Mastering Distributed Tracing

Exercise 1 – the Hello application

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 ... ...