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ptstream / QtUPnP

QtUPnP framework is a C++ framework, based on QT5, to build easily an UPnP control point. It focuses on the UPnP/AV standards.
GNU General Public License v3.0
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Discover finished notification #5

Closed steveq61 closed 6 years ago

steveq61 commented 6 years ago

Hi, Perhaps I haven't fully grasped how CControlPoint::discover() works, so I'm sorry if this is a bad question. I would like to get some sort of notification when the discover process is complete. I am successfully discovering network devices, but I want to know when QtUPnP has stopped looking because they have all been found. Is there a slot notification for this? Is this possible please? Thanks, Steve Q. :-)

ptstream commented 6 years ago

Hi,

I understand your question, but it is not possible to make this.

The UPnP protocol works like this: (big simplification)

  1. A control point sends a set of UDP discovery messages using a multicast address (239.255.255.250). Normally all UPnP compatibles devices listen this address and have to send back a response.

  2. The control point waits the response of the devices. The response delay is extremely variable. It depends on the network load, the number of compatible devices, the algorithm used by the devices and a lot of other thinks (e.g. the device is not ready to intercept the M-SEARCH message).

In fact, the control point does not know when the devices will respond. This can be between a few seconds and several minutes. Moreover, some devices can leave the network (turn off or wireless out of reach), some other are turned on after the discovery message. The control point always listen for network input or output.

I hope to have been clear Regards, Patrice

steveq61 commented 6 years ago

Hey Patrice, Thanks so much for your prompt reply. To be honest I thought your answer may be along these lines, but I was hoping not. I guess I'll have to look at the way I am structuring my software. Thank you,

Steve Q. :-)