# One request, one trace id, four services. Lines are 'service | traceId-spanId | message' from each service's log.

--- POST /api/orders sent to the gateway; trace id 6ad8f16556352b627323a47cb0510c20 ---
gateway | 6ad8f16556352b627323a47cb0510c20-7323a47cb0510c20 | gateway received POST /api/orders
order-service | 6ad8f16556352b627323a47cb0510c20-fe6e6271c03b82ea | placing order for product 2 x1
product-service | 6ad8f16556352b627323a47cb0510c20-a01e14c8e2434acc | looking up product 2
inventory-service | 6ad8f16556352b627323a47cb0510c20-419570d38f840942 | reserved 1 of product 2, 7 left
order-service | 6ad8f16556352b627323a47cb0510c20-fe6e6271c03b82ea | order 2 is CONFIRMED

--- a caller that already has a trace id (W3C traceparent header): the same id comes out the other end ---
gateway | 4bf92f3577b34da6a3ce929d0e0e4736-91a3561198164d6c | gateway received GET /api/products/1
product-service | 4bf92f3577b34da6a3ce929d0e0e4736-bce2498c85b72fc7 | looking up product 1