PHP - XML Exercise

SimpleXML

Since PHP 5.0, a very simple way of accessing and updating XML has been available - SimpleXML. This set of functions allows XML strings and files to be converted to objects so that nodes (elements) in the tree can be accessed just with object references. In PHP the equivalent of the . in Java is -> so $x->y accesses the y child of $x. Attributes are accessed as an associative array $x['p1']. This provides a much more natural way of navigating in a tree structure than that provided by the W3C DOM interface based on childNode() etc.

• PHP Manual
• ZEND article - shows how much easier SimpleXML is to use than the W3C DOM interface with a simple example.
• PHP wiki article

Weather.com

To make this exercise more dynamic, we will use The Weather Channel at www.weather.com. This site provides live weather date for places around the world, but it also provides an API so that the data can be read into a server script for further processing. The interface uses a URL-line to send parameters to the service and the return is an XML document. To access the service, you must apply for a partner identifier and key, which enables the Weather Channel to track usage made by the partners. This key data should not be revealed to outsiders.

The guide sets out the terms and conditions for use of this data, which include links back to the Weather Channel site. These would have to be followed in any commercial use of the data but I am assuming that for educational purposes, this requirement is fullfilled by the general links on this page. There are also a number of constraints on refresh rates which require caching of data to reduce the hit rate. The code provide here is for teaching purposes only and would require a lot more work to create a commercial-strength application.

• The Weather Channel
• Bristol weather
• Local copy of the API Guide

Weather from a file

• Bristol weather from 13th December at 6.29 PM
• Simple display of this data
• The PHP script
• All 64x64 icons zipped

Task 1

• Save the xml file to your own workspace.
• Select the PHP script text and save to a text editor such as notepad or PFE32 and save it.
• unzip the images into a folder called images.
• Execute your version of the script.
• Add one more item of information from the XML file to your display.

Weather from a remote source

• Simple display of data for Bristol
• The PHP script
• A couple of scripts zipped

Task 2

• Unzip the two scripts bristol.php and weatherKeys.php
• Test your version of this application
• Amend the script to include the data you added in task 1.
• Using the weather.com site, look up the weather in a place of interest to you. Note the code following local/ in the URL.
• Replace 'UKXX0025' in the php script with the code for your chosen location.
• The guide states that the icon should link to the weather.com site. Read the guide to identify how this should be done, and add this link. You will need the partner id from the weatherKeys file.
• Generalise the script so that any code can be entered as part of the URL.