هذه المقالة متوفرة أيضا باللغة العربية، اقرأها هنا.

Read more about URL shortening services here.

Source- Elsheimy.Samples.ShortenSvcs.zip

Contents

Contents of this article:

• Contents
• Overview
• Introduction
• Description
• API
• Where to go next

Overview

Just another article of the URL shortening services series.

Today, we are going to talk about another hot and easy-to-use service, it’s Tweetburner. If you haven’t used it before, then it’s the time to.

We’re going to discuss how to use Tweetburner first. After that, we’ll inspect its API and learn how to use it in your .NET application.

Introduction

Again, one of the most popular URL shortening services ever.

Today is dedicated for Tweetburner (known as twurl,) one of the hot, simple, and easy-to-use shortening services that you can compare to is.gd.

Description

When you visit Tweetburner website (via http://tweetburner.com or http://twurl.nl,) you can see that it allows users to register to gain more functionalities (specifically, link analytics.) However, at the time of this writing, the account page is disabled for technical issues and nothing interesting would happen if you register there.

One of the hot features of Tweetburner is that it allows you to post your links to twitter (you guessed) and friendfeed as soon as they’re shortened just click ‘Share this link’ before you leave the page.

Unfortunately, you can’t benefit from this sharing feature programmatically, but of course, you can create your own routines.

After shrinking your URL, you get a new short link about 22 characters long (18 in is.gd) prefixed with http://twurl.nl.

API

Actually, Tweetburner doesn’t help you with an API. Instead, it provides you with a simple web page (used for shortening URLs) that you can access it from your code and get your short URLs.

Let’s try it! Browse to our key page, http://tweetburner.com/links, and push your long URL and click the shortening button.

So how you can access this page via your .NET application and fill in its single field? Let’s get the idea! If you check the API documentation page, you might find that you are required just to request information from that page, post it the required URL via a simple string included in the request body, link[url]={0} (where {0} is the long URL, and just wait for the response that would contain the short URL of course if the function succeed.

Do you find that ‘link[url]={0}’ strange? Try this with me! Browse to our page, http://tweetburner.com/links, and save it as HTML in your PC (not required, just grab its HTML code.)

Sure we are interested on this magical text box, so scroll down to its definition that looks like this:

Notice that the text box is given the name ‘link[url]’, that’s why we push ‘link[url]={0}’ on the request body. Given that hot information, you can push any data to any web form, just get the information required.

Now, let’s code! The next function browses to our page, http://tweetburner.com/links, pushes the long URL specified, and gets the short URL back from the server. (Remember to include the namespace System.Net for the code to work properly.)

// C#

string Short(string url)
{
    url = Uri.EscapeUriString(url);

    HttpWebRequest req = (HttpWebRequest)WebRequest.Create("http://tweetburner.com/links");
    req.Timeout = 5000;
    req.Method = "POST";
    req.ContentType = "application/x-www-form-urlencoded";

    byte[] buffer = System.Text.Encoding.UTF8.GetBytes("link[url]=" + url);
    req.ContentLength = buffer.Length;

    System.IO.Stream ios = req.GetRequestStream();
    ios.Write(buffer, 0, buffer.Length);

    try
    {

        using (System.IO.StreamReader reader =
            new System.IO.StreamReader(req.GetResponse().GetResponseStream()))
        {
            return reader.ReadLine();
        }
    }
    catch (WebException ex)
    {
        return ex.Message;
    }
}

' VB.NET

Function Shorten(ByVal url As String) As String
    url = Uri.EscapeUriString(url)

    Dim req As HttpWebRequest = _
        CType(WebRequest.Create("http://tweetburner.com/links"), HttpWebRequest)
    req.Timeout = 5000
    req.Method = "POST"
    req.ContentType = "application/x-www-form-urlencoded"

    Dim buffer() As Byte = _
        System.Text.Encoding.UTF8.GetBytes("link[url]=" + url)
    req.ContentLength = buffer.Length

    Dim ios As System.IO.Stream = req.GetRequestStream()
    ios.Write(buffer, 0, buffer.Length)

    Try
        Dim reader As System.IO.StreamReader = _
            New System.IO.StreamReader(req.GetResponse().GetResponseStream())

        Dim retValue As String = reader.ReadLine()

        reader.Close()

        Return retValue
    Catch ex As WebException
        Return ex.Message
    End Try
End Function

Notice that we have specified the POST method because it’s required if you are going to change some data in the server. It’s worth mentioning too that we have set the content type to application/x-www-form-urlencoded because it’s required if you are going to push data to a web form (it’s usually perfect for all web forms except file-uploads.)

In addition, we have included the input required in the request stream.

What’s next

Some other articles about URL shortening services are available here.

هذه المقالة متوفرة أيضا باللغة العربية، اقرأها هنا.

Read more about URL Shortening Services here.

Source- Elsheimy.Samples.ShortenSvcs.zip

Contents

Contents of this article:

• Contents
• Overview
• Introduction
• API
• What’s next

Overview

Another article of our series that talks about accessing URL shortening services programmatically.

