SNOMED Classification Service (CS)

The SNOMED Classification Service (CS) is a Spring Boot–based, stateless web application that performs OWL-based classification of SNOMED CT ontologies. It accepts RF2 delta change-sets, runs an embedded reasoner (ELK by default) and produces an RF2 delta of inferred relationship changes ready for import back into a terminology server such as Snowstorm.

CS integrates with ActiveMQ, AWS S3 / local file-system storage, Consul and Vault, while exposing a REST API documented via Swagger-UI.

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1 High-Level Architecture

flowchart TD
    Client["Web UI / CI pipelines"] --> CS["Classification Service"]
    CS -->|REST| Reasoner["OWL Toolkit<br/>(ELK)"]
    CS -->|JMS| ActiveMQ["ActiveMQ Broker"]
    CS -->|S3 SDK / FS| Storage["Release & Job Store"]
    CS -->|Config| Consul["Consul"]
    CS -->|Secrets| Vault["Vault"]

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Typical Classification Workflow

sequenceDiagram
    participant User
    participant CS as Classification Service
    participant Store as Storage
    participant ActiveMQ
    participant Reasoner as OWL Toolkit
    User->>CS: POST /classifications (multipart RF2 delta)
    CS->>Store: Persist delta & metadata
    CS--)ActiveMQ: Enqueue classification-job
    ActiveMQ-->>CS: Async job delivery
    CS->>Reasoner: Run classification (snapshot + delta)
    Reasoner-->>CS: Relationship delta (results.zip)
    CS->>Store: Persist results
    CS-->>User: 201 Created / polling endpoint

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Key points:

• Stateless – all state lives in S3 or the local file-system allowing horizontal scalability.
• Spring JMS & Async Executors power distributed job processing and notifications.
• Packaged both as a fat JAR and a Debian .deb (for supervisord-based deployments).

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2 Feature Highlights

• Interactive Swagger-UI / OpenAPI 3 docs – see SwaggerConfig.java.
• Simple Basic-Auth security enabled by default (overridable / extendable).
• Distributed Classification Pipeline
  • Job producer – ClassificationController (REST)
  • Worker – ClassificationJobManager (JMS listener)
• JMS messaging (ActiveMQ) – queue configured via classification.jms.job.queue; prefetch size tuned for scale.
• Pluggable storage layer (local FS or S3) unified via ResourceManager.
• Consul & Vault support for distributed configuration and secrets.
• Configurable reasoner implementation – default ELK, switchable via REST parameter.

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3 Project Layout

src/
  main/
    java/org/snomed/otf/reasoner/server   ← Java sources
    resources/                            ← configuration, logback, etc.
  test/                                   ← unit & integration tests

Package conventions:

• configuration Spring @Configuration classes & beans
• rest Spring MVC controllers / DTOs
• service Business logic & integration code
• pojo Immutable POJOs & enums used in the API

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4 Getting Started Locally

4.1 Prerequisites

1. JDK 17
2. Maven 3.8+ (wrapper provided)
3. ActiveMQ 5.x – an embedded broker is started by default, but an external one is recommended for multi-instance testing.
4. (Optional) AWS S3, Consul & Vault if you want to mirror production setups.

Tip: A docker-compose.yml bundling CS + ActiveMQ is included for quick startup.

4.2 Clone & Build

git clone https://github.com/IHTSDO/classification-service.git
cd classification-service
./mvnw clean verify

• verify runs the test-suite and produces target/classification-service-${VERSION}.jar.
• Run ./mvnw -Pdeb package to additionally create target/classification-service-${VERSION}-all.deb.

4.3 Configuration

1. Copy src/main/resources/application.properties to src/main/resources/application-local.properties (already .gitignored).
2. Override at least the following properties:

   spring.security.user.name=<username>
   spring.security.user.password=<pwd>
   # --- Storage Locations ---
   snomed.release.storage.local.path=store/releases
   classification.job.storage.local.path=store/classifications
   # --- ActiveMQ ---
   spring.activemq.broker-url=tcp://localhost:61616
   classification.jms.job.queue=classification-jobs

3. Any property can also be supplied via environment variables, e.g. SPRING_ACTIVEMQ_BROKER_URL.

4.4 Run

java -Xms1g -Xmx4g \
     -jar target/classification-service-${VERSION}.jar \
     --server.port=8089 \
     --server.servlet.contextPath=/classification-service \
     --spring.config.additional-location=classpath:/,file:./ \
     --spring.profiles.active=local

Swagger UI will be available at http://localhost:8089/classification-service/swagger-ui/index.html.

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5 Messaging & Async Workflows

• Classification jobs are published to ${classification.jms.job.queue}.
• Prefetch size can be tuned via spring.activemq.queuePrefetch (default 1 for fair distribution).
• Consumers must be idempotent – messages may be redelivered when using ActiveMQ in fail-over mode.

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6 Deployment

6.1 Fat JAR

java -Xms1g -Xmx4g \
     -Dspring.profiles.active=prod \
     -jar classification-service-${VERSION}.jar

6.2 Debian package

1. ./mvnw -Pdeb package
2. Copy the resulting .deb to your server.

3. sudo dpkg -i classification-service-${VERSION}-all.deb
   sudo systemctl restart supervisor        # if applicable

   The application is installed under /opt/classification-service/ and logs to /var/log/classification-service/.

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© SNOMED International – Apache 2.0 License.