

Scott Guthrie had a nice simple tutorial for this add-on on his blog:
http://weblogs.asp.net/scottgu/archive/2005/11/06/429723.aspx

And this is the screen shot of the property page for Web Deployment add-on project, where I can define I do not want the aspx pages to be update able, i.e., pre-compile them to binary code:

However exposing the sensitiive data like the password and user name in the web config file can bring big damage to your system when it being seen by unauthorized user.

In the ASP.net 2.0 this problem can solve by adding an encryption method. This encryption can be applied by normal without any programming background. To do this you will need the aspnet_regiis.exe a built in framework tool provided by Microsoft.

Steps:

1. Open a windows command prompt.

2. Find and locate the aspnet_regiss.exe framework directory. The version number depends on the Microsoft.Net version in use.

Example : C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727

3. Once you have located the aspnet_regiis.exe. Run the command as below:

aspnet_regiis -pe "connectionStrings" -app "/TestSite" -prov "DataProtectionConfigurationProvider"

Where:

connectionStrings : -Element section need to be encrypted in the web.config file.

/TestSite : - For example purpose I'm using /TestSite as the virtual directory. Please change to your virtual site.

DataProtectionConfigurationProvider : - This is protection/encryption method selected. So far there are two method. DataProtectionConfigurationProvider & RSAProtectedConfigurationProvider. For this example I'm running the DataProtectionConfigurationProvider. You may go for the RSAProtectionConfigurationProvider method when you are running a web farm.

4. Open the web.config file. Depends on the element selected above. The system will encrypt this section in the configuration file.

Before Encryption:

After Encryption:

Place the below code in Global.asax file and run any .aspx page from the web site and then check for the result at footer of the page.


DateTime timeReq;
protected void Application_OnBeginRequest()
{
timeReq = DateTime.Now;
}

protected void Application_OnEndRequest()
{
TimeSpan diffTime = DateTime.Now - timeReq;

Response.Write("<hr/>This page was served at: " + DateTime.Now.ToString() + " in " + System.Math.Round(diffTime.TotalMilliseconds,2).ToString() + " milli seconds");

}

Advantages wtih HttpServerUtility.Transfer() or Page.Server.Transfer():
It doesn't involves the browser for redirection. Instead of sending a redirect message back to browser, ASP.Net simply starts processing new page. This saves a bit of time.

Limitations with Transfer():
It can't send the user to another website or to a non-ASP.Net page(ex: HTML page). It also won't change the URL in browser even server processes new page in background. This may cause problem to support browser bookmarks.

But wait. What if you are required to put in a static item in the dropdown? Something like "-- Please Select --" as the first item in the list to force the user to make a conscious choice. Hmmm, so you look around and find the nice little property named AppendDataBoundItems that will take care of that. All you have to do is declare the first (static) item in the Items collection in the designer (or put a <asp:ListItem> tag inside your <asp:DropDownList> tags) and set AppendDataBoundItems to true. This nice little property tells the DropDownList to add the databound items after the statically declared items, so you can have your happy little "-- Please Select --" in your dropdown.

The Side-effect:

The side-effect becomes evident when you play around with your two dropdowns. Its immediately clear that something is not quite right. The AppendDataBoundItems property forces your dropdown's items from the previous postback to be treated as static objects onthis display. Sort of where you get an ever-growing second dropdown with a hangover from the postback, which is clearly not what you wanted in the first place!

Continue Reading >>

ไม่อยากจะเรียกว่า Final Project ถึงใครๆจะชอบเรียกมันว่าอย่างนั้น แต่ที่จริงแล้วควรจะเป็น Begin Project ซะมากกว่า เพราะยังไงๆมันก็เป็นแค่โปรเจคแรกที่จะได้ทำอย่างเป็นการเป็นงานสักที

สำหรับตอนนี้ขอบเขตงานแล้วก็ตัวงานเริ่มเข้าที่เข้าทางแล้ว เลยถึงเวลาที่จะต้องเลือกว่าจะพัฒนาด้วยอะไร
เท่าที่คิดไว้ก็มี

• PHP
  แต่ยังหา Framework ที่ถูกใจไม่ได้
• ROR
  จะดีเหรอ? แต่ก็เริ่มเล่นกับ Aptana ไปบ้างแล้ว ...มั่วแต่เล่น แต่ยังไม่ได้เริ่มจริงสักที (ลบ/สร้าง Project ไปหลายสิบที)
• ASP .Net
  ถ้าจับด้วยตัวนี้คงไปได้เร็วเพราะเคยเรียนมาแล้ว แต่ไม่ค่อยชอบตัว Visual สักเท่าไหร่ มันดู....นู๊ปๆ

อันนี้สำหรับโปรแกรมฝั่ง Server ส่วนโปรแกรมฝั่งลูกอีกตัวคิดไว้แล้วว่าจะต้องเป็น .Net C# เพราะไปได้ Source ไว้เชื่อมกับ GPS (เรียกได้ว่าขี้เกียจ เลยก๊อปเขามา)

ยังเหลือโปรแกรมฝั่งลูกอีกตัว กำลังดูๆว่าจะทำเองเลยดีไหม ก็เลยอยุ่ในขั้นทดลอง กำลังรวบรวมโปรแกรมเลยมองๆ WebKit ไว้ลองเล่นดูถ้าไม่ถูกใจยังไงอาจเปลี่ยนอีกที

