Messaging Deep Dive Basics

Seven examples that build a working SNS-to-SQS fan-out from scratch - five basic and two intermediate.

Each example shows the same operation in both Python (boto3) and TypeScript (AWS SDK for JavaScript v3).

Prerequisites

Python: pip install boto3 (boto3 1.43.x, Python 3.10+). TypeScript: npm install @aws-sdk/client-sns @aws-sdk/client-sqs (Node.js 18+).
IAM permissions for sns:* and sqs:* on the resources you create.
A default region, set with AWS_REGION or passed per client.

Basic Examples

1. Create the Topic and Two Queues

Start with one SNS topic and two independent SQS queues that will each get a copy of every message.

# --- Python (boto3) ---
import boto3
 
sns = boto3.client("sns", region_name="us-east-1")
sqs = boto3.client("sqs", region_name="us-east-1")
 
topic_arn = sns.create_topic(Name="order-events")["TopicArn"]
billing_url = sqs.create_queue(QueueName="billing-queue")["QueueUrl"]
shipping_url = sqs.create_queue(QueueName="shipping-queue")["QueueUrl"]

// --- TypeScript (AWS SDK v3) ---
import { SNSClient, CreateTopicCommand } from "@aws-sdk/client-sns";
import { SQSClient, CreateQueueCommand } from "@aws-sdk/client-sqs";
 
const sns = new SNSClient({ region: "us-east-1" });
const sqs = new SQSClient({ region: "us-east-1" });
 
const { TopicArn } = await sns.send(new CreateTopicCommand({ Name: "order-events" }));
const billing = await sqs.send(new CreateQueueCommand({ QueueName: "billing-queue" }));
const shipping = await sqs.send(new CreateQueueCommand({ QueueName: "shipping-queue" }));

CreateTopic and CreateQueue are both idempotent for the same name and attributes.
Two separate queues means two separate consumers can process the same event differently.
Nothing is wired together yet - the topic and queues exist independently until subscribed.
Naming queues after the consumer (billing-queue, shipping-queue) keeps ownership obvious.

Related: SNS & SQS Together: Fan-Out Messaging - the pattern this builds.

2. Look Up Each Queue's ARN

Subscriptions need a queue's ARN, not its URL, so fetch it with GetQueueAttributes.

# --- Python (boto3) ---
billing_arn = sqs.get_queue_attributes(
    QueueUrl=billing_url, AttributeNames=["QueueArn"])["Attributes"]["QueueArn"]
shipping_arn = sqs.get_queue_attributes(
    QueueUrl=shipping_url, AttributeNames=["QueueArn"])["Attributes"]["QueueArn"]

// --- TypeScript (AWS SDK v3) ---
import { GetQueueAttributesCommand } from "@aws-sdk/client-sqs";
 
const billingAttrs = await sqs.send(new GetQueueAttributesCommand({
  QueueUrl: billing.QueueUrl, AttributeNames: ["QueueArn"],
}));
const shippingAttrs = await sqs.send(new GetQueueAttributesCommand({
  QueueUrl: shipping.QueueUrl, AttributeNames: ["QueueArn"],
}));

The URL identifies a queue for SendMessage/ReceiveMessage; the ARN identifies it for permissions and subscriptions.
GetQueueAttributes accepts a list of attribute names, so request only QueueArn when that is all you need.
Both queues' ARNs are required before you can grant SNS permission or create subscriptions.
ARNs are stable for the life of the queue, so cache them if you subscribe repeatedly.

Each queue must explicitly allow the SNS service to call SendMessage on it.

# --- Python (boto3) ---
import json
 
def allow_sns(queue_url, queue_arn, topic_arn):
    policy = {
        "Version": "2012-10-17",
        "Statement": [{
            "Effect": "Allow", "Principal": {"Service": "sns.amazonaws.com"},
            "Action": "sqs:SendMessage", "Resource": queue_arn,
            "Condition": {"ArnEquals": {"aws:SourceArn": topic_arn}},
        }],
    }
    sqs.set_queue_attributes(QueueUrl=queue_url, Attributes={"Policy": json.dumps(policy)})
 
allow_sns(billing_url, billing_arn, topic_arn)
allow_sns(shipping_url, shipping_arn, topic_arn)

// --- TypeScript (AWS SDK v3) ---
import { SetQueueAttributesCommand } from "@aws-sdk/client-sqs";
 
async function allowSns(queueUrl: string, queueArn: string, topicArn: string) {
  const policy = {
    Version: "2012-10-17",
    Statement: [{
      Effect: "Allow", Principal: { Service: "sns.amazonaws.com" },
      Action: "sqs:SendMessage", Resource: queueArn,
      Condition: { ArnEquals: { "aws:SourceArn": topicArn } },
    }],
  };
  await sqs.send(new SetQueueAttributesCommand({
    QueueUrl: queueUrl, Attributes: { Policy: JSON.stringify(policy) },
  }));
}
 
await allowSns(billing.QueueUrl!, billingAttrs.Attributes!.QueueArn, TopicArn!);
await allowSns(shipping.QueueUrl!, shippingAttrs.Attributes!.QueueArn, TopicArn!);

Without this policy, SNS's deliveries to the queue fail and the Publish call still reports success.
Scoping with aws:SourceArn restricts writes to this specific topic, not every SNS topic in the account.
This is a one-time setup step per queue, not something you repeat on every publish.
The policy attribute is a queue attribute like any other, set via SetQueueAttributes.

