Adding Information about the measured value?

  • Erikerik

    Erikerik - 2006-01-20


    I'm interested in m2m-xml. When I looked in the specs I noticed that m2m-xml doesn't describe the information that is measured.

    A Percept Request responds with e.g. value="32.5". I would like to add that this value is a "temperature". Is it possible to add this information by your self? If yes, what is the best way to do so?


    Erik Langius

    • Austin Mills

      Austin Mills - 2006-01-23

      Actually, the way that I think it's intended to be used is that you request a percept from a given address -- and that you would know ahead of time that address 'A1' (for example) correlates to a temperature sensor.  There's been some occasional discussion before about adding a 'self-description' capability to the spec which would allow a device to publish a list of the sensors and actuators on it and information about those sensors (such as type, name, units, description, etc.), which would allow you to send that kind of imformation through the protocol rather than having it be part of the application-specific setup.

    • Erikerik

      Erikerik - 2006-01-25

      Ok, thanks Austin.

      Is a property-tag allowed in a "Percept Request"?

      • Austin Mills

        Austin Mills - 2006-01-25

        No, the spec doesn't currently allow that. Can you go into a bit more detail about what you're interested in doing with it?

    • Erikerik

      Erikerik - 2006-01-26

      I'm looking for a way to connect a lot of different sensors that send their measured value on a certain interval. In this case the information is pushed from the sensors to a server. So I don’t know in advance what the value means that is measured. I would like to add something that could tell me that a measured value ‘6’ is a temperature (or something else).

      Maybe M2M-XML is designed with a pull scenario in mind (a server asks for the measured values) ?

    • Byron K. Appelt

      Byron K. Appelt - 2006-01-27

      M2MXML is definitely used in push scenarios all the time. Maybe I don't understand your application, but  the way this is usually accomplished is that each sensor is associated with a device unique address. The device and the server share information about this address. So when the server recieves a percept from address 'T1' it knows it is a temperature, for example.

      It is possible to use M2MXML commands such as 'queryConfiguration' to communicate sensor metadata such as measurement units although the exact details of this are currently left to the application developer and are not specified in the spec.


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