I am building a series of interactive shiny web apps for a project that I am considering turning into a Company. My background is in data science and I don't have a lot of experience on the web app / server side of things, but these are important aspects for me to consider with my project. I currently have an Amazon Linux AMI EC2 instance with ShinyServer (free, open-source) installed, and I am currently hosting early versions of my web apps there. So far everything works fine, but I haven't made the links public yet.
My first question is whether anyone knows if there are certain limitations (scalability limitations, integration with database limitations, security / authentication limitations, etc.) that I will inevitably run into using RShiny apps and ShinyServer? I haven't heard of many successful, super-popular web apps being shiny apps hosted on ShinyServer, but rather my feeling is that ShinyServer is mainly used for hosting RShiny apps that are shared amongst only a small number of people (i.e. shared amongst team members at a company.). Per this thread - Does R-Server or Shiny Server create a new R process/instance for each user? - I am particularly concerned that my app won't be able to handle thousands of users simultaneously since only 1 R process is created for the app regardless of the # of concurrent users of the app. Having 10-20 processes through ShinyServer pro probably doesn't solve the issue either if I ever intend to scale greater than the hundreds or thousands of users. I also noticed that ShinyServer Pro would run me a not-so-negligible $10K per year.
My second question is whether RShiny apps can be deployed using other server technologies, such as Heroku. I came across this github page (https://github.com/virtualstaticvoid/heroku-buildpack-r/tree/heroku-16) but haven't dug too deep into it yet. I've been told that heroku makes it easy to update releases to apps whose code is on github (git push heroku:master), amongst other things.
My third question involves certain specific considerations of mine. In particular, I am currently working on a script that queries data from an API and writes that data to a (not-yet-setup) database of mine. This is the data my apps use, and I'd be interested in having the apps update in real time as the database updates, without requiring the user to refresh the webpage. A buddy of mine suggested AJAX for this type of asynchronous behavior, and it looks like this may be possible in R with something like this (https://github.com/daattali/advanced-shiny/tree/master/api-ajax).
Sorry that this is such a loaded question, but I hope it doesn't get closed down as I think it is fairly educational. Any suggestions / sources / pointing me in the right direction would be greatly appreciated on this.
