title: How to create an observable from an open file
body: <p>Suppose that I want to open a simple text file and start typing in it. If I create an Arraylist of the contents of the file as an observable, then it would be processed very quickly and it will reach the EOF. What I want is to have an observable that watches my writing and spits the result through some function to another file. The latter part is doable. The problem is getting the first part where the observable is waiting for me punching the characters. I guess this is the opposite side of back pressure.</p>