This article is talking about is.gd shortening service, how you can use it, and how to access it via your C#/VB.NET application.

Introduction

is.gd is one of the most popular shortening services ever in the web because of its simple interface and its easy-to-use API.

When you visit service website, http://is.gd, you can see that nothing easier from is.gd, just push your long URL into the text box and click the shortening button.

API

is.gd provides you a very simple easy-to-use API. This API contains only one function that’s used for shortening URLs. Another good thing is that this function doesn’t require any kind of authentication for users. Therefore, you need just to spam it with your long URL (as you did with the website.)

This glorious function is called http://is.gd/api.php, it accepts only a single argument, longurl, which can be set to the long URL you need to shorten. When you call the function, it simply returns the shortened URL as plain text (no more overhead.)

Now, let’s try this function. We’ll try to shorten the URL http://JustLikeAMagic.com with our function. First, connect the arguments, http://is.gd/api.php?longurl=http://JustLikeAMagic.com. Now copy this address and paste it into your favorite browser. If everything was OK, you should see the short URL after clicking €˜Go’ in the browser toolbar.

Now, let’s do it in C# and VB.NET. Check the following function that tries to shorten long URLs via the id.gd API:

// C#

string Shorten(string url)
{
    url = Uri.EscapeUriString(url);
    string reqUri = String.Format(@"http://is.gd/api.php?longurl={0}", url);

    HttpWebRequest req = (HttpWebRequest)WebRequest.Create(reqUri);
    req.Timeout = 5000;

    try
    {
        using (System.IO.StreamReader reader =
            new System.IO.StreamReader(req.GetResponse().GetResponseStream()))
        {
            return reader.ReadLine();
        }
    }
    catch (WebException ex)
    {
        return ex.Message;
    }
}

' VB.NET

Function Shorten(ByVal url As String) As String

    url = Uri.EscapeUriString(url)
    Dim reqUri As String = _
        String.Format("http://is.gd/api.php?longurl={0}", url)
    Dim req As WebRequest = WebRequest.Create(reqUri)
    req.Timeout = 5000

    Try
        Dim reader As System.IO.StreamReader = _
            New System.IO.StreamReader(req.GetResponse().GetResponseStream())

        Dim retValue As String = reader.ReadLine()
        reader.Dispose()

        Return retValue
    Catch ex As WebException
        Return ex.Message
    End Try

End Function

Notice that we have used the function System.Net.Uri.EscapeUriString() to eliminate unacceptable characters from the URL by encoding them.

Notice too that we have included our code in a Try-Catch block so we can catch exceptions before they blow up our application.

What’s next

Consider reading other articles in this series here.

هذه المقالة متوفرة أيضا باللغة العربية، اقرأها هنا.

Read more about URL shortening services here.

Source- Elsheimy.Samples.ShortenSvcs.zip

Contents

Contents of this article:

• Contents
• Overview
• Introduction
• Accessing the API
• Authentication
• .NET Support
• Encoding
• Sample
• Where to Go Next
• Poll: What are your favorite URL shortening services?

Overview

This is the first article of our series that talks about accessing URL shortening services programmatically.

Here we introduce new concepts like the REST API. We also have a brief discussion of URL shortening services APIs and how you can access them.

In addition, we are going to talk about .NET support for the REST API and tools and techniques available that would help us during our journey through the API.

A working example built using C# and WinForms is available at the end of this article.

This article is the base for all other articles. Articles other than this discuss specific services and their APIs. We will make use of code and techniques discussed here throughout the rest of articles.

Let’s go!

Introduction

URL shortening services are very popular these days since web addresses tend to be very long and very difficult to be exchanged via email or other micro-blogging services like Twitter.

Today, there’re tenths of URL shortening services spread out all over the web. Most of them are listed in the following articles:

• URL Toolbox: 90+ URL Shortening Services
• URL Shortening Services, The Ultimate List

In this series, we are going to talk about how to consume URL shortening services in your .NET application. In other words, we will discuss how to program URL shortening services; we mean how to access them programmatically. In addition, we will have a brief discussion of each service and its unique features.

How we will go through this discussion? This is going to be a series of articles published regularly. Each article discusses a given shortening service from the following list (updated regularly, expect new services to be added):

• is.gd
• twurl.nl
• cli.gs
• bit.ly

The preceding list may not be comprehensive, many other popular services exist. However, not all shortening services have APIs! The preceding list contains the shortening services we know that allow developers to consume their functionalities via an exposed API.

Before we start with a specific service, let’s have a brief discussion of features of the API and how we can access them.

Accessing the API

Most APIs in the web are just REST (Representational State Transfer) web services. A REST web service is simply a collection of functions (HTTP endpoints) that can be used to retrieve data in a variety of formats (optional.)

Given an endpoint (function) like http://ab.c/api/shrink, we could supply the required input arguments as query strings in the URL. For example, we could shorten the URL www.google.com using a call to the HTTP endpoint http://ab.c/api/shrink?url=www.google.com supplied with the required information. It is worth mentioning that every service has its own API functions and arguments. Although they all do the same thing (shortening the URL,) they differ in function and argument names.

