I found both links to be quite informative with convenient examples to try out alongside.

This addon provides the user to store and sync all his personal information from the browser like bookmarks, browsing history, saved passwords etc……just what I was looking for. If you face a similar issue you should really try out this addon. It’s really cool. It’s also secure in the sense, it encrypts all this data on the client end before it stores it on the server(provided by Mozilla). You can check more on this here.

Microsoft makes development pretty easy ain’t it

• It seems there is some IPv6 issue due to which Firefox could not connect. This could be disabled from Firefox’s config. Open Firefox, type about:config in the address bar and change the value of the flag “network.dns.disableIPv6″ to true. Restart firefox. This should resolve the issue.
• The second issue was occuring since the DNS was resolving all the ubuntu source archives to 1.0.0.0. I changed my network settings so that my DNS name servers always point to the open DNS servers rather than those provided by my local ISP. openDns nameservers are: 208.67.220.200 & 208.67.222.222

This followed by a machine restart fixed the issue. However I wonder why I had to resort to these workarounds just for network connectivity. I had no such issues with Ubuntu 9.04. Ubuntu seems to have surely achieved a much more polished and slick UI in place in 9.10 , however something as basic as connectivity seems to have taken a backseat.
]]> http://techrealm.wordpress.com/2009/11/05/connectivity-woes-in-karmic-koala/feed/ 0 Sundeep http://techrealm.wordpress.com/2009/10/22/wubis-magic/ http://techrealm.wordpress.com/2009/10/22/wubis-magic/#comments Thu, 22 Oct 2009 19:28:08 +0000 sundeepk http://techrealm.wordpress.com/?p=48 ]]> There was this issue I faced a couple of days ago. I have Windows Vista installed on my laptop. I wanted to install ubuntu on a separate partition. Now since I have a single partition on my laptop I decided to create a dedicated partition for ubuntu. I realized that Norton’s partition magic does not supports windows vista and people who tried partitioning their hard drive with Vista pre-intalled, had their partitions screwed up.

Later on I found that Vista has this inbuilt partition manager with options like shrink/extend volume which were useless most of the time and were not flexible enough. I had almost given up when I came across the
wubi installer.

This is a really cool software which allows you to install ubuntu as just another application in windows without the need to create a dedicated partition. I would strongly recommend this installer for all those who would like to try out ubuntu or who would like to use it without creating a dedicated partition.

There are ofcourse a few minor limitations of using the OS this way. You can check these out in the
FAQ section.

The foll code helps us achieve the above GET request.
Comments have been added inline wherever needed.

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

namespace SampleScraper
{
  class Program
  {
    static void Main(string[] args)
    {
      string url = "http://www.example.net";
      WebRequest wbRequest;

      //This initializes the request object
      wbRequest = WebRequest.Create(url);

      //In cases whereby one needs to request URLs that are outside the local network
      //and the system is behind a proxy the proxy settings can be set using the foll
      //WebProxy class.
      //The WebProxy constructor provides a number of options to set the proxy server
      //details
      WebProxy proxy = new WebProxy();

      //In case one wishes to use the settings that were already configured in Internet
      //Explorer one can do this using the GetDefaultProxy() static method of the
      //WebProxy class
      proxy.BypassProxyOnLocal = true;
      wbRequest.Proxy = proxy;

      //Once the response stream is available one can read through its contents line
      //by line as shown below.
      Stream objStream;
      objStream = wbRequest.GetResponse().GetResponseStream();
      StreamReader objReader = new StreamReader(objStream);
      string sLine = "";
      int i = 0;

      while (sLine != null)
      {
         i++;
         sLine = objReader.ReadLine();
         if (sLine != null)
            Console.WriteLine("{0}",sLine);
      }
      Console.ReadLine();
   }
 }
}

This is mainly achieved through modularity and encapsulation. Usually in any major application we have a number of layers like the presentation, business logic, data access and the database layer. This is also an example of separation of concerns(SoC).

The most common and lucid example of separation of concerns has to be the web page. It is a combination of html(content), css(style) and javascript(behaviour). As a good practice all these 3 layers are always maintained separately (SoC) so that the content is always available(visible to the user) irrespective of failures of the presentation and the behaviour layers.

MVC also achieves something similar by separating the content from presentation and model from content.
Languages like C#, Java etc achieve this by separating concerns into objects while procedural programming languages like C etc achieve the same by separating concerns into procedures.

