Is that possible to demultiplex the method call request

[dingy]

Hello, support team:

I'm developing an UA based gateway program. This program will be able to process some method call request which will lead blocking I/O operation, for example, update address space configuration file or access user account data file.

In single thread mode, this kind of request will block the event loop of UA Server until the I/O blocking operation is done.

So, I wonder if it is possible to dispatch this kind of request to anther thread, and this thread will be in charge of processing and responding to the client?

If it is possible, do I need to do some lock job when I send back the responds to UA Stack? At which moment do I need to lock?

Thanks a lot

[Support Team]

Hello,

you can dispatch all calls to the provider to another thread and process them there.

The only thing to remember is that the according XYZ_WriteComplete-callback needs to be called by the main thread that is calling UaServer_DoCom() in a loop. Hence you will have to create some sort of message queue that is filled with the responses by the worker thread and that is processed by the main thread.

Additionally you can call

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OpcUa_SocketManager_SignalEvent(OpcUa_Null, OPCUA_SOCKET_RENEWLOOP_EVENT, OpcUa_True);

out of the worker thread to signal the stack to return from the UaServer_DoCom() function, so that the new response in your message loop can be handled as soon as possible.

Best regards,
Unified Automation Support Team

[dingy]

Ok, Thanks a lot

[Support Team]

Hello,

please note that it is important to set the define

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OPCUA_USE_SYNCHRONISATION

in order to use OpcUa_SocketManager_SignalEvent from other threads, otherwise you might run into problems.

If you are using the CMake files provided with the SDK, you can enable the define by setting the CMake option

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BUILD_UASTACK_USE_SYNC

to ON.

Best regards,
Unified Automation Support Team