Using Web service in C Sharp

Step 1: Creating a proxy

Goto visual studio command prompt. Type wsdl url

for example:

C:\Program Files\Microsoft Visual Studio 10.0\VC>cd c:\

c:\>wsdl http://www50.brinkster.com/vbfacileinpt/np.asmx?wsdl

Step2: Create an windows Application

copy the .cs file (here for example PrimeNumbers.cs) file from c:\ and paste into windows application folder. In visual studio right click on PrimeNumbers.cs and include in project

Step3: Goto project Add reference->.NET tab->system.web.services

Step4: create a namespace.

Ex: open PrimeNumbers.cs file and namspace Myprime{ enclosed by body of code ... }

Step5: create an object.

Ex: Myprime.PrimeNumbers p=new Myprime.PrimeNumbers();

Step6: now call the method in your application using object

Ex : p.GetPrimeNumbers(); it will return string containing prime numbers.

Step7: Run the windows application.

You can able to find lot of webservices at

http://xmethods.com/ve2/index.po

http://www.webservicex.net/WCF/default.aspx

Click here to download project files

Click here to see demo

Ajax Tutorial

AJAX

AJAX is not a new programming language, but a new way to use existing standards.AJAX is the art of exchanging data with a server, and update parts of a web page - without reloading the whole page.

With Ajax, web applications can retrieve data from the server asynchronously in the background without interfering with the display and behavior of the existing page. The use of Ajax techniques has led to an increase in interactive or dynamic interfaces on web pages. Data is usually retrieved using the XMLHttpRequest object. Despite the name, the use of XML is not actually required, nor do the requests need to be asynchronous.

Drawbacks

• Owing to their dynamic nature, Ajax interfaces are often harder to develop when compared to static pages.
• Pages dynamically created using successive Ajax requests do not automatically register themselves with the browser's history engine, so clicking the browser's "back" button may not return the user to an earlier state of the Ajax-enabled page, but may instead return them to the last full page visited before it. Workarounds include the use of invisible IFrames to trigger changes in the browser's history and changing the URL fragment identifier (the portion of a URL after the '#') when Ajax is run and monitoring it for changes.
• Dynamic web page updates also make it difficult for a user to bookmark a particular state of the application. Solutions to this problem exist, many of which use the URL fragment identifier (the portion of a URL after the '#') to keep track of, and allow users to return to, the application in a given state
• Depending on the nature of the Ajax application, dynamic page updates may interfere disruptively with user interactions, especially if working on an unstable internet connection. For instance, editing a search field may trigger a query to the server for search completions, but the user may not know that a search completion popup is forthcoming, and if the internet connection is slow, the popup list may show up at an inconvenient time, when the user has already proceeded to do something else.
• Because most web crawlers do not execute JavaScript code,publicly indexable web applications should provide an alternative means of accessing the content that would normally be retrieved with Ajax, to allow search engines to index it.
• Any user whose browser does not support JavaScript or XMLHttpRequest, or simply has this functionality disabled, will not be able to properly use pages which depend on Ajax. Similarly, devices such as mobile phones, PDAs, and screen readers may not have support for the required technologies. Screen readers that are able to use Ajax may still not be able to properly read the dynamically generated content.The only way to let the user carry out functionality is to fall back to non-JavaScript methods. This can be achieved by making sure links and forms can be resolved properly and do not rely solely on Ajax. In JavaScript, form submission could then be halted with "return false".
• Like other web technologies, Ajax has its own set of vulnerabilities that developers must address. Developers familiar with other web technologies may have to learn new testing and coding methods to write secure Ajax applications.
• Ajax-powered interfaces may dramatically increase the number of user-generated requests to web servers and their back-ends (databases, or other). This can lead to longer response times and/or additional hardware needs.

Hello World PDF