• Before AJAX the only way to change page data was through the normal browser page-request mechanism.
• However AJAX made it possible for the browser to make a call to the server without going through the normal  browser page-request mechanism.
• This means that JS can now make behind the scenes server requests while a page is being viewed.
• This allows to pull down extra data from the server, manipulate the page using DOM – replacing, adding or deleting sections.

Understanding the XMLHttpRequest object

• IE5 and 6 were the first browsers to implement XMLHttpRequest object. They did so using an ActiveX object.

    var requester = new ActiveXObject("Microsoft.XMLHTTP");

• Every other browser including IE7 does so using

    var requester = new XMLHttpRequest();

• The correct way to create an XMLHttpRequest object would be as follows:

  try
  {
      var requester = new XMLHttpRequest();
  }
  catch (error)
  {
      try
      {
          var requester = new ActiveXObject("Microsoft.XMLHTTP");
      }
      catch (error)
      {
          var requester = null;
      }
  }

• The XMLHttpRequest object has two methods open and send.
• The open method initializes the connection
  1. The first parameter is the type of HTTP request i.e. GET, POST, DELETE etc.
  2. The second is the location from which we want to request the data.This can be either an absolute or relative URL. But due to cross domain security constraints the target must reside on the same domain as the page that is requesting it.
  3. The third argument signifies the type of request i.e. synchronous(false) or asynchronous(true)
  4. open also has 4th and 5th optional arguments that specify the user’s name and password for authentication purposes when a password-protected URL is requested.

      requester.open("GET", "http://localhost:8080/test1.html", true);

• The send function is the one that actually makes the request and one can send query parameters as its arguments.

      requester.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
      requester.open("POST", "http://localhost:8080/test1.aspx", true);
      requester.send("name=peter&email=peter.parker@gmail.com");

• We can also use the following approach

      requester.open("GET","http://localhost:8080/test1.aspx?name=peter&email=peter.parker@gmail.com", true);
      requester.send(null);

• We have to use an event handler to catch the server’s response.
• The XMLHttpRequest object has a readyState property that specifies the status of the objects connection. It takes the foll values:
  0 uninitialized
  1 loading
  2 loaded
  3 interactive
  4 complete
• readyState increments from 0 to 4, and the readystatechange event is triggered for each increment.
• This can be seen by the foll eg:

  requester.onreadystatechange = function()
  {
      if (requester.readyState == 4)
      {
          if (requester.status == 200 || requester.status == 304)
          {
              code to handle successful request
          }
          else
          {
              code to handle failed request
          }
      }
  }

• NOTE:
  • Even though an XMLHttpRequest object allows you to call the open method multiple times, each object can effectively only be used for one call, as the readystatechange event refuses to fire again once readyState changes to 4 (in Mozilla browsers). Therefore, you will have to create a new XMLHttpRequest object every time you want to retrieve new data from the server.
• Once the request is sent there are 2 options for reading the server’s responses
  • responseXML
  • responseText
• responseXML
  • If the server returned a response with the content type “text/xml” then the data is stored in this property as a DOM tree. We can then access/modify the data from the DOM tree using the standard JS DOM access methods such as getElementsByTagName,childNodes, and parentNode.

  Example of using responseXML

  <?xml version="1.0" ?>
  <user>
    <name>peter</name>
    <email>peter.parker@gmail.com</email>
  </user>
  <user>
    <name>bruce</name>
    <email>bruce.wayne@gmail.com</email>
  </user>
  
  var nameNode = requester.responseXML.getElementsByTagName("name")[0];
  var nameTextNode = nameNode.childNodes[0];
  var name = nameTextNode.nodeValue;

  The name variable will now take as its value the first user’s name: “peter”.
  NOTE:

  • As in HTML documents, be aware that whitespace between tags in XML will often be interpreted as a text node.If in doubt, remember that you can check if a given node is an element by looking at its nodeType property.
• responseText
  • If the server returns the response with the content type “text/plain” or “text/html” then this property will contain the data in the form of a single string.

But the last few days I have been determined to go all the way once and for all, and I actually have managed a good start, being on leave from work has also helped a bit. I’m hoping that I become proficient enough in this language by this weekend(coz I’m really enjoying it)….and yeah, I really really hope that I don’t give up on it AGAIN!!!

If I do get going …. I’ll surely make it a practice to keep posting all the cool stuff that I come across whilst learning this really wonderful language.