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SEMI E41-95 © SEM I 1995 8 9 P OSTE D Reporting disabled. NOT POSTED 10 not EXSTAT E Default entry into recovery concu rrent state at ini tial exceptio n conditio n creation. NOTRECOVERING 11 NOTRECOV ERING “EX Recover” …

SEMI E41-95 © SEMI 19957

the recovery action activities as quickly as possible.

The abort command terminates the recovery action.

8.2 Exception Condition State Model — The behavior

required for exception management is fully specified by

the exception agent (service-provider) behavior. This is

described by the exception agent exception condition

state model. All required decision authority (service-

user) behavior is inferred by this model.

Message flow diagrams presented in the previous

section are useful to show simple situations. The

exception condition state model presented in this

section provides the information necessary to

extrapolate the message flow diagrams for all situations

within the scope of this standard.

The exception condition provides for exception agent

reporting on an abnormal situation in the equipment and

management of a recovery action requested by the

decision authority to resolve the situation. Recovery is

requested in the context of a particular exception

condition so the recovery action behavior forms a part

of the exception condition behavior.

Figure 3 shows the state diagram for an exception

condition. The Harel state model notation used is

described in Conventions, Section 5.1. The

corresponding state transition table is shown in Table 1

on the following page.

Figure 3

Exception Condition State Model

The detailed state definitions follow:

EXSTATE — When created by the exception agent, an

exception condition enters the EXSTATE. It is in this

state as long as it is in existence, irrespective of

association to the decision authority. The exception

condition has two concurrent subsets, which together

fully describe its state. These subsets are Reporting and

Recovery.

The exception condition initializes to the SET state if

the abnormal situation related to the exception

condition is apparent and relevant; otherwise, it

initializes to the CLEARED state.

Reporting — Reporting is one concurrent subset of

EXSTATE. It includes the substates describing whether

the abnormal situation related to the exception

condition is apparent and relevant, and whether the

latest information on the situation has been reported.

Table 1 Exception Condition Transition Table

# Current State Trigger New State Action(s)

1 not EXSTATE The exception agent creates the

exception condition.

EXSTATE

2 not EXSTATE Initial creation and the abnormal

situation is either not apparent or

irrelevant.

CLEARED

3 not EXSTATE Initial creation and the abnormal

situation is both apparent and

relevant.

SET

4 CLEARED The abnormal situation is detected. SET

5 not SET Default entry into SET state. NOT POSTED

6 NOT POSTED Reporting enabled. POSTED Send “EX Post” message.

7 POSTED Change in the list of possible

recovery actions.

POSTED Send “EX Post” message.

8 SET The abnormal situation is either no

longer apparent or has become

irrelevant.

CLEARED Send “EX Cleared” message.

SEMI E41-95 © SEMI 1995 8

9 POSTED Reporting disabled. NOT POSTED

10 not EXSTATE Default entry into recovery

concurrent state at initial exception

condition creation.

NOTRECOVERING

11 NOTRECOVERING “EXRecover” message received

while in the SET state and accepted.

RECOVERING Initiate requested recovery action

and execute to completion.

12 RECOVERING Recovery action completed. NOTRECOVERING Send “EX Recovery Complete”

message.

13 RECOVERING “EXRecoveryAbort” message

received.

ABORTING-

RECOVERY

Perform the abort procedure to

terminate the recovery action in

progress.

14 ABORTING-RECOVERY Abort procedure is complete. NOTRECOVERING Send “EX Recovery Complete”

message.

CLEARED — The abnormal situation related to the exception condition is either not apparent or not relevant.

SET — The abnormal situation related to the exception condition is apparent and relevant.

The exception agent should generate a collection event each time an exception condition transitions from

CLEARED to SET and another from SET to CLEARED.

NOT POSTED — The latest information on the detected abnormal situation has not yet been reported by the

exception agent. This may be transient on entering the SET state or may be because reporting is disabled. NOT

POSTED is the default state when entering the SET state.

POSTED — The latest information on the detected abnormal situation has been reported by the exception agent to

the decision authority.

Recovery — Recovery is one concurrent subset of EXSTATE. It includes the substates describing the behavior in

relation to exception condition recovery actions.

NOTRECOVERING — In the NOTRECOVERING substate, there is no recovery action in progress directly related

to the exception condition. NOTRECOVERING is the default state when an exception condition is initially created.

Recovery actions may only be initiated when the exception condition is in the SET state.

RECOVERING — A recovery action related to the exception condition is in progress when in the RECOVERING

state.

ABORTINGRECOVERY — In the ABORTINGRECOVERY substate, the abort procedure is performed to

immediately terminate the recovery action. It is the responsibility of the exception agent to cease physical activity as

quickly as possible, having achieved a safe condition.

9 Object Definitions

Exception management defines one standard object, the Exception Condition.

9.1 Exception Condition Object Definition — The exception condition is a persistent object created by the

exception agent. It provides the decision authority with reporting on, access to, and the possibility to direct

resolution of an abnormal situation detected. It also tracks progress of a requested recovery action. The exception

condition is uniquely identified by the EXID attribute.

The object attribute notation used in Table 2 is described in Conventions, Section 5.2.

Table 2 Exception Condition Attributes

Attribute Name Definition Rqmt Access Form

ObjType The object type. Y RO Text:

“EXCEPTION”

ObjID Exception agent unique identifier for the

exception condition.

YROText:

Unique with respect to the exception agent.

EXType Identifies the type of exception condition. Y RO Enumerated:

AlarmError

EXMessage Text message describing the abnormal

situation monitored.

YROText

EXEnabled Indicates that reporting to the decision

authority on the exception condition is

enabled.

Y RW Boolean:

TRUE – Enabled

FALSE - Disabled

EXRecActList List of possible recovery actions. N RO List of:

Text

EXStateList All concurrent sub-states of the exception

condition according to the state model in

Figure 3.

Y RO List of:

Text

EXRecoveryAction Recovery action which may be requested to

resolve the abnormal situation.

NROText

EXState A unique sub-state of the exception

condition according to the state model in

Figure 3.

YROText:

EXSTATE/CLEARED

EXSTATE/SET/NOTPOSTED

EXSTATE/SET/POSTED

EXSTATE/NOTRECOVERING

EXSTATE/RECOVERING

EXSTATE/ABORTINGRECOVERY

10 Messaging Services Detai l

This section defines the messaging services required to implement the exception management concepts. The

messages were introduced in Section 8.1. These services are independent of the messaging protocol used. They may

be mapped to SECS-II (SEMI-E5) or to other comparable protocols.

These messaging services define the messages to be used, the nature of the parameters contained within the

messages, and data type of the parameters. Not defined here is the internal structure of the actual messages as

transferred, including order of the parameters and how various data structures and data types are represented.

The service message notation used in the tables below is described in Conventions, Section 5.3.

10.1 Service List — The messages shown in Table 3 are exchanged between service-provider and service-user for

the purpose of accomplishing exception management tasks.

Table 3 Service List

Message Name Type Description

EXPost N Notification by the exception agent that the abnormal situation related to the exception

condition has been detected or significant information has changed while the situation exists.

EXCleared N Notification by the exception agent that the abnormal situation related to the exception

condition is no longer apparent or relevant.

EXRecover R Decision authority request that a particular recovery action be performed.

EXRecoveryComplete N Notification by the exception agent that a recovery action has completed.

EXRecoveryAbort R Decision authority request that a recovery action be terminated immediately.