Victoria Series Release Notes¶
There has been a big change in the Mistral action management. All Mistral subsystems don’t access the database directly if they need to work with action definitions. Instead, they work action providers registered in the new entry point “mistral.action.providers”. All action providers need to implement the base class ActionProvider declared in “mistral-lib” starting with the version 2.3.0. Action providers are responsible for delivering so-called action descriptors that carry all the most important information about particular actions like “name”, “description”, names of input parameters and so on. The entire system has now been refactored with action providers. Using this new mechanism it’s now possible to deliver actions into the system dynamically w/o having to reboot Mistral. We just need to come up with an action provider implementation that can do that and register it in the entry point from any Python project installed on the same Python environment. This approach also means that actions don’t have to be stored in the database anymore. It fully depends on a particular action provider how to store action descriptors and how to perform lookup. It is possible to create action providers fetching information about actions over HTTP, AMQP and potentially any other protocol. Additionally, switching to action providers allowed to make engine code much cleaner and more encapsulated. For example, ad-hoc actions are no longer a concern of the Mistral engine. Instead of implementing all ad-hoc action logic in the engine there’s now a special action provider fully responsible for ad-hoc actions. The detailed documentation on using action providers will be added soon.
As part of the transition to action providers the compatibility of the /actions REST API endpoint has been broken to some extent. For ad-hoc actions it remained almost the same. We still can do all CRUD operations upon them. However, all the standard actions (prefixed with “std.”) are not stored in the DB anymore. For that reason this type of actions doesn’t have IDs anymore, and generally actions are not identified by IDs anymore, only by name. This change needs to be taken into account when updating to this version of Mistral.