The majority of the web servers, that are based on Apache, have the mod_rewrite enabled so you don’t have to get dirty to install it on the hosting server.But anyone of those that are developing web application based on Apache server,  using PHP have a local installed server therefore mode_rewrite is also  necessary in testing process.

Installing mod_rewrite :

1. On Linux: edit the Apache configuration file (  httpd.conf ) and uncomment   LoadModule rewrite_module modules/mod_rewrite.so (remove the pound ‘#’ sign from in front of the line) . Also be sure that the lines containing ClearModuleList and AddModule mod_rewrite.c are uncommented . Now you can create the famous .htacess file on the root of you website and start adding your code.
2. On Windows: well as we are expecting, things are a bit more complicated because on Windows you cannot create a file that doesn’t have a name (.htacess is a file that only have an extension). For first just uncomment the same lines as in the Linux example. Now you have to tell Apache to use you’re custom file instead of  .htacess file, so search in the configuration file (httpd.conf)  for the following lines:

# AccessFileName: The name of the file to look for in each directory # for additional configuration directives. See also the AllowOverride
# directive.
#
AccessFileName .htaccess (change the .htaccess to [name].htaccess where name can be whatever what you wish )

You can escape this step and create the .htacess file even on windows, actually the restriction of creating a file without name is an restriction of Windows Explorer is not an restriction of the operating system . Open the command (cmd), go to the root folder of the website and type copy con .htacess and press Ctrl+Z. well… that’s all folks.

Maybe you are asking yourself  about mod_rewrite and where to use it, well the short and  simple answer is :  for simplifying the URL of a website, simpler/shorter URL are easier to write easier to remember. For example instead of having an URL  like this www.example.com?id_product=23123&color=23 you can have something like www.example.com/iphone-white. Mod_rewrite basicly make   use of regular expression to rewrite an specified URL.

When to use it: mod_rewrite can be used in many circumstances where you may want to rewrite the an URL, also you can create dynamically virtual hosting entry;  practically mode_rewrite is an “Swiss Army Knife”.

When not to use it: well as I have mentioned  before mode_rewrite make use of regular expression, and evaluating regular expression takes time, use memory and the global performance of the server is decreasing.

I will provide you some basic example of using mode_rewrite. .htaccess file should begin with:

Options +FollowSymLinks
RewriteEngine On
RewriteBase /

1. Redirecting
   Redirect /index.php   http://www.example.com/    -this example redirect the current site to www.example.com
   RedirectMatch (.*)\.gif http://images.example.com$1.png      -In this example, we’ve taken all of our GIF files, converted them to PNG files, and
   moved them to another server
2. Require www

   Options +FollowSymLinks
   RewriteEngine On
   RewriteBase /
   RewriteCond %{HTTP_HOST} !^www\.example\.com$ [NC]
   RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L]

3. Denying access to a folder except of fopen file from php

   RewriteEngine On
   RewriteBase /
   RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([^/]+)/.*\ HTTP [NC]
   RewriteRule .* - [F,L]

4. Limit access during some hours

   Options +FollowSymLinks
   RewriteEngine On
   RewriteBase /
   # If the hour is 7
   RewriteCond %{TIME_HOUR} ^7$
   RewriteRule ^.*$ - [F,L]

These samples are here just to open your appetite for mode_rewrite. Practically this tool can be used in any other ways,yes… the limit is your imagination.

Well seriously, there are some meta methods to protect you’re HTML source from being seen by a common user not from an expert user.I will enumerate some methods starting with the simplest.

• The first method, maybe the most stupid one but used by many people (stupid ideas work for stupid people ) is putting a lot of empty line in front of HTML source. If the user looks at the source will see just empty white page. But if he scroll down on bottom of the page he will see the source.
• The  second method is to disable right click on page. To do that just take a look at next code://Disable right click script III- By Renigade (renigade@mediaone.net)
  //For full source code, visit http://www.dynamicdrive.com

  var message=”";
  ///////////////////////////////////
  function clickIE() {if (document.all) {(message);return false;}}
  function clickNS(e)
  {
  if(document.layers||(document.getElementById&&!document.all))
  {
  if (e.which==2||e.which==3)
  {(message);return false;}
  }
  }

  if (document.layers)
  {
  document.captureEvents(Event.MOUSEDOWN);document.onmousedown=clickNS;
  }
  else
  {
  document.onmouseup=clickNS;document.oncontextmenu=clickIE;
  }

  document.oncontextmenu=new Function(”return false”)
  // –>

  Now that the user can do right click->show page source,  you have achieved a good protection method,  if you user is a old granny  that doesn’t know to use  (Ctrl+U)  shortcut or Edit->View page soure.

