Class Signal

Sends a signal to one or more paused flows, resuming their execution. The signal activity is the counterpart to a Hook activity configured with a webhook listener. It allows any flow to reach into another flow and deliver data to a waiting hook, regardless of the relationship between the flows.

YAML Configuration — Signal One

Resumes a single paused flow by publishing to the hook's topic. Use subtype: one when you know the specific hook topic to signal.

app:
  id: myapp
  version: '1'
  graphs:
    - subscribes: signal.start
      expire: 120

      activities:
        t1:
          type: trigger

        resume_hook:
          type: signal
          subtype: one
          topic: my.hook.topic          # the hook's registered topic
          status: success               # optional: success (default) or pending
          code: 200                     # optional: 200 (default) or 202 (keep-alive)
          signal:
            schema:
              type: object
              properties:
                approved: { type: boolean }
            maps:
              approved: true            # data delivered to the hook

        done:
          type: hook

      transitions:
        t1:
          - to: resume_hook
        resume_hook:
          - to: done

A code: 202 signal delivers data but keeps the hook alive for additional signals. A code: 200 (default) closes the hook.

YAML Configuration — Signal All

Resumes all paused flows that share a common job key facet. Use subtype: all for fan-out patterns where multiple waiting flows should be resumed simultaneously.

app:
  id: myapp
  version: '1'
  graphs:
    - subscribes: signal.fan.out
      expire: 120

      activities:
        t1:
          type: trigger

        resume_all:
          type: signal
          subtype: all
          topic: hook.resume
          key_name: parent_job_id       # index facet name
          key_value: '{$job.metadata.jid}'
          scrub: true                   # clean up indexes after use
          resolver:
            maps:
              data:
                parent_job_id: '{$job.metadata.jid}'
              scrub: true
          signal:
            maps:
              done: true                # data delivered to all matching hooks

        done:
          type: hook

      transitions:
        t1:
          - to: resume_all
        resume_all:
          - to: done

Execution Model

Signal is a Category B (Leg1-only with children) activity:

  • Bundles the hook signal with the Leg 1 completion marker in a single transaction (hookOne) or fires best-effort (hookAll).
  • Executes the crash-safe executeLeg1StepProtocol to transition to adjacent activities.

See

SignalActivity for the TypeScript interface

Hierarchy (view full)

Constructors

constructor

Properties

adjacencyList adjacentIndex code config context data engine guidLedger hook leg logger metadata status

Methods

assertGenerationalId authorizeEntry bindActivityData bindActivityError bindActivityMetadata bindActivityMetadataPaths bindActivityState bindDimensionalAddress bindJobError bindJobMetadata bindJobMetadataPaths bindJobState executeLeg1StepProtocol executeStepProtocol filterAdjacent getJobStatus getState getTriggerConfig initDimensionalAddress initPolicies initSelf isJobComplete jobWasInterrupted mapInputData mapJobData mapOutputData mapResolverData mapSignalData mapStatusThreshold process processEvent registerTimeout resolveAdjacentDad resolveDad resolveStatus resolveThresholdHit setLeg setState setStatus shouldEmit signalAll signalOne verifyEntry verifyLeg1Entry verifyReentry

Constructors

constructor

Properties

adjacencyList

adjacencyList: StreamData[]

adjacentIndex

adjacentIndex: number = 0

code

code: number = 200

config

config: SignalActivity

context

context: JobState

data

data: ActivityData

engine

engine: EngineService

guidLedger

guidLedger: number = 0

hook

hook: ActivityData

leg

leg: ActivityLeg

logger

logger: ILogger

metadata

metadata: ActivityMetadata

status

status: StreamStatus = StreamStatus.SUCCESS

Methods

assertGenerationalId

  • assertGenerationalId(jobGID, msgGID?): void

  • if the job is created/deleted/created with the same key, the 'gid' ensures no stale messages (such as sleep delays) enter the workstream. Any message with a mismatched gid belongs to a prior job and can safely be ignored/dropped.

    Parameters

    • jobGID: string
    • OptionalmsgGID: string

    Returns void

authorizeEntry

bindActivityData

bindActivityError

bindActivityMetadata

bindActivityMetadataPaths

bindActivityState

bindDimensionalAddress

bindJobError

  • bindJobError(data): void

  • unhandled activity errors (activities that return an ERROR StreamMessage status and have no adjacent children to transition to) are bound to the job

    Parameters

    • data: Record<string, unknown>

    Returns void

bindJobMetadata

bindJobMetadataPaths

bindJobState

executeLeg1StepProtocol

  • executeLeg1StepProtocol(delta): Promise<boolean>

  • Executes the 3-step Leg1 protocol for Category B activities (Leg1-only with children, e.g., Hook passthrough, Signal, Interrupt-another). Uses the incoming Leg1 message GUID as the GUID ledger key.

    Step A: setState + notarizeLeg1Completion + step1 markers (transaction 1) Step B: publish children + step2 markers + setStatusAndCollateGuid (transaction 2) Step C: if edge → runJobCompletionTasks + step3 markers + finalize (transaction 3)

    Parameters

    • delta: number

    Returns Promise<boolean>

    true if this transition caused the job to complete

executeStepProtocol

  • executeStepProtocol(delta, shouldFinalize): Promise<boolean>

  • Executes the 3-step Leg2 protocol using GUID ledger for crash-safe resume. Each step bundles durable writes with its concluding digit update in a single transaction.

    Parameters

    • delta: number
    • shouldFinalize: boolean

    Returns Promise<boolean>

    true if this transition caused the job to complete

filterAdjacent

getJobStatus

getState

getTriggerConfig

initDimensionalAddress

initPolicies

initSelf

isJobComplete

jobWasInterrupted

mapInputData

mapJobData

mapOutputData

mapResolverData

mapSignalData

mapStatusThreshold

process

processEvent

registerTimeout

resolveAdjacentDad

resolveDad

resolveStatus

resolveThresholdHit

setLeg

setState

setStatus

shouldEmit

signalAll

  • signalAll(): Promise<string[]>

  • Signals all paused jobs that share the same job key, resuming their execution.

    Returns Promise<string[]>

signalOne

  • signalOne(transaction?): Promise<string>

  • The signal activity will hook one. Accepts an optional transaction so the hook publish can be bundled with the Leg1 completion marker.

    Parameters

    Returns Promise<string>

verifyEntry

verifyLeg1Entry

  • verifyLeg1Entry(): Promise<boolean>

  • Leg1 entry verification for Category B activities (Leg1-only with children). Returns true if this is a resume (Leg1 already completed on a prior attempt). On resume, loads the GUID ledger for step-level resume decisions.

    Returns Promise<boolean>

verifyReentry

  • verifyReentry(): Promise<number>

  • Upon entering leg 2 of a duplexed activity. Increments both the activity ledger (+1) and GUID ledger (+1). Stores the GUID ledger value for step-level resume decisions.

    Returns Promise<number>

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YAML Configuration — Signal OneYAML Configuration — Signal AllExecution Model
Constructors
Properties
Methods