Subscriptions in old servers|OPC UA Standard|Forum|OPC Foundation

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Subscriptions in old servers
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Jaime Clavijo
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01/12/2021
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02/19/2021 - 01:58
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Hi, I’m developing a client to retrieve data from any OPC UA server. I have a list of given nodes and I subscribe to data changes. I’d like to know if there’s a chance that an OPC UA server doesn’t support Subscriptions. Since the client is general purpose, I take into account that I might encounter old OPC UA servers. So, do all OPC UA servers support Subscriptions?

Thanks in advance.

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Randy Armstrong
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02/19/2021 - 10:38
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The “Nano Embedded Device 2017 Server Profile” does not require subscriptions:
https://opcfoundation.org/UA-P…..Device2017

However, this profile is only for use by servers running on low cost devices with small fixed address spaces.

You can design your client assuming subscription support but offer a fallback to polled reads.

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