• The third method is to use javascript to hide the HTML content. A short example is presented next:
  Let’s suppose that the page has the following code:<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
  <html xmlns=”http://www.w3.org/1999/xhtml”>
  <head>
  <meta http-equiv=”Content-Type” content=”text/html; charset=utf-8″ />
  <title>Sample HTML-hide sorece code</title>
  </head>

  <body>
  Blah blah blah
  </body>
  </html>

  Now what we have to do next is to “encrypt” this content, go to http://www.swingnote.com/tools/texttohex.php or a similar page and convert the text source code to an hexa representation. You will obtain something similar to this:
  %3c%21%44%4f%43%54%59%50%45%20%68%74%6d%6c%20%50%55%42%4c%49%43%20%5c%22%2d%2f%2f%57%33%43%2f%2f%44%54%44%20%58%48%54%4d%4c%20%31%2e%30%20%54%72%61%6e%73%69%74%69%6f%6e%61%6c%2f%2f%45%4e%5c%22%20%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%54%52%2f%78%68%74%6d%6c%31%2f%44%54%44%2f%78%68%74%6d%6c%31%2d%74%72%61%6e%73%69%74%69%6f%6e%61%6c%2e%64%74%64%5c%22%3e%20%3c%68%74%6d%6c%20%78%6d%6c%6e%73%3d%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%31%39%39%39%2f%78%68%74%6d%6c%5c%22%3e%20%3c%68%65%61%64%3e%20%3c%6d%65%74%61%20%68%74%74%70%2d%65%71%75%69%76%3d%5c%22%43%6f%6e%74%65%6e%74%2d%54%79%70%65%5c%22%20%63%6f%6e%74%65%6e%74%3d%5c%22%74%65%78%74%2f%68%74%6d%6c%3b%20%63%68%61%72%73%65%74%3d%75%74%66%2d%38%5c%22%20%2f%3e%20%3c%74%69%74%6c%65%3e%53%61%6d%70%6c%65%20%48%54%4d%4c%2d%68%69%64%65%20%73%6f%72%65%63%65%20%63%6f%64%65%3c%2f%74%69%74%6c%65%3e%20%3c%2f%68%65%61%64%3e%20%20%3c%62%6f%64%79%3e%20%09%42%6c%61%68%20%62%6c%61%68%20%62%6c%61%68%20%3c%2f%62%6f%64%79%3e%20%3c%2f%68%74%6d%6c%3e

  The page is the same but now has a different representation that is strange to a common user but remember that this is a meta protection method an advanced user can and will do the reverse method to obtain you’re source.
  The next step is to create the “protected” page, create a new HTML document and add the next code:

  <script>
  document.write(unescape(”%3c%21%44%4f%43%54%59%50%45%20%68%74%6d%6c%20%50%55%42%4c%49%43%20%5c%22%2d%2f%2f%57%33%43%2f%2f%44%54%44%20%58%48%54%4d%4c%20%31%2e%30%20%54%72%61%6e%73%69%74%69%6f%6e%61%6c%2f%2f%45%4e%5c%22%20%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%54%52%2f%78%68%74%6d%6c%31%2f%44%54%44%2f%78%68%74%6d%6c%31%2d%74%72%61%6e%73%69%74%69%6f%6e%61%6c%2e%64%74%64%5c%22%3e%20%3c%68%74%6d%6c%20%78%6d%6c%6e%73%3d%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%31%39%39%39%2f%78%68%74%6d%6c%5c%22%3e%20%3c%68%65%61%64%3e%20%3c%6d%65%74%61%20%68%74%74%70%2d%65%71%75%69%76%3d%5c%22%43%6f%6e%74%65%6e%74%2d%54%79%70%65%5c%22%20%63%6f%6e%74%65%6e%74%3d%5c%22%74%65%78%74%2f%68%74%6d%6c%3b%20%63%68%61%72%73%65%74%3d%75%74%66%2d%38%5c%22%20%2f%3e%20%3c%74%69%74%6c%65%3e%53%61%6d%70%6c%65%20%48%54%4d%4c%2d%68%69%64%65%20%73%6f%72%65%63%65%20%63%6f%64%65%3c%2f%74%69%74%6c%65%3e%20%3c%2f%68%65%61%64%3e%20%20%3c%62%6f%64%79%3e%20%09%42%6c%61%68%20%62%6c%61%68%20%62%6c%61%68%20%3c%2f%62%6f%64%79%3e%20%3c%2f%68%74%6d%6c%3e”));
  </script>
  As you can see all we are doing is to use javascript to write the content (document.write method).
  !!! Important : if user has the javascript disabled he will not see anything because the code will not execute, therefore will  be nothing displayed. Also remember that most of searchengine as Google or Yahoo crawl  the web in text mode,  remember that javascript is luxury not a necessity.

• Now is time to get serious and speak about some more advanced, a little bit harder to break (not impossible to break), technique   to keep you HTML source protected.The base idea is to encrypt the content of the HTML page, this time really encryption . Let imagine  a function for encryption this time a simple one that is using xor logic function to achieve encryption. The code to do that is showed next:
  //Encryptionfunction encrypt(text,key){

  var rez=new Array(text.length);
  for(i=0;i<text.length;i++){
  rez[i]=text.charCodeAt(i) ^key.charCodeAt(i%key.length);
  }
  return rez;
  }

  //Decryption

  function decrypt(text,key){
  var rez=”";
  for(i=0;i<text.length;i++){
  rez+=String.fromCharCode(text[i] ^key.charCodeAt(i%key.length));

