However, there are issues with this approach. Some of the considerations:
- How does the new connector service represent the device in a way that the application can understand its capabilities and/or limitations? Generally, you should be able to define this easily from the original protocol or the specification of the device. One way to approach this might be through the use of JSON or name/value pairs to define a capabilities matrix.
- If your device is not on a dedicated network, how will you communicate with it? Many of the legacy devices will "call home" on either an event occurring or based on a time interval. This works well for the normal case, but what if you need to change one of these parameters. You might consider having a back channel protocol like possible SMS messaging to send a signal to the device to force it to "call home" and ask for new information.
- Security should also be a consideration. Unfortunately, older devices have limited security capabilities. Very few have any sort of encrypted data or even the capability to use SSL techniques to transfer their data. Because of this issue, you must consider if the information you are getting from the device can be trusted. Use of firewalls and secure networks may help in this regard but you must take precautions in your connectors to prevent service attacks.
- Managing IP and Port addresses is critical. As many of the legacy devices do not handle DNS lookup and most only communicate over a standard TCP socket, you have to dedicate an IP address and Port combination to those devices. In addition, you may be forced to have multiples of these addresses for the various versions of the protocols. Over time this can be a large management and deployment issue.
As IoT matures, devices become more capable, and as standards emerge it is expected that many of these issues will begin to disappear. Unfortunately, we will still have a tremendous legacy of older devices to manage for years to come. However, taking an approach to disaggregate the proprietary protocols from the actual useful information of the device can be a way to collect useful operational technology information and apply it to specific business processes and decisions.
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