We have been successfuly using a SETVALUEEX over HTTP to set values on field loggers. A new system requires that HTTPS be used, and despite configuring the logger with HTTPS enabled requests are timing out.
The form of our request is: http://###.###.###.###//?command=setvalueex&uri=dl:public.sdiRead&value=True&format=json
Is this a limitation of the web API? Has anyone had success using SETVALUEEX over HTTPS?
When using HTTP or HTTPS, the datalogger takeson the role of a the server (responder to requests). When this is done in the context of HTTPS, there is a great deal of calculation that the server has to perform in order to accomplish the TLS handshake and, depending upon how busy the datalogger is with its program, the type of the datalogger, and the size of the TLS private key, I have seen this negotiation take up to minutes for the datalogger to be able to complete the required calculations. The ramifications of this are that HTTPS clients need to be more generous when it comes to waiting for HTTPS connections (and the TLS handshake) to complete.
This post is under review.