  }
  return rez;
  }

  Using the functions in this form won’t help to much because the user will see clear what is about, so I am going to obfuscate the code (if you don’t know what is that google it ). Now the code looks not so friendly :

  eval(function(p,a,c,k,e,d){e=function(c){return c.toString(36)};if(!”.replace(/^/,String)){while(c–){d[c.toString(a)]=k[c]||c.toString(a)}k=[function(e){return d[e]}];e=function(){return’\\w+’};c=1};while(c–){if(k[c]){p=p.replace(new RegExp(’\\b’+e(c)+’\\b’,'g’),k[c])}}return p}(’8 c(2,4){9 3=d b(2.5);7(1=0;1<2.5;1++){3[1]=2.6(1)^4.6(1%4.5)}a 3}8 f(2,4){9 3=”";7(1=0;1<2.5;1++){3+=e.g(2[1]^4.6(1%4.5))}a 3}’,17,17,’|i|text|rez|key|length|charCodeAt|for|function|var|return|Array|encrypt|new|String|decrypt|fromCharCode’.split(’|'),0,{}))

  The next step is to convert you’re page in hexa as showed previously in this post, suppost that we are using the same page the hexa will be:

  %3c%21%44%4f%43%54%59%50%45%20%68%74%6d%6c%20%50%55%42%4c%49%43%20%5c%22%2d%2f%2f%57%33%43%2f%2f%44%54%44%20%58%48%54%4d%4c%20%31%2e%30%20%54%72%61%6e%73%69%74%69%6f%6e%61%6c%2f%2f%45%4e%5c%22%20%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%54%52%2f%78%68%74%6d%6c%31%2f%44%54%44%2f%78%68%74%6d%6c%31%2d%74%72%61%6e%73%69%74%69%6f%6e%61%6c%2e%64%74%64%5c%22%3e%20%3c%68%74%6d%6c%20%78%6d%6c%6e%73%3d%5c%22%68%74%74%70%3a%2f%2f%77%77%77%2e%77%33%2e%6f%72%67%2f%31%39%39%39%2f%78%68%74%6d%6c%5c%22%3e%20%3c%68%65%61%64%3e%20%3c%6d%65%74%61%20%68%74%74%70%2d%65%71%75%69%76%3d%5c%22%43%6f%6e%74%65%6e%74%2d%54%79%70%65%5c%22%20%63%6f%6e%74%65%6e%74%3d%5c%22%74%65%78%74%2f%68%74%6d%6c%3b%20%63%68%61%72%73%65%74%3d%75%74%66%2d%38%5c%22%20%2f%3e%20%3c%74%69%74%6c%65%3e%53%61%6d%70%6c%65%20%48%54%4d%4c%2d%68%69%64%65%20%73%6f%72%65%63%65%20%63%6f%64%65%3c%2f%74%69%74%6c%65%3e%20%3c%2f%68%65%61%64%3e%20%20%3c%62%6f%64%79%3e%20%09%42%6c%61%68%20%62%6c%61%68%20%62%6c%61%68%20%3c%2f%62%6f%64%79%3e%20%3c%2f%68%74%6d%6c%3e

  now is time to encrypt the hexa representation with a key, so apply encrypt(”…hexa text ….”,”…you personal key…”) . I used as key “secret” and have obtained this:

