What framework or libraries would you suggest if one wants to serialize data in production environment for Scala project?
I quite like Pickling (http://lampwww.epfl.ch/~hmiller/pickling/), but this project looks like discontinuous. Others include upickle (http://www.lihaoyi.com/upickle/), but I have not seen too much discussion.
Any other recommendation?
If your classes are immutable, then all the internal fields are determined by the constructor arguments, hence you only need to serialize the constructor arguments. I created my own custom XML code to serialize my classes based on their constructor arguments. That may be slightly more work, but I had a reason for it.
Any specific requirements?
Note that there are a lot of alternatives – I suspect a dozen major options, and lots more minor ones. So as @nafg says, more requirements would be helpful. (Eg, do you prefer binary or JSON? Do you care about whether it is standards-based? Does it need to be compatible with external systems? Is this serialization for wire transport or persistence? Do you need schema evolution?)