The orientation is used to indicate the method of signaling or status change.

There are two methods for recording a signal a service: EMIT or RECEIPT.

The EMIT method is used by a named service itself to signal an operation such as START or an outcome of an operation such as SUCCEED – this is from the perspective of the self, the service owner of the context.

The RECEIPT method is used when an observer, such as a service that is calling another service, experiences an outcome such as an exception or error code within a response, which would map to the FAIL signal.

Receipt of a signal should be taken as being generated in the past, whereas emit is the present moment assuming discrete time steps.