12.1 What Is Server-Side Development?

Chapters 1 and 8 introduced the basic client-server model at the heart of the web. So far, this book has been almost completely focused on the client-side of that model, that is, with the technologies of HTML, CSS, and JavaScript. While contemporary web development is heavily client-side focused, the server-side of the model is still essential.

12.1.1 Front End versus Back End

You may recall that the terms “front end” and “back end” are often used interchangeably with “client-side” and “server-side” when it comes to web development. HTML, CSS, and JavaScript are the technologies of the front-end and are focused on the presentation and control of the web application’s user interface.

What are the technologies of the back end and what are they used for? The answer to these questions has varied over time. Server-side technologies provide access to data sources, handled security, and allowed web sites to interact with external services such as payment systems. Traditionally, most sites made use programs running on the server-side to programmatically generate the HTML sent to the browser. Figure 12.1 illustrates this traditional division between the responsibilities of the front end and the back end.

The image contains 5 steps, 2 browser windows and 1 server window. The image shows Front-end versus back-end.

Figure 12.1 Full Alternative Text

In contemporary web development, such traditional approaches are still being used, but no longer universally so. With the wide-spread adoption of JavaScript-focused web applications, back ends have become “thinner”. That is, today many web sites are principally front ends; back end processing is used only for implementing the external APIs that provide data to the front end, for handling security, and for interacting with external services that do not have any front-end API.

12.1.2 Common Server-Side Technologies

There are many different server-side technologies. The most common include the following:

ASP (Active Server Pages). This was Microsoft’s first server-side technology (also called ASP Classic). Like PHP, ASP code (using the VBScript programming language) can be embedded within the HTML; though it supported classes and some object-oriented features, most developers did not make use of these features. ASP programming code is interpreted at run time; hence, it can be slow in comparison to other technologies.
ASP.NET. This replaced Microsoft’s older ASP technology. ASP.NET is part of Microsoft’s .NET Framework and can use any .NET programming language (though C# is the most commonly used). ASP.NET uses an explicitly object-oriented approach that typically takes longer to learn than ASP or PHP, and is often used in larger corporate web application systems. It also uses special markup called web server controls that encapsulate common web functionality such as database-driven lists, form validation, and user registration wizards. ASP.NET pages are compiled into an intermediary file format called MSIL that is analogous to Java’s byte-code. ASP.NET then uses a JIT (Just-In-Time) compiler to compile the MSIL into machine executable code so its performance can be excellent. Originally a Windows-only technology, ASP.NET Core can now run on different platforms.
JSP (Java Server Pages). JSP uses Java as its programming language and like ASP.NET it uses an explicit object-oriented approach and is used in large enterprise web systems and is integrated into the J2EE environment. Since JSP uses the Java Runtime Engine, it also uses a JIT compiler for fast execution time and is cross-platform. While JSP’s usage in the web as a whole is small, it has a substantial market share in the intranet environment, and is still used on a number of very large sites.
Node.js (or just Node). Uses JavaScript on the server side, thus allowing developers already familiar with JavaScript to use just a single language for both client-side and server-side development. Because of its unique architecture, Node is especially well suited for busy sites and for sites requiring push interactions.
Perl. Until the development and popularization of ASP, PHP, and JSP, Perl was the language typically used for early server-side web development. As a language, it excels in the manipulation of text. It was commonly used in conjunction with the Common Gateway Interface (CGI), an early standard API for communication between applications and web server software.
PHP. Like ASP, PHP is a dynamically typed language that can be embedded directly within the HTML, and supports most common object-oriented features such as classes and inheritance. Originally, PHP stood for personal home pages, although it now is a recursive acronym that means PHP: Hypertext Processor.
Python. This terse, object-oriented programming language has many uses, including being used to create web applications. It is also used in a variety of web development frameworks such as Django and Pyramid.
Ruby on Rails. This is a web development framework that uses the Ruby programming language. Like ASP.NET and JSP, Ruby on Rails emphasizes the use of common software development approaches, in particular the MVC design pattern. It integrates features such as templates and engines that aim to reduce the amount of development work required in the creation of a new site.

Some of these technologies are only used for older legacy applications, while others have only a relatively small market share. Of these technologies, PHP, ASP.NET, Ruby on Rails, and Node.js are the most popular. This chapter will focus on PHP, while the next will examine Node.

Tools Insight

To run the PHP examples in this book you will need to use some type of specialized software that will recognize PHP files and execute them appropriately. We find that students are sometimes confused about the relationship between their local PHP files and their local PHP environment. As you saw earlier in Figure 12.1, server scripts are executed on a server. When you are developing (for instance, as a student), your local machine may likely be hosting both the browser software and the web server software, as can be seen in Figure 12.2. From the browser’s perspective, it is making a request of an external server (even though the web server software is actually running on the same machine as the browser) because it is requesting from a different process.

Figure 12.2 Hosting a web server locally

Figure 12.2 Full Alternative Text

There are numerous alternative ways to run and test your PHP files. This Tools Insight section provides an overview of some of the options that you (or your instructor) can use.

