title E2T Init flow
participant E2 Manager as E2M
participant E2 Terminator instance as E2T
participant RanReconnectionManager as RRM
participant E2tAssociationManager as EAM
participant E2TInstancesManager as E2TM
participant RoutingManagerClient as RMC
participant rNib DB as RNIB

E2T->E2M: INIT {<E2TAddress>}
E2M->E2TM: GetE2TInstance(e2tAddress)
E2TM->RNIB: GetE2TInstance(e2tAddress)


alt existing E2T
    RNIB->E2TM: E2TInstance {Address:...,AssociatedRanList:[...]}
    E2TM->E2M: E2TInstance
    alt state: TO_BE_DELETED
        note over E2M: Log it.\nSTOP
    else state: RM_FAILURE
        E2M->+E2TM: SetE2tInstanceState(RM_FAILURE, ACTIVE)
        alt error
        E2TM->E2M: error
        note over E2M: Log it.\nSTOP
        else success
        E2TM->-E2M: ok
        end
        note over E2M: Proceed as ACTIVE...
    else state: ACTIVE
        loop all associated RANs
            E2M->RRM: ReconnectRan
            RRM->RNIB: GetNodeb
            RNIB->RRM: ok
            alt RAN's connection status is SHUT_DOWN
                note over RRM: return
            else RAN's connection status is SHUTTING_DOWN
                RRM->RNIB: UpdateNodeb(SHUT_DOWN) 
            else RAN's connection attempts >= MaxConnectionAttempts?
                RRM->RNIB: UpdateNodeb(DISCONNECTED)
                RRM->+EAM: DissociateRan(ranName, e2tAddress)
                note over EAM: Detailed in another sequence diagram...
                EAM-->-RRM: ok
            else Can reconnect
                note over RRM: execute Setup
            end
        end
    
else new E2T (error: ResourceNotFoundError)
    RNIB->E2TM: err ResourceNotFoundError
    E2TM->E2M: err ResourceNotFoundError
    E2M->+RMC: POST /handles/v1/e2t
    alt RM failure
        RMC->E2M: 4xx/5xx/TO
        note over E2M: Log it.\nSTOP
    else RM success
        RMC->-E2M: 201
    end
    E2M->+E2TM: AddE2TInstance(et2Address)
    note over E2TM: Create E2tInstance:\nkeepAliveTimestamp = now\nstate = ACTIVE
    note over E2TM: Lock (atomic operation)
    E2TM->+RNIB: SaveE2TInstance(E2TInstance:<address>)
    RNIB-->-E2TM: ok
    E2TM->+RNIB: GetE2TAddresses
    RNIB-->-E2TM: []string
    note over E2TM: add e2t address to list 
    E2TM->+RNIB: SaveE2TAddresses
    RNIB-->-E2TM: ok
    note over E2TM: Unlock
    E2TM-->-E2M: ok
    note over E2M: In case of save failure, log it 
    #E2M->E2M: iterate orphan RANs (?)
    #counter (?)
    
else error (InternalError)
    RNIB->-E2TM: err InternalError
    E2TM->E2M: err InternalError
    note over E2M: log error
end