OPC UA采样率设置为0是否可以与OPC UA Ecplise Milo服务器一起使用

Question

Does the open source OPC UA Milo server support event based data sources? Eg when the server sets sampling rate to 0 (zero) for a node (measuring point), would the server then produce all samples the event source produces? And if so where to look for an example or instruction how to achieve that? The example namespace of the example server seem to add attribute delegates that are reactive, ie they only produce values when asked by the subscription mechanism to do so.

Answer 1

A sampling interval of zero means use the "fastest practical rate", which can mean report by exception or event-based if the underlying source supports it, but in the case of the example namespace it's not supported.

An implementation of Namespace is free to handle that rate however it wants, including as event-based if the source actually supports it. A namespace is simply told when items have been created, modified, or deleted, and it's the implementation's responsibility to then start sampling those items at the requested rate. The SDK will take into account any MinimumSamplingInterval attribute the node has set on it before instructing the namespace to start sampling.