สรุปแล้วงานก็ยังไม่เดินเท่าที่ควร เพราะอยากลอง Ruby เดี๋ยวเริ่มจริงๆจังๆไปสักนิดดูก่อนว่าใช้งานได้ไหม ถ้าไม่ได้ยังไงจะได้เปลี่ยนใจทัน

...ฟังเพลงต่อดีกว่า

[/sourcecode]

[sourcecode language='csharp']using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Text;

public partial class Admin_Login : System.Web.UI.Page
{
String strCon = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
protected void Page_Load(object sender, EventArgs e)
{
String ReturnUrl = Request.QueryString["ReturnUrl"];
if (ReturnUrl != null) {
if (Page.User.Identity.IsAuthenticated)
Response.Redirect("../.." + ReturnUrl);
}
}

//驗證用戶
protected void Login1_Authenticate(object sender, AuthenticateEventArgs e)
{
String strMD5 = FormsAuthentication.HashPasswordForStoringInConfigFile(Login1.Password.ToString(), "MD5");
try
{
if (ChkLogin(Login1.UserName, strMD5))
{
FormsAuthentication.RedirectFromLoginPage(Login1.UserName, Login1.RememberMeSet);
Server.Transfer("~/Admin/Default.aspx");
//Response.Write("");
}
}
catch(Exception ex)
{
Response.Write("");
}
}

//檢查登入帳號、密碼是否存在
public Boolean ChkLogin(String UserName, String UserPassword)
{
SqlConnection objCon = new SqlConnection(strCon);
SqlCommand objCmd = new SqlCommand();
SqlParameter pmtUserName = new SqlParameter();
SqlParameter pmtUserPassword = new SqlParameter();
String strSql;
SqlDataReader objReader;

try
{
objCon.Open();

strSql = "SELECT * FROM Users WHERE Account = @UserName AND Password = @Passwd";
objCmd.Connection = objCon;
objCmd.CommandText = strSql;

pmtUserName.ParameterName = "@UserName";
pmtUserName.Value = UserName;
pmtUserPassword.ParameterName = "@Passwd";
pmtUserPassword.Value = UserPassword;
objCmd.Parameters.Add(pmtUserName);
objCmd.Parameters.Add(pmtUserPassword);
objReader = objCmd.ExecuteReader();

if (objReader.Read())
return true;
else
return false;
}
catch
{
return false;
}
finally
{
pmtUserName = null;
pmtUserPassword = null;
objCmd.Clone();
objCon.Close();
}
}

//將傳入值轉成 MD5 碼
public string GetMD5(string str)
{
byte[] md5In = System.Text.Encoding.UTF8.GetBytes(str);
System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
byte[] md5Out = md5.ComputeHash(md5In);

StringBuilder sb = new StringBuilder();
for (int i = 0; i < md5Out.Length; i++)
{
sb.Append(md5Out[i].ToString("x2"));
}
return sb.ToString();
}
}[/sourcecode]

參考資料：
topcat姍舞之間的極度凝聚

asp:GridView ID="grid2" runat="server" AutoGenerateColumns="False"
Columns
asp:BoundField DataField="Columna_1" HeaderText="Columna 1" SortExpression="Columna 1"
asp:ImageField HeaderText="foto" DataImageUrlField="foto"
asp:ImageField
Columns
asp:GridView

Nota: eliminamos los simbolos para abrir y cerrar etiquetas de ASP (<>) para poder agregar el código.
De esta manera podemos especificar un DataReader como fuente para nuestro control GridView y llenarlo dinamicamente en tiempo de ejecucion igualando cada uno de los campos de la base de datos del DataReader con los DataFields que especificamos.

• Es más fácil hacer este tipo de modificaciones en el código HTML de la página en la que estamos trabajando.
• Hay cosas muy escondidas de cada uno de los controles de ASP.NET.

El caso es que para lograr lo que necesitamos tenemos que hacer lo siguiente dentro del archivo ASPX de la página dentro de las declaraciones de columnas:

• Para columnas tipo DATE: asp:BoundField DataField="Fecha Registro" HeaderText="Fecha Registro" SortExpression="Fecha Registro" dataformatstring="{0:dd/MM/yy}" htmlencode="False".

Con esto logramos que la fecha sólo contenga realmente la fecha sin agregar la hora (la tenga el campo o no). Además la formateamos como dia/mes/año (que es como se usa en Español).
El formato que necesitamos también se puede agregar en el GUI seleccionando "Editar Columnas" y poniendo la expresión regular en el renglón DataFormatString, sin embargo lo que nadie nos dice es que tenemos que ajustar la opción HtmlEncode a "off" para que esto funcione.

• Para columnas de tipo numérico podemos usar lo siguiente: asp:BoundField DataField="precio" HeaderText="Precio" SortExpression="precio" DataFormatString="{0:$#,#.00}" HtmlEncode="False".

Lo que produce una columna de precio en donde vemos los números con el formato correcto para pesos y centavos.

Estos dos ejemplos utilizan las expresiones regulares para dar formato a los campos. Este tipo de expresiones son muy utilizadas tanto en programación como en otras cosas en donde queremos dar formato a cadenas de caracteres (por ejemplo en Excel). Para los que quieran leer mas al respecto les dejo los siguientes links: Regular Expresion y Regular-Expressions.info

Espero que les sirva!

P.D. recuerden que tengo que eliminar los "< />" de los tags HTML.