TransitionExpressionStatus Object

Sepasoft MES Module Suite

TransitionExpressionStatus Object

Overview

A Transition Expression Status is a read-only runtime snapshot of how a batch recipe transition expression is evaluating during batch execution. Transition expressions are the boolean conditions on SFC transitions (for example, parameter comparisons combined with AND/OR logic) that must become true before the batch engine can fire the transition.

TransitionExpressionStatus is not a persisted MES object. It is returned by system.mes.batch.queue.getTransitionStatus() and system.mes.batch.queue.getPendingTransitions(), and is also published on the gateway event bus so components such as Batch Recipe Monitor can show live expression results. You cannot create, modify, or save instances from scripts.

Obtaining a TransitionExpressionStatus

Query status for one transition, or list transitions that are still waiting to evaluate to true.

Copy Code

Python

# Single transition — path includes the transition step name
status = system.mes.batch.queue.getTransitionStatus(
    'BATCH-042', '/{}/Mix:Ready Transition'
)

# Same call using a BatchQueueEntry
entry = system.mes.batch.queue.getEntry('BATCH-042')
status = system.mes.batch.queue.getTransitionStatus(
    entry, '/{}/Mix:Ready Transition'
)

# Pending transitions under a logic item — path is Procedure / Unit Procedure / Operation only
pending = system.mes.batch.queue.getPendingTransitions('BATCH-042', '/{}/Mix')

Path formats

Function	Path pattern	Example
getTransitionStatus()	/{Procedure}/{Unit Procedure}/{Operation}:{Transition}	/{}/Mix:Ready Transition
getPendingTransitions()	/{Procedure}/{Unit Procedure}/{Operation}	/{}/Mix

Use {} as a placeholder for the procedure name when the batch runs under a single procedure context. Paths use friendly (human-readable) names; the gateway converts them internally to UUID-based paths.

Object Identity

Field	Value
Type name	TransitionExpressionStatus
Kind	Runtime response object (not an AbstractMESObject)
Required module	Batch
Persistence	None — snapshot only; not stored in the MES database

Properties

All properties are read-only. There are no setters and no save() method.

Property	Access	Type	Description
Batch ID	getBatchID()	String	Batch ID of the executing queue entry.
Item Path	getItemPath()	String	Friendly path to the transition (procedure, unit procedure, operation, and transition name).
Change Path	getChangePath()	BatchItemPath	UUID-based path to the transition. Use segment accessors such as getProcedure(), getUnitProcedure(), getOperation(), and getStep() when you need structured path data.
Expression	getExpression()	List of String	Text of each comparison clause in the transition expression, in evaluation order.
Status	getStatus()	List of Boolean	Evaluated result for each clause. Parallel to Expression — index i in Status corresponds to index i in Expression. Values may be None when a clause has not yet been evaluated.
Display Status	getDisplayStatus()	List of Boolean	Whether each clause should be shown in operator UI. Parallel to Expression. Internal or hidden predicates may have False here even when Status has a value.
Overall Status	getOverallStatus()	Boolean	Combined result of the full expression. True when the transition condition is satisfied; False when it is not yet satisfied; None when evaluation has not completed or was reset (for example after a skip).
Evaluation Skipped	isEvaluationSkipped()	Boolean	True when the engine is reusing a previous evaluation instead of re-running the expression. When True, Expression may include a synthetic row (This expression was previously evaluated).

Parallel arrays

getExpression(), getStatus(), and getDisplayStatus() always have the same length. Iterate them together to build a clause-by-clause view:

Copy Code

Python

status = system.mes.batch.queue.getTransitionStatus(
    'BATCH-042', '/{}/Mix:Ready Transition'
)
if status is not None:
    for i in range(len(status.getExpression())):
        if status.getDisplayStatus()[i]:
            print(status.getExpression()[i], status.getStatus()[i])
    print('Overall:', status.getOverallStatus())

When isEvaluationSkipped() is True, per-clause Status values reflect the cached overall result rather than live re-evaluation, and the UI typically hides individual clauses (getDisplayStatus() is False for those rows).

Scope / Availability

Context	How to access
Gateway scripts	system.mes.batch.queue.getTransitionStatus() / getPendingTransitions()
Client / Designer scripts	Same module via RPC when registered on the gateway
Perspective / engineering UI	Batch Recipe Monitor subscribes to live TransitionExpressionStatus events on the gateway event bus

Both lookup functions require an actively executing batch whose execution controller is running. If the batch is not running or the controller is inactive, getTransitionStatus() returns None and getPendingTransitions() returns an empty list.

Exceptions and Constraints

Situation	Behavior
Batch ID not found	getTransitionStatus() / getPendingTransitions() raise an exception (via assertBatchIDExistsAndGet).
Invalid or unknown transition path (controller active)	getTransitionStatus() raises NoSuchElementException with message No expression for path ….
Batch not executing / controller inactive	getTransitionStatus() returns None; getPendingTransitions() returns [].
getPendingTransitions() filter	Returns transitions whose Overall Status is explicitly False and that are not in a previously-evaluated (skipped re-evaluation) state. Scope is limited to transitions under the procedure, unit procedure, and operation given in the path.
Persistence	Not applicable — objects are snapshots only.

Example Usage

Minimal — check one transition

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Python

status = system.mes.batch.queue.getTransitionStatus(
    'BATCH-042', '/{}/Fill:Level OK'
)
if status is not None and status.getOverallStatus():
    system.mes.batch.queue.executeStepCommand(
        'BATCH-042',
        '/{}/Fill:Level OK',
        system.mes.batch.queue.COMMAND_START
    )

Complex — monitor pending transitions and log clause detail

Copy Code

Python

batchID = 'BATCH-042'
logicPath = '/{}/Crystallize/Cool Down'

pending = system.mes.batch.queue.getPendingTransitions(batchID, logicPath)
if not pending:
    system.util.getLogger('batch.monitor').info(
        'No pending transitions under %s' % logicPath
    )
else:
    for transition in pending:
        logger = system.util.getLogger('batch.monitor')
        logger.info(
            'Pending: %s (overall=%s, skippedEval=%s)' % (
                transition.getItemPath(),
                transition.getOverallStatus(),
                transition.isEvaluationSkipped()
            )
        )
        for i in range(len(transition.getExpression())):
            if not transition.getDisplayStatus()[i]:
                continue
            logger.info(
                '  [%s] %s' % (
                    transition.getStatus()[i],
                    transition.getExpression()[i]
                )
            )

# Drill into one specific transition for operator display
detail = system.mes.batch.queue.getTransitionStatus(
    batchID, '/{}/Crystallize/Cool Down:Temp Reached'
)
if detail is not None:
    ready = detail.getOverallStatus() is True
    system.tag.writeBlocking(['[default]Batch/TransitionReady'], [ready])

Related Functions

Function	Description
system.mes.batch.queue.getTransitionStatus(batchID, path)	Returns one TransitionExpressionStatus for the named transition.
system.mes.batch.queue.getTransitionStatus(batchQueueEntry, path)	Same as above using a BatchQueueEntry.
system.mes.batch.queue.getPendingTransitions(batchID, path)	Returns a collection of pending TransitionExpressionStatus objects under a logic path.
system.mes.batch.queue.getPendingTransitions(batchQueueEntry, path)	Same as above using a BatchQueueEntry.
system.mes.batch.queue.getEntry(batchID)	Load the queue entry when you already have a batch ID.
system.mes.batch.queue.getStatus(batchID)	Batch-level state (Idle, Running, etc.) — useful before querying transitions.

Related Objects and Components

BatchQueueEntry — Queue entry handle; can be passed instead of a batch ID to transition status functions.
BatchItemPath — Type returned by getChangePath(); shared path utility for batch recipe locations.
Batch Recipe Monitor — Perspective component that displays live transition expression results

Sepasoft MES Module Suite