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Execution debugging - Temporal Nexus

SUPPORT, STABILITY, and DEPENDENCY INFO

Temporal Nexus is now Generally Available for Temporal Cloud and self-hosted deployments.

Nexus supports end-to-end execution debugging across caller Workflows, Nexus Operations, and handler Workflows - even across multi-level calls spanning multiple Namespaces.

Bi-directional linking​

Bidirectional links connect Nexus Operation events in the caller's Workflow History to corresponding events in the handler's Workflow History. They are automatically wired by SDK builder functions like New-Workflow-Run-Operation, enabling click-through navigation across Namespaces, regions, and clouds in the Temporal UI.

Bi-directional linking

Bi-directional linking

  • Forward: From a caller's Nexus Operation event to the handler's Workflow.
  • Backward: From the handler's Workflow back to the caller's Nexus Operation event.

Pending Operations​

Pending Nexus Operations are displayed in the Workflow details page and with temporal workflow describe, similar to pending Activities.

From the UI:

Pending Operations

Pending Operations

From the CLI:

temporal workflow describe

Pending Nexus Operations: 1

  Endpoint                 myendpoint
  Service                  my-hello-service
  Operation                echo
  OperationToken
  State                    BackingOff
  Attempt                  6
  ScheduleToCloseTimeout   0s
  NextAttemptScheduleTime  20 seconds from now
  LastAttemptCompleteTime  11 seconds ago
  LastAttemptFailure       {"message":"handler error (INTERNAL): internal error","applicationFailureInfo":{}}

Retryable errors surface in the Pending Operation. Non-retryable errors resolve the Operation with a Failed, TimedOut, or Canceled event.

Pending Callbacks​

Nexus completion callbacks are sent from the handler's Namespace to the caller's Namespace for asynchronous Operations. These appear in the UI and with temporal workflow describe.

From the UI:

Pending Callbacks

Pending Callbacks

From the CLI:

temporal workflow describe

Callbacks: 1

  URL               https://nexus.phil-caller-Namespace.a2dd6.cluster.tmprl.cloud:7243/Namespaces/phil-caller-Namespace.a2dd6/nexus/callback
  Trigger           WorkflowClosed
  State             Succeeded
  Attempt           1
  RegistrationTime  32 minutes ago

Tracing​

Temporal integrates with OpenTelemetry and OpenTracing to visualize call graphs across Activities, Nexus Operations, and Child Workflows. Enable tracing by installing an interceptor on the Client or Worker: