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From Christofer Dutz <>
Subject Re: Symbol metadata for connections
Date Sat, 02 May 2020 12:38:29 GMT

but we should make it compatible with all protocols (in theory) so we shouldn't name things
with OPC UA as reference and try to map things to that.
Would be cool if someone could describe how this mechanism works in the different protocols
and how the operations are named.


Am 02.05.20, 11:06 schrieb "Julian Feinauer" <>:


    this is a very good point.
    You mean something like "getAllSymbols()" (which would only be possible in S7 case with
either TIA File or S7Comm+ Protocol).
    But totally makes sense for ADS or OPC UA.

    Would love to see a Design Doc for that (starting with OPC UA and ADS gives quite a wide
range of needs).

    Von: Christofer Dutz <>
    Gesendet: Donnerstag, 30. April 2020 22:32
    An: <>
    Betreff: Re: Symbol metadata for connections

    Hi Lukasz,

    Initially we were planning on supporting a "browse" functionality alongside the "read",
"write" and "subscribe" ...
    might that be more what you are referring to?


    Am 30.04.20, 21:54 schrieb "Łukasz Dywicki" <>:

        I been going through some ideas what could be improved here and there
        after doing my ADS try outs and come to following.

        Current API for PlcConnectionMetadata offers few basic canRead,
        canWrite, canSubscribe methods. It does not offer any api to read plc
        kind or symbol, even if some drivers do discover device kind. For
        comparison, with JDBC, we have few more options when we fetch metadata -
        ie. java.sql.DataBaseMetadata#getTypeInfo, #getTables, #getColumns and
        so on. I tend to opt for TypeInfo and Columns (symbols) as first class
        citizens which we can make.

        Currently protocols which can handle metadata requests can not support
        discovery of available symbols cause there is no way to supply that.
        This is something possible with ADS, for sure also with OPC UA. It
        shouldn't be to hard to provide one.

        Best regards,

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