Building reactjs Generative AI apps with Amazon Bedrock and AWS JavaScript SDK

This article was written in colaboration Enrique Rodriguez

Integrating generative AI into existing applications presents challenges. Many developers have limited experience in training foundations models, but the aim is to integrate generative AI capabilities with minimal code changes.

To solve this, we created an application that integrates the power of generative AI with a call to the Amazon Bedrock API from a web application such SPA built with JavaScript and react framework. With no middleware, lowering the barrier for incorporating AI generation through minimal code integration.

In this blog you will learn how to use Amazon Cognito credentials and IAM Roles to invoke Amazon Bedrock API in a react-based application with JavaScript and the CloudScape design system. You will deploy all the resources and host the app using AWS Amplify.

How Does This Application Work?

In the repository of this application, you will find the code ready to deploy the backend and frontend.

✅ Backend: An Amazon Cognito User Pool and Identity Pool, with an AWs Identity and Access Managemen Role (IAM Role) that contains the policy with the permissions to invoke Amazon Bedrock.

{ policyName: "amplify-permissions-custom-resources",
            policyDocument: {
                Version: "2012-10-17",
                Statement: [
                    {
                        Resource: "*",
                        Action: ["bedrock:InvokeModel*", "bedrock:List*", "bedrock:Retrieve*"],
                        Effect: "Allow",
                    }
                ]
            }
        }

Check ["Integrating Amazon Cognito authentication and authorization with web and mobile apps" guide][def] and can invoke API operations for users authentication and authorization.

This permissions can be customized here: IAM Role Code

✅ Frontend: a reactjs single page application (SPA) and CloudScape design system.

This application comprises 2 demos:

• Chat with Amazon Bedrock
• Knowledge Bases for Amazon Bedrock

All demos have in common the use of the BedrockRuntimeClient or BedrockAgentRuntimeClient to invoke the Bedrock or BedrockAgent service for a conversational interaction. The BedrockAgentClient is also used to list current Bedrock KnowledgeBases deployed in the same account.

import { BedrockAgentClient} from "@aws-sdk/client-bedrock-agent"
import { BedrockAgentRuntimeClient} from "@aws-sdk/client-bedrock-agent-runtime"

Amazon Bedrock is a fully managed service that offers a choice of high-performing foundation models (FMs) along with a broad set of capabilities that you need to build generative AI applications.

An instance of a Large Language Model

To use a LLM in your application (for instance anthropic.claude-instant-v1) you create instance of Bedrock Class from Langchain. You need to specify
the region, streaming responses, and API credentials from the user pool authentication. For model arguments, you specify the model to sample up to 1000 tokens and for more creative and freedom of generation use a temperature of 1.

export const getModel = async () => {
    const session = await fetchAuthSession(); //Amplify helper to fetch current logged in user
    const model = new Bedrock({
        model: "anthropic.claude-instant-v1", // model-id you can try others if you want
        region: "us-east-1", // app region
        streaming: true, // this enables to get the response in streaming manner
        credentials: session.credentials, // the user credentials that allows to invoke bedrock service
        // try to limit to 1000 tokens for generation
        // temperature = 1 means more creative and freedom 
        modelKwargs: { max_tokens_to_sample: 1000, temperature: 1 }, 
    });
    return model;
};

Code --> llmLib.js

We'll walk you through each demo group to highlight their differences.

First: Chat With Amazon Bedrock

Here you will talk directly with the Large Language Model (LLM) implemented by the Bedrock API through a chain, in two different ways:

- Chat Q&A: Send prompt input request and the model answer with a generated output.

- Chat with Memory: Send prompt input request along with the with previous messages (if they exist) and the model responds with a generated output. This implementation uses local memory.

This chat is built with a ConversationChain with Buffer Memory to store and get past dialogs. There are other types of memory, learn more in Working With Your Live Data Using LangChain.

To set up this demo, it is necessary to instantiate the Bedrock library for Lagnchain, ConservationChain to manage the conversation and BufferMemory to invoke memory usage.

import { Bedrock } from "@langchain/community/llms/bedrock/web";
import { ConversationChain} from "langchain/chains";
import { BufferMemory } from "langchain/memory";

// create a memory object
const memory = new BufferMemory({ humanPrefix: "H",  memoryKey:"chat_history"});

Why humanPrefix: "H"?

Anthropic Claude has been trained to understand the prompt in terms of Human: and Assistant: indicators. For memory you use "H:" to identify the human part (instead of Human:) to prevent model confusion on where the last Human instrucition starts.

The chain will look at chat_history key in the memory to get past dialogs, hence you use that key as memoryKey in BufferMemory.

Second: Knowledge Bases for Amazon Bedrock

In this demo, you will ask questions to the Knowledge Bases for Amazon Bedrock taking advantage of retrieval augmented generation (RAG). You must have at least one knowledge base created, do it by following Create a knowledge base guide.

Questions to the Knowledge Bases for Amazon Bedrock will be asked in two ways:

- Amazon Bedrock Retrieve => LLM:

List the knowledge bases with ListKnowledgeBasesCommandas follows:

import { ListKnowledgeBasesCommand } from "@aws-sdk/client-bedrock-agent"

export const getBedrockKnowledgeBases = async () => {
    const session = await fetchAuthSession()
    const client = new BedrockAgentClient({ region: "us-east-1", credentials: session.credentials })
    const command = new ListKnowledgeBasesCommand({})
    const response = await client.send(command)
    return response.knowledgeBaseSummaries
}

