Configuration Tokens

A configuration token is a simple reference to a value. When configuration tokens are resolved, the result is always a string. Transformation described in Transformations can be used to coerce the output type.

Configuration Tokens for File System

IG provides ig.instance.dir and ig.instance.url to define the file system directory and URL for configuration files.

Their values are computed at startup, and evaluate to a directory such as $HOME/.openig (appdata\OpenIG). You can use these tokens in your configuration without explicitly setting their values.

For information about how to change the default values, see Change the Default Location of the Configuration Folders.

Syntax

Configuration tokens follow the syntax &{token[|default]}, as follows:

  • Are preceded by an ampersand, &

  • Are enclosed in braces, {}

  • Define default values with a vertical bar (|) after the configuration token

  • Are in lowercase

  • Use the period as a separator, .

When a configuration token is supplied in a configuration parameter, it is always inside a string enclosed in quotation marks, as shown in the following example:

"&{listen.port|8080}"

To escape a string with the syntax of a configuration token, use a backslash (\). The following string is treated as normal text:

"\&{listen.port|8080}"

A configuration property can include a mix of static values and expressions, as shown in the following example:

"&{hostname}.example.com"

Configuration tokens can be nested inside other configuration tokens as shown in the following example:

"&{&{protocol.scheme}.port}"

Default values or values in the property resolver chain can be nested, as shown in the following example:

"&{&{protocol.scheme|http}.port|8080}"