Writing a simple greeting bot for MediaWiki/Introduction to MediaWiki scripting access

From Wikiversity

On this page you will get an introductory overview over how MediaWiki works and in which ways it can be accessed from scripts.

Note: The code examples in this course use C# and the .NET Framework. The use of an Integrated development environment(IDE) is strongly recommended. For Windows users, Microsoft provides a free C# IDE called Visual C# Express. For Linux and Mac users, there is a free IDE called MonoDevelop available.

[edit] Fundamentals

MediaWiki is a PHP web application based on HTTP. Because of that, scripts communicate with MediaWiki in a series of requests and responses. To get the contents of a page, for example, the script sends a request to the server hosting MediaWiki (e.g. http://en.wikiversity.org/). The server then responds with the page content plus some additional statistical information. Each script action, such as loading or saving a page, requires a new set of requests and responses.

[edit] Exercise 1 - A simple request

In this exercise, we will send a request to retrieve the contents of Wikiversity's main page. Here's the code:

using System;
using System.Net;
using System.IO;
using System.Text;

namespace BotCourse {
  class Program {
    static void Main(string[] args) {
      Uri uri = new Uri("http://en.wikiversity.org/wiki/Wikiversity:Main Page");

      HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

      request.UserAgent = "Wikiversity bot course/1.0";
      request.ContentType = "application/x-www-form-urlencoded";

      using (WebResponse response = request.GetResponse())
        using (StreamReader strmReader = new StreamReader(response.GetResponseStream()))
	  File.WriteAllText("Main page.txt", strmReader.ReadToEnd(), Encoding.UTF8);
    }
  }
}

Let's take a closer look at what this code does. We

1. We create an Uri object to hold the address of the page, in this case Wikiversity:Main Page.
2. We create a new HTTP request object by calling WebRequest's Create page with the address of the page we want. If you are not familiar with HTTP at all, I suggest taking a quick peek at w:HTTP.
3. We then set the user agent and content type headers typical for HTTP requests. Although innocent looking, these are actually quite important: MediaWiki refuses any request which does not provide these two headers.
4. By calling GetResponse, the request is sent and a response retrieved.
5. We read the content of the response and save it to a local file called "Main page.txt".

If you open the file, you will see the same content that would be shown if you went to Wikiversity:Main Page with your browser and look at the source of that page (the menu option is commonly called View source oder Page source in graphic browsers).