The AmazonKnowledgeBaseRetriever Langchain class creates a retriever, an object capable to retrieve documents similar to a query from a knowledge base (in this case is a Knowledge Base from Bedrock)

import { AmazonKnowledgeBaseRetriever } from "@langchain/community/retrievers/amazon_knowledge_base";

export const getBedrockKnowledgeBaseRetriever = async (knowledgeBaseId) => {
    const session = await fetchAuthSession();

    const retriever = new AmazonKnowledgeBaseRetriever({
        topK: 10, // return top 10 documents
        knowledgeBaseId: knowledgeBaseId,
        region: "us-east-1",
        clientOptions: { credentials: session.credentials }
    })

    return retriever
}

The ConversationalRetrievalQAChain is instantiated with the retriever and the memory. It takes care of the memory, query the retriever and formulate the answer (with the documents) using the llm instance.

import { ConversationalRetrievalQAChain } from "langchain/chains";

export const getConversationalRetrievalQAChain = async (llm, retriever, memory) => {

    const chain = ConversationalRetrievalQAChain.fromLLM(
        llm, retriever = retriever)
    chain.memory = memory

    //Here you modify the default prompt to add the Human prefix and Assistant suffix needed by Claude.
    //otherwise you get an exception
    //this is the prompt that uses chat history and last question to formulate a complete standalone question

    chain.questionGeneratorChain.prompt.template = "Human: " + chain.questionGeneratorChain.prompt.template +"\nAssistant:"
     // Here you finally answer the question using the retrieved documents.

    chain.combineDocumentsChain.llmChain.prompt.template = `Human: Use the following pieces of context to answer the question at the end. If you don't know the answer, just say that you don't know, don't try to make up an answer. 

{context}

Question: {question}
Helpful Answer:
Assistant:`

return chain
}

- Amazon Bedrock Retrieve & Generate:

Here you will use a complete AWS Managed RAG service. There is no need for extra packages (Langchain) or increased complexity with prompts. You will use only one API Call to BedrockAgentRuntimeClient. Also the memory is managed by the service by using a sessionId.

Bedrock is initialized with BedrockAgentRuntimeClient and with RetrieveAndGenerateCommand queries a knowledge base and a foundation model generates responses based on the retrieved results. In this demo Langchain is no needed.

import { BedrockAgentRuntimeClient, RetrieveAndGenerateCommand } from "@aws-sdk/client-bedrock-agent-runtime"

export const ragBedrockKnowledgeBase = async (sessionId, knowledgeBaseId, query) => {
    const session = await fetchAuthSession()
    const client = new BedrockAgentRuntimeClient({ region: "us-east-1", credentials: session.credentials });
    const input = {
        input: { text: query }, // user question
        retrieveAndGenerateConfiguration: {
            type: "KNOWLEDGE_BASE",
            knowledgeBaseConfiguration: {
                knowledgeBaseId: knowledgeBaseId,
                //your existing KnowledgeBase in the same region/ account
                // Arn of a Bedrock model, in this case we jump to claude 2.1, the latest. Feel free to use another
                modelArn: "arn:aws:bedrock:us-east-1::foundation-model/anthropic.claude-v2:1", // Arn of a Bedrock model
            },
        }
    }

    if (sessionId) {
        // you can pass the sessionId to continue a dialog.
        input.sessionId = sessionId
    }

    const command = new RetrieveAndGenerateCommand(input);
    const response = await client.send(command)
    return response
}

Let's Deploy React Generative AI Application With Amazon Bedrock and AWS Javascript SDK

Step 1 - Enable AWS Amplify Hosting:

The application is built with AWS Amplify. To deploy it in your account:

1. first fork this repo:

https://github.com/build-on-aws/building-reactjs-gen-ai-apps-with-amazon-bedrock-javascript-sdk/forks

1. Create a New branch: dev-branch.

2. Then follow the steps in Getting started with existing code guide.

3. In Step 1 Add repository branch, select main branch and Connecting a monorepo? Pick a folder and enter reactjs-gen-ai-apps as a root directory.

1. For the next Step, Build settings, select building-a-gen-ai-gen-ai-personal-assistant-reactjs-apps(this app) as App name, in Enviroment select Create a new envitoment and write dev

1. If there is no existing role, create a new one to service Amplify.

2. Deploy your app.

Step 2 - Access to the App URL:

Once the application has been deployed, go to the link in the application, which is located under the white box.

When you enter the link, the Sing In window will appear, so you must create a Amazon Cognito User Pool User.

✅ How To Create A User

In the App go to Backend environments and click on Authentication.

Then, under Authentication, click View in Cognito:

In the User Pool, click the name of your user pool and Create User.

Create your user and then sing in.

Note: You can create the user directly from the application by changing False hideSignUp: false in App.jsx, but this can introduce a security flaw by giving anyone access to it.

Let's Try React Generative AI Application With Amazon Bedrock Javascript SDK

Before you can use a foundation model in Amazon Bedrock, you must request access to it. Follow the step in Add model access guide.

Go to the application link and sign in with the user you created.

🤖🚀 Try and test the app!

✅ Chat with Amazon Bedrock:

✅ Ask follow-up questions, and test the model's multi-language capabilities

✅ Query the knowledge base using the LLM to deliver the best answer

✅ Finally consult the knowledge database directly without an intermediary

Conclusion

In this blog, you created a React web application that can directly access the Amazon Bedrock API using Amazon Cognito for authentication. Integrating generative AI services like Bedrock into a React interface securely can be achieved by leveraging AWS managed services like Cognito and AWS IAM.

With this, you can incorporate powerful Amazon Bedrock generative AI capabilities into new and existing React applications. This allows developers to focus on creating engaging conversation and RAG experiences with managed knowledge service, without the need of backend code. It also show the power of the streaming responses, that improves user experience and wait times with conversational AI.

🚀 Some links for you to continue learning and building:

• Amplify Workshops
• Amplify JavaScript Sample Applications
• Actions and scenarios using SDK for JavaScript