Workflow engines for FHIR-based systems have several options in 2026. Understanding the trade-offs shapes architecture decisions.
Category 1: General-purpose workflow engines
1. Camunda. BPMN-based, mature. Best fit for clinical workflow diagrams and regulated environments. 2. Temporal. Code-first, event-driven. Best fit for engineering-heavy teams.
Category 2: FHIR-native workflow
1. **Medplum bots. Event-driven scripts triggered by FHIR resource changes. 2. Aidbox app SDK.** Sidecar services inside Aidbox platform.
Category 3: FHIR Subscription-based
1. **FHIR Subscription as workflow trigger.** Simple event → single-step reaction. Best for straightforward flows.
Decision matrix
| Situation | Choice |
|---|---|
| Multi-step clinical workflow, BPMN-friendly | Camunda |
| Multi-step engineering-heavy | Temporal |
| Simple event-driven, Medplum stack | Medplum bots |
| Simple event-driven, Aidbox stack | Aidbox app |
| Single-step reaction | Subscription |
FHIR-specific workflow needs
1. Order lifecycle. Order placed → sent to lab → results received → charted. 2. Referral lifecycle. Referral created → PCP alerted → specialist visits → results returned. 3. Prior auth flow. Order + patient data → payer request → payer response → status update. 4. Care coordination. Multi-provider task assignment and tracking.
FHIR primitives for workflow
1. **Task resource — work items across providers. 2. CommunicationRequest — messaging requests. 3. ServiceRequest — clinical orders. 4. CarePlan** — longitudinal care intent.
Common workflow architecture mistakes
1. Application code implementing workflow logic. 2. No compensation for failed steps. 3. State scattered across resources. 4. Manual step tracking outside FHIR. 5. Over-engineering for simple flows.
Investment considerations
1. Camunda: enterprise license + BPMN expertise. 2. Temporal: engineering learning curve + operational overhead. 3. Medplum bots: bundled with Medplum. 4. Aidbox app: bundled with Aidbox. 5. Subscription: minimal but limited.
FHIR workflow engines are worthwhile investments when clinical processes span days and touch multiple systems. Match complexity to the primitive.
