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Archive:PHP and MySQL Programming/XML and PHP

2008-04-25T00:27:33Z

75.62.254.22: fixed typo

== Introduction ==

XML (eXtensible Markup Language) is used in mainstream development. It might have started off as an attempt at a web standard, but is now used even in more traditional applications as a document standard. For example, the Open Document Format employed by Sun in their StarOffice and OpenOffice suites is based on XML pawan .

Because of its wide-spread use in the IT industry, it is fitting that we as PHP developers know how to make use of XML files in our PHP applications.

== XML Structure ==

Since XML documents are extensible, there are no limits to the tags that you can create to define data with. Here is an example of a simple XML document :

<?xml version="1.0"?>
<document>
<title>Isn't this simple!</title>
<body>XML is as simple as pie. :-)</body>
</document>

The reason that it looks so simple, is because it is so simple! Just as in HTML, elements are enclosed by angled brackets : "<" and ">", where the start element differs from the end element by the exclusion of a forward slash : "/".

== Creating an XML Parser in PHP ==

=== Defining the XML Parser ===

In PHP, you define an XML Parser by using the xml_parser_create() function as shown below.

<?
$parser = xml_parser_create(ENCODING);
?>

You can think of the $parser variable in terms of a parsing engine for the XML document. Note that the ENCODING can be either :

1. ISO-8859-1 (default)

2. US-ASCII

3. UTF-8

=== Defining the Element Handlers ===

Element handlers are defined by means of the xml_set_element_handler() function as follows :

<?
xml_set_element_handler(XML_PARSER, START_FUNCTION, END_FUNCTION);
?>

The three arguments accepted by the xml_set_element_handler() function are :

1. XML_PARSER - The variable that you created when you called the xml_parser_create() function.

2. START_FUNCTION - The name of the function to call when the parser encounters a start element.

3. END_FUNCTION - The name of the function to call when the parser encounters an end element.

e.g. :

<?
$parser = xml_parser_create();
xml_set_element_handler($parser, "startElement", "endElement");
?>

=== Defining Character Handlers ===

Character handlers are created by means of the set_character_handler() function as follows :

<?
xml_set_character_handler(XML_PARSER, CHARACTER_FUNCTION);
?>

The two arguments accepted by the set_character_handler() function are :

1. XML_PARSER - The variable that you created when you called the xml_parser_create() function.

2. CHARACTER_FUNCTION - The name of the function to call when the parser encounters character data.

=== Starting the Parser ===

To finally start the parser, we call the xml_parse() function as follows :

<?
xml_parse(XML_PARSER, XML);
?>

The two arguments accepted by the xml_parse() function are :

1. The variable that you created when you called the xml_parser_create() function.

2. The XML that is to be parsed.

e.g. :

<?
$f = fopen ("simple.xml", 'r');
$data = fread($f, filesize("simple.xml"));
xml_parse($parser, $data);
?>

=== Cleaning Up ===

After parsing an XML document, it is considered good practice to free up the memory that is holding the parser. This is done by calling the xml_parser_free() function as follows :

<?
xml_parser_free(XML_PARSER);
?>

=== Example ===

<?
# --- Element Functions ---

function startElement($parser, $name, $attributes){
# ... some code
}

function endElement ($parser, $name){
# ... some code
}

function characterData ($parser, $data){
# ... some code
}

function load_data($file){
$f = fopen ($file, 'r');
$data = fread($f, filesize($file));
return $data;
}

# --- Main Program Body ---
$file = "simple.xml";
$parser = xml_parser_create();
xml_set_element_handler($parser, "startElement", "endElement");
xml_set_character_data_handler($parser, "characterData");
xml_parse ($parser, load_data($file));
xml_parser_free($parser);
?>

== Parsing XML Documents ==

We have seen the steps needed to successfully parse a XML document with PHP. Lets take a moment to reflect on how these steps are interconnected.

When a XML parser is initialized, php will go through the XML file. When a starting tag is found, a predefined function created by you, the programmer, is called. The same thing happens when php encounters the text between tags, and the end tags.

