Library tutorials & articles
Retrieving HTTP content in .NET
Wrapping it up
By now you're probably getting an idea of the power that is provided by the HttpWebRequest object. While using these objects is a straight forward process it does require a fair amount of code and , using these objects required a fair amount of code and knowledge of a number of classes.
Since I use HTTP access in just about every application I create, I decided to create a wrapper class called wwHttp that simplifies the whole process quite a bit (the class is included in the code download for this article). Rather than creating two separate Request and Response objects the single class handles in a single object with simple string properties. The class handles setting up POST variables for you, creating any authentication and proxy settings from strings rather than objects, manages cookie and provides an optional simplified error handler that sets properties instead of throwing exceptions. It does this while allowing access to the base objects – you can pass in a WebRequest object and retrieve a reference to both the Request and Response objects, so you can get the best of both worlds with simplicity without giving up any of the features of the framework classes. The class also provides several overloaded methods for returning strings, streams and running output to file. The class can be set up to fire events at buffer retrieval points when data is downloaded to provide feed back in a GUI application.
Start by adding the namespace:
using Westwind.Tools.Http;
Using the class you can retrieve content from a site as simply as this:
wwHttp loHttp = new wwHttp();
loHttp.Username = "ricks";
loHttp.Password = "password";
loHttp.ProxyAddress = "http://proxy-server.hawaii.rr.com:8080";
loHttp.AddPostKey("Name","Rick Strahl");
loHttp.AddPostKey("Company","West Wind Technologies");
loHttp.HandleCookies = true; // enable automatic tracking for 5 cookies
string lcHtml = loHttp.GetUrl("http://www.west-wind.com/TestPage.wwd");
Most of those property settings are optional but just about everything in the class is accessible with simple strings. AddPostKey() automates the creation of UrlEncoded strings. Several different POST modes are supported including UrlEncoded (0), Multi-Part (2) and raw XML (4) POSTs.
The GetUrl() method has several different signatures. You can pass in an optional WebRequest object that is preconfigured so if you need to set one of the to override some properties that are not exposed you can override them there. For example:
HttpWebRequest oReq = (HttpWebRequest) WebRequest.Create(lcUrl);
oReq.Expires = -1
oReq.Headers.Add("SoapAction","http://west-wind.com/soap#Method");
wwHttp Request = new wwHttp();
string lcHTML = Request.GetUrl(oReq);
wwHttp also exposes Error and ErrorMsg properties that can be used to quickly check for error conditions:
lcHtml = Request.GetUrl(lcUrl);
if (Request.Error)
MessageBox.Show(Request.ErrorMsg);
Else
this.txtResult.Text = lcHtml;
Explict error retrieval is the default, but you can use the ThrowExceptions property to have the class pass forward exceptions to your code.
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if (oReqCookie.Name ==
oRespCookie.Name) {
oReqCookie.Value =
oRespCookie.Name;
Do you mean?
if (oReqCookie.Name ==oRespCookie.Name) {
oReqCookie.Value =
oRespCookie.Value;
You have a paragraph that states:
"The most common use of delegates is an eventhandler, which uses the delegate to fire events. When the event publisher fires the event method, the delegate that is assigned to handle the event is called and you're event subscriber object then can simply handle the event by implementing a method in your class."
Unfortunately, for someone trying desparately to learn C#, this sounds like:
"blah blah blah blah blah blah"
I'm sorry but could you publish a REAL SIMPLE example and explanation of asynch calls in Asp.net/C#. I have been all over the web looking for one and they all assume you already know C# so all the delegate calling callback calling method calling delegate calling calling callingcallingcalling.................has just finally gotten on my nerves.
hi
i have similar problem like you (in a previous time) with in using httwebrequest to login in a website... especially how to handle event clicking ex: onkeypress="checklogin()"
i hope you can help me to solve the problem..
thnx b4
hi
I use httpwebrequest to login into a website (using Networkcrendential). When i got that page i need to click a link. How can we achieve this (axwebbrowser ?) and it contains frames. And also after clicking that menu in second page i have to click a Javascript button. Is there anyway to achieve this.
Rajesh
Also, you should consider having your class implement the IDisposable interface. And in that implementation clean up, close, and release the resources used by your private variables.
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