Language Model API Reference

public class VertexAiLanguageModel implements LanguageModel {
    public Response<String> generate(String prompt);
    public static Builder builder();
}

/**
 * Generate text completion from a prompt.
 *
 * @param prompt The input text prompt
 * @return Response containing generated text and metadata
 */
public Response<String> generate(String prompt);

/**
 * Create a new builder for configuring a VertexAiLanguageModel.
 *
 * @return A new Builder instance
 */
public static Builder builder();

/**
 * Create a VertexAiLanguageModel with explicit parameters.
 *
 * @param endpoint GCP API endpoint URL
 * @param project Google Cloud Project ID
 * @param location GCP region
 * @param publisher Model publisher (typically "google")
 * @param modelName Model name/version
 * @param temperature Sampling temperature (0.0-1.0)
 * @param maxOutputTokens Maximum output tokens
 * @param topK Top-K sampling parameter
 * @param topP Top-P nucleus sampling parameter
 * @param maxRetries Maximum retry attempts
 */
public VertexAiLanguageModel(
    String endpoint,
    String project,
    String location,
    String publisher,
    String modelName,
    Double temperature,
    Integer maxOutputTokens,
    Integer topK,
    Double topP,
    Integer maxRetries
);

/**
 * Set the GCP API endpoint URL.
 *
 * @param endpoint The API endpoint (e.g., "https://us-central1-aiplatform.googleapis.com/v1/")
 * @return This builder
 */
public Builder endpoint(String endpoint);

/**
 * Set the Google Cloud Project ID.
 *
 * @param project The GCP project ID
 * @return This builder
 */
public Builder project(String project);

/**
 * Set the GCP region/location.
 *
 * @param location The region (e.g., "us-central1", "europe-west1")
 * @return This builder
 */
public Builder location(String location);

/**
 * Set the model publisher.
 *
 * @param publisher The publisher name, typically "google"
 * @return This builder
 */
public Builder publisher(String publisher);

/**
 * Set the model name/version.
 *
 * @param modelName The model name (e.g., "text-bison@001", "text-bison@002")
 * @return This builder
 */
public Builder modelName(String modelName);

/**
 * Set the sampling temperature for randomness control.
 *
 * @param temperature Temperature value between 0.0 (deterministic) and 1.0 (random)
 * @return This builder
 */
public Builder temperature(Double temperature);

/**
 * Set the maximum number of output tokens.
 *
 * @param maxOutputTokens Maximum tokens in response (default: 200)
 * @return This builder
 */
public Builder maxOutputTokens(Integer maxOutputTokens);

/**
 * Set the top-K sampling parameter.
 *
 * @param topK Number of highest probability tokens to consider
 * @return This builder
 */
public Builder topK(Integer topK);

/**
 * Set the top-P (nucleus) sampling parameter.
 *
 * @param topP Cumulative probability threshold for token selection
 * @return This builder
 */
public Builder topP(Double topP);

/**
 * Set the maximum number of retry attempts on API failures.
 *
 * @param maxRetries Maximum retry attempts (default: 3)
 * @return This builder
 */
public Builder maxRetries(Integer maxRetries);

/**
 * Build the VertexAiLanguageModel instance.
 *
 * @return Configured VertexAiLanguageModel instance
 */
public VertexAiLanguageModel build();

public class Response<T> {
    public T content();
    public TokenUsage tokenUsage();
    public FinishReason finishReason();
}

public class TokenUsage {
    public Integer inputTokenCount();
    public Integer outputTokenCount();
    public Integer totalTokenCount();
}

public enum FinishReason {
    STOP,           // Natural completion
    LENGTH,         // Max tokens reached
    SAFETY,         // Safety filter triggered
    RECITATION,     // Recitation detected
    OTHER           // Other reason
}