Observer pattern

[Podolski]

Hi,
SCADA system usually requires that integraters query data repeatly. And timers are often used in this pattern.
However, in some cases, a lot of software need more instant response rather than fixed time interval update.

As far as I know, Rapidscada provides file access and TCP access to update data. Perhaps it is more convenient to develop Modules (or shipped in server) which implements observer pattern. It will help a lot for real-time applications.

FYI,
Reactivex is a a framework implements observer pattern.

[Mikhail]

Hi,
Could you describe an example? Do you mean something like SNMP traps?

[Podolski]

Hi,
I don’t know SNMP traps. I read some articles about the tech, and I think the idea is the same.

Observer pattern is also name publish-subscribe pattern. Subscribers can register themselves to the publisher. When publisher gets an update/modification, it will notify all the subscribers to update the status.

Sounds like delegate in C#.

[Mikhail]

This is generic. This approach may be included in Rapid SCADA for different tasks

[Podolski]

Do you mean I should implement it on my own server module? Or particularly in driver?

[Mikhail]

Depends on the task. What task are you solving?

[Podolski]

I am trying to build a WPF based UI for a system. MVVM is my preferred option. It is not so elegant to leverage the tech by polling infos constantly in my opinion.

[Mikhail]

It would be great. Please notify me about results.
I suppose, you should create a module for SCADA-Server that provides API with such pattern. Also you could use OPC UA for this purpose. The module should be OPC UA server and your app is OPC UA client.

[Author]

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