NI web server on cRIO Linux RT target Pros and Cons

[Noriker]

Hi,

We have a mission critical control system running on NI 9035, Linux RT target. We want to add NI web server to run web service for the web based UI. We'd like to know if NI web server is reliable or if it could cause any instability or performance problems, i.e. if it crashes would it take the control system down with it? Is it safer to have NI web server run on a separate dedicated machine? Has anyone had experience or knowledge on the issue? Please help. Many thanks.

[James_McN]

I appreciate this is an old post but I'll fill you in on my experience.

I've been running it on a non-linux cRIO (vxWorks and Pharlap) for a while now to provide a web-UI as well as some remote status updates.

I've not had any stability issues but I will say:

1. The web server is an embedded one. It is not designed for typical web server applications but just for the odd user query. I would not expect it to perform especially well if you have multiple users wanting to access it at once. We never proved a limit but started to see issues when we wanted to use it on a server application (i.e. not the cRIO but a data server with multiple users).

2. It is running on the same OS and has no isolation from your main application so be gentle! On the lower powered cRIOs we use we see a noticable CPU increase when the web interface is polling for data so make sure you account for this. Again multiple simultaneous users will make this worst.

3. There is no heavy processing in our web VIs themselves. They are just pulling data from FGVs populated by the main application and formatting to JSON in most cases.

4. I've not seen any stability issues of concern. Admittidly the full UI is only loaded during investigations so this is rare. We are polling basic status information about once every 10 minutes from every unit (around 12-15 in the field for 2 years atm) and its not caused problems.

So hopefully that gives you some ideas - generally I've been happy but do remember it is embedded and not server grade.