It's a number of services written in a mix of Java and C++. https://code.facebook.com/posts/820258981365363/building-mobile-first-infrastructure-for-messenger/

It's a number of services written in a mix of Java and C++. https://code.facebook.com/posts/820258981365363/building-mobile-first-infrastructure-for-messenger/ https://code.facebook.com/posts/820258981365363/building-mob... https://code.facebook.com/posts/699902483369896/inside-facebook-messages-application-server/ https://code.facebook.com/posts/699902483369896/inside-faceb... https://code.facebook.com/posts/403496919755405/scaling-the-messages-application-back-end/ https://code.facebook.com/posts/403496919755405/scaling-the-...