BedrockSessionSaver LangGraph ライブラリを使用して会話履歴とコンテキストを保存および取得する

Amazon Bedrock セッション管理 APIs を直接使用する代わりに、BedrockSessionSaverライブラリを使用して会話履歴とコンテキストを LangGraph に保存して取得できます。これは LangGraph CheckpointSaver のカスタム実装です。LangGraph ベースのインターフェイスで Amazon Bedrock APIs を使用します。詳細については、LangChain GitHub リポジトリのlanggraph-checkpoint-aws」を参照してください。

次のコードサンプルは、BedrockSessionSaver LangGraph ライブラリを使用して、ユーザーが Claude とやり取りする際の状態を追跡する方法を示しています。このコードサンプルを使用するには：

import boto3
from typing import Dict, TypedDict, Annotated, Sequence, Union
from langgraph.graph import StateGraph, END
from langgraph_checkpoint_aws.saver import BedrockSessionSaver
from langchain_core.messages import HumanMessage, AIMessage
import json


# Define state structure
class State(TypedDict):
    messages: Sequence[Union[HumanMessage, AIMessage]]
    current_question: str


# Function to get response from Claude
def get_response(messages):
    bedrock = boto3.client('bedrock-runtime', region_name="us-west-2")
    prompt = "\n".join([f"{'Human' if isinstance(m, HumanMessage) else 'Assistant'}: {m.content}"
                        for m in messages])

    response = bedrock.invoke_model(
        modelId="anthropic.claude-3-5-sonnet-20241022-v2:0",
        body=json.dumps({
            "anthropic_version": "bedrock-2023-05-31",
            "max_tokens": 1000,
            "messages": [
                {
                    "role": "user",
                    "content": [
                        {
                            "type": "text",
                            "text": prompt
                        }
                    ]
                }
            ],
            "temperature": 0.7
        })
    )

    response_body = json.loads(response['body'].read())
    return response_body['content'][0]['text']


# Node function to process user question
def process_question(state: State) -> Dict:
    messages = list(state["messages"])
    messages.append(HumanMessage(content=state["current_question"]))

    # Get response from Claude
    response = get_response(messages)
    messages.append(AIMessage(content=response))

    # Print assistant's response
    print("\nAssistant:", response)

    # Get next user input
    next_question = input("\nYou: ").strip()

    return {
        "messages": messages,
        "current_question": next_question
    }


# Node function to check if conversation should continue
def should_continue(state: State) -> bool:
    # Check if the last message was from the user and contains 'quit'
    if state["current_question"].lower() == 'quit':
        return False
    return True


# Create the graph
def create_graph(session_saver):
    # Initialize state graph
    workflow = StateGraph(State)

    # Add nodes
    workflow.add_node("process_question", process_question)

    # Add conditional edges
    workflow.add_conditional_edges(
        "process_question",
        should_continue,
        {
            True: "process_question",
            False: END
        }
    )

    # Set entry point
    workflow.set_entry_point("process_question")

    return workflow.compile(session_saver)


def main():
    # Create a runtime client
    agent_run_time_client = boto3.client("bedrock-agent-runtime",
                                         region_name="REGION")
            
    # Initialize Bedrock session saver. The Region must match the Region used for the agent_run_time_client.
    session_saver = BedrockSessionSaver(region_name="REGION")

    # Create graph
    graph = create_graph(session_saver)

    # Create session
    session_id = agent_run_time_client.create_session()["sessionId"]
    print("Session started. Type 'quit' to end.")

    # Configure graph
    config = {"configurable": {"thread_id": session_id}}

    # Initial state
    state = {
        "messages": [],
        "current_question": "Hello! How can I help you today? (Type 'quit' to end)"
    }

    # Print initial greeting
    print(f"\nAssistant: {state['current_question']}")

    state["current_question"] = input("\nYou: ").strip()

    # Process the question through the graph
    graph.invoke(state, config)
    print("\nSession contents:")
    for i in graph.get_state_history(config, limit=3):
        print(i)


if __name__ == "__main__":
    main()