Class MySQLConnection
{
// ———————–
// variable initialisation
// ———————–
var $SERVER = “hostname”; // Server name
var $USER = “dbusername”; // Database username
var $PWD = “dbpassword”; // Database password
var $DBNAME = “dbname”; // Database name
var $DBCONN = “”;
// —————————
// flag an error and terminate
// —————————
function db_error($strText)
{
$errno = mysql_errno();
$errmsgmsg = mysql_error();
echo “ERROR: $strText Error: ($errno) $errmsg )”;
exit;
}
// ——————————-
// attempt database initialisation
// ——————————-
function init_db ()
{
// create connection string and attempt connection
$dbconn = mysql_connect($this->SERVER,$this->USER,$this->PWD);
if (!$dbconn) { $this->db_error(”Database Connection Failed”); }
// attempt to open the chosen database
if (!mysql_select_db($this->DBASE,$dbconn)) { $this->error(”Unable To Select Database”); }
// make the connection available
$this->DBCONN = $dbconn;
}
} // Class MySQLConnection
?>

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At least there is a way around this using PHP: Removing HTML Tags from Strings and PHP: Avoiding mySQL Injections. There are also a few other tricks up our sleeves to combat this sort of activity but more investigation and research needs to be carried out on the effective mechanisms for securing input data. One possibility would be to allow only text based input but that could ultimately prove difficult in a multi-lingual environment.

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Fortunately, PHP has the command strip_tags to remove these tags.

$myString = "<p><a href='gohere.html'>This is some text</a></p>";
$newString = strip_tags($myString);

You can allow specified tags by using the option parameter of strip_tags, so to include the <p> tag in the string above but remove the <a> tag use this command

$newString = strip_tags($myString,"<a>");

It would also be useful to use the mysql_real_escape_string in this instance to avoid SQL Injections.

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On the page to activate Session Handling use

session_start();

You can always check the Session is working by obtaining the Session ID using

session_id();

Now variables can be registered and used using the form

$_SESSION['variable'] = “value”;

Removal of a session variable can be performed using

session_unset( $_SESSION['variable'] );

Alternatively just calling session_unset(); would remove all session variables but maintain the session ID.

To finally close the session use

session_destroy();

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<!--p
$url = “www.yourchosendomain.com”;
$apikey = “putyourapikeyhere”;
$service = “http://api.technorati.com/bloginfo?key=” . $apikey . “&url=” .urlencode($url);
// call the service and get results
$xmlresult = file_get_contents($service);
// results found?
if ($xmlresult === false)
{ die(”Unable to process request”); }
// attempt to process xml
$error = null;
if (!$dom = domxml_open_mem($xmlresult, DOMXML_LOAD_PARSING ))
{ die(”Unable to parse XML”); }
else
{
echo get_details( $dom,”name” );
echo get_details( $dom,”url” );
echo get_details( $dom,”inboundblogs” );
echo get_details( $dom,”rank” );
}
// search elements until target tag found
function get_details( $dom,$searchtag )
{
$root = $dom->document_element();
$node = $root->first_child();
$myitem = $root->get_elements_by_tagname($searchtag);
// loop through elements
for($i=0;$i { echo “<p>” . $searchtag . ” is [" . $myitem[$i]->get_content() . “]</p>”; }
}
?>

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<!--p
// xml input file
$xmldoc = “sitemap.xml”;
// test to open file
if ( !$dom = domxml_open_file($xmldoc) )
{
echo “The file cannot be loaded.”;
}
else
{
// show top level item
$elem = $dom->document_element();
print_r( $elem );
}
?>

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• Requirements Analysis

Pull together information to understand the problem domain and document the requirement.

• Conceptual Design

Identify Entities and high-level Relationships between them.

• Logical Design

Identify Attributes, Constraints, Keys and perform Normalisation.

• Physical Design

Translate the logical design to physical SQL commands and tables. Specify all the tables (from the entities) and the features of the tables including columns (from the Attributes), Primary Keys and Foreign Keys (from the relationships).

• Testing

Ensure suitability of system and identify potential bugs or design errors.

• Review

Highligh made during development of system together with a final evaluation of the tools and techniques.

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• First Normal Form (1NF) requires no duplicate records in a proposed table and no repeating groups of similar information. Each Attribute must hold an atomic value and there must be a candidate key.

• Second Normal Form (2NF) requires First Normal Form. If the proposed table has no composite candidate keys (i.e. a single Attribute is the candidate key) then it qualifies for 2NF. However, if a composite candidate key exists then Attributes other than the candidate key must not be dependent upon part/or the entire candidate key.

• Third Normal Form (3NF) requires Second Normal Form. In addition, there must be no non-trivial Functional Dependencies between non-prime key Attribute. Basically, this means that all the Attributes that are not part of a primary key are compared with each other to ensure uniqueness.

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Bots are ideal for this repetitive automated activity by taking a work queue (a given list of URLs) and producing a set of information that can be passed to the next stage in the submission process. Even though these techniques are called bots they are essentially just software programs that run either at a scheduled time or in a loop constantly checking the work queue.

In addition to the usual information a bot can periodically extract additional words from body text itself by parsing out html tags, removing stop words and building a word frequency table. A word frequency table is simply a list of words with the number of times a word appears in the given text.

Recently I have been working to find a way of automatically extracting information for a given URL by accessing the html from a submitted URL, parsing the relevant information and using this information as input to the submission process. Information is often placed as meta tags in the HEAD section of html but I have found this process so far to somewhat hit and miss as some sites include the information and others do not. For those that do not an additional ways needs to be identified to provide a suitable link title and description - it may be the case that this will always require some user intervention but further analysis should identify more.

The bot also needs to be aware of the period of time since the last change of a web page to ensure that valuable information or updates is not missed and that processing power isn’t wasted on a link that does not change very much. The way we can address this is by producing a hash for a page and comparing it with a previously stored hash.

A hash, simply put is the result of a consistent algorithm applied to information. MD5 is a well known hash mechanism that I may investigate in a later article. For now a simple example to demonstrate a hash would be to calculate a check digit by taking letter values of a phrase, adding them together then finding the modulus using a number say 27 (allowing 26 letters and the space), in the example the first two phrases give the same answer however the third phrase with one letter different gives a much different check digit.

I have a working program up and running - but not in bot mode yet -but can be initiated manually. I need to add the loop code to continually check the work queue for submitted URLs.

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