  86,86,0,87,87,69,86,81,87,87,81,18,86,81,80,87,80,64,86,80,90,87,80,68,86,81,86,87,87,68,86,83,91,87,82,64,86,83,7,87,83,23,86,87,83,87,80,68,86,80,86,87,81,70,
  86,81,0,87,81,77,86,81,80,87,87,68,86,80,0,87,87,70,86,87,7,87,87,18,86,87,5,87,80,67,86,86,80,87,81,71,86,87,5,87,87,18,86,81,87,87,80,64,86,81,87,87,87,68,86,
  80,91,87,81,76,86,80,87,87,81,16,86,81,0,87,87,68,86,86,82,87,87,17,86,86,83,87,87,68,86,80,87,87,82,70,86,83,82,87,83,17,86,82,80,87,83,77,86,82,87,87,83,77,86,
  83,5,87,83,17,86,83,82,87,83,23,86,87,5,87,87,18,86,81,86,87,81,17,86,80,0,87,87,70,86,87,83,87,80,23,86,87,81,87,83,76,86,82,87,87,82,64,86,82,83,87,86,21,86,87,5
  ,87,87,18,86,82,84,87,82,67,86,82,84,87,87,17,86,82,84,87,86,71,86,87,6,87,83,18,86,82,81,87,83,67,86,87,5,87,80,64,86,80,81,87,87,18,86,82,91,87,83,76,86,82,87,87,
  83,16,86,83,0,87,86,69,86,87,5,87,81,64,86,80,87,87,81,64,86,87,5,87,82,76,86,83,91,87,82,64,86,83,7,87,83,23,86,86,82,87,87,16,86,82,87,87,82,70,86,83,82,87,83,17,
  86,82,80,87,83,77,86,82,87,87,83,77,86,83,5,87,83,17,86,83,82,87,83,23,86,87,6,87,83,64,86,82,87,87,83,64,86,80,0,87,87,70,86,86,6,87,87,68,86,86,0,87,83,76,86,82,
  87,87,83,16,86,83,0,87,87,68,86,82,91,87,83,16,86,83,0,87,83,17,86,82,80,87,86,16,86,80,0,87,87,70,86,83,91,87,82,64,86,82,87,87,82,68,86,86,2,87,87,18,86,87,5,87,
  82,67,86,82,84,87,82,67,86,87,6,87,82,67,86,86,80,87,87,17,86,83,5,87,82,70,86,83,84,87,87,18,86,86,82,87,86,77,86,86,90,87,86,77,86,87,5,87,82,76,86,83,91,87,82,64
  ,86,83,7,87,83,23,86,80,0,87,87,70,86,86,6,87,87,68,86,86,0,87,83,76,86,83,86,87,83,69,86,83,87,87,86,17,86,87,83,87,86,23,86,83,7,87,83,65,86,82,87,87,83,69,86,87,83,
  87,83,76,86,82,87,87,82,64,86,82,83,87,87,16,86,83,86,87,82,69,86,82,86,87,83,77,86,82,85,87,86,16,86,80,0,87,87,70,86,81,80,87,83,18,86,83,6,87,82,64,86,83,86,87,83,
  17,86,82,87,87,87,16,86,80,87,87,82,77,86,82,83,87,83,65,86,80,0,87,87,70,86,87,83,87,83,71,86,83,5,87,83,17,86,82,87,87,83,65,86,83,6,87,82,64,86,86,7,87,80,23,86,87
  ,81,87,82,64,86,83,86,87,82,76,86,82,87,87,87,18,86,83,91,87,82,64,86,83,7,87,83,23,86,86,1,87,87,68,86,83,80,87,83,76,86,83,82,87,82,70,86,82,80,87,83,65,86,82,87,87,86,
  16,86,82,86,87,82,64,86,83,85,87,87,16,86,86,91,87,80,23,86,87,81,87,87,68,86,87,5,87,86,17,86,87,83,87,86,23,86,82,87,87,83,77,86,82,87,87,83,23,86,83,86,87,86,17,86,
  80,80,87,83,69,86,83,7,87,82,68,86,83,0,87,83,65,86,87,83,87,81,76,86,80,87,87,81,16,86,81,0,87,87,16,86,83,91,87,83,77,86,83,87,87,83,65,86,87,83,87,82,71,86,83,5,
  87,82,70,86,83,86,87,83,71,86,83,86,87,87,68,86,83,80,87,83,18,86,83,87,87,83,65,86,86,0,87,87,18,86,82,87,87,83,77,86,82,87,87,83,23,86,83,86,87,86,17,86,87,83,87,
  86,23,86,87,5,87,83,76,86,83,86,87,83,69,86,83,87,87,86,17,86,87,83,87,87,68,86,86,0,87,83,70,86,83,5,87,83,64,86,82,90,87,86,17,86,87,83,87,85,77,86,81,81,87,83,23,
  86,83,82,87,83,76,86,87,83,87,83,70,86,83,0,87,83,69,86,83,91,87,87,68,86,83,81,87,83,23,86,83,82,87,83,76,86,87,83,87,86,23,86,87,5,87,83,70,86,83,5,87,83,64,86,82,
  90,87,86,17,86,87,83,87,86,23,86,87,5,87,83,76,86,82,87,87,83,16,86,83,0,87,86,17

  Now let’s create the script,that will display the content of page, that will be the final step:

