Data Management Mechanisms for Embedded System Gateways
It is becoming increasingly common to connect traditional embedded system networks to the Internet for remote monitoring, high-level control and integration. It is necessary to protect each part of the interconnected system from faults and attacks which propagate from the other side. One architectural approach is to add a gateway to the embedded system to receive Internet traffic and disperse data to the embedded system, but there is no clear recipe for building such gateways. Since Internet routers commonly use queues to manage traffic, we examine the effectiveness of queues for the embedded system gateway domain. We perform a series of experiments to evaluate the effectiveness of the queue mechanism and various queue management techniques. We show that queues can exhibit poor performance in the context of real-time embedded system gateways due to problems with message latency and dropped messages. We then introduce the concept of a filter mechanism and show that a simple filter mechanism can outperform queue mechanisms when used in the gateway to manage real-time state-oriented data streams.