I’m new to OpenHab and Smart Home in general.
While reading about SmartHome I came across the terms SmartHub, Bridge and Gateway. Sometimes people differentiate between these terms and sometimes they’re used synonymously, which left me completly confused. Could anybody explain the roles of these terms in a Smart Home System and if OpenHab could be considered as one of them?
It is really hard to answer without more context on where you are seeing those terms.
For the most part, at least in this community (other smart home communities might have different definitions):
Smart Hub: a central device that interacts with one or more technology (e.g. Zwave) and either exposes that through an API or controls the devices directly. OH can serve the role of a Smart Hub. SmartThings, Wink, and Vera are examples of other Smart Hubs. Where is gets complicated and confusing is Smart Hubs can integrate with each other. For example, one can add a Vera to openHAB using the MiOS Binding which would allow OH to control and get data from everthing connected to the Vera.
Bridge: As a generic term, a Bridge is usually a device that allows two or more technologies to communicate with each other. In OH, Bridge is a technical term for a special type of Thing which is required to gain access to other Things (see the concepts section of the User’s Guide for a deeper explanation of Things in the OH context). For example, when integrating OH with another Smart Hub, the Smart Hub itself might be represented as a Bridge Thing in OH and the Bridge Thing allows us access to all the devices connected to that Smart Hub.
Gateway: Again, as a generic term, a Gateway is often used the same as Bridge. It’s a device that provides access to some other technology. In the OH context, some bindings will call their “bridge” a Gateway (e.g. KNX Bindging).
For the most part, each binding in OH will have it’s own definitions for terms like these because they are terms that have a specific meaning for that specific technology. This is why knowing the context is so important.