@atomic-ehr/fhir-canonical-manager

A TypeScript package manager for FHIR resources that provides canonical URL resolution. This library helps you discover, resolve, and manage FHIR packages and their resources through a simple, functional API.

Features

• 🚀 Automatic Package Management - Automatically installs and manages FHIR packages
• 💾 Persistent Caching - Caches package metadata to disk for fast subsequent loads
• 🔍 Canonical URL Resolution - Resolve canonical URLs to specific resource versions
• 📦 Multiple Package Support - Work with multiple FHIR packages simultaneously
• 🎯 Flexible Search - Search resources by type, kind, URL, version, or package
• ⚡ Performance Optimized - In-memory cache with disk persistence
• 🛠️ TypeScript First - Full TypeScript support with comprehensive types
• 🖥️ CLI Tool - Command-line interface for package management and resource discovery

Installation

bun install @atomic-ehr/fhir-canonical-manager
# or
npm install @atomic-ehr/fhir-canonical-manager

Quick Start

import { CanonicalManager } from '@atomic-ehr/fhir-canonical-manager';

// Create and initialize the manager
const manager = CanonicalManager({
    packages: ["hl7.fhir.r4.core"],
    workingDir: "tmp/fhir",
    registry: "https://fs.get-ig.org/pkgs/" // optional, default registry
});

await manager.init();

// Resolve and read a resource
const resource = await manager.resolve('http://hl7.org/fhir/StructureDefinition/Patient');
console.log(resource.url); // http://hl7.org/fhir/StructureDefinition/Patient

CLI Usage

The package includes a powerful command-line interface (fcm) for managing FHIR packages and searching resources without writing code.

Installation

# Install globally
npm install -g @atomic-ehr/fhir-canonical-manager

# Or use with npx
npx @atomic-ehr/fhir-canonical-manager

# Or run directly with bunx
bunx @atomic-ehr/fhir-canonical-manager

Getting Started

# Create a new project and initialize with FHIR packages
mkdir my-fhir-project && cd my-fhir-project
fcm init hl7.fhir.r4.core

# Search for resources
fcm search Patient

# Get a specific resource
fcm resolve http://hl7.org/fhir/StructureDefinition/Patient

Commands

fcm init

Initialize FHIR packages in the current directory.

# Initialize with packages
fcm init hl7.fhir.r4.core [email protected]

# With custom registry
fcm init hl7.fhir.r4.core --registry https://packages.simplifier.net

# Initialize from existing package.json
fcm init

Configuration is stored in package.json:

{
  "fcm": {
    "packages": ["hl7.fhir.r4.core", "[email protected]"],
    "registry": "https://fs.get-ig.org/pkgs/"
  }
}

fcm list

List installed packages or resources.

# List all packages
fcm list

# List resources in a package
fcm list hl7.fhir.r4.core

# Filter by type
fcm list hl7.fhir.r4.core --type StructureDefinition

# Output as JSON
fcm list --json

fcm search

Search for resources with advanced filtering and prefix matching capabilities.

Basic Usage:

# Search by URL pattern
fcm search Patient

# Prefix search - space-separated terms match URL components
fcm search str def pat  # Matches: StructureDefinition/Patient

Resource Type Shortcuts:

fcm search -sd          # All StructureDefinitions
fcm search -cs          # All CodeSystems
fcm search -vs          # All ValueSets
fcm search -sd patient  # Patient-related StructureDefinitions

Advanced Filtering:

# Filter by type (-t)
fcm search -t Extension              # All Extensions
fcm search -t Patient                # Resources with type="Patient"
fcm search -sd -t Patient            # Patient StructureDefinition specifically

# Filter by kind (-k)
fcm search -k resource               # All resources (Patient, Observation, etc.)
fcm search -k complex-type           # All complex types (HumanName, Address, etc.)
fcm search -k primitive-type         # All primitive types (string, boolean, etc.)

# Combine filters
fcm search -t Extension -k complex-type  # All Extension complex types
fcm search -sd pat -t Extension          # Patient-related Extensions

# Filter by package
fcm search allergy --package hl7.fhir.us.core

# Output as JSON
fcm search Patient --json

Output Format: By default, results are displayed one per line in the format:

url, {"resourceType":"...", "kind":"...", "type":"..."}

Example output:

http://hl7.org/fhir/StructureDefinition/Patient, {"resourceType":"StructureDefinition","kind":"resource","type":"Patient"}

fcm resolve

Get a resource by its canonical URL.

# Display resource
fcm resolve http://hl7.org/fhir/StructureDefinition/Patient

# Save to file
fcm resolve http://hl7.org/fhir/ValueSet/administrative-gender > gender.json

# Show only specific fields
fcm resolve http://hl7.org/fhir/StructureDefinition/Patient --fields url,type,kind

fcm searchparam

Display search parameters for a specific FHIR resource type.

# Display search parameters for Patient resource
fcm searchparam Patient

# Output as JSON
fcm searchparam Observation --format json

# Export as CSV for spreadsheet analysis
fcm searchparam Encounter --format csv > encounter-params.csv

Output Formats:

• table (default): Displays each parameter in a multiline format with full data
• json: Outputs as JSON array with code, type, expression, and url fields
• csv: Exports as CSV for spreadsheet analysis

Example output (table format):

Code:       active
Type:       token
Expression: Patient.active
URL:        http://hl7.org/fhir/SearchParameter/Patient-active
---
Code:       address
Type:       string
Expression: Patient.address | Person.address | Practitioner.address |
            RelatedPerson.address
URL:        http://hl7.org/fhir/SearchParameter/individual-address
---
Code:       identifier
Type:       token
Expression: Patient.identifier
URL:        http://hl7.org/fhir/SearchParameter/Patient-identifier
---

Total: 29 search parameters

CLI Examples

# Set up a new FHIR project
mkdir my-fhir-project && cd my-fhir-project
fcm init hl7.fhir.r4.core

# Search for Observation-related resources
fcm search observation

# Get a specific resource and save it
fcm resolve http://hl7.org/fhir/StructureDefinition/Observation > observation.json

# List all ValueSets in JSON format
fcm search --type ValueSet --json > valuesets.json

Quick Reference

| Task | Command | |------|---------| | Initialize project | fcm init hl7.fhir.r4.core | | List packages | fcm list | | List package resources | fcm list hl7.fhir.r4.core | | Search all resources | fcm search | | Search by name | fcm search Patient | | Search with prefix | fcm search str def pat | | All StructureDefinitions | fcm search -sd | | All CodeSystems | fcm search -cs | | All ValueSets | fcm search -vs | | Filter by type | fcm search -t Extension | | Filter by kind | fcm search -k resource | | Combine filters | fcm search -sd -t Patient | | Get resource | fcm resolve <url> | | Get search parameters | fcm searchparam Patient | | Export as JSON | fcm search --json | | Export params as CSV | fcm searchparam Patient --format csv | | Help | fcm --help |

Core Concepts

Package Management

The manager automatically handles FHIR package installation:

1. Creates a working directory if it doesn't exist
2. Initializes a package.json for dependency management
3. Installs specified FHIR packages using npm
4. Scans packages for .index.json files
5. Builds an in-memory index of all resources
6. Persists cache to .fcm/cache/index.json

Resource Resolution

Resources are identified by:

• Canonical URL: The unique identifier for a FHIR resource
• Reference ID: An opaque, deterministic hash based on package and file path
• Package Context: Optional package name/version constraints

API Reference

CanonicalManager(config)

Creates a new instance of the canonical manager.

interface Config {
  packages: string[];      // FHIR packages to install (e.g., ["hl7.fhir.r4.core"])
  workingDir: string;      // Directory for packages and cache
  registry?: string;       // NPM registry URL (optional)
}

Example:

const manager = CanonicalManager({
    packages: [
        "hl7.fhir.r4.core",
        "[email protected]"
    ],
    workingDir: "./fhir-packages",
    registry: "https://fs.get-ig.org/pkgs/"
});

init(): Promise<void>

Initializes the manager. This method:

• Ensures working directory exists
• Creates .fcm/cache directory
• Checks for existing cache
• If no cache: installs packages and builds index
• If cache exists: loads from disk (fast startup)

await manager.init();

resolve(url, options?): Promise<Resource>

Resolves a canonical URL directly to a FHIR resource.

// Simple resolution
const patient = await manager.resolve(
    'http://hl7.org/fhir/StructureDefinition/Patient'
);

// With package constraint
const patient = await manager.resolve(
    'http://hl7.org/fhir/StructureDefinition/Patient',
    { package: 'hl7.fhir.r4.core' }
);

// With version constraint
const patient = await manager.resolve(
    'http://hl7.org/fhir/StructureDefinition/Patient',
    { version: '4.0.1' }
);

resolveEntry(url, options?): Promise<IndexEntry>

Resolves a canonical URL to an index entry (metadata only).

const entry = await manager.resolveEntry(
    'http://hl7.org/fhir/StructureDefinition/Patient'
);

console.log(entry);
// {
//   id: "opaque-reference-id",
//   resourceType: "StructureDefinition",
//   url: "http://hl7.org/fhir/StructureDefinition/Patient",
//   version: "4.0.1",
//   kind: "resource",
//   type: "Patient",
//   package: { name: "hl7.fhir.r4.core", version: "4.0.1" }
// }

read(reference): Promise<Resource>

Reads a resource using its reference.

const entry = await manager.resolveEntry(url);
const resource = await manager.read(entry);

search(params): Promise<Resource[]>

Searches and returns full resources matching criteria.

// Get all StructureDefinitions
const structures = await manager.search({
    type: 'StructureDefinition'
});

// Get all resources of kind "resource"
const resources = await manager.search({
    kind: 'resource'
});

// Complex search
const valuesets = await manager.search({
    type: 'ValueSet',
    package: { name: 'hl7.fhir.r4.core', version: '4.0.1' }
});

searchEntries(params): Promise<IndexEntry[]>

Searches and returns index entries (metadata only).

// Find all CodeSystems
const entries = await manager.searchEntries({
    type: 'CodeSystem'
});

// Find by URL
const entries = await manager.searchEntries({
    url: 'http://hl7.org/fhir/StructureDefinition/Patient'
});

Search parameters:

• kind?: string - Resource kind (e.g., 'resource', 'datatype', 'primitive')
• url?: string - Canonical URL (exact match)
• type?: string - Resource type (e.g., 'StructureDefinition', 'ValueSet')
• version?: string - Resource version
• package?: PackageId - Filter by package name and version

packages(): Promise<PackageId[]>

Lists all loaded packages.

const packages = await manager.packages();
// [
//   { name: "hl7.fhir.r4.core", version: "4.0.1" },
//   { name: "hl7.fhir.us.core", version: "5.0.1" }
// ]

addPackages(packages: string[]): Promise<void>

Add (and install if needed) extra FHIR packages at runtime.

await manager.addPackages(
    "[email protected]",
    "hl7.fhir.us.davinci-drug-formulary"
);

• Accepts one or more package specifiers: name or name@version
• If manager not yet initialised, they are appended and normal init() flow handles install
• Already present packages are skipped (idempotent)
• New ones are installed, node_modules re‑scanned, cache persisted
• Resources become immediately available to resolve, search, CLI commands

Returns: Promise<void> (resolves when indexing is updated)

getSearchParametersForResource(resourceType): Promise<SearchParameter[]>

Gets all search parameters applicable to a specific FHIR resource type.

// Get search parameters for Patient resource
const searchParams = await manager.getSearchParametersForResource('Patient');

// Each parameter contains FHIR SearchParameter fields
searchParams.forEach(param => {
    console.log(`${param.code}: ${param.type} - ${param.expression}`);
});

// Example output:
// identifier: token - Patient.identifier
// name: string - Patient.name
// birthdate: date - Patient.birthDate
// gender: token - Patient.gender

Returns an array of SearchParameter resources with all FHIR fields preserved, including:

• url: Canonical URL of the search parameter
• code: Search parameter name used in queries
• type: Parameter type (token, string, date, reference, etc.)
• expression: FHIRPath expression
• base: Array of resource types this parameter applies to
• Additional FHIR SearchParameter fields

destroy(): Promise<void>

Cleans up resources and clears cache from memory (disk cache persists).

await manager.destroy();

CLI Reference

The fcm command-line interface provides comprehensive FHIR resource management capabilities.

