Alternative to OPC-UA [closed]

Answer 1

OPC-UA has some very interesting parts, especially concerning information modelling, interoperability and the publish/subscribe pattern.

However, even though it's a standard in the strictest of senses, I've found that to use it in a webapp you need to code a gateway server. Because it uses raw sockets and a binary (although fast) serialization protocol.

This is why we created an alternative protocol called Woopsa at my university. We decided to base it on HTTP + JSON. We tried to make a protocol that's similar to OPC-UA: it has Information Modelling, publish/subscribe, and even multi-requests. It's all completely open-source.

We've just released version 1.0 here: http://www.woopsa.org/

You can get the source code directly on our GitHub: https://github.com/woopsa-protocol/Woopsa

Basically, our protocol is just a standardized RESTful API using HTTP+JSON. For example, you can read a value by making a GET /woopsa/read/Temperature and it will reply you in JSON:

{"Value":24.2,"Type":"Real"}

You can also get the object tree by using the meta word, for example: GET /woopsa/meta/ which will give you something like that:

{
  "Name":"WeatherStation", 
  "Properties": [
    {"Name":"Temperature","Type":"Real"},
    ...
  ],
  "Methods": { ... }
  "Items": [ 
    "Thermostat",
    ...
  ]
}