[FLINK-21865] Add a Docker Compose greeter example to StateFun playgrounds

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: statefun-3.0.0
• Component/s: Stateful Functions
• Labels: pull-request-available
• Assignee: Tzu-Li (Gordon) Tai
• Reporter: Tzu-Li (Gordon) Tai
• Created: 19/Mar/21 05:18
• Updated: 27/Apr/21 18:03
• Resolved: 22/Mar/21 03:02

Description

This example is intended as a follow-up after completion of the Java SDK Showcase Tutorial (FLINK-21862).

If users are already familiar with the Java SDK fundamentals and would like to get a better understanding of how a realistic StateFun application looks like, then this would be the example they start with. Otherwise, we would recommend users to take a look at the Showcase tutorial first.

This example works with Docker Compose, and runs a few services that build up an end-to-end StateFun application:

• Functions service that runs functions and expose them through an HTTP endpoint.
• StateFun runtime processes (a manager plus workers) that will handle ingress, egress, and inter-function messages as well as function state storage in a consistent and fault-tolerant manner.
• Apache Kafka broker for the application ingress and egress.

To motivate this example, we'll implement a simple user greeter application, which has two functions - a UserFn that expects UserLogin JSON events from an ingress and keeps in state storage information about users, and a GreetingsFn that accepts user information to generate personalized greeting messages that are sent to users via an egress.

Issue Links

• links to: GitHub Pull Request #4