Conceptually, multiple sessions can be active in parallel. Dialog execution can be governed by a sessions, e.g. to free resources of ASR and NLU engines when a session expires. Linguistic phenomena, like anaphoric references and ellipsis, are expected to work within a session. The selected IPA Providers or the Dialog Manager may have leading roles for this task.
A session begins when the user starts to interact with an IPA, may continue over multiple interaction turns, i.e. an input and output cycle, and ends if the user does not start a new input within a predefined time span. This includes the possibility that a session may persist over multiple requests.
In https://w3c.github.io/voiceinteraction/voice%20interaction%20drafts/paArchitecture/paArchitecture-1-3.htm#session we defined a session as:
Check of this definition of sufficient