  document.write(unescape(decrypt(new Array(86,86,0,87,87,69,86,81,87,87,81,18,86,81,80,87,80,64,86,80,90,87,80,68,86,81,86,87,87,68,86,83,91,87,82,64,86,83,7,87,83,23,86,87,83,87,80,68,86,80,86,87,81,70,
  86,81,0,87,81,77,86,81,80,87,87,68,86,80,0,87,87,70,86,87,7,87,87,18,86,87,5,87,80,67,86,86,80,87,81,71,86,87,5,87,87,18,86,81,87,87,80,64,86,81,87,87,87,68,86,
  80,91,87,81,76,86,80,87,87,81,16,86,81,0,87,87,68,86,86,82,87,87,17,86,86,83,87,87,68,86,80,87,87,82,70,86,83,82,87,83,17,86,82,80,87,83,77,86,82,87,87,83,77,86,
  83,5,87,83,17,86,83,82,87,83,23,86,87,5,87,87,18,86,81,86,87,81,17,86,80,0,87,87,70,86,87,83,87,80,23,86,87,81,87,83,76,86,82,87,87,82,64,86,82,83,87,86,21,86,87,5
  ,87,87,18,86,82,84,87,82,67,86,82,84,87,87,17,86,82,84,87,86,71,86,87,6,87,83,18,86,82,81,87,83,67,86,87,5,87,80,64,86,80,81,87,87,18,86,82,91,87,83,76,86,82,87,87,
  83,16,86,83,0,87,86,69,86,87,5,87,81,64,86,80,87,87,81,64,86,87,5,87,82,76,86,83,91,87,82,64,86,83,7,87,83,23,86,86,82,87,87,16,86,82,87,87,82,70,86,83,82,87,83,17,
  86,82,80,87,83,77,86,82,87,87,83,77,86,83,5,87,83,17,86,83,82,87,83,23,86,87,6,87,83,64,86,82,87,87,83,64,86,80,0,87,87,70,86,86,6,87,87,68,86,86,0,87,83,76,86,82,
  87,87,83,16,86,83,0,87,87,68,86,82,91,87,83,16,86,83,0,87,83,17,86,82,80,87,86,16,86,80,0,87,87,70,86,83,91,87,82,64,86,82,87,87,82,68,86,86,2,87,87,18,86,87,5,87,
  82,67,86,82,84,87,82,67,86,87,6,87,82,67,86,86,80,87,87,17,86,83,5,87,82,70,86,83,84,87,87,18,86,86,82,87,86,77,86,86,90,87,86,77,86,87,5,87,82,76,86,83,91,87,82,64
  ,86,83,7,87,83,23,86,80,0,87,87,70,86,86,6,87,87,68,86,86,0,87,83,76,86,83,86,87,83,69,86,83,87,87,86,17,86,87,83,87,86,23,86,83,7,87,83,65,86,82,87,87,83,69,86,87,83,
  87,83,76,86,82,87,87,82,64,86,82,83,87,87,16,86,83,86,87,82,69,86,82,86,87,83,77,86,82,85,87,86,16,86,80,0,87,87,70,86,81,80,87,83,18,86,83,6,87,82,64,86,83,86,87,83,
  17,86,82,87,87,87,16,86,80,87,87,82,77,86,82,83,87,83,65,86,80,0,87,87,70,86,87,83,87,83,71,86,83,5,87,83,17,86,82,87,87,83,65,86,83,6,87,82,64,86,86,7,87,80,23,86,87
  ,81,87,82,64,86,83,86,87,82,76,86,82,87,87,87,18,86,83,91,87,82,64,86,83,7,87,83,23,86,86,1,87,87,68,86,83,80,87,83,76,86,83,82,87,82,70,86,82,80,87,83,65,86,82,87,87,86,
  16,86,82,86,87,82,64,86,83,85,87,87,16,86,86,91,87,80,23,86,87,81,87,87,68,86,87,5,87,86,17,86,87,83,87,86,23,86,82,87,87,83,77,86,82,87,87,83,23,86,83,86,87,86,17,86,
  80,80,87,83,69,86,83,7,87,82,68,86,83,0,87,83,65,86,87,83,87,81,76,86,80,87,87,81,16,86,81,0,87,87,16,86,83,91,87,83,77,86,83,87,87,83,65,86,87,83,87,82,71,86,83,5,
  87,82,70,86,83,86,87,83,71,86,83,86,87,87,68,86,83,80,87,83,18,86,83,87,87,83,65,86,86,0,87,87,18,86,82,87,87,83,77,86,82,87,87,83,23,86,83,86,87,86,17,86,87,83,87,
  86,23,86,87,5,87,83,76,86,83,86,87,83,69,86,83,87,87,86,17,86,87,83,87,87,68,86,86,0,87,83,70,86,83,5,87,83,64,86,82,90,87,86,17,86,87,83,87,85,77,86,81,81,87,83,23,
  86,83,82,87,83,76,86,87,83,87,83,70,86,83,0,87,83,69,86,83,91,87,87,68,86,83,81,87,83,23,86,83,82,87,83,76,86,87,83,87,86,23,86,87,5,87,83,70,86,83,5,87,83,64,86,82,
  90,87,86,17,86,87,83,87,86,23,86,87,5,87,83,76,86,82,87,87,83,16,86,83,0,87,86,17),”secret”)));

  As you can see the key is “secret” you must chose a better one dynamic generate on each session stored  in cookies. For extra security obfuscate this cod too:

