The FAIL signal signals a failed service execution or call.

An example of signaling during the execution of a service request.

S1 EMIT    START
S1 EMIT    FAIL
S1 EMIT    STOP

An example of signaling during the execution of a service request that involves another service.

S1 EMIT    START
S2 EMIT    CALL
S2 RECEIPT FAIL
S1 EMIT    FAIL
S1 EMIT    STOP

An example of signaling from the perspective of both ends in a service-to-service interaction.

S1 CONTEXT          |  S2 CONTEXT
------------------------------------------
S1 EMIT    START    |    
S2 EMIT    CALL     |    
                    |  S2 EMIT    START
                    |  S2 EMIT    FAIL
                    |  S2 EMIT    STOP
S2 RECEIPT FAIL     |
S1 EMIT    FAIL     |
S1 EMIT    STOP     |

An example of signaling from the perspective of both ends in a service-to-service interaction in which the service name was transferred with the request payload.

S1 CONTEXT          |  S2 CONTEXT
------------------------------------------
S1 EMIT    START    |    
S2 EMIT    CALL     |    
                    |  S2 EMIT    START
                    |  S1 RECEIPT CALL
                    |  S1 EMIT    FAIL
                    |  S2 EMIT    FAIL
                    |  S2 EMIT    STOP
S2 RECEIPT FAIL     |
S1 EMIT    FAIL     |
S1 EMIT    STOP     |