In recent years, web development and deployment has become extremely fast and easy with the usage of open source software development tools and frameworks.  The usage of open source software has reduced capital and operating expenses for web startups to a greater extend that there is a significant increase in the volume of new internet startups with applications developed using open source software.

One of the widely used open source stack for web application development is LAMP. As the expansion implies, LAMP stack consists of a web server (Apache), a database server (MySQL) and a set of scripting languages (PHP/Perl/Python) that can run on any flavor of Linux. In general it is described as an open source operating system, open source web server, open source database server and open source programming languages.     The Linux, Apache, MySQL, PHP (LAMP) stack can provide an efficient and cost effective open source architecture to build and run web applications.

This article introduces LAMP software stack on zLinux (Linux on IBM System z).  Let's call it zLAMP. We will delve into configuring and starting up individual components of zLAMP and then downloading, installing and testing few LAMP based off the shelf open source applications.

Why zLAMP Stack
Linux on System z combines the advantages of the IBM mainframes with the flexibility and open standards of the Linux operating systems. System z's high virtualization and utilization capabilities make it an ideal platform for running LAMP based web applications than x86 servers. Linux on System z virtual servers are enabled by default for vertical scalability, thus making it possible to meet scalability requirements by enhancing with additional processors or memory dynamically. If the vertical scalability is not sufficient, a new Linux image on system z can be deployed within minutes without interrupting the operations.

Recently, LAMP based social network Facebook has migrated some of their application modules to non LAMP stack due to high scaling demands which often caused outages of their x86 servers. Even though LAMP on x86 systems is highly reliable and cost effective alternative compared to other web development stacks, it can meet extreme scalability requirements if it runs on top of a hardware (like System z) with high resource (Processor, Memory, Storage, Networks etc) virtualization capabilities.

In x86 world, different LAMP components might be running on dedicated Linux servers.  All these servers can be consolidated to run on one physical System z machine. This saves power and space in the datacenter, and reduces the administration efforts while meeting scalability needs very efficiently.

zLAMP Components
The zLAMP acronym points more to a selection of one the "P" elements (PHP, Perl, and Python) rather than to a need for the inclusion of all of them. It's more likely to find both Perl and Python useful tools for administrative tasks, so they'll probably be installed on system whether or not your intent is to use them as an element of LAMP web development.    Enterprise Linux distributions for System z provide the most recent version of each of these packages available along with the Enterprise Linux version release. Apache, PHP, Perl, and Python are provided as defaults in the installation of Enterprise Linux, while MySQL requires selection at the time of installation.

zLinux: Clearly, the most important element of the zLAMP combination is the Linux distribution installed on System z server. With dozens of System z specific distributions available, the choice can be a bit perplexing. Of the available distributions, however, Enterprise Linux (RedHat or SuSe) has grabbed the strongest niche in enterprise-grade LAMP web servers for several reasons.

Apache Server: Apache web server has been dominant web server since 1996 and has since evolved to rival other web servers in terms of functionality and performance.   In 2009 it became the first web server software to surpass the 100 million web site milestone.  Apache is primarily used to serve both static content and dynamic Web pages on the World Wide Web.

MySQL Database: MySQL is a multithreaded, multi-user, SQL database management system (DBMS) MySQL database has grown the world's most popular open source database with over eleven million installations worldwide. Free-software projects that require a full-featured database management system often use MySQL.

PHP/Perl/Python: These are reflective programming language originally designed for producing dynamic web pages. They are often used to create powerful and yet intuitive web based applications that access backend systems, content management systems or databases.

The scripting component of zLAMP varies depending on different installations. Most commonly, PHP is used in conjunction with the other components. However, Perl or Python are also viable options. These general scripting languages can be modified in open source and embedded with standard HTML code to execute dynamic or "on-the-fly" website content based on specific actions taken by the user.

With these components, zLAMP offers a full service web development platform through open source that allows website programmers and designers to create sites rich in customized content.

Configuration
Open source tools have some great advantages over other proprietary tools. Among those advantages is the general ability to configure the tools by editing a text-based configuration file. Nearly any setting can be configured and modified by editing these files. That allows the user to create a configuration that's customized for the particular and unique use of the tool, down to the smallest detail.

As zLAMP components are installed by default along with the OS installation, this section will focus on configuration of each components.  If any of the components are not available (check version commands to confirm availability) as part of the installation,  follow the same installation instructions for x86 Linux distributions.

Configuring Apache:
The text configuration file for the Apache server in Enterprise Linux is located at /etc/httpd/conf/httpd.conf. While the file offers complete customization of all the server parameters, to run apache web server first make a small modification to the apache configuration file, then start the Apache service (known as "httpd"), and finally configure it so it will always start when the machine is booted:

Figure 1: Out of the box applications on zLinux

WordPress
Popular open source blog hosting platform WordPress can be setup on zLinux by downloading the source from wordpress.org website.  Unzip the downloaded tar file into a folder which the apache server can access. Typically, root html document folder (/var/www/html) is used for installation.

Configuration of WordPress includes the setup of a database and the modification of the WordPress configuration file. WordPress uses a MySQL database to store the data. Therefore a database with specific user privileges must be setup.

In the given example, the "root" user is the MySQL admin who creates the database "wordpressdb" and grants the privileges to the new user "wordpress".

Next step is to copy the sample configuration file /var/www/html/wordpress/wp-configsample.php to the configuration file which gets recognized by WordPress modules, which is /var/www/html/wordpress/wp-config.php. Adopt the settings for the MySQL database into the configuration file /var/www/html/wordpress/wp-config.php as user "root" with following attributes:

Now, restart the Apache HTTP server and access WordPress from the URL http://localhost/wordpress

MediaWiki
MediaWiki, the project behind Wikipedia, is a Wiki implemented in PHP.  Download mediawiki packages from the MediaWiki webpage and unzip all files into a folder which the Apache Web server can access.To configure MediaWiki start a Web browser and open the URL http://localhost/mediawiki/config. Follow the instructions on the web page and complete the configuration by clicking "Install MediaWiki!".

It is important to place the configuration file localsettings.php, which has been created during the configuration step, into the MediaWiki main folder.  This can be opted during the configuration from the installation web page of MediaWiki or can be manually moved by issuing following command at terminal:

Finally, restart the Apache HTTP server and access MediaWiki at http://localhost/mediawiki.

Drupal
A Content Management System (CMS) is used to organize content of different types such as documents, multimedia files, Web pages or other electronic data.  Drupal is a highly popular content management system (CMS) implemented in PHP.   Like other packages explained earlier, Drupal package also need to be extracted into a folder where Apache have read and write access.

The configuration of Drupal includes the setup of a database and the execution of the installation wizard. Drupal can use a MySQL database to store the information. Drupal setup with specific MySQL database user privileges is achieved using following commands:

Now, start the Drupal installation wizard, open a Web browser and access the wizard at the following the URL http://localhost/drupal. The upcoming wizard guides the user to complete the setup. After the wizard completed, change the access rights of the Drupal configuration file settings.php.

Conclusion
System z's powerful virtualization capabilities make it possible to run multiple Linux images inside a single System z box.  Scalability needs of web applications can be easily met by bringing up additional Linux images as clones of existing images without interrupting services to end users.  Moreover, presence of System z architecture ensures high utilization rates for all the underlying components of a web application.

Combining the features of open source software and System z, zLAMP based web applications can be extremely reliable, highly available and zero fault tolerant systems compared to x86 based systems.  So when building your next web application, remember to consider using LAMP on system z. If you already have one at the center of your mission-critical enterprise, you already know the advantages of using System z for hosting large scale web applications.

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