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Posts Tagged ‘Web Service’

Web forms or ASHX (Handlers) (a short differentiation)

“What should I choose [Web-forms or Handlers] when I want a simple response from the server? “. After 6 years of development with C#.net I heard this question a lot. Due to this, I decide to answer it here.

Web forms VS ASHX

Fig 1.0

Assume that you are developing a JQuery AJAX based application that sends its requests to servers and receives a specific response from it. In this case the first solution that may strike you is using handlers. Maybe because of some features I list here:

–          It returns only a specific response; it is so light and is not derived from a heavy class that may have some performance penalties.

–          Unlike a web form it doesn’t need to compile its interface, generates HTML and returns the generated HTML to clients.

–          Unlike web services (mostly used before .Net 3.0), it returns almost all of request’s properties. One of the most prominent one is users’ identity.

Yes, using Handlers has many, many benefits but choosing to use them for such purpose may bring many problems as well.

In a standard web-form programming (I’d better say as a good OOP practice) you should implement a multi-layered

Web forms VS ASHX (Handlers)

Fig 2.0

inheritance for all of your web-forms. It is totally a beginner’s mistake to inherit a web-form directly from System.Web.UI.Page.

In this approach (Fig 2.0) you distribute each group of actions to separate layers. For instance, you place secure parts (handling authorized users) inside SecurityWeb class, non-secure parts placed into NonSecureWeb class etc. Finally, all of your customized classes can inherit from WebBase class which executes your common and shared operations. WebBase class is also derived from the built-in System.Web.UI.Page class.

Now, you have built a clean architecture for security, caching, common operations/properties and many more. Just assume that you want to enforce all of the functionalities you defined in your layered architecture take place in you AJAX handlers. Assuming that you handle the incoming requests with a handler class. A handler class that cannot inherit anything from a parent class. So there is almost no clean and neat way to have all of your efforts happen before executing the handler’s block. You have no choice to make external calls to other classes by passing heavy objects and parsing the return values!!

This is just duplicating many of your codes that results in inconsistent and non-secure consequences.

Better solution:
The alternative is to replace the handler class with a web-form one that inherits from an/other parent class/es. Now you can have all of the important actions happen in almost everywhere without any code duplication or security problem outcomes.

Indeed, Web forms are heavy, very heavy. Here I provided my common practice to decrease some weigh of this fatty class.

How to make web forms act close to handlers:

By adding the following code you can easily change the behavior of ASPX files to act similarly with ASHX files:

Response.Clear();
Response.ContentType = "text/html";
Response.Expires = -1;
Response.CacheControl = "no-cache";
Response.AddHeader("Pragma", "no-cache");
Line6: string response = "";</pre>
<pre>// your process over Request and generate the Response</pre>
<pre>Response.Write(response);
Response.End();

Above, is a sample that returns a text. Obviously, you can change it to any desired return value. Line 6 is where you should place your operation to feed the response variable.

You reached the end:). I should thank for your attention, deeply appreciate your sharing thoughts about this post and looking forward to receiving them here 😉

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JQuery Autocomplete with ASP.Net

March 29, 2011 4 comments

In this article I want to describe combination of Autocomplete of JQuery and ASP.Net web service. Up to now I really couldn’t find a good article about this issue so it can be useful in the web.

Autocomplete is a plugin of JQuery that you can be used to implement autocomplete with the least efforts. You can find it here.

JQuery Autocomplete plugin has a property called source, in Ajax based programming you should change its source regarding what is entered into the textbox. Assume that you enter “ala” after that a callback is generated that sends some parameters to the web service (textbox.text and other parameters that you want) then in the response data you can feed source property of Autocomplete plugin. I think this stage can be your unique part of your job.

AutoComplete

Fig 1

In this article I’ll discuss about generating a new callback on typing each new word and how to assign the returned value with the source property of Autocomplete plugin. You then can change the web service section with your desired code such as connecting to database and retrieving data on what is sent as parameter to the web service.

Web Service:

I start with web service because it is really simple.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Services;

using System.Xml;

using System.Text;

using System.Web.Script.Services;

namespace ArticleDean.web.Service

{

/// <summary>

/// Summary description for WSDataService

/// </summary>

[WebService(Namespace = "http://tempuri.org/")]

[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

[System.ComponentModel.ToolboxItem(false)]

// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.

[ScriptService]

public class WSDataService : System.Web.Services.WebService

{

[WebMethod]

public string GetStates(string typedValue, string test)

{

test = "ALABAMA:ALASKA:AMERICAN SAMOA:ARIZONA:ARKANSAS:CALIFORNIA:COLORADO:CONNECTICUT:DELAWARE:DISTRICT OF COLUMBIA:FEDERATED STATES OF MICRONESIA:FLORIDA:GEORGIA:GUAM:HAWAII:IDAHO:ILLINOIS:INDIANA:IOWA:KANSAS:KENTUCKY:LOUISIANA:MAINE:MARSHALL ISLANDS:MARYLAND:MASSACHUSETTS:MICHIGAN:MINNESOTA:MISSISSIPPI:MISSOURI:MONTANA:NEBRASKA:NEVADA:NEW HAMPSHIRE:NEW JERSEY:NEW MEXICO:NEW YORK:NORTH CAROLINA:NORTH DAKOTA:NORTHERN MARIANA ISLANDS:OHIO:OKLAHOMA:OREGON:PALAU:PENNSYLVANIA:PUERTO RICO:RHODE ISLAND:SOUTH CAROLINA:SOUTH DAKOTA:TENNESSEE:TEXAS:UTAH:VERMONT:VIRGIN ISLANDS:VIRGINIA:WASHINGTON:WEST VIRGINIA:WISCONSIN:WYOMING";

return test;

}

}

}

The first parameter that web service gets is typedValue. This parameter returns the typed value in textbox. The second parameter is a test one; it is just to show how to send more than one parameter in JSON datatype. You can use them to retrieve your desired data from database but here we just return a long text with ‘:’ separator (This is for training purpose).

ASPX file:

Sorry that it is Image, because of the problem of wordpress to accept html and aspx code, I have to publish this section in image

In the front of the source, there is a function that returns the callback result. It has two parameters, the second one is a method called response (this is a key note) that you should pass the resulting data from callback to it.

In data section of Ajax, I wrote a JSON data, JSON is a pair of key, value that is separated by a ‘:’.

$(".QueryText").val()

returns the typed words in text box

In success section, I splited the resulting string with ‘:’ character and assigned it an array (because JavaScript is a dynamic type checker you don’t need to specify the variable as array, it detects it automatically). Then I sent it to the response method as parameter. This is the only way to return data to the source property of Autocomplete. [return] keyword can’t do this (I wasted a lot of my time to return a value from return keyword, so you can save yours).

Among Autocomplete properties I’m going to discuss some of them. First delay, this parameter is to postpone the callback request to the server. It is very important to do this because ignoring it causes a lot of overhead on the server (it would be a self Denial of Service attack :D). The next is minLength, it depicts that your Autocomplete sends the request after typing a specific number of characters. It also reduces the overhead if you increase it to a meaningful number according to your need.

In header of your form I included JQuery file (jquery-1.5.1.min.js), Autocomplete plugin file (jquery-ui-1.8.custom.min.js) this is a customized file; you can generate it at this address. And also a CSS file that is the official released theme for Autocomplete; you can download and edit it.

Should you have any questions comment me.

Love and peace for you all.