Running PHP from the Command Line

Your development machine may already have a built-in PHP server already installed. For instance, at the time of writing, computers running Mac OS X have PHP 5.4 or 5.5 installed. Using the terminal, you can start developing right away without worrying about server configuration (at least for a little while). This capability allows one to quickly start a server from any folder, see log output in the console, and develop small scripts.

To launch the PHP server, navigate (using commands like cd) to the folder you wish work from. Once in the folder you can start the server (on port 8000) by typing:

php –S localhost:8000

As you can see in Figure 12.3, this command will allow you to make local PHP file requests from the browser. This daemon will continue to run until you use CTRL C to stop the server. As you make requests for pages using a browser from the URL http://localhost:8000/, you will see output in the console that will display requests, status codes, and error messages when a requested page encounters them.

Figure 12.3 Running PHP server from the command line

Figure 12.3 Full Alternative Text

Although you cannot use this server for production (it’s not designed for it), it does offer a very quick way for students to get started with ease, and can come in handy if you need to start a server for a quick demonstration or other reason.

You may wonder if this command line approach is available for Windows. While PHP is not part of a standard Windows installation, installing an environment like easyPHP or XAMPP will allow you to run PHP from the command window as well.

Installing Apache, PHP, and MySQL for Local Development

One of the true benefits of the LAMP web development stack is that it can run on almost any computer platform. Similarly, the AMP part of LAMP can run on most operating systems, including Windows and the Mac OS. Thus it is possible to install Apache, PHP, and MySQL on your own computer.

While there are many different ways that one can go about installing this software, you may find that the easiest and quickest way to do so is to use an all-in-one management software that bundles popular tools together. The easyPHP (www.easyphp.org) or XAMPP (www.apachefriends.org) for Windows or Mac will install and configure Apache, PHP, and MySQL (or MariaDB, which is the new open-source equivalent replacement for MySQL) using a graphical user interface.

For instance, once the XAMPP package is installed, you can then run the XAMPP control panel, which looks similar to that shown in Figure 12.4 (as you can see in this screen capture, we did not install all the components). You may need to click the appropriate Start buttons to launch Apache (and later MySQL). Once Apache has started, any subsequent PHP requests in your browser will need to use the localhost domain (or the equivalent IP address 127.0.0.1), as shown in Figure 12.4.

Figure 12.4 Using XAMPP

Figure 12.4 Full Alternative Text

As you progress as a developer, you will develop more familiarity with LAMP installations, at which point you may prefer managing Apache and MySQL without the overhead (and simplicity) of an all-in-one tool. At this time we want to focus on PHP development rather than system configuration so we will describe XAMPP, and allude to Linux command line tools that also work on many Mac systems. In Chapter 17, more detail on server administration is provided.

Whatever approach you take to having a web host you are ready to start creating your own PHP pages. If you used the default XAMPP installation location, your PHP files will have to be saved somewhere within the C:\xampp\htdocs folder.

On a Mac computer, Apache comes installed (though not activated) and the default location for your PHP files is /Library/Webserver/Documents. On Linux installation many apache configurations serve files from /var/www/html/ and many shared systems require students to publish files in a folder off their home directory at ~/public_html/.

If you are using a lab server or an external web host, then check the appropriate documentation from your institution or host to find out where you will need to save or upload your PHP files.

Running PHP from an Online-Only Environment

An alternative to running PHP locally on your development machine is to make use of an online-based (also called cloud-based) development environment such as repl.it or codeanywhere (www.codeanywhere.com). These provide a hassle-free approach to running a LAMP stack. While this means you will need an Internet connection in order to code and test, these online development environments provide some intriguing benefits for PHP development. First, you do not have to clutter your personal computer with both an editor and web server software, nor do you need to worry about any server configuration details since they already include the key components of the LAMP stack as well as other web development workflow tools such as sass, npm, and git. A key benefit for developers with Windows machines is that these online systems typically provide a Linux terminal, which is especially useful whenever you want to make use of these other web development workflow tools. Finally, web development is a collaborative endeavor typically involving the work of multiple developers; these online environments shine in this regard since multiple users can share and even edit the same code simultaneously. Figure 12.5 illustrates one of these cloud coding environments.

Figure 12.5 Online PHP development environments

Figure 12.5 Full Alternative Text

Pro Tip

Although PHP is designed for hosting web applications, it can also be used as a scripting language on your system, and called directly from the command line. To interpret a file and echo its output directly to the console, simply type php and the file name to run it.

php example1.php

Running PHP in this way can be useful to developers since it allows one to run code without having to have a configured web server, and allows output to be captured and redirected. Used in combination with crontab (scheduling software), the command line use of PHP can facilitate scheduled tasks running on your web applications, for example, sending email each night to subscribers.

Since the output is displayed as plain text and not interpreted through a browser, and headers are not sent like in a regular web development environment, we discourage you developing in this manner while you are learning.

Note

The labs for this chapter have been split into two files: Lab12a and Lab12b.