API gateway takes all API calls from clients, then routes them to the appropriate backend service with request routing, composition, and protocol translation. API gateway secures, protects, manages, and scales API calls by intercepting API requests and applying policies such as throttling and security using handlers and managing API statistics.
Service chaining is a concept that help centrally manage and control exposing several services as a single service. For a single client request, there will be a chain of backend services invoked, one after the other, to compose the response to the client.
Cross-Origin Resource Sharing (CORS) is a security mechanism that allows a web page from one domain (in other words, Origin) to access a resource with a different domain (a cross-domain request).
An SSL handshake is a process that begins when your browser sends a secure connection request to a web server. SSL Handshake Error is a message you receive when the SSL handshake process fails.
A keepalive (KA) is a message sent by one device to another to check that the link between the two is operating, or to prevent the link from being broken. Heartbeat refers more specifically to a communication protocol, where to or more members of a high-availability setup periodically send “Yes, I’m still alive!” messages.