Major Whisperer version changes are scheduled approximately every 9 months.

These upgrades are necessary to keep the API in good order and are not backwardly compatible. If clients wish to utilise functionality released after that date it will be necessary to migrate to the latest schema version.

The changes typically include:

• Removal of deprecated messages and components (impacting message layout), datatypes and enumeration values.
• Reordering of message components.
• Changing wire representations of individual fields (e.g. String lengths).
• Renaming of fields, enumeration values and messages (typically semantic types and wire values will remain unchanged).