Command Overview

| Command | Description | |---------|-------------| | fcm init [packages...] | Initialize FHIR packages in current directory | | fcm list [package] | List packages or resources | | fcm search [terms...] | Search resources with advanced filtering | | fcm resolve <url> | Get a resource by canonical URL | | fcm searchparam <resourceType> | Display search parameters for a resource type |

Global Options

• --help, -h - Show help information
• --version, -v - Show version number
• --json - Output results as JSON (available for list, search, resolve)

Search Options

| Option | Description | Example | |--------|-------------|---------| | -sd | Filter to StructureDefinitions | fcm search -sd | | -cs | Filter to CodeSystems | fcm search -cs | | -vs | Filter to ValueSets | fcm search -vs | | -t <type> | Filter by type field | fcm search -t Extension | | -k <kind> | Filter by kind field | fcm search -k resource | | --type <resourceType> | Filter by resourceType | fcm search --type ValueSet | | --package <name> | Filter by package | fcm search --package hl7.fhir.us.core |

Prefix Search

The search command supports intelligent prefix matching. When you provide multiple space-separated terms, each term is matched as a prefix against URL components:

# Search for "str" AND "def" AND "pat" as prefixes
fcm search str def pat

# This matches URLs like:
# - http://hl7.org/fhir/StructureDefinition/Patient
# - http://hl7.org/fhir/StructureDefinition/PatientContact

Filter Combinations

Filters can be combined for precise searching:

# Find all Extension complex types
fcm search -t Extension -k complex-type

# Find Patient-related Extensions
fcm search -sd pat -t Extension

# Find all primitive types in US Core
fcm search -k primitive-type --package hl7.fhir.us.core

Output Formats

Default (Single-line):

http://hl7.org/fhir/StructureDefinition/Patient, {"resourceType":"StructureDefinition","kind":"resource","type":"Patient"}

JSON Format:

fcm search Patient --json

Returns full IndexEntry objects as JSON array.

Directory Structure

After initialization, your working directory will contain:

workingDir/
├── package.json          # NPM package file
├── node_modules/         # Installed FHIR packages
│   ├── hl7.fhir.r4.core/
│   │   ├── package.json
│   │   ├── .index.json   # FHIR resource index
│   │   └── *.json        # FHIR resources
│   └── .../
└── .fcm/
    └── cache/
        └── index.json    # Cached index for fast startup

Cache Format

The cache is stored as a JSON file with the following structure:

{
  entries: {
    "http://hl7.org/fhir/StructureDefinition/Patient": [
      {
        id: "hash-based-id",
        resourceType: "StructureDefinition",
        url: "http://hl7.org/fhir/StructureDefinition/Patient",
        version: "4.0.1",
        kind: "resource",
        type: "Patient",
        package: { name: "hl7.fhir.r4.core", version: "4.0.1" }
      }
    ]
  },
  packages: {
    "hl7.fhir.r4.core": {
      id: { name: "hl7.fhir.r4.core", version: "4.0.1" },
      path: "/path/to/node_modules/hl7.fhir.r4.core",
      canonical: "http://hl7.org/fhir",
      fhirVersions: ["4.0.1"]
    }
  },
  references: {
    "hash-based-id": {
      packageName: "hl7.fhir.r4.core",
      packageVersion: "4.0.1",
      filePath: "/path/to/resource.json",
      resourceType: "StructureDefinition",
      url: "http://hl7.org/fhir/StructureDefinition/Patient",
      version: "4.0.1"
    }
  }
}

Advanced Usage

Working with Multiple Packages

const manager = CanonicalManager({
    packages: [
        "hl7.fhir.r4.core",
        "[email protected]",
        "hl7.fhir.us.davinci-drug-formulary"
    ],
    workingDir: "./fhir-packages"
});

await manager.init();

// Search across all packages
const allValueSets = await manager.search({ type: 'ValueSet' });

// Search in specific package
const usCoreProfiles = await manager.search({
    type: 'StructureDefinition',
    package: { name: 'hl7.fhir.us.core', version: '5.0.1' }
});

Custom Registry Configuration

// Use the default FHIR package registry
const manager = CanonicalManager({
    packages: ["hl7.fhir.r4.core"],
    workingDir: "./fhir-packages",
    registry: "https://fs.get-ig.org/pkgs/"
});

// Use a custom NPM registry
const manager = CanonicalManager({
    packages: ["hl7.fhir.r4.core"],
    workingDir: "./fhir-packages",
    registry: "https://my-private-registry.com"
});