Here is a complete example of parsing XML documents. This example is a RSS reader which can be used to display News Articles from any RSS feed which conforms to RSS 1.0 standards.

=== Example ===
<html>
<head>
<title> Google Articles </title>
</head>
<body>
<h2>Google Articles</h2>
<dl>
<?php

$insideitem = false;
$tag = "";
$title = "";
$description = "";
$link = "";

function startElement($parser, $name, $attrs) {
global $insideitem, $tag, $title, $description, $link;
if ($insideitem) {
$tag = $name;
}
elseif ($name == "ITEM") {
$insideitem = true;
}
}

function endElement($parser, $name) {
global $insideitem, $tag, $title, $description, $link;
if ($name == "ITEM") {
printf("<dt><b><a href='%s'>%s</a></b></dt>",
trim($link),trim($title));
printf("<dd>%s</dd>", trim($description));
$title = "";
$description = "";
$link = "";
$insideitem = false;
}
}

function characterData($parser, $data) {
global $insideitem, $tag, $title, $description, $link;
if ($insideitem) {
switch ($tag) {
case "TITLE":
$title .= $data;
break;
case "DESCRIPTION":
$description .= $data;
break;
case "LINK":
$link .= $data;
break;
}
}
}

$xml_parser = xml_parser_create();
xml_set_element_handler($xml_parser, "startElement", "endElement");
xml_set_character_data_handler($xml_parser, "characterData");
# $fp = fopen("http://www.newsforge.com/index.rss", 'r')
$fp = fopen("http://news.google.co.za/nwshp?hl=en&tab=wn&q=&output=rss", 'r')
or die("Error reading RSS data.");
while ($data = fread($fp, 4096)) {
xml_parse($xml_parser, $data, feof($fp))
or die(sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($xml_parser)),
xml_get_current_line_number($xml_parser)));
}
fclose($fp);
xml_parser_free($xml_parser);
?>
</dl>
</body>
</html>

== Dumping Database Contents into an XML File ==

[[../Common Functions and Operators/|Previous: Common Functions and Operators]] | [[../|TOC]]

[[Category:PHP and MySQL Programming|{{SUBPAGENAME}}]]

Lunar Boom Town/Fabbers R Us

2008-04-12T21:44:06Z

75.62.113.75: /* Possibly Applicable Information Resources */

==Business Model==
It is cheaper and more efficient to import or create generic materials which can be used to manufacture items on demand than it is to make people wait for delivery or stock excess items in anticipation of customer demand.

==Products and Services==

Operate a fab machine to create useful items on demand.
:An open community, Fab@Home[http://www.fabathome.org/wiki/index.php?title=Main_Page] is already prototyping and experimenting with open source fabbers, materials, and products.[http://www.fabathome.org/wiki/index.php?title=Fab%40Home:Design_Library]

:Sell supplies and designs to others operating fab machines.

==Possibly Applicable Information Resources==
http://www.fabathome.org/wiki/index.php?title=Main_Page
http://reprap.org/
http://smay.okstate.edu/

[[Category:Lunar Boom Town]]

Lifeboat Foundation

2007-10-14T21:32:16Z

75.62.111.57:

[[Image:Lifeboatfoundation.jpg|thumb|350px|right|The Lifeboat Foundation advocates the creation of space colonies to serve as 'backup drives' for the human race.]]

'''The Lifeboat Foundation''' is a non-profit organization dedicated to helping humanity survive [[existential risk]]s and possible misuse of increasingly powerful technologies, including [[genetic engineering]], [[nanotechnology]], and [[AI|robotics/AI]], in the event of a [[technological singularity]].

The Lifeboat Foundation is pursuing a variety of options, including helping to accelerate the development of technologies to defend humanity, new methods to combat viruses (such as RNA interference and new vaccine methods), effective nanotechnological defensive strategies, and even self-sustaining [[space colonies]] in case the other defensive strategies fail.

