In the first exercise, we are going to run a simple, single-process "Hello" application, and review its source code, so that we can later instrument it for distributed tracing. The application is implemented as a web service, which we can access by sending it HTTP requests like this:
$ curl http://localhost:8080/sayHello/John Hello, John! $ curl http://localhost:8080/sayHello/Margo Hello, Margo!
The application has some creepy big brother tendencies, however, by occasionally volunteering additional knowledge about the person:
$ curl http://localhost:8080/sayHello/Vector Hello, Vector! Committing crimes with both direction and magnitude! $ curl http://localhost:8080/sayHello/Nefario Hello, Dr. Nefario! Why ... why are you so old?
It looks up the information in the MySQL database that we created and seeded earlier. In the later exercises, we will extend this application to run several microservices.