# Terminology Service Providers

## Terminology Service Requirements

Terminology service providers should refer to the following sections of this guide for statements of requirements that their services should meet when accessing SNOMED CT:

* [Terminology Service Users](https://snomed-international.gitbook.io/uat-snomed-international-docs/kdfQQ4zexrP8YsnhBh12/snomed-practical-guides/snomed-ct-terminology-services-guide/2-terminology-services-overview/2.3-terminology-service-roles/2.3.1-terminology-service-users)
  * Outlines user requirements for high-performance services that provide appropriate access to SNOMED CT.
* [Healthcare Application Providers](https://snomed-international.gitbook.io/uat-snomed-international-docs/kdfQQ4zexrP8YsnhBh12/snomed-practical-guides/snomed-ct-terminology-services-guide/2-terminology-services-overview/2.3-terminology-service-roles/2.3.2-healthcare-application-providers)
  * Outlines requirements from the perspective of healthcare applications that consume terminology services.
* [Terminology Service Use Cases](https://snomed-international.gitbook.io/uat-snomed-international-docs/kdfQQ4zexrP8YsnhBh12/snomed-practical-guides/snomed-ct-terminology-services-guide/3-terminology-service-use-cases)
  * Provides examples of practical use cases involving access to SNOMED CT that an application may need to complete. For each of these use cases, it identifies one or more of the required terminology services that can be used to complete the required activity.
* [Terminology Service Types](https://snomed-international.gitbook.io/uat-snomed-international-docs/kdfQQ4zexrP8YsnhBh12/snomed-practical-guides/snomed-ct-terminology-services-guide/4-terminology-service-types)
  * Describes specific terminology services or functions that are required to enable effective use of SNOMED CT.

## Support for Different Terminologies and Interfaces

Clinical systems can be effectively implemented using a service oriented architecture, in which the terminology services are designed as an independent software component, accessible via an API (Application Programming Interface) gateway. This enables the other system components to access the key services without being affected by changes to the way these services are implemented.

When designing terminology services for SNOMED CT, it is important to utilize the sophisticated design features of the terminology, as this will support its effective use. When designing terminology services to support a range of different terminologies, it is important to consider the commonality between these terminologies. The table below summarizes some of the advantages and disadvantages of designing terminology services that only work with SNOMED CT, compared with designing services that can also enable access to terminologies or code systems. It also identifies advantages and disadvantages of supporting one or more interfaces through which applications can access SNOMED CT and/or other terminologies.

### Terminology Service Design Options

The following tables outline key design choices for terminology services, focusing on the types of terminologies supported and the interfaces provided. Each option includes potential advantages and disadvantages from the perspective of service design, helping organizations assess trade-offs between specialization, interoperability, and maintainability. These options can inform procurement decisions, integration strategies, and long-term terminology management planning.

#### Terminologies Supported

<table><thead><tr><th width="212.69140625">Option</th><th>Notes</th></tr></thead><tbody><tr><td><strong>SNOMED CT only</strong></td><td>A terminology service provider may develop and deliver services that are specific to SNOMED CT.<br><br>✅ <strong>Advantage</strong>: Services can be tailored to the structure and features of SNOMED CT.<br>❌ <strong>Disadvantage</strong>: May be less attractive to organizations seeking broader terminology support.</td></tr><tr><td><strong>SNOMED CT and other code systems</strong></td><td>A provider may support access to SNOMED CT along with other terminologies, code systems, or classifications.<br><br>✅ <strong>Advantage</strong>: Single solution for customers needing access to multiple terminologies.<br>❌ <strong>Disadvantage</strong>: Risk of underutilizing SNOMED CT-specific features.</td></tr></tbody></table>

#### Terminology Service Interfaces Supported

<table><thead><tr><th width="209.83203125">Option</th><th>Notes</th></tr></thead><tbody><tr><td><strong>Proprietary interface</strong></td><td>A provider may define a custom interface to access SNOMED CT and/or other terminologies.<br><br>✅ <strong>Advantage</strong>: Interface can be optimized for specific service features.<br>❌ <strong>Disadvantages</strong>:<br>• Application providers may resist supporting multiple proprietary interfaces.<br>• Vendor lock-in risk makes switching providers difficult.</td></tr><tr><td><strong>SNOMED CT-specific interface</strong></td><td>Example: SNOMED International's <strong>Snowstorm API</strong>.<br><br>✅ <strong>Advantage</strong>: Allows services optimized for SNOMED CT features.<br>❌ <strong>Disadvantage</strong>: Requires app providers to use separate interfaces for other code systems.</td></tr><tr><td><strong>General-purpose interface</strong></td><td>Example: <strong>FHIR Terminology Service API</strong>.<br><br>✅ <strong>Advantages</strong>:<br>• Uniform interface for accessing multiple code systems.<br>• Easier to switch between service implementations.<br>❌ <strong>Disadvantage</strong>: May not support full optimization for SNOMED CT features.</td></tr><tr><td><strong>Multiple interfaces</strong></td><td>Example: <strong>Snowstorm</strong> supports both its native REST API and FHIR API.<br><br>✅ <strong>Advantage</strong>: Combines benefits of SNOMED-specific and general-purpose interfaces.<br>❌ <strong>Disadvantage</strong>: Increased maintenance burden; differences in behavior, performance, or output may exist between interfaces.</td></tr></tbody></table>

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