The conversation scope allows developers to demarcate the lifespan of the session scope.
The conversation scope is committed to the user's interaction with JSF applications and represents a unit of work from the point of view of the user; a bean in this scope is able to follow a conversation with a user. We may charge the conversation scope as a developer-controlled session scope across multiple invocations of the JSF life cycle; while session scoped lives across unlimited requests, the conversation scopes lives only across a limited number of requests.
Note
The conversation scope bean might get passivated by the container and should be capable of passivity by implementing the java.io.Serializable interface.
The developer can explicitly set the conversation scope boundaries and can start, stop, or propagate the conversation scope based on the business logic flow. All long-running conversations are scoped to a particular HTTP servlet session and may not cross session boundaries...