datasocket stale data

[redfoot]

Hello. I have a stale data problem with datasockets. I have a remote DS writer processes and a local reader. The writer dynamically creates URLS when it is ready to send, and periodically updates the URLS when new data is available. I have a reader (which is not a creator) that looks to see if a URL has been created, and if it has been, the reader retrieves data from the DS server and logs the values to a file.

The problem is, after all this is up and running, if the DS writer goes down, the DS reader still sees the URL--it never goes away as long as the reader is alive. The reader keeps reading stale data and writing it to the file.

So my question is: How can the reader detect stale data? The reader is in CVI 7.1.0, the writer is LabVIEW 7.1, both systems are under Windows 2K. The CVI datasocket handles are opened with AutoUpdate, Polling Model options.

Hope someone has an answer. Thanks. Kevin Redmond (redfoot)

[Scott Y]

Hello,

Would it be reasonable for your to add some additional dataitem that indicates that the writer is still active? The reader could turn this setting off every so often, and the writer will turn it back on more often than the reader turns it off. This way you can tell that that the writer is still producing data.

Alternatively you could include a dataitem which is incremented with each new packet. This would allow you to determine if you are reading the same data repeatedly.

Scott Y