The fact that you've posted your question in RESTful PI System Access indicates that you have PI Web API in mind as the Developer Technology to use.
I must admit that I don't know anything about Open-VMS but PI Web API claims to be a RESTFul service that can be consumed from any platform. A client must support https communication. Kerberos security will very likely not be an option but Basic and Anonymous authentication should work. If you don't have PI Web API (PI Coresight) installed yet, please consider installing it. You can easily test communication and different queries from different clients and compare results. All you need client side is a web browser supporting https communication.
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It would be interesting to see the use case. Long time ago when working on the VMS integration we ended up using file transfers to/from the VMS boxes once we understood what the data requirements were; regular updates of a number of PI Points. There wasn't any ad hoc data requests or the like. Oh and there was no PI Web API back in those days, just PI API.
Anyway, it seems libcurl and json-c are the way to go when using PI Web API...
Thanks for your reply. Currently I'm just grasping/reaching for anything
that might work or point us in the right direction. The RESTful PI System
Access just seams like a forum that might be helpful. Our existing custom
model code interacts with PI via PI-API.
We currently have two sets of PI2 (OpenVMS) systems running, wherein on
the PI2 Server exist custom model code that communicates to PI via PI-API
calls. We're in the process of migrating to the latest PI3 Windows Server
platform, which appears to be straight-forward regarding the PI upgrade
(PI2 to PI3). However, we've just learned that the remaining custom model
code that also resides on the PI2 Server will not be able to communicate
from the OpenVMS (existing location) platform to the new PI3 Windows
Is there anyone out there that has encountered this problem or has a
You've asked the same question in 2 different places. Interestingly the places (sub spaces) you've chosen had a big impact on the initial replies and indicate we are understanding questions differently depending on the technology that appears to be involved. Turns out both threads are almost parallelized just after a few posts on each. Therefore please allow me bringing both your identical, different questions together by referring to Chuck's reply on your other different, equal question.
I must admit that my answer is influenced by a commercial currently on German television. I was lucky finding an enhanced English version on youtube and there's even more. Enjoy!
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Dave... the answer is yes. You should be able to use a PI-to-PI interface to move data between a PI 2 and a PI 3 system.
A number of years back, I was at a site where we migrated from a PI 2 to a PI 3 system.
Because of the number of interfaces on the PI 2 system running on VMS interface nodes, it was a phased cut-over.
The PI 3 system was instantiated and then and multiple PI-to-Pi interfaces created to starting moving data from the PI 2 to the PI 3 system.
We started by migrating the non-VMS interfaces (Windows server based) first; as each interface was moved, the corresponding PI-to-PI interface was disabled.
Finally, only the VMS interfaces remained, and then they were reconfigured to point to the PI 3 server directly.
That system, using a VMS interface node, stayed in place for years until each of the data sources could be finally migrated.
Please note: if a interface on VMS is restarted, it can take a lengthy period of time to get data flowing again - the interface doesn't have disconnected startup and needs to get the full tag list pulled and built before starting to send data again.