langsmith-java/langsmith-java-example

LangSmith Examples

This module contains runnable Kotlin examples organized by feature:

• example/ - SDK examples (ListRuns, Dataset, PromptManagement, RecordExperiment, E2eEval)
• example/otel/ - OpenTelemetry tracing examples

Prerequisites

All examples require:

./gradlew :langsmith-java-example:run -Pexample=ExampleName -Dlangchain.langsmithApiKey=your_api_key

Alternatively, you can use environment variables:

export LANGSMITH_API_KEY=your_api_key

The langchain.baseUrl system property (or LANGSMITH_ENDPOINT environment variable) is optional and defaults to https://api.smith.langchain.com/ if not set.

OpenTelemetry Tracing Examples

Located in src/main/kotlin/com/langchain/smith/example/otel/

OpenAI + LangSmith (Real API Calls)

Make actual OpenAI API calls with automatic tracing to LangSmith.

./gradlew :langsmith-java-example:run -Pexample=OtelOpenAI \
  -Dlangchain.langsmithApiKey=your_api_key \
  -DOPENAI_API_KEY=your_openai_key \
  -DLANGSMITH_PROJECT=my-project  # optional, defaults to "default"

View traces at https://smith.langchain.com

LangSmith (Standalone)

Send mock traces to LangSmith without external API calls.

./gradlew :langsmith-java-example:run -Pexample=OtelLangSmith \
  -Dlangchain.langsmithApiKey=your_api_key \
  -DLANGSMITH_PROJECT=my-project  # optional, defaults to "default"

View traces at https://smith.langchain.com

Spring Boot API to LangSmith

REST API with OpenTelemetry traces sent to LangSmith.

# Start server
./gradlew :langsmith-java-example:run -Pexample=SpringBootLangSmith \
  -Dlangchain.langsmithApiKey=your_api_key \
  -DLANGSMITH_PROJECT=my-project  # optional

# In another terminal, test endpoints:
curl -X POST http://localhost:8080/api/chat \
  -H "Content-Type: application/json" \
  -d '{"message": "Hello!"}'

curl "http://localhost:8080/api/analyze?text=This%20is%20great"

Prompt Management Example

Located in src/main/kotlin/com/langchain/smith/example/

Prompt Management (Getting Started)

RECOMMENDED - Clean, simple example following the same pattern as the Dataset example.

./gradlew :langsmith-java-example:run -Pexample=PromptManagement \
  -Dlangchain.langsmithApiKey=your_api_key

Features demonstrated:

1. Create prompt repositories using client.repos().create()
2. Add prompt content with variables using client.commits().update()
3. List and filter prompts using client.repos().list()
4. Retrieve prompt content using client.commits().retrieve()
5. View prompts in the LangSmith UI

This example follows the LangSmith Prompt Management docs and uses the SDK directly.

**Additional features:**
- Use prompts with OpenAI to generate responses
- Update prompt metadata and descriptions
- Pull specific commit versions
- System + user message prompts