FHIR-Based Workflow Engine

A robust workflow engine built on FHIR (Fast Healthcare Interoperability Resources) that orchestrates complex task execution flows with support for parallel processing, response paths, and event-driven activities.

Requires svelte and node.

Core Features

• FHIR-Native Architecture: Built around FHIR resources (Task, ActivityDefinition, PlanDefinition)
• Hierarchical Task Management: Three-level task hierarchy (Workflow -> Basic Plan -> Activity)
• Event-Driven Execution: Support for webhook endpoints and FHIR resource change notifications
• Parallel Task Processing: Execute multiple activities concurrently with synchronization
• Response Path Handling: Support for approval workflows and user interactions
• State Recovery: Robust recovery mechanism using Provenance resources
• Context Resolution: Dynamic property resolution with FHIRPath support

System Components

ActivityExecutor

Handles the execution of individual activities defined in PlanDefinitions:

• Activity initialization and setup
• Value resolution using PropertyResolver
• API endpoint construction and execution
• Response path handling for approval workflows

ContextProvider

Manages execution context across different scenarios:

• User session context
• System process context
• Event handling context
• FHIR practitioner and organization resolution

EventManager

Orchestrates event handling and triggers:

• Webhook endpoint registration and management
• FHIR subscription handling
• Response path coordination
• Event-to-plan mapping

PlanExecutor

Manages the execution of workflow plans:

• Plan initialization and recovery
• Action sequencing and dependencies
• Response path coordination
• Parallel group execution

PlanLoader

Handles the loading and validation of workflow definitions:

• PlanDefinition resource loading
• Hierarchy validation
• Trigger-to-plan mapping
• ActivityDefinition resolution

PropertyResolver

Resolves values needed during workflow execution:

• FHIRPath expression evaluation
• Dynamic value resolution
• Context-based property mapping
• URL endpoint validation

TaskManager

Orchestrates FHIR Task resources:

• Task hierarchy management
• Status tracking and updates
• Provenance record creation
• Recovery state management

TaskCoordinator

Coordinates task state changes and updates:

• Task status management
• Output formatting
• Parallel group completion checking
• Provenance tracking

Task Hierarchy

The system uses a three-level task hierarchy:

1. Workflow Instance (Grandparent)

   • Top-level workflow coordination
   • Tracks overall workflow state

2. Basic Plan Instance (Parent)

   • Groups related activities
   • Manages execution order

3. Activity Task (Child)

   • Individual unit of work
   • Stores execution inputs/outputs

Setup and Configuration

Prerequisites

• FHIR Server
• Node.js environment
• Google Cloud Platform (for PubSub and Scheduler features)

Environment Variables

• PROJECT_ID: Google Cloud project ID
• LOCATION: GCP location
• DATASET_ID: Healthcare dataset ID
• FHIR_STORE_ID: FHIR store ID
• CLIENT_URL: Base URL for API endpoints

Security Considerations

• HTTPS required for all endpoints
• Webhook validation
• Task ownership verification
• FHIR server authentication
• Input validation and sanitization

Recovery Mechanism

The system implements a robust recovery mechanism:

• Provenance-based state tracking
• Task status recovery
• Webhook re-registration
• Parallel group state recovery

Event Handling

Supports multiple event types:

• Named webhook events
• FHIR resource changes
• Scheduled events
• Response path events

Contributing

Please refer to our contributing guidelines for:

• Code style and formatting
• Testing requirements
• Pull request process
• Documentation standards

License

See LICENSE.md

FHIREngine is available under a dual license model:

Open Source License: GNU General Public License v2.0 with FOSS exception Commercial License: Available for OEMs, ISVs, and VARs who cannot comply with GPLv2

For most users developing open-source software, the GPLv2 license is suitable. If you are: developing and distributing closed-source applications, unwilling or unable to comply with GPLv2 requirements, or requiring dedicated support and customization, please contact us about a commercial license.

See LICENSE.md for detailed terms.

Recommended IDE Setup

VS Code + Svelte.

Need an official Svelte framework?

Check out SvelteKit, which is also powered by Vite. Deploy anywhere with its serverless-first approach and adapt to various platforms, with out of the box support for TypeScript, SCSS, and Less, and easily-added support for mdsvex, GraphQL, PostCSS, Tailwind CSS, and more.

Why include .vscode/extensions.json?

Other templates indirectly recommend extensions via the README, but this file allows VS Code to prompt the user to install the recommended extension upon opening the project.

Why enable checkJs in the JS template?

It is likely that most cases of changing variable types in runtime are likely to be accidental, rather than deliberate. This provides advanced typechecking out of the box. Should you like to take advantage of the dynamically-typed nature of JavaScript, it is trivial to change the configuration.