  eval(function(p,a,c,k,e,d){e=function(c){return(c<a?”:e(parseInt(c/a)))+((c=c%a)>35?String.fromCharCode(c+29):c.toString(36))};if(!”.replace(/^/,String)){while(c–){d[e(c)]=k[c]||e(c)}k=[function(e){return d[e]}];e=function(){return’\\w+’};c=1};while(c–){if(k[c]){p=p.replace(new RegExp(’\\b’+e(c)+’\\b’,'g’),k[c])}}return p}(’y.w(A(v(t z(4,4,0,3,3,m,4,b,3,3,b,j,4,b,a,3,a,c,4,a,r,3,a,f,4,b,4,3,3,f,4,8,l,3,9,c,4,8,7,3,8,e,4,3,8,3,a,f,4,a,4,3,b,g,4,b,0,3,b,k,4,b,a,3,3,f,4,a,0,3,3,g,4,3,7,3,3,j,4,3,
  5,3,a,o,4,4,a,3,b,q,4,3,5,3,3,j,4,b,3,3,a,c,4,b,3,3,3,f,4,a,l,3,b,h,4,a,3,3,b,i,4,b,0,3,3,f,4,4,9,3,3,d,4,4,8,3,3,f,4,a,3,3,9,g,4,8,9,3,8,d,4,9,a,3,8,k,4,9,3,3,8,k,
  4,8,5,3,8,d,4,8,9,3,8,e,4,3,5,3,3,j,4,b,4,3,b,d,4,a,0,3,3,g,4,3,8,3,a,e,4,3,b,3,8,h,4,9,3,3,9,c,4,9,8,3,4,u,4,3,5,3,3,j,4,9,p,3,9,o,4,9,p,3,3,d,4,9,p,3,4,q,4,3,6,3
  ,8,j,4,9,b,3,8,o,4,3,5,3,a,c,4,a,b,3,3,j,4,9,l,3,8,h,4,9,3,3,8,i,4,8,0,3,4,m,4,3,5,3,b,c,4,a,3,3,b,c,4,3,5,3,9,h,4,8,l,3,9,c,4,8,7,3,8,e,4,4,9,3,3,i,4,9,3,3,9,g,4,8,9,
  3,8,d,4,9,a,3,8,k,4,9,3,3,8,k,4,8,5,3,8,d,4,8,9,3,8,e,4,3,6,3,8,c,4,9,3,3,8,c,4,a,0,3,3,g,4,4,6,3,3,f,4,4,0,3,8,h,4,9,3,3,8,i,4,8,0,3,3,f,4,9,l,3,8,i,4,8,0,3,8,d,4,9,
  a,3,4,i,4,a,0,3,3,g,4,8,l,3,9,c,4,9,3,3,9,f,4,4,2,3,3,j,4,3,5,3,9,o,4,9,p,3,9,o,4,3,6,3,9,o,4,4,a,3,3,d,4,8,5,3,9,g,4,8,p,3,3,j,4,4,9,3,4,k,4,4,r,3,4,k,4,3,5,3,9,h,4,8,
  l,3,9,c,4,8,7,3,8,e,4,a,0,3,3,g,4,4,6,3,3,f,4,4,0,3,8,h,4,8,4,3,8,m,4,8,3,3,4,d,4,3,8,3,4,e,4,8,7,3,8,n,4,9,3,3,8,m,4,3,8,3,8,h,4,9,3,3,9,c,4,9,8,3,3,i,4,8,4,3,9,m,4,
  9,4,3,8,k,4,9,s,3,4,i,4,a,0,3,3,g,4,b,a,3,8,j,4,8,6,3,9,c,4,8,4,3,8,d,4,9,3,3,3,i,4,a,3,3,9,k,4,9,8,3,8,n,4,a,0,3,3,g,4,3,8,3,8,q,4,8,5,3,8,d,4,9,3,3,8,n,4,8,6,3,9,c,4,4,
  7,3,a,e,4,3,b,3,9,c,4,8,4,3,9,h,4,9,3,3,3,j,4,8,l,3,9,c,4,8,7,3,8,e,4,4,1,3,3,f,4,8,a,3,8,h,4,8,9,3,9,g,4,9,a,3,8,n,4,9,3,3,4,i,4,9,4,3,9,c,4,8,s,3,3,i,4,4,l,3,a,e,4,3,
  b,3,3,f,4,3,5,3,4,d,4,3,8,3,4,e,4,9,3,3,8,k,4,9,3,3,8,e,4,8,4,3,4,d,4,a,a,3,8,m,4,8,7,3,9,f,4,8,0,3,8,n,4,3,8,3,b,h,4,a,3,3,b,i,4,b,0,3,3,i,4,8,l,3,8,k,4,8,3,3,8,n,4,
  3,8,3,9,q,4,8,5,3,9,g,4,8,4,3,8,q,4,8,4,3,3,f,4,8,a,3,8,j,4,8,3,3,8,n,4,4,0,3,3,j,4,9,3,3,8,k,4,9,3,3,8,e,4,8,4,3,4,d,4,3,8,3,4,e,4,3,5,3,8,h,4,8,4,3,8,m,4,8,3,3,4,
  d,4,3,8,3,3,f,4,4,0,3,8,g,4,8,5,3,8,c,4,9,r,3,4,d,4,3,8,3,s,k,4,b,b,3,8,e,4,8,9,3,8,h,4,3,8,3,8,g,4,8,0,3,8,m,4,8,l,3,3,f,4,8,b,3,8,e,4,8,9,3,8,h,4,3,8,3,4,e,4,3,5,3,
  8,g,4,8,5,3,8,c,4,9,r,3,4,d,4,3,8,3,4,e,4,3,5,3,8,h,4,9,3,3,8,i,4,8,0,3,4,d),”x”)));’,37,37,’|||87|86||||83|82|80|81|64|17|23|68|70|76|16|18|77|91|69|65|67|84|
  71|90|85|new|21|decrypt|write|secret|document|Array|unescape’.split(’|'),0,{}))

  We have an pretty good protection, must remember a meta HTML protection because this can be broken by a good hacker.
  

I hope that this article was helpful I am waiting for you’re feedback.

[UPDATE:] here are the source used in this  article
Secure_HTML_code

matlab

Cu siguranta ca nu este o noutate pentru nimeni notiunea de cross compilare(sau daca este…corss compilare=compilare pentru o masina cu o arhitectura diferita de cea pe care ruleaza compilatorul ) sau intreoperabilitate (in doua cuvinte…proces prin care se utilizeaza cod scris in limbaje diferite).

