reference supported constructs

Supported BPMN constructs

An honest inventory of what the library does with each BPMN 2.0 construct. The point of this page is the "no" column.

How to read it

Status	Meaning
Supported	Modeled, round-tripped, and interpreted with BPMN's meaning.
Degraded	Read, but in a reduced form, with an element-scoped Degraded finding saying what it became.
Retained	Modeled and round-tripped, but carries no executable meaning. It survives; it does nothing.
Dropped	Not represented. The reader emits a Dropped finding naming the element, and the sequence flows that referenced it cascade-drop with it.

Nothing is dropped silently. Every row below that is not "Supported" produces a finding you can inspect before committing an import — see Reading and writing BPMN XML.

Support here is before capabilities: a supported construct is still refused at graph-build time if your host has not declared what it needs. See Host capabilities.

Activities

Construct	Status	Notes
task	Supported	Abstract task; binds work and completes when the work completes.
userTask, serviceTask, manualTask, businessRuleTask	Supported	The element is supported. What it does is the host's, bound through an UnboundTask work binding.
scriptTask	Supported	The element is supported. The script is not executed — the host owns the script engine.
businessRuleTask	Supported	The decision is not evaluated; there is no DMN here.
sendTask	Supported	Publishes a named message and continues.
receiveTask	Supported	Waits for a named message.
callActivity	Supported	Behaves as a member of the task family; the host resolves and runs the called process. A calledElement-less call activity reads with an Info finding.
callActivity failure mapping	Supported	The outcomes Faulted, DispatchFailed and Cancelled are translated into BPMN error handling instead of ordinary flow, so an enclosing error catcher can take them.
subProcess, embedded	Supported	The nested body travels as a NestedProcess work binding.
subProcess, event (triggeredByEvent)	Supported	Error and escalation triggers are dormant catchers. Message, signal and timer triggers additionally get a ListenerBindingRef: work armed at scope start so the trigger can be observed while the scope runs.
transaction	Supported	Modeled as subProcess with isTransaction: true. May not also carry loop characteristics.
Event subprocess with more than one start event	Dropped	The body must declare exactly one.
Second error-triggered event subprocess in one scope	Dropped	At most one. The same rule applies to a second code-less catch-all escalation event subprocess, and to two event subprocesses claiming the same escalation code.
Non-interrupting error event subprocess	Dropped	BPMN does not allow it.
adHocSubProcess	Dropped	Not part of the model the reader builds.

Gateways

Construct	Status	Notes
exclusiveGateway	Supported	Routes exactly one outgoing flow. Default flow honored.
parallelGateway	Supported	Splits into all outgoing flows; joins when all incoming arrive.
inclusiveGateway	Supported	Splits down every matching flow; joins the branches that actually ran.
eventBasedGateway	Supported	Opens a first-catch-wins race across its outgoing catch events. The winner routes; every losing member token is cancelled and its armed child subtree torn down.
complexGateway	Dropped	Not part of the model the reader builds.

Events

Start events

Construct	Status	Notes
None (plain)	Supported
Message, signal	Supported	Matched on the resolved message or signal name. An unresolvable messageRef / signalRef degrades to a plain start.
Timer	Supported	Must be a recurring schedule: an ISO-8601 interval or a cron expression. A timer start that is not recurring degrades.
Error (event subprocess body only)	Supported	An error-triggered event subprocess.
Escalation (event subprocess body only)	Supported
More than one event definition	Degraded	Reads with one trigger; the finding says which.
Conditional, link, and every other definition	Degraded	Reported as an unsupported definition and read as a plain start event.