When you call a web function, you just end up with the results in the format used in that function (XML, Atom, JSON, etc.) The function could also return plain text! It’s all about the function documentation that you should check carefully before calling the function. In addition, the returned value from a function may also contain error details if the function didn’t success.

Keep in mind that API calls are limited and you can’t just leave the shortening code in an end-less loop! Other limitations of specific APIs should be discussed later.

Authentication

Most URL shortening services allow users to consume the service without being registered, some of allow users to register, and others not. Many other services require users to be registered in order to use the service.

Likewise, service APIs may or may not require user authentication. Some services give the user an API key that can be used in the authentication process. Other services require user to enter his login details in the API calls. Most use the API key approach.

.NET Support

Does .NET support the REST API? Sure! As long as REST web services are just collections of HTTP endpoints, we do not need to worry about accessing them from .NET since that the BCL offers us a bunch of classes (available in System.dll) that can help with HTTP requests and responses.

In addition, we will rely heavily on classes of System.Xml.dll to handle the data returned from functions (we will make use of functions that support XML.)

If we could write something in C# that calls our fake web function http://ab.c/api/shrink, we could end up with some code like this:

// C#

public void string Shorten(string url)
{
    string reqUri = @"http://ab.c/api/shrink?url=" + url;

    WebRequest req = WebRequest.Create(reqUri);
    req.Timeout = 5000;

    XmlDocument doc = new XmlDocument();
    doc.Load(req.GetResponse().GetResponseStream());

    return HandleXml(doc);
}

' VB.NET

Function Shorten(ByVal url As String) As String

    Dim reqUri As String = "http://ab.c/api/shrink?url=" & url

    Dim req As WebRequest = WebRequest.Create(reqUri)
    req.Timeout = 5000

    Dim doc As new XmlDocument()
    doc.Load(req.GetResponse().GetResponseStream())

    Return HandleXml(doc)

End Function

Encoding

If the URL to shorten have special characters like ‘&’, ‘?’, ‘#’, or ‘ ‘, those characters should be handled first before the URL is sent to the shortening function.

This special handling for URLs is usually called Percent-encoding or URL Encoding. This encoding replaces unsafe characters with their hexadecimal values preceded by percentage (‘%’) signs.

There are many unsafe characters that should be percent-encoded including ‘$’, ‘+’, ‘&’, ‘:’, and ‘=’. A nice discussion of URL Encoding can be found in the article URL Encoding by Brian Wilson.

Why unsafe characters are problematic? Consider the following example: we need to shorten the URL http://justlikeamagic.com/?s=twitter with our fake shortening service http://ab.c, we end up with a call to the function using the following address http://ab.c/api/shrink?url=http://justlikeamagic.com/?s=twitter. Now we have two ‘?’s!!!

So how can we encode URLs? Simply use the EscapeUriString() function of System.Net.Uri class it would work well for us here. If you need a full-featured encoder; a procedure that would work for all and every situation, you will need to consider creating one yourself, or you can use this:

// C#

char[] _chars = new char[]
{
     '%',
     '$' ,
     '&',
     '+',
     ',',
     '/',
     ':',
     ';',
     '=',
     '?',
     '@',
     ' ',
     '"',
     '',
     '#',
     '{',
     '}',
     '|',
     '\',
     '^',
     '~',
     '[',
     ']',
     ''', };

string EncodeUrl(string url)
{
    for (int i = 0; i < _chars.GetUpperBound(0); i++)
        url = url.Replace(
            _chars[i].ToString(),
            string.Format("{0:X}", (int)_chars[i]));

    return url;
}

string DecodeUrl(string url)
{
    for (int i = 0; i < _chars.GetUpperBound(0); i++)
        url = url.Replace(
            string.Format("{0:X}", (int)_chars[i]),
            _chars[i].ToString());

    return url;
}

' VB.NET

Private _chars() As String = _
{ _
"%", _
"$", _
"&", _
"+", _
",", _
"/", _
":", _
";", _
"=", _
"?", _
"@", _
" ", _
"", _
"”, _
“#”, _
“{“, _
“}”, _
“|”, _
“”, _
“^”, _
“~”, _
“[“, _
“]”, _
“‘”}

Public Function EncodeUrl(ByVal url As String) As String
For i As Integer = 0 To _chars.GetUpperBound(0) – 1
url = url.Replace( _
_chars(i).ToString(), _
String.Format(“{0:X}”, CInt(_chars(i))))
Next

Return url
End Function

Public Function DecodeUrl(ByVal url As String) As String
For i As Integer = 0 To _chars.GetUpperBound(0) – 1
url = url.Replace( _
String.Format(“{0:X}”, CInt(_chars(i))), _
_chars(i))
Next

Return url
End Function

Sample

Download the sample from here.

Where to Go Next

Now start with any shortening service you like (links are update regularly, new services will be available too):

• is.gd
• twurl.nl
• cli.gs
• bit.ly
• x.co
• 1click.at

Or else, check our URL Shortening Services tag.

Poll