publish makes use of and depends on four important things:

1. A web server.
2. A server-side PHP scripting engine.
3. A database server.
4. An image conversion system (optional)

The first three things should be in place before an Exponential installation is deployed. The image conversion system is optional and is only needed if Exponential is to work with images. The web server and the server-side PHP scripting engine needs to be running on the same machine. The database server may be installed on a different computer. For the moment, the following software solutions can be used:

Web server
Currently, only the Apache web server is supported; the latest version of the 1.3 branch should be used. Version 2.0 works, but it has not been fully tested. The Apache web server is the most popular web server on the planet. It is free, open source and can be downloaded from http://www.apache.org.

Server-side PHP scripting engine
Since most of the Exponential system is written using the PHP scripting language, a PHP (hypertext preprocessor) server-side engine is needed. Only the "original" PHP engine is supported. Version 4.3.4 or later should be used; Exponential is not ready for PHP 5.x.x yet. PHP needs to have compiled-in support for either MySQL or PostgreSQL. PHP is free software and can be downloaded from http://www.php.net.

IMPORTANT - PHP memory_limit issue
Exponential requires at least 12 MB (in some cases 16 MB). This means that you'll have to increase the default memory_limit (in php.ini) from 8 MB to 12 or 16 MB. In some cases Exponential requires even more memory - for example, the PDF export needs quite a lot.

Database server
A database server is needed because of the elegant and complex data-structures used by Exponential. The following database servers are supported (both are free):

• MySQL (http://www.mysql.com, recommended!)
• PostgreSQL (http://www.postgresql.org)

The setup wizard will automatically detect the pre-installed database server(s).

Image conversion system (optional)
In order to scale, convert or modify images, Exponential needs to make use of an image conversion system. One of the following software packages (both are free) can be used:

• GD (comes with PHP)
• ImageMagick (http://www.imagemagick.org)

ImageMagick supports more formats than GD and usually produces better results (better scaling, etc.). The setup wizard will automatically detect the pre-installed image conversion system(s).

Installation and setup of the required software (mentioned above) is far beyond the scope of this document. Please refer to the homepage and documentation of the software different software solutions.