End events

Construct	Status	Notes
None (plain)	Supported	Consumes a token; the process completes when none remain.
Terminate	Supported	Ends the process, discarding remaining tokens. Late child completions are ignored.
Message	Supported	Publishes by name and ends. An unresolvable name degrades to a plain end event.
Escalation	Supported	Requires a code; a ref-less escalation end is dropped.
Cancel	Supported	Only inside a transaction. Outside one it degrades to a plain end event.
Compensation	Supported	Triggers compensation replay; activityRef narrows the target, and an activityRef naming an element with no compensation boundary is dropped.
Error	Degraded	There is no error end event. It reads as a plain end event with a finding. Raise an error by faulting the bound work instead.
Signal, conditional, link	Degraded	Reported as unsupported definitions; reads as a plain (or terminate) end event.

Intermediate events

Construct	Status	Notes
Catch: timer	Supported	Requires a one-shot <timeDuration>. A timer catch without one is dropped.
Catch: message, signal	Supported	Dropped when the name cannot be resolved.
Catch: anything else, or more than one definition	Dropped
Throw: message	Supported	Publishes by name; dropped when the name cannot be resolved, because a throw must say what it publishes.
Throw: escalation	Supported	Requires a code; a ref-less escalation throw is dropped.
Throw: compensation	Supported	A ref-less throw compensates everything registered; an activityRef is kept only when it names an element carrying a compensation boundary.
Throw: signal, and everything else	Dropped	Only message, escalation and compensate throws are supported.

Boundary events

Construct	Status	Notes
Interrupting (cancelActivity: true)	Supported	The BPMN default. Terminates the host activity and routes the boundary path.
Non-interrupting (cancelActivity: false)	Supported	The boundary path runs alongside the still-running activity.
Error	Supported	Always interrupting — BPMN fixes this, and a non-interrupting error boundary is dropped. A boundary with no code catches any error.
Escalation	Supported	May be non-interrupting. A code-less boundary is the catch-all; a second code-less one on the same host, or a duplicate code, is dropped.
Timer	Supported	Requires a one-shot <timeDuration>; without one it is dropped.
Message, signal	Supported	Dropped when the name cannot be resolved.
Cancel	Supported	Only on a transaction host, and at most one per transaction.
Compensation	Supported	Must associate with a flow-less compensation handler activity, or it is dropped.
Conditional, and any other definition	Dropped
No attachedToRef, or attached to a non-activity	Dropped	A boundary event needs a host that binds work to interrupt.
More than one event definition	Dropped

Flow and connectivity

Construct	Status	Notes
sequenceFlow	Supported	Dropped when it is missing sourceRef / targetRef, or when either endpoint was dropped.
Default flow	Supported	Taken only when no conditional flow matched. Declared on both sides: defaultFlowId on the element, isDefault on the flow.
Conditional flow, outcome-based	Supported	A flow with a ConditionOutcome is taken when the source element's completing work reported that outcome name.
Conditional flow, expression-based	Degraded	A <conditionExpression> is not evaluated; the flow reads as unconditional and the finding quotes the expression. This is a permanent design position, not a gap — see Interpreter, not engine.
Cyclic flow (loop-backs)	Supported	A token traversing a backward flow mints a fresh iteration key; join accounting groups arrivals by element and iteration, so a revisited join never conflates one pass with the next.
association	Supported	Read to associate a compensation boundary event with its handler.
textAnnotation, group	Dropped	Reported and dropped; they carry no executable meaning.

Multi-instance and loops

Construct	Status	Notes
Multi-instance, cardinality, parallel	Supported	All instances scheduled up front. Requires a positive integer <loopCardinality>.
Multi-instance, cardinality, sequential	Supported	One instance at a time; the next starts when the previous completes.
Multi-instance, collection	Supported	The collection is read once at loop start and snapshotted; each instance is seeded with its item. The named collection must be a declared container-scoped variable of the process, or the graph build throws. Needs ScopeVariables.
Per-iteration loopIndex	Supported	Zero-based, seeded into every instance's frame.
Loop characteristics on a non-activity	Degraded	BPMN allows them only on activities.
Item variable named loopIndex	Degraded	The key is reserved.
standardLoopCharacteristics (while / until)	Degraded	Not represented. Express a loop with a cyclic sequence flow instead.
Multi-instance completion condition	Not modeled

Exactly one of a cardinality and a collection variable may be set; any other shape is rejected at graph-build time.