Create the subscriptions using each queue's ARN as the endpoint.

# --- Python (boto3) ---
sns.subscribe(TopicArn=topic_arn, Protocol="sqs", Endpoint=billing_arn)
sns.subscribe(TopicArn=topic_arn, Protocol="sqs", Endpoint=shipping_arn)

// --- TypeScript (AWS SDK v3) ---
import { SubscribeCommand } from "@aws-sdk/client-sns";
 
await sns.send(new SubscribeCommand({ TopicArn, Protocol: "sqs", Endpoint: billingAttrs.Attributes!.QueueArn }));
await sns.send(new SubscribeCommand({ TopicArn, Protocol: "sqs", Endpoint: shippingAttrs.Attributes!.QueueArn }));

SQS subscriptions confirm automatically - there is no PendingConfirmation state to wait out.
Order does not matter: subscribe before or after granting the queue policy, as long as both exist before you publish.
Subscribe returns a SubscriptionArn you can use later to set a filter policy or unsubscribe.
A topic can have any mix of SQS, email, HTTPS, and Lambda subscriptions at once.

5. Publish Once, Receive From Both Queues

A single publish reaches both queues; drain each independently.

# --- Python (boto3) ---
sns.publish(TopicArn=topic_arn, Subject="Order placed", Message="order o-100 placed")
 
for url in (billing_url, shipping_url):
    resp = sqs.receive_message(QueueUrl=url, WaitTimeSeconds=5)
    for m in resp.get("Messages", []):
        print(url, "got", m["Body"])
        sqs.delete_message(QueueUrl=url, ReceiptHandle=m["ReceiptHandle"])

// --- TypeScript (AWS SDK v3) ---
import { PublishCommand } from "@aws-sdk/client-sns";
import { ReceiveMessageCommand, DeleteMessageCommand } from "@aws-sdk/client-sqs";
 
await sns.send(new PublishCommand({ TopicArn, Subject: "Order placed", Message: "order o-100 placed" }));
 
for (const url of [billing.QueueUrl, shipping.QueueUrl]) {
  const resp = await sqs.send(new ReceiveMessageCommand({ QueueUrl: url, WaitTimeSeconds: 5 }));
  for (const m of resp.Messages ?? []) {
    console.log(url, "got", m.Body);
    await sqs.send(new DeleteMessageCommand({ QueueUrl: url, ReceiptHandle: m.ReceiptHandle! }));
  }
}

Each queue receives its own independent copy of the message with its own message id.
The default SNS-to-SQS delivery wraps your message in a JSON envelope with Message, MessageId, and TopicArn fields.
Deleting from one queue does not affect the copy sitting in the other queue.
A slow or crashed billing worker never blocks the shipping queue from being drained.

Intermediate Examples

By default the queue body is a JSON wrapper around your message; raw delivery removes it.

# --- Python (boto3) ---
sub_arn = sns.subscribe(TopicArn=topic_arn, Protocol="sqs", Endpoint=billing_arn)["SubscriptionArn"]
sns.set_subscription_attributes(
    SubscriptionArn=sub_arn, AttributeName="RawMessageDelivery", AttributeValue="true")

// --- TypeScript (AWS SDK v3) ---
import { SetSubscriptionAttributesCommand } from "@aws-sdk/client-sns";
 
const sub = await sns.send(new SubscribeCommand({ TopicArn, Protocol: "sqs", Endpoint: billingAttrs.Attributes!.QueueArn }));
await sns.send(new SetSubscriptionAttributesCommand({
  SubscriptionArn: sub.SubscriptionArn, AttributeName: "RawMessageDelivery", AttributeValue: "true",
}));

With raw delivery on, Body in the receive response is your original message text, not an SNS envelope.
Turn this on when a consumer expects a specific payload shape and should not need to parse SNS metadata.
Message attributes still travel with the message and remain usable for filtering either way.
Set this per subscription, so one queue can get raw delivery while another keeps the envelope.

7. Clean Up Topic and Queues

Delete subscriptions implicitly by deleting the topic, then delete the queues.

# --- Python (boto3) ---
sns.delete_topic(TopicArn=topic_arn)
sqs.delete_queue(QueueUrl=billing_url)
sqs.delete_queue(QueueUrl=shipping_url)

// --- TypeScript (AWS SDK v3) ---
import { DeleteTopicCommand } from "@aws-sdk/client-sns";
import { DeleteQueueCommand } from "@aws-sdk/client-sqs";
 
await sns.send(new DeleteTopicCommand({ TopicArn }));
await sqs.send(new DeleteQueueCommand({ QueueUrl: billing.QueueUrl }));
await sqs.send(new DeleteQueueCommand({ QueueUrl: shipping.QueueUrl }));

Deleting a topic removes its subscriptions too; you do not need to unsubscribe first.
Deleting a queue does not touch the topic or other queues subscribed to it.
Queue deletion can take up to 60 seconds to fully propagate before the name is reusable.
Always clean up test topics and queues to avoid confusing them with production resources of the same name