The requestHandle in Cancel Service Parameters

[j.zhou.5q]

Hi,

I am not quite understand the requestHandle in Cancel Service Parameters.
In description, "The requestHandle assigned to one or more requests that should be cancelled." is written.
I wonder that how a requestHandle means MORE requests.(I think a requestHandle only means one request.)

I am looking forward your answer. Thank you!

Best Regards,
James

[Support Team]

James,

please, what is your question here, and what is the relation to the C++ based SDK? Questions regarding the OPC UA Specification belong to the "Technical" forum. In this section we answer questions related to our C++ based SDK only.

If you read the specification about the requestHandle and the Cancel Service you will find that the requestHandle is a number defined by the Client. Therefor the Client can use this number for several Requests e.g.of the same type like 20 parallel read requests, and could now cancel all of them with one single Cancel Service call, because if one Read did not return in time, it is very likely that the other 19 will also not return in time. This is under full control of the Client, the server will just cancel all outstanding requests that have the given number.

So, yes you can Cancel more than one Request (when you have given all those Requests the same requestHandle)

Best Regards
Support Team

[j.zhou.5q]

Hi Support Team,

If I am over the line, please accept my apologies.
I am developing UA server using the C++ based SDK. Perhaps my question has no relation to the C++ based SDK, I am sorry.

Thank your answer. I got it.

Best Regards,
James

James,

please, what is your question here, and what is the relation to the C++ based SDK? Questions regarding the OPC UA Specification belong to the "Technical" forum. In this section we answer questions related to our C++ based SDK only.

If you read the specification about the requestHandle and the Cancel Service you will find that the requestHandle is a number defined by the Client. Therefor the Client can use this number for several Requests e.g.of the same type like 20 parallel read requests, and could now cancel all of them with one single Cancel Service call, because if one Read did not return in time, it is very likely that the other 19 will also not return in time. This is under full control of the Client, the server will just cancel all outstanding requests that have the given number.

So, yes you can Cancel more than one Request (when you have given all those Requests the same requestHandle)

Best Regards
Support Team