Inter-process communication

Question

I have two applications: X and Y.
X is the main application and it handles a lot of XML files. It has a history of more than 10 years and half a dozen techniques have

Answer 1

You could have X write its output to a memory-mapped file - Y can retrieve the data if it is running. This way X does not care whether or not Y is up.

X could write some kind of control info at a known location (eg. store the offsets of last 1000 written XMLs starting at offset 0 in the mapped file) and use the rest of the file as a circular buffer for the raw data.

If you need Y to be the determining factor for actions in X, have Y create the mapped file, and then use its presence/absence as a check on the data production on the X side of the 'channel'. There is example code for creator and second user here.