Re: Simple Components 4.12 with MQTT implementation released

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 2016-04-15 12:06, slos wrote:

> We share some of the vision.
> "Ada for Automation" is a framework with which one can build his own
> control application using Ada. I would not call it a middleware.

Why not?

> And MQTT or OPC UA would just connect it to some SCADA or cloud based
> application like one using IBM BlueMix.

Neither is good for SCADA, especially regarding safety requirements and 
performance.

>> Note that without OPC UA everything could work far better and require
>> far less resources. E.g. having all process data the OPC cannot access
>> because it is too slow to pace with the middleware capable to deliver
>> data at less than 1ms rate and does not properly support
>> push-subscriptions, does not support distributed time stamping, physical
>> units, error states etc.
>>
> I agree that OPC UA does not fit where EtherCAT, Sercos III or PROFINET IRT would.
> OPC was created for office and SCADA / GUI applications access to
> PLC  data, not for IO processing.

Why SCADA or DB server should ever use some other middleware protocols? 
The point is that one middleware can stretch from the ERP levels down to 
the field. But when the middleware is OPC or MQTT you cannot not put it 
into a device and expect that working. This is the reason we must live 
with EtherCAT, ProfiNET down there, which are nightmare to any system 
integrator. That defeats the very idea of a middleware.

The real advantage of Ada is that it is scalable from heavy duty to hard 
real-time embedded. The ugly protocols like XML, HTTP, OPC etc only 
hinder developing of safe and efficient systems.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de