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How does the Control Point know if the Device disappears without saying goodbye?
22-10-2012, 12:22 PM
Post: #7
RE: How does the Control Point know if the Device disappears without saying goodbye?
(22-10-2012 10:55 AM)dough Wrote:  Yes, they do refer to file systems: NFS (Network File System) and FFS (Flash File System) respectively.

The problem of NOTIFYs seems to be independent of the file system. There are times when the Control Point cannot discover the Device. I recall that when running the OhNet tests on iOS (also the platform of my Control Point), they eventually failed to discover any Devices. Did you manage to investigate this further?

I improved but didn't fully stabilise discovery. I have time scheduled next week to finish this off.


(22-10-2012 10:55 AM)dough Wrote:  I notice that when the Control Point stack starts or when the Device List is created, the Control Point issues an M-SEARCH for the specific device type. Using Wireshark I can see that the M-SEARCH is issued only once. Other control point tools (both Device Spy & Device Sniffer) seem to issue two M-SEARCHes. Is this likely to reduce the chance of an M-SEARCH going missing (since it is using UDP)? Can I reissue the M-SEARCH once the Device list has been built?

We didn't duplicate MSEARCH requests on the assumption that UDP isn't all that unreliable on local networks so requests won't actually get lost very often. If it turns out this is only true for wired networks, we could change device lists to issue repeated MSEARCHes. For now, you can call CpDeviceListRefresh which will issue a new MSEARCH, merging the new and previous lists.


(22-10-2012 10:55 AM)dough Wrote:  Clearly my Upnp operational knowledge is lacking, but using OhNet, should I need to understand how Upnp works?

You shouldn't need to understand implementation details of UPnP. We've found however that you do need to learn a little about network administration to debug deployment issues caused by poorly setup networks.
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RE: How does the Control Point know if the Device disappears without saying goodbye? - simonc - 22-10-2012 12:22 PM

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