How is Wii U ripping happening?

Iv'e been noticing plenty of people getting into these model files. Not only music but everything. I only have one question, how? How does one even access the files to the games? Either they install it to an external hard drive and go from there or they get the PC to read the disks. And if you know an answer on how at all to get to this, please tell me. At least tell me how to get the files of any game for ex. Pikmin 3, and what tools I can to extract them.



Again, all I'm asking is how to get access these things.





-Thanks