The Lifeboat Foundation was formed with the ethical premise that decreasing the likelihood of human extinction is the activity with the most positive [[utility]] on the planet today. In recent years, several prominent public figures have stepped forward strongly in favor of mitigating extinction risks. Oxford philosopher [[Nick Bostrom]] writes, “For standard utilitarians, priority number one, two, three and four should consequently be to reduce [[existential risk]]. The utilitarian imperative “Maximize expected aggregate utility!” can be simplified to the maxim “Minimize existential risk!”. <ref>Nick Bostrom, "[http://www.nickbostrom.com/astronomical/waste.html Astronomical Waste: The Opportunity Cost of Delayed Technological Development]", Preprint, ''Utilitas'' Vol. '''15''', No. 3, pp. 308-314</ref>

==Administration and advisory board==

The President and Founder of the Lifeboat Foundation is [[Eric Klien]], its International Spokesperson is [[Philippe van Nedervelde]], its Fundraising Director, North America is [[Michael Anissimov]], and its Director of Long-term Strategy is Michael Vassar. The Lifeboat Foundation is [[tax exemption|tax exempt]] under [[501(c)(3)|Section 501(c)(3) of the United States Internal Revenue Code]].

The organization also has a very large Scientific Advisory Board (SAB), composed of 370 members as of August 2007. This includes philosophers, economists, biologists, nanotechnologists, AI researchers, educators, policy experts, engineers, lawyers, ethicists, futurists, neuroscientists, physicists, and space experts. The SAB includes [[Ray Kurzweil]] and [[Nobel Prize]] winners [[Clive Granger]] and [[Wole Soyinka]].

==Lifeboat Foundation Programs==

The Lifeboat Foundation's Scientific Advisory Board is working on a number of programs to assess risks, negate them ("shields"), and survive catastrophic events ("preservers"):

*[http://lifeboat.com/ex/asteroid.shield AsteroidShield]
*[http://lifeboat.com/ex/bio.shield BioShield]
*[http://lifeboat.com/ex/nano.shield NanoShield]
*[http://lifeboat.com/ex/security.preserver Security Preserver]
*[http://lifeboat.com/ex/space.habitats Space Habitats]

Many future programs are in the works, including programs to prevent risks from AI, particle accelerator mishaps, and to maintain communications networks in case of disaster.

==See also==

Related topics:
*[[existential risk]]
*[[molecular nanotechnology]]
*[[utility fog]]
*[[seed AI]]
*[[space colonization]]
*[[space and survival]]
*[[biosecurity]]
*[[technological singularity]]

==References==
<references/>

==External links==

*[http://lifeboat.com/ex/main Lifeboat Foundation]
*[http://www.nickbostrom.com/existential/risks.html Existential Risks: Analyzing Human Extinction Scenarios] by Nick Bostrom
*[http://www.nickbostrom.com/astronomical/waste.html Astronomical Waste: The Opportunity Cost of Delayed Technological Development] by Nick Bostrom
*[http://answers.yahoo.com/question/;_ylt=AtjblpXOSMXPaKrJ2N9lui8jzKIX?qid=20060704195516AAnrdOD How can the human race survive the next hundred years?] - question on Yahoo Answers by Stephen Hawking
*[http://www.wired.com/wired/archive/8.04/joy.html Why the future doesn't need us] by Bill Joy
*[http://query.nytimes.com/gst/fullpage.html?res=9C02E6D9163FF93BA25756C0A9659C8B63 It Was Fun While It Lasted] by Martin Rees
*[http://paulboutin.weblogger.com/stories/storyReader$1439 Biowar for Dummies] by Paul Boutin
*[http://www.acceleratingfuture.com/michael/blog/?cat=21&paged=2 Accelerating Future] - regularly updated blog that discusses existential risks
*[http://www.oceania.org/] - the Atlantis Project. The earlier efforts of Eric Klien

[[Category:Risk]]
[[Category:Space colonization]]

Lifeboat Foundation

2007-10-06T20:17:34Z

75.62.0.211:

[[Image:Lifeboatfoundation.jpg|thumb|350px|right|The Lifeboat Foundation advocates the creation of space colonies to serve as 'backup drives' for the human race.]]

