Two services talking using NodeJS and Ruby, Sinatra.

There are a number of ways to make services or applications talk to each other. You can make one service access another service synchronously or asynchronously.

Usually two services can talk to each other each other using databases, or plain HTTP or using message queues. Message queues are used for asynchronous communication. 

Here's a short video that shows two services, one created using NodeJS and the other created using Ruby, Sinatra. NodeJS service uses axios HTTP library to access the Ruby Service.