converseStream.js

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

// snippet-start:[javascript.v3.bedrock-runtime.ConverseStream_AmazonNovaText]
// This example demonstrates how to use the Amazon Nova foundation models
// to generate streaming text responses.
// It shows how to:
// - Set up the Amazon Bedrock runtime client
// - Create a message
// - Configure a streaming request
// - Process the streaming response

import {
  BedrockRuntimeClient,
  ConversationRole,
  ConverseStreamCommand,
} from "@aws-sdk/client-bedrock-runtime";

// Step 1: Create the Amazon Bedrock runtime client
// Credentials will be automatically loaded from the environment
const client = new BedrockRuntimeClient({ region: "us-east-1" });

// Step 2: Specify which model to use
// Available Amazon Nova models and their characteristics:
// - Amazon Nova Micro: Text-only model optimized for lowest latency and cost
// - Amazon Nova Lite:  Fast, low-cost multimodal model for image, video, and text
// - Amazon Nova Pro:   Advanced multimodal model balancing accuracy, speed, and cost
//
// For the most current model IDs, see:
// https://docs.aws.amazon.com/bedrock/latest/userguide/models-supported.html
const modelId = "amazon.nova-lite-v1:0";

// Step 3: Create the message
// The message includes the text prompt and specifies that it comes from the user
const inputText =
  "Describe the purpose of a 'hello world' program in one paragraph";
const message = {
  content: [{ text: inputText }],
  role: ConversationRole.USER,
};

// Step 4: Configure the streaming request
// Optional parameters to control the model's response:
// - maxTokens: maximum number of tokens to generate
// - temperature: randomness (max: 1.0, default: 0.7)
//   OR
// - topP: diversity of word choice (max: 1.0, default: 0.9)
// Note: Use either temperature OR topP, but not both
const request = {
  modelId,
  messages: [message],
  inferenceConfig: {
    maxTokens: 500, // The maximum response length
    temperature: 0.5, // Using temperature for randomness control
    //topP: 0.9,        // Alternative: use topP instead of temperature
  },
};

// Step 5: Send and process the streaming request
// - Send the request to the model
// - Process each chunk of the streaming response
try {
  const response = await client.send(new ConverseStreamCommand(request));

  for await (const chunk of response.stream) {
    if (chunk.contentBlockDelta) {
      // Print each text chunk as it arrives
      process.stdout.write(chunk.contentBlockDelta.delta?.text || "");
    }
  }
} catch (error) {
  console.error(`ERROR: Can't invoke '${modelId}'. Reason: ${error.message}`);
  process.exitCode = 1;
}
// snippet-end:[javascript.v3.bedrock-runtime.ConverseStream_AmazonNovaText]