NadeauSoftware.com articles from all months, all years

Don't bother using CSS optimization to speed up a web site

Dave_Nadeau — Thu, 19 Jun 2008 19:15:25 -0700

CSS optimization (a.k.a. minimization, cleaning, or tidying) removes white-space and comments, merges similar selectors, removes redundant properties, and cleans up a CSS file to make it more compact. The optimized file is smaller and faster to send to a site visitor. This article uses the CSS Tidy optimizer and measures the improvement first for CSS from 30 popular web sites, and second for CSS from 30 site themes for the Drupal content management system. Unfortunately, in all cases the improvement is small and will not have a noticeable impact on page load times.

PHP tip: How to convert a relative URL to an absolute URL

Dave_Nadeau — Tue, 27 May 2008 21:39:08 -0700

An absolute URL is complete and ready to use to download a web file. But web pages often include incomplete relative URLs with missing parts, such as an "http" or host name, or the first part of a file path. These parts need to be filled in by copying them from a base absolute URL. This article shows how and includes code to do it.

PHP tip: How to parse and build URLs

Dave_Nadeau — Tue, 27 May 2008 21:35:20 -0700

Splitting apart and rebuilding URLs is essential for link checkers, phishing detectors, spiders, and so on. PHP's standard parse_url( ) function works pretty well to parse simple URLs, but it has problems with complex and relative URLs. Once split apart, there is no standard PHP function to reassemble the URL properly. This article reviews the official syntax of URLs, discusses URL parsing complexities, and provides new PHP functions to split apart a URL and join its parts together again.

Java tip: How to list and find threads and thread groups

Dave_Nadeau — Sun, 20 Apr 2008 10:38:14 -0700

Java's threads are essential for building complex applications, but thread control is split across several classes in different packages added at different times in the JDK's history. This tip shows how to connect these classes together to find threads and thread groups, and get thread information.

PHP tip: How to extract keywords from a web page

Dave_Nadeau — Sun, 13 Apr 2008 10:12:00 -0700

Web page keywords characterize the page's topic for a search engine. Extracting keywords requires that you recognize the page's character encoding, strip away HTML tags, scripts, and styles, decode HTML entities, and remove unwanted punctuation, symbols, numbers, and stop words. This article shows how.

Java tip: How to get CPU, system, and user time for benchmarking

Dave_Nadeau — Thu, 20 Mar 2008 08:38:32 -0700

Performance optimization requires that you measure the time to perform a task, then try algorithm and coding changes to make the task faster. Prior to Java 5, the only way to time a task was to measure wall clock time. Unfortunately, this gives inaccurate results when there is other activity on the system (and there always is). Java 5 introduced the java.lang.management package and methods to report CPU and user time per thread. These times are not affected by other system activity, making them just what we need for benchmarking. This tip shows how to use them to benchmark your application.

Java tip: How to read files quickly

Dave_Nadeau — Sun, 24 Feb 2008 08:05:33 -0800

Java has several classes for reading files, with and without buffering, random access, thread safety, and memory mapping. Some of these are much faster than the others. This tip benchmarks 13 ways to read bytes from a file and shows which ways are the fastest.

Java tip: How to get a web page

Dave_Nadeau — Sun, 06 Jan 2008 08:19:27 -0800

The starting point for building a link checker, web spider, or web page analyzer is, of course, to get the web page from the web server. Java's java.net package includes classes to manage URLs and to open web server connections. This tip shows how to use them to a get text, image, audio, or data file from a web server.

PHP tip: How to extract URLs from a web page

Dave_Nadeau — Thu, 03 Jan 2008 11:20:03 -0800

URL extraction is at the core of link checkers, search engine spiders, and a variety of web page analysis tools. While <a> and <img> elements are primary sources of URLs, there are more than 70 element attributes with URLs in HTML, XHTML, WML, and assorted HTML extensions. This tip shows how to extract URLs from all of these.

PHP tip: How to extract URLs from a CSS file

Dave_Nadeau — Thu, 03 Jan 2008 11:12:49 -0800

Though HTML is usually the focus for extracting URLs for a link checker or analysis tool, CSS files also include URLs. The CSS @import rule uses a URL to include another CSS file, and many style properties include a URL to load an image or other content. This tip shows how to scan a CSS file and extract its URLs.