'''The Lifeboat Foundation''' is a non-profit organization dedicated to helping humanity survive [[existential risk]]s and possible misuse of increasingly powerful technologies, including [[genetic engineering]], [[nanotechnology]], and [[AI|robotics/AI]], in the event of a [[technological singularity]].

The Lifeboat Foundation is pursuing a variety of options, including helping to accelerate the development of technologies to defend humanity, new methods to combat viruses (such as RNA interference and new vaccine methods), effective nanotechnological defensive strategies, and even self-sustaining [[space colonies]] in case the other defensive strategies fail.

==Administration and advisory board==

The President and Founder of the Lifeboat Foundation is [[Eric Klien]], its International Spokesperson is [[Philippe van Nedervelde]], its Fundraising Director, North America is [[Michael Anissimov]], and its Director of Long-term Strategy is Michael Vassar. The Lifeboat Foundation is [[tax exemption|tax exempt]] under [[501(c)(3)|Section 501(c)(3) of the United States Internal Revenue Code]].

The organization also has a very large Scientific Advisory Board (SAB), composed of 370 members as of August 2007. This includes philosophers, economists, biologists, nanotechnologists, AI researchers, educators, policy experts, engineers, lawyers, ethicists, futurists, neuroscientists, physicists, and space experts. The SAB includes [[Ray Kurzweil]] and [[Nobel Prize]] winners [[Clive Granger]] and [[Wole Soyinka]].

==Lifeboat Foundation Programs==

The Lifeboat Foundation's Scientific Advisory Board is working on a number of programs to assess risks, negate them ("shields"), and survive catastrophic events ("preservers"):

*[http://lifeboat.com/ex/asteroid.shield AsteroidShield]
*[http://lifeboat.com/ex/bio.shield BioShield]
*[http://lifeboat.com/ex/nano.shield NanoShield]
*[http://lifeboat.com/ex/security.preserver Security Preserver]
*[http://lifeboat.com/ex/space.habitats Space Habitats]

Many future programs are in the works, including programs to prevent risks from AI, particle accelerator mishaps, and to maintain communications networks in case of disaster.

==See also==

Related topics:
*[[existential risk]]
*[[molecular nanotechnology]]
*[[utility fog]]
*[[seed AI]]
*[[space colonization]]
*[[space and survival]]
*[[biosecurity]]
*[[technological singularity]]

==References==
<references/>

==External links==

*[http://lifeboat.com/ex/main Lifeboat Foundation]
*[http://www.nickbostrom.com/existential/risks.html Existential Risks: Analyzing Human Extinction Scenarios] by Nick Bostrom
*[http://www.nickbostrom.com/astronomical/waste.html Astronomical Waste: The Opportunity Cost of Delayed Technological Development] by Nick Bostrom
*[http://answers.yahoo.com/question/;_ylt=AtjblpXOSMXPaKrJ2N9lui8jzKIX?qid=20060704195516AAnrdOD How can the human race survive the next hundred years?] - question on Yahoo Answers by Stephen Hawking
*[http://www.wired.com/wired/archive/8.04/joy.html Why the future doesn't need us] by Bill Joy
*[http://query.nytimes.com/gst/fullpage.html?res=9C02E6D9163FF93BA25756C0A9659C8B63 It Was Fun While It Lasted] by Martin Rees
*[http://paulboutin.weblogger.com/stories/storyReader$1439 Biowar for Dummies] by Paul Boutin
*[http://www.acceleratingfuture.com/michael/blog/?cat=21&paged=2 Accelerating Future] - regularly updated blog that discusses existential risks

[[Category:Risk]]
[[Category:Space colonization]]

Lifeboat Foundation

2007-10-02T18:38:20Z

75.62.0.211: