Fog Computing

aka edge computing

There are a lot of concerns about cloud computing solved by the fog. Let’s try to summarize them !

The protocols Babel tower

The first role of a field gateway is the protocol translation. This scenario is always true : it’s true for devices which are already TCP/IP capable for connecting to the Internet but it’s also true for legacy and low constrained devices which need a bridging point to the cloud. Devices could be able to connect directly to the cloud from a network capabilities point of view but they couldn’t speak the same “language”, it means the same protocol. Babel tower is the home for a lot of protocols today and the online IoT platforms can’s speak all of them. The first need is a local translation from devices protocol to cloud protocol in both cases if it’s based on TCP/IP (see MQTT, AMQP, HTTP, …) or on personal area network (see BLE for example).

Reducing cloud workload

Using an IoT field gateway, part of the work is done in the fog at the edge of our complex solution and it means reducing the cloud workload. Data centers are huge with powerful public servers but the resources aren’t unlimited; speaking about million/billion/trillion of connected devices is a problem for the cloud and reducing this number could be a very good solution. Thanks to a central node at the edge, we can establish to few connections but at same time sending data that are representative of more devices in a local network. Sometimes not all produced data are needed for processing in the cloud so a pre-processing is executed at the edge to analyze, filter, reduce, elaborate data to send.

Real time reaction

A lot of IoT solutions need a near real time reaction time. Connection to the cloud introduces latency : to control a device, the data is sending to the cloud through the “big net”, the server processes it and replies with a command to start an action on the device itself. There is a not negligible round trip related to the connection and to the server workload too, because it’s serving not only one device but a huge number of them.

Offline handling

Without an Internet connection, an IoT solution which is entirely based on an online platform can’t work ! Of course, all cloud providers offer a SLA (Service Level Agreement) very closed to 100% but a lot of times we have to consider the very low percentage of failure. With fog computing we have a local node and we have to deal with local network connection only. The same is true when the cloud platform is available but the connection isn’t reliable (and it’s like having the platform offline) or the bandwidth is low. Thanks to the central node at the edge we are able to handle a lot of offline scenarios : we can leverage on local storing data when the connection isn’t available.

Security and privacy

In a lot of scenarios protecting data is a must. Even if all cloud connections are encrypted and based on SSL/TLS protocol, more companies which build IoT solution prefer to have data in their private server to protect themselves and their customers (who are the data owners). Using a field gateway, we can filter data to avoid sending all of them to the cloud; we can hold sensible data in our local network and send the non sensible ones to the public servers.

Reducing price

All IoT cloud platforms aren’t for free but they have a cost which is related to the number of connected devices and the number of messages exchanged per hours/days. Thanks to the field gateway we can connect more local devices using only a single connection (for the gateway itself) and thanks to the pre-processing we can filter and reduce the amount of data to send : it means reducing cost. It’s more important when the traffic isn’t “free” but it has an higher cost like using GSM connection for example.

What's more, please see How IoT can benefit from fog computing

• 考虑延时和响应速度：如车载系统
• 考虑网络传输及数据量，如CCTV的摄像头设备
• Security and privacy
  • 这块有个矛盾点，一方面要说服用户云是安全的，一方面又不得不担忧可能带来的安全隐患；
  • Fog computing will reduce many of these risks by considerably decreasing the amount of dependency on internet connections. Moving data and command exchange into the local area network will make it much harder for hackers to gain remote access to your data and devices. Moreover, with device-cloud exchanges no longer happening in real-time, it will be much harder to discern life and usage patterns by eavesdropping on your network.
  • 支持动态升级，减少风险；

Important: A study by IDC Futurescape shows that by 2018, some 40 percent of IoT-created data will be stored, analyzed and processed at the edge.