I'm an Engineer of over 40 years standing, working on some exciting projects such as Concorde in my time. I'm not a specialist in avionics but certain aircraft still use my pitot static system today.
My granddaughter is interested in robotics - she is very young but very smart and with good attention to detail.
I am really happy meet you on this forum as such grate experience engineer ,
So What can I do for you in my end
.... get your Robot arm working reliably with App Inventor 
That's a kind offer Dayan but I cannot accept. If the Power Users started accepting gifts of any form, it would not sit right. We are here for everyone, everyone is equal, our service is free.
I will be one of your customers though 
Orrr I am sorry
Let me know before purchase
You have nothing to be sorry about Dayan. How is your progress with the Arm?
Its ok
The arm is working it all the basic steps , and App also working base on your help. Now I need to check app with several phones. So I need to send apk file to my students for the testing ,
So keep this project bit away. The best way is testing with students. I will come back to this tread
Now I stated IoT project with Blynk App, To automated my room pedestal fan
Have you experience with Blynk app
Just now is the first time I have heard of Blynk App
Using Blynk you can automated your home , ( IoT ), You can ON and OFF your room bulb from the bed, and anything
Everything you do in the blynk app, you can do in the inventor app. Obviously, it will not be as easy as in fluid.
Orrr Nice can we able to build an app like Blink app doing
That requires some expertise in security and databases..The Blynk pricing is very hefty for such a service.
Good for fun and testing, and if you don't want to build your own system. Very good for beginners copying arduino projects from the internet.
Blynk is ruing on cloud server , and it needs a token, It is better if we can run it client base , I mean without a server
Patry do you believe that the App inventor can do as same as Blynk app, and I sow Blynk offer some images those who would like to make the App same as Blynk
There are extensions e.g. MQTT. For example, you can create an MQTT server on Rassbery. Then it is easy to create an application in app inventor that will send and read information from the server. And create multiple end devices, e.g. arduino or esp32 that will connect to your mqtt server and read and send information from it. You can build your system completely from scratch.
Don you believe that like Grade 7,8,9 student can understand this project once I teach them
Because I would like to introduce this project for our students
I think if you explain it well to them, they will understand it better than "blynk". And they'll learn more by the way. It's just a matter of presenting it to them in an accessible way, although I know teachers would prefer it to be as easy as possible for themselves.
See the "MQTT" extension, the extension page has a very nice description. The extension itself is also very easy to use. There is also an example application for two phones. One phone works as a control application, the other phone imitates the terminal device. From one phone you turn on the light on the other phone, while you see if the light has actually been turned on. To simplify presentations you can use MQTT online server (broker mqtt), some are free. There are also free android applications that can run the MQTT server (broker mqtt) on a local IP address.
https://ullisroboterseite.de/android-AI2-PahoMQTT-en.html
The rest are graphic skills to create a nice application.
Can you please elaborate more requirement for security , If we build the app for open source and any body can use it free of charge
It should only be possible for a db owner and their verified clients to access their data space on the server. If outsiders could gain access, personal and or business data could be hacked. Huge penalties in the EU for breaches of that nature.
If the site is developed as an Open Source package, that would be different because all responsibility is in the User's hands - but it would be reasonable for tUsers to expect a level of competence, just as people who use App Inventor's source do. If you are an expert on this subject, that's fine, that's who should be doing it. Should it impact the commercial operations of existing platforms, you might find that they will take any action available to them. In a very competitive market, not everybody is nice.
