Inter-application communication in HCP

In micro-service architecture, inter-service communication shall be very efficient, in which case HTTP is not a good option. Can we open a server socket in HCP application for other applications to connect? In other word, is it possible to open TCP/UDP port in HCP application? If yes, is there any constraint for other application to connect the application which is listening?

To be more specific, attached the illustration, how is it (marked as yellow) supported in HCP? thanks.