Core Concepts

You write Voice Applications with Violet by composing what users-can-say and users-will-hear in voice scripts. Sophisticated applications can add application logic via controllers, write reusable scripts as widgets, and externalize integration logic into plugins.

Voice interactions with the user build on a set of concepts. At the highest-level are Conversations, which are implemented - primarily beneath the covers - using Goals for state management, and at the lowest-level are Responses from both a user and the application.


Once a user initiates a Voice Application a conversation is said to have begun. Conversations are modeled primarily using the Conversation Flow Language which manages the conversational state for the application developer. After being initiated, conversations are ongoing i.e. a response from the application is expected to be followed by a user responding back. Conversations reach an end once they reach a leaf in the flow script, but can be continued using the jump element or by calling the keepConversationRunning method.

Goals (States & Dialog Management)

Active parts of a conversation are tracked as Conversational States. They can be managed using code. Consider conversations as having a set of small milestones or Goals. Goals allow for the grouping of application and user responses.

Applications can add a goal or clear a goal, and later respond differently depending on if a goal has been set. Applications will also likely want to define goals that tells the conversation engine to prompt the user and to wait for one of multiple responses back.

When using Goals, an application will typically want to define a series of goals upfront. Once this is done, a user’s response can add (and therefore queue/set) a goal. Once the goal has been set, any future responses from a user will be first checked in the context of the set goals. Multiple goals can be set at a time, and goals are checked in a first-in-first-out manner. Goals are also automatically cleared up if a method processing a goal returns true.

User & Application Response

At the lowest level, a Voice App is a list of items that the user might say followed by how an application might respond to it.

Related user responses are grouped into intents that an application can respond to. When an intent is triggered the application logic is called with a response parameter to allow the application logic to provide a response back to the user. Applications can say something or ask for something from the user.

Under the covers all the calls to the response object are converted in an SSML string and sent to the users voice-enabled device.