Developer Documentation for CMSimple_XH

This documentation is meant for core and plugin developers as well as template designers. It documents the core and the standard plugins which are not developed externally (currently Filebrowser, Meta_tags and Page_params).

System Architecture

All requests to the website are directed to index.php in the root folder of the installation or to index.php in a language folder. These index.php files are just thin wrappers for including cms.php which defines variables and constants and includes necessary files according to the individual request.


Plugins are handled by the "plugin loader". This term stems from the past, where it was an external component that had to be installed to be able to use plugins. CMSimple_XH integrated the plugin loader to the default distribution and extended it to cater for the new page data functionality. Since CMSimple_XH 1.6 the plugin loader has been merged into the core; nonetheless it seems to be reasonable to speak of the "plugin loader" to refer to the functionality regarding the loading of plugins and editing of plugin files.

The plugin loader includes files of plugins in several stages, where the respective files of all plugins are included:

  • required classes
  • configuration and language files
  • index.php files
  • admin.php files

Each stage processes the plugins in alphabetical order (before CMSimple_XH 1.6 the order was undetermined). However, it is not recommended to rely on this loading order and to name a plugin respectively (e.g. "zzz"). If you have to do something after all plugins have been loaded, use XH_afterPluginLoading to register an appropriate callback.

More developer information about plugins can be found in the Wiki.


At the end of usual page requests the file template.htm of the active template is included. That is an HTML file with embedded PHP, the so-called template tags, which are defined in tplfuncs.php.

More developer information about templates can be found in the Wiki.


An important part of the API of CMSimple_XH consists of global variables which are documented in cms.php. Not all global variables are part of the public API, only those tagged as public. Furthermore many of the public variables should be treated as read-only or read-write as documented.

All parameter names of functions and methods are subject to change, and none of the CMSimple_XH APIs should be called using named arguments for now.