Building a FHIR Validator

async function validateResource(resource: any, manager: CanonicalManager) {
    // Get the profile URL from the resource
    const profileUrl = resource.meta?.profile?.[0];
    if (!profileUrl) {
        throw new Error('No profile specified');
    }

    // Resolve the StructureDefinition
    const profile = await manager.resolve(profileUrl);

    // Validate resource against profile
    // ... validation logic ...
}

Analyzing Package Dependencies

async function analyzeValueSetDependencies(manager: CanonicalManager) {
    // Get all ValueSets
    const valueSets = await manager.search({ type: 'ValueSet' });

    const dependencies = new Map<string, Set<string>>();

    for (const vs of valueSets) {
        const vsPackage = vs.package?.name || 'unknown';

        // Check compose.include for external code systems
        if (vs.compose?.include) {
            for (const include of vs.compose.include) {
                if (include.system) {
                    try {
                        const cs = await manager.resolve(include.system);
                        const csPackage = cs.package?.name || 'unknown';

                        if (csPackage !== vsPackage) {
                            if (!dependencies.has(vsPackage)) {
                                dependencies.set(vsPackage, new Set());
                            }
                            dependencies.get(vsPackage)!.add(csPackage);
                        }
                    } catch {
                        // External code system not in our packages
                    }
                }
            }
        }
    }

    return dependencies;
}

Performance Considerations

Startup Performance

• First run: Slower due to package installation and index building
• Subsequent runs: Fast startup by loading from disk cache
• Cache invalidation: Delete .fcm/cache to force rebuild

Memory Usage

• All index entries are kept in memory for fast lookup
• Resource content is loaded on-demand
• For large package sets, consider memory requirements

Best Practices

1. Reuse manager instances: Create once, use many times
2. Use searchEntries() for metadata: Faster than search() when you don't need full resources
3. Specify package constraints: Faster resolution when package is known
4. Cache working directory: Share between application instances

Error Handling

The manager throws errors for:

• Not initialized: Call init() before other methods
• Resource not found: Canonical URL doesn't exist
• Invalid reference: Reference ID is invalid
• Package installation failures: Network or registry issues

try {
    const resource = await manager.resolve('http://invalid.url/Resource');
} catch (error) {
    console.error('Failed to resolve:', error.message);
}

TypeScript Types

interface Reference {
    id: string;              // Opaque identifier
    resourceType: string;    // FHIR resource type
}

interface PackageId {
    name: string;           // Package name
    version: string;        // Package version
}

interface IndexEntry extends Reference {
    indexVersion: number;   // Index format version
    kind?: string;         // resource, datatype, primitive, etc.
    url?: string;          // Canonical URL
    type?: string;         // Specific type (e.g., "Patient")
    version?: string;      // Resource version
    package?: PackageId;   // Source package
}

interface Resource extends Reference {
    url?: string;          // Canonical URL
    version?: string;      // Resource version
    [key: string]: any;    // Other FHIR properties
}

interface SourceContext {
    id?: string;
    package?: PackageId;
    url?: string;
    path?: string;
}

Development

To install dependencies:

bun install

To run tests:

bun test

To run the example:

bun run example.ts

Project Structure

fhir-canonical-manager/
├── src/
│   ├── index.ts          # Core library implementation
│   ├── compat.ts         # Bun/Node.js compatibility layer
│   └── cli/              # CLI implementation
│       ├── index.ts      # CLI entry point
│       ├── init.ts       # Init command
│       ├── list.ts       # List command
│       ├── search.ts     # Search command
│       └── resolve.ts    # Resolve command
├── test/
│   ├── index.test.ts     # Core library tests
│   ├── cli.test.ts       # CLI unit tests
│   └── cli-integration.test.ts # CLI integration tests
├── dist/                 # Compiled output (generated)
├── example.ts            # Usage example
├── package.json
├── tsconfig.json
└── README.md

Requirements

• Node.js 18+ or Bun 1.0+
• TypeScript 5.0+
• Network access for package installation

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Development Guidelines

1. All code in single file: src/index.ts
2. Functional programming style
3. No external dependencies except Node.js built-ins
4. Comprehensive tests in test/index.test.ts
5. Update README.md with API changes