Design: Microservices Architecture with Fan-Out Publish/Subscribe Messaging Pattern

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Anjali Sharma answered on February 1, 2023 Popularity 3/10 Helpfulness 1/10

answer Design: Microservices Architecture with Fan-Out Publish/Subscribe Messaging Pattern

Design: Microservices Architecture with Fan-Out Publish/Subscribe Messaging Pattern

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Create DynamoDB tables

order — PK — id — inventory — PK — code

default settings and create table

Create Downstream microservices

notification microservices

inventory microservices

shipment microservices

Basically, we should think of lambda interactions and give required permissions for execution roles.

goto lambda — execution role — add policy

inventory microservice

DynamoDB: Put

sqs: poller

notification-queue

inventory-queue

shipment-queue

sqs:poller

Create SQS queues

notification-queue, inventory-queue, shipment-queue

standart default created

Create Event Source Mapping Polling Invocation SQS and Lambdas

goto lambda functions

add trigger — sqs

notification->queue, inventory->queue, shipment->queue

As you can see that, we have successfully created lambda functions and sqs queues, in the next part, we are continue to create SNS topic.

Create SNS Topic

Create topic — standart — OrderTopic

create SNS Topic

Create subscriptions SNS — SQS subs

protocol — SQS, inventory-queue, shipment-queue

Create subscription

import { v4 as uuidv4 } from ‘uuid’;
import {PublishCommand } from “@aws-sdk/client-sns”;
import {snsClient } from “./snsClient.js”;
export const handler = async (event) => {
 console.log(“event:”, JSON.stringify(event, undefined, 2));
// pseo code
 // 1- get request body payload
 // 2- generate id with uuid library and prepare payload 
 // 3- publish message to sns topic with using sns sdk package
 // 4- save order item into dynamodb with using dnamodb sdk package
 // 5- return back snyc order payload with generated id to the api gateway 
 
 try {
 
 // validations
 if (event.httpMethod != ‘POST’) {
 throw new Error(`Http Method should be POST. You are requesting : “${event.httpMethod}”`);
 }
// 1- get request body payload
 // expected request payload : { userName : swn, attributes[firstName, lastName, email ..] 
 const orderRequest = JSON.parse(event.body);
 if (orderRequest == null || orderRequest.type == null) {
 throw new Error(`order type should exist in orderRequest: “${orderRequest}”`);
 }
// 2- generate id with uuid library 
 const orderId = uuidv4();
 orderRequest.id = orderId;
// 3- publish message to sns topic with using sns sdk package 
 let params = {
 Message: JSON.stringify(orderRequest),
 TopicArn: process.env.TOPIC_ARN,
 }; 
 const data = await snsClient.send(new PublishCommand(params));
 console.log(“Successfully published SNS Message.”, data);
 
 // 4- save order item into dynamodb with using dnamodb sdk package
// 5- return back snyc order payload with generated id to the api gateway 
 return {
 statusCode: 200,
 body: JSON.stringify({
 message: `Successfully finished order create operation: “${JSON.stringify(orderRequest)}”`,
 body: data
 })
 };
} catch (e) {
 console.error(e);
 return {
 statusCode: 500,
 body: JSON.stringify({
 message: “Failed to perform operation.”,
 errorMsg: e.message,
 errorStack: e.stack,
 })
 };
 } 
};

https://medium.com/aws-lambda-serverless-developer-guide-with-hands/publish-subscribe-fan-out-pattern-in-serverless-architectures-using-sns-sqs-and-lambda-bccaa3abac9e

Popularity 3/10 Helpfulness 1/10 Language javascript

Source: Grepper

Tags: architecture javascript microservices

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Contributed on Feb 01 2023

Anjali Sharma

0 Answers Avg Quality 2/10

Design: Microservices Architecture with Fan-Out Publish/Subscribe Messaging Pattern

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