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Validating MaxRequestMessageSize and MaxResponseMessageSize
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Ganesh Gaikwad
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06/11/2020 - 04:25
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Hi Team,

We are using default value(4194304) which is defined by opc ua stack  when gievn value is 0 for MaxResponseMessageSize in createSession call. Also we are not validating MaxRequestMessageSize  given in createsession response. Is it mandatory for opc ua client certification? we are referring below test cases.

Err-026CTTCreateSession The Server returns a maxRequestMessageSize of 500 (bytes).Verify that client honors this max by testing with a call that should exceed this space, such as a large Read/Write/Browse request.
TOOL: WireShark to verify? Or a `stack watcher` tool? Actually, the Server and/or Client should reject messages that are too big with an error `Bad_RequestTooLarge` or Bad_ResponseTooLarge` as applicable.
Err-027CTTCreateSession maxRequestMessageSize is decades larger than maxResponseMessageSize, e.g. maxResponseMessageSize * 10.
If the requested MaxResponseMessageSize == 0 then set revise the MaxRequestMessageSize = 500;
Client reports an informational message to the end-user to report the limitations on the channel. The Client continues to communicate with the UA Server while abiding by the message size constraint.

 

Regards,

Ganesh

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Ganesh Gaikwad
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06/16/2020 - 22:30
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Hi Team,

Can you please respond to above query?

Regards.

Ganesh

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Paul Hunkar
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06/17/2020 - 06:28
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Ganesh,

   In general, all test cases in the CTT are required for the ConformanceUnit/profile to which they are applied.  If you have questions about the wording of a test cases and don't understand what it is trying to test, we can clean them up and improve them as needed.  The first test is checking that a client will honor the maxmessage size that a server reports.  All well behaved client shall attempt to honor this constraint that a server might have.  the second is that a client can deal with a server that does not have symmetric buffer sizes - again a well behaved client shall attempt to honor this.  The reporting part could be improved in wording or removed - "i.e. Client reports an informational message to the end-user to report the limitations on the channel." is not part of what is required.

Paul

Paul Hunkar - DSInteroperability

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Deepali Ahirrao
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06/24/2020 - 23:27
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Hi Paul,

Just to confirm my understanding - When client sends Hello message, the MaxMessageSize sent in this message represents MaxResponseMessageSize. And when Server responds with Acknowledge, the MaxMessageSize sent in Acknowledge represents MaxRequestMessageSize. Is this correct?

Thanks,

Deepali

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