Spring Expression Language

A number of components in CAS are able to take advantage of the Spring Expression Language syntax for their internal configuration. This is primarily useful when the component wishes to have access to system variables, environment properties or in general requires a more dynamic or programmatic strategy before it can be fully functional.

Expressions are expected to be encapsulated inside the ${...} syntax. Predefined variables are expected to be preceded with the # character. The following predefined variables are available:

Variable	Description
systemProperties	Map of system properties, loaded once typically on startup.
sysProps	Same as above.
environmentVars	Map of environment variables, loaded once typically on startup.
environmentVariables	Same as above.
envVars	Same as above.
env	Same as above.
tempDir	Path to the temp directory.
uuid	Auto-generated UUID value.
randomNumber2	2-digit random number.
randomNumber4	4-digit random number.
randomNumber6	6-digit random number.
randomNumber8	8-digit random number.
randomString4	4-character random word.
randomString6	6-character random word.
randomString8	8-character random word.

Examples

• Assuming system property tier with a value of production is available, the configuration value file://${#systemProperties['tier']}/file.json translates to file://production/file.json
• Assuming environment variable tier with a value of qa is available, the configuration value file://${#environmentVariables['tier']}/file.json translates to file://qa/file.json
• Using ${#randomString6} translates to a 6-character random word, such as qemguz.
• Using ${#randomNumber8} translates to a 8-digit random number, such as 75915283.