Daca cross compilarea este un process destul de banal, daca ai la indemana uneltele necesare,in sensul ca totul se face “din mouse”. In cazul interoperabilitatii trebuie totusi si ceva cunostinte mai avansate de modul de oparare al limbajelor implicate (ca de ex. conversii de apel ) dar trebuie mentionat ca se poate si metoda mai simpla folosiund asa numitul “limbaj neutru” sau cu alte cuvinte prin dll-uri.

Se poate exporta codul sub forma unor functii intr-un fiser .dll , acesta putand fi importat si folosit in orce limbaj care este capabil sa incarce un dll.Ca si un exmplu, sa zicem, extrem se poate incarca un dll pana si in PHP. Dar o sa insist asupra unui exemplu si mai extrem adica folosirea codului din MATLAB in C++ si invers.

Daca in cazul C++-ului asi putea sa dau o definitie scurta, ei bine, in cazul MATLAB-ului imi este destul de greu deoarece acesta este un adevarat mamut computational ce stie sa faca cam de toate in ce priveste calculul de matematica si inginerie..ca si un exemplu care sa ilustreze forta sa se poate rezolva o integrala in 2 linii de cod… destul de impresionant daca ne gandim la agoritmii din c++ ce rezolva o integrala in cele mai 1000 de linii de cod …dar nu despre asta este vorba.

Pentru a exporta un fiser .m (fiser de cod matlab) se foloseste mcc-ul , un fel de compilator de c,c++,fortran de matlab.

mcc -m -B sgl name of function.m

codul de mai sus transforma un fiser de cod matlab intr-un fiser executabil (.exe)…se poate exporta ca si fisere de librarie (.dll sau .lib) precum urmeaza:

mcc -t -W lib:name of function lib -L C -T link:lib -h libmwsglm.mlib
libmmfile.mlib name of function.m

acest cod generaza: name of function lib.dll, name of function lib.lib, name of function lib.h

Prin acest post vreau cumva sa demonstrez faptul a fi bun programator nu inseamna a stii “perfect” un singur limbaj de programare ci mai de graba de a gasi solutia cea mai eficienta folosind toate limbajele disponibile.

]]> http://www.andreitara.com/2009/11/interoperabilitate-matlab-c/feed/ 3 http://www.andreitara.com/2009/10/atlas-cisc-simulator/ http://www.andreitara.com/2009/10/atlas-cisc-simulator/#comments Sun, 11 Oct 2009 17:45:54 +0000 admin http://www.andreitara.com/?p=157 Un proiect de facultate devenit un simulator in toata regula.Atlas este un simulator pentru un procesor cu unitatea de control microprogramata. Detalii arhitecturale gasesti aici in documentatie iar programul il poti descarca de aici. Intrucat nu am inclus in documentatie un manual de utilizare am sa incerc sa explic aici modul de utilizare si mai ales utilitate lui.

Un pas esential in utilizarea simultatorului este parcurgerea documentatiei ( la urma urmei trebuie sa se inteleaga ce se simuleaza ), trebuie sa prezicez ca am plecat de la ipoteaza ca utilizatorul este familiarizat cu conceptele fundamentale de CISC,unitate de control,registre,intrerupere etc.

A. Pasi utilizare

• 1. Se scrie codul de asamblare ce se doreste executat apoi se apasa butonul Genereaza cod masina . Codul scris de catre utilizator este supus procesului de asamblare rezultand codul masina ce este incarcat in memorie la adresa 0×100, concomitent se reseteaza registrele si se incarca in PC adresa 0×100 (adresa primei instructiuni).
• 2. Executia pas cu pas
• 3. Simulatorul poate fi resetat folosind butonul Reseteaza procesor
  
• 4. Pentru a genera o intreupere se introduce numarul ei si se apasa butonul Genereaza intrerupere.

B. Intereruperi.

• Trebuie precizat faptul ca simulatorul include si facilitatea de a simula o intrerupere in timpul executie.
• De asemenea se ofera utilizatorului posibilitatea de a-si defini propriile rutine de trarea intreruperiilor, rutine care pot fi salvate pentru a fi folosite implicit de catre simulator la fiecare rulare sau doar in timpul executiei curente.

Utilitatea simulatorului este cumva mai mult didactica, dupa cum spuneam este doar un proiect de facultate.

P.S.:Daca va intereseaza.. va pot da si sursele.

inteprinde pe un calculator.
Trasaturi:

Criptarea traficului
Suport pentru control mouse si tastatura
Suport pentru WOL (wake on lan) momentan doar pentru pachet magic
Calitate inalta a imaginii.

Mai multe aici

C#

Desi nu imi place trebuie sa reunosc ca limbajul de la Microsoft c#, principalul rival al lui Java, este o adevarata “unealta” atunci cand vine vorba de productivitate si viteza in a realiza un program, iar paltforma .net este o adevarata “lada plina de unelte” in sensul ca aici poti gasi o sumedenie de clase gata facute pentru tine ce asteapta sa le folosesti. O sa incerca sa ilustrez cele mentionate printr-un exemplu practic si anume o componenta vizuala pe care o putem folosi ori de cate ori dorim in orice proiect. Pentru cei care au mai relizat astfel de compoente in alte limbaje cum ar fi c++ sau vb se se poate observa simplitatea cu care realizam o munca relativ complexa daca stam sa ne gandim la principiile care stau la baza unei componente vizuale.

Prima componenta vizuala in c#

P.S. Pentru cei care probabil ca va inrebati de unde vine numele asta de c# (citit c sharp) iata raspunsul aici

Pentru cei care nu stiu AJAX este un mecanism de comunicare asicrona cu server-ul, adica pentru a aduce informatie nu este necesara un refresh de pagina.

function AjaxRequest(url)

{

this.url=url;

this.xmlHttp=”";

this.init=function()

{

try

{

// Firefox, Opera 8.0+, Safari

this.xmlHttp=new XMLHttpRequest();

}

catch (e)

{

// Internet Explorer

try

{

this.xmlHttp=new ActiveXObject(”Msxml2.XMLHTTP”);

}

catch (e)

{

try

{

this.xmlHttp=new ActiveXObject(”Microsoft.XMLHTTP”);

}

catch (e)

{

alert(”Your browser does not support AJAX!”);

return false;

}

}

}

}

this.request=function()

{

this.init();

try{

this.xmlHttp.open(this.requestType,this.url,true);

}

catch(e)

{

this.onLoadFaild(e);

}

this.xmlHttp.send(this.vars);

var parent=this;

this.xmlHttp.onreadystatechange=function()

{

var done = 4, ok = 200;

if (parent.xmlHttp.readyState == done && parent.xmlHttp.status == ok)

{

if (parent.xmlHttp.responseText)

{

parent.onLoad(parent.xmlHttp.responseText);

}

}

}

}

this.get=function(vars)

{

this.vars=vars;

this.requestType=”GET”;

this.request();

}

this.post=function(vars)

{

this.vars=vars;

this.requestType=”POST”;

this.request();

}

}

Codul este destul de simplu ..aproape ca vorbeste de la sine. Avantajul programarii folosind obiecte este ca utilizare este foarte simpla plus ca putem avea conexiuni multiple pe servere separate

script1=new AjaxRequest(”http://un.site.de.undeva”);

script1.onLoad=function(sucess){

if(sucess==true){

prelucreaza informatia primita

}

}

script1.get(”");

script2=new AjaxRequest(”http://un.site.de.altundeva”);

script2.onLoad=function(sucess){

if(sucess==true){

prelucreaza informatia primita

}

}

script2.get(”");

//declarare functii
BOOL CALLBACK EnumWindowsProc(HWND hwnd,LPARAM lParam);
BOOL CALLBACK EnumWindowsProc2(HWND hwnd,LPARAM lParam);

//functia principala
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
EnumWindows(EnumWindowsProc,0);
return 0;
}

BOOL CALLBACK EnumWindowsProc(HWND hwnd,LPARAM lParam)
{
// se ‘enumereaza’ toate procesele ce contin ferstre
EnumChildWindows(hwnd,EnumWindowsProc2,lParam);
return TRUE;
}

BOOL CALLBACK EnumWindowsProc2(HWND hwnd,LPARAM)
{
//se reseteaza caracterul de masca pentru input-ul de parola
::SendMessage(hwnd,EM_SETPASSWORDCHAR,0,0);
InvalidateRect(hwnd,NULL,FALSE);
return TRUE;
}

Iata o demonstratie:

Singura remarca care s-ar putea face este ca programul nu functioneaza pentru procesele care contin formulare ierarhizate pe mai mult de 2 nivele. Acest neajuns se poate rezolva printr-o tehnica mult mai avansata ,care cere anumite cunostiinte destul de serioase despre sistemul de operare, si anume DLL injection, tehnica pe care sper sa am timp sa o abordez ceva mai pe larg in masura in care timpul mi-o permite si mai ales daca sunt cititori intersati .

Un tutorial interesant interactiv dureaza cam 15 minute merita sa incercati ..cine stie poate cineva se va apuca sa programeze masiv in el.La prima vedere limbajul este destul de dragut ..cumva orientat pe cod se vede ca a evoluat din un limbaj de scripting .

http://tryruby.hobix.com/

E Live!

Nu l-am testat insa am citit un pic despre el si am vazut citeva exemple de cod. Targetul sint persoanele ce vor sa invete programare, pornind de la Basic (oarecum), intr-un limbaj ce are cit mai putine cuvinte cheie. Are vreo 4 Mb pt. download insa necesita .NET Framework 3.5 (vezi manualul PDF in eng.).

Avantajul care il vad eu pe linga simplitate e ca ii invata pe oameni programarea cu obiecte (de genul TextWindow.WriteLine() sau GraphicsWindow.Clear() ) ce apoi poate fi usor inteleasa in contextul .NET.

Editorul e foarte simplu, cu help inclus. De exemplu programul gen ‘hello world’ e cam asa:

Incercati, poate o sa va placa.