Glossary

Configuration vs settings

While sometimes the terms are used interchangeably and this is not an exact definition, a general rule of thumb is:

configuration:

Is used mostly to describe configuration that is initialized once using configuration files and cannot be changed on the fly in the backend.

settings:

Are options that can be modified in the backend, mostly in Admin Tools > Settings

Syntax vs method

We refer to a configuration language, that only defines the syntax as configuration syntax or configuration language.

When we refer to semantics, where the values are stored, the scope etc. we use the term configuration method. Thus, the configuration language is part of the configuration method.

This differentiation is important to make because there is often confusion about the term TypoScript: TypoScript can be used to describe the TypoScript syntax, but it can also be used to describe TypoScript templating, which can be considered a configuration method. TypoScript syntax is used in both TypoScript templating and TSconfig.

Configuration methods

In TYPO3 there are several ways to configure the system, depending on what is to be configured, where the values are stored and how and where they can be changed.

"Configuration methods" is not a generally used term. We use it in this chapter to differentiate between "configuration syntax" (as explained above), which only defines the syntax and the "configuration method". For each type of configuration method, the following may differ:

• The used configuration syntax or configuration language
• Schema (data types, default values, what settings are required, ...)
• What do these variables mean, how will they be interpreted?
• Where the values are stored (persistence): In a configuration file, the database, etc.
• Who can change the values (privileges), e.g. only a system maintainer or admin in the TYPO3 backend.
• To what the values apply (scope). Are they global or do they only apply to certain extension, page, plugin, users or usergroups?

An example for a TYPO3 specific configuration methods is TSconfig. This uses the TypoScript syntax. The values can be changed in the backend only by admins or in extensions.

Configuration syntax

Syntax describes common rules for a language (e.g. how are lines terminated, how are values assigned, what are separators, etc.) while semantics define the meaning.

For example, using only the basic syntax of yaml, this is a syntactically correct snippet:

foo: bar

Most of the configuration languages used in TYPO3 basically assign values to variables in one way another. In its simplest form, these can be simple string assignments as in the yaml example, which may result in assigning the value 'bar' to a variable foo.

The assignment in TypoScript syntax would look like this:

foo = bar

Without defining what are correct keys, values and data types, we have no idea about the meaning (semantics) of the file and cannot interpret it. We (or rather the TYPO3 Core ) have no idea, what foo (in the example above) means, whether it is a valid assignment, what data type can be used as value etc. We can only check whether the syntax is correct.

These are the main languages TYPO3 uses for configuration:

• TypoScript syntax is used for TypoScript and TSconfig.
• TypoScript constant syntax is used for Extension Configuration and for defining constants for TypoScript.
• Yaml is the configuration language of choice for newer TYPO3 system extensions like rte_ckeditor, form and the sites module. It has partly replaced TypoScript and TSconfig as configuration languages.
• XML is used to define a schema for FlexForms.
• PHP is used for the $GLOBALS array which includes TCA ($GLOBALS['TCA'] ), Global Configuration (GLOBALS['TYPO3_CONF_VARS']), etc.

Configuration definition

A configuration definition or schema can be used to define what may be configured:

• What are allowed variables and datatypes?
• What are the default values?

So, for example in the example above we would define that there is a variable 'foo' with a datatype string and a default value might be an empty string.

There are specific languages for defining a schema to be applied, for example for XML, this might be DTD or XML schema. For YAML and JSON there is for example a schema validator Kwalify which uses YAML as language for the schema.

If you use a schema to define the configuration, this often has the additional advantage, that configuration can be validated with that schema.

TYPO3 does not use an explicit schema for most configuration methods. Often, the parsing and validation is done in the PHP source.

Examples for using a configuration definition file in TYPO3:

• TypoScript constant syntax is used to define Extension Configuration in the file ext_conf_template.txt of an extension.
• Flexforms are defined using XML in an extension.