Compensation and transactions

Construct	Status	Notes
Compensation handler (isForCompensation)	Supported	Binds work, participates in no sequence flows, invoked only by compensation replay. A handler referenced by no compensation boundary is dropped.
Compensation registration	Supported	A successful completion of an activity carrying a compensation boundary is logged.
Reverse-order replay	Supported	Last registered, first compensated. Entries are never pruned; a claimed entry whose run is torn down before it ran is released back to registered.
Targeted compensation (activityRef)	Supported	Compensates only that element's registrations; absent means everything registered in the process.
Transaction subprocess	Supported	Cancel from within stops other live work, replays compensations, and completes with the Cancelled outcome. A transaction that completes Cancelled with no cancel boundary attached raises a fault.

Collaboration

Construct	Status	Notes
participant (pool), white-box	Retained	Modeled with its processRef. Visual and organizational; carries no executable semantics. A processRef naming no process in the document degrades.
participant (pool), black-box	Retained	No processRef; recorded as an Info finding.
lane, laneSet	Retained	Elements carry a LaneId. Visual and organizational.
messageFlow	Retained	Endpoints, pools and message name are recorded so cross-pool wiring survives the round-trip and surfaces as a finding. The graph validator ignores it and it is stripped from the compiled structure — execution rides name-keyed messaging instead.
Choreography, conversation	Dropped	Not part of the model the reader builds.

Data

Construct	Status	Notes
Process variable declarations	Supported	Name, optional host-interpreted type hint, optional JSON default. The semantics core reads only the name.
dataObject, dataObjectReference	Dropped	Reported by element id.
dataStore, dataStoreReference	Dropped	Reported by element id.
dataInputAssociation, dataOutputAssociation, ioSpecification	Dropped	Reported by element id.
Item definitions and typed data	Not modeled	Values cross the boundary as JSON with a host-interpreted type hint. The library assigns no meaning to a type system.

Document-level

Construct	Status	Notes
<definitions> metadata	Supported	Id, target namespace, exporter, exporter version.
Root <message>, <signal>, <error>, <escalation>	Supported	Matching is on the name for messages and signals, and on the code for errors and escalations.
<documentation>	Supported	Retained, with textFormat.
extensionElements (any vendor)	Supported	camunda:*, zeebe:*, flowable:* and anything else are retained verbatim as data and written back at their recorded position.
Foreign attributes	Supported	Retained with their qualified names.
Unrecognized child elements	Supported	Retained with the index they occupied, because BPMN's tFlowNode is an xsd:sequence and re-emitting a child out of position produces schema-invalid XML.
BPMN DI (BPMNDiagram, BPMNPlane, BPMNShape, BPMNEdge, labels)	Supported	First-class in the model. The writer always emits complete layout: a shape per element, pool and lane, and an edge with at least two waypoints per flow, synthesized from the endpoint boxes when the source carried none.
<import> of another BPMN document	Dropped	Not modeled.
XSD schema validation	Not supported	Deliberately. The reader reports what it could not use, which is a different and more useful job. A document that is not readable at all raises BpmnInterchangeException.
Byte-exact round-trip	Not supported	Content is preserved; attribute order, whitespace, comments, CDATA-versus-text and namespace prefixes are not.

Not in scope at all

• DMN. Business rule tasks are modeled; decisions are not evaluated.
• CMMN.
• Expression and script languages. FEEL, JUEL, JavaScript, Groovy — none, permanently.
• Rendering. Layout is preserved and synthesized, not drawn.
• Vendor server protocols. This is not a client for anyone's engine.

Related

• Reading and writing BPMN XML — what a finding looks like.
• Errors and escalation — the five failure constructs, in detail.
• Host capabilities — why a supported construct can still be refused.