Before writing the first line of code and a tool selection, I would first collect the requirements. So far we have:
- Several thousand simultaneous accesses
- A database
This means that Xojo Web would have failed without load balancing across a large number of servers or Xojo Cloud instances.
But the product in question can still be anything. Maybe it’s a pure API to make data available to others, or a full blown UI. But here too, there could be at least 2 possibilities:
- Desktop app that reads data from the cloud or
- A web app
With 1) the question arises as to which platforms this should run on (cross-platform clients?).
But I assume 2) is the case anyway, but then there are questions as to whether it is important that the app also looks good on mobile (responsive design) and whether concepts such as PWA are important or just nice-to-have. Second, you should evaluate at 2 which “controls” are important. Should tables only be displayed, for example, or should they also be editable, etc.
With the database, it also depends on what you want to save and how. If you only work with JSONs, newer concepts such as mongoDB are very interesting, but there is a limit of just over 20 MB per data record, and the latest postgres can also process JSON files very easily, mySQL less well.
In this respect @thorstenstueker’s recommendation with Vaadin and Java IMHO is the better one. Because at least you would only have to deal with one language, more or less a simple (but above all powerful) language at your disposal, a simple deployment and for a similar price as for Xojo even with a layout manager.
Now comes my assessment (from my own experience): No matter what you will do, set yourself realistic goals. Even with Java you have to reckon with at least 3-6 months “onboarding”. I would even say 6-9 months full time. I’m not talking about a new programming language, that’s the most trivial point, but the entire ecosystem (UI technology, IDE, using databases, test cases, error management, trainings, tutorials, finding the right information sources and this list could be almost endless).
It’s like VB, Xojo. A master doesn’t just fall out of the sky. And once you’re a master, it’s easy to forget how much time and effort you’ve put into it over the years. I.e. no matter what well-intentioned advice we give here, unfortunately you have to implement it and get your head around it. And that’s tedious, sometimes frustrating, but it’s a lot more fun with almost all other languages than with Xojo. There is only one problem: with Xojo you regularly end up with a show stopper and can blame the manufacturer, with other languages it is almost always your own fault.
But please don’t be intimidated. The most important thing is to make a decision and start! I wish you success!
Edit: I forgot one of the most important things about web apps: security and authentication. That alone is a challenge. Something that Vaadin and other server-side rendering solutions largely do for you. If you deal intensively with the topic, you quickly realize how many solutions on the web are extremely insecure and easily hackable. But here, too, it depends on your requirements and how sensitive your data and apps are.