PHP is a server-side scripting language used to create dynamic web pages. You create pages via PHP and HTML. When a visitor opens a web page, the server will process the PHP instructions and then send the processing results to the visitor's browser, just like ASP or ColdFusion. However, unlike ASP or ColdFusion, PHP is cross-platform and open source. PHP can be executed under Windows NT and many different Unix versions. It can also be compiled as an Apache module, or as a CGI binary. PHP is especially lightweight and convenient when compiled into the Apache module. It doesn't have any of the burden of tedious programming, so results can be returned quickly, and there's no need to tweak mod_perl to keep the server's memory image small. In addition to being used to generate the content for your web pages, PHP can also be used to deliver HTTP headers. You can set cookies, manage authorizations, and redirect users to new pages. It also has good access to many databases and ODBC. It also integrates with a variety of external libraries, allowing you to do almost anything from creating PDF files to parsing XML. The PHP code is embedded in the Web page, so you don't have to set up a special development environment or IDE for it. You mark PHP code with (you can also set PHP to use the ASP form of the mark or even use it). The PHP engine will handle anything between these flags. The syntax of the PHP language is very similar to C and Perl. You don't need to declare variables before using them. Creating arrays and hashes (associative arrays) is also fast. PHP's initial object-oriented features also provide an easy way to organize and encapsulate code. Although PHP runs fastest when embedded inside Apache, there are instructions on how to seamlessly integrate it with Microsoft IIS and Netscape Enterprise Server on the PHP related site. If you don't have PHP yet, you can download it from its official website. A user manual covering all PHP functions and features can also be found there. Create your own commands Because PHP scripts are written in HTML documents, you don't have to use a special editor to create the page. However, you must execute PHP on a server that supports PHP. This is easy to do if you are using your own server. If the page is processed through an ISP service, you need to contact your ISP's customer service team and ask them to help you install PHP. For Unix systems, you must have basic Unix skills, such as using make and a C compiler. On your system, you will also need an ANSI C compiler, and a Web server. For Windows 95/NT, you need one of the following servers: Microsoft Personal Web Server, Microsoft Internet Information Server 3 or 4, Apache 1.3.x, or Omni HTTPd 2.0b1. You can find all the information about installing and setting up PHP on the PHP website. David Sklar is Chief Information Officer at Student.Net Publishing. Adam Trachtenberg is associate director of product at Student.Net Publishing.
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