event_cache.js

var deviceAttr = {
    device: {{deviceID}},
    activateDate: ISODate,
    recentSession: ISODate,
    platform: [PC, Android, ios],
    users: [{{userID}}]
}

var userAttr = {
    user: {{userId}},
    recentPCSession: ISODate,
    recentMobileSession: ISODate
}

// 45min consecutive events
var eventFlow = {
    device: {{deviceId}},
    user: {{userId}}.
    startTime: ISODate,
    endTime: ISODate,
    eventFlow: ["openTopic", "startLearning", "openVideo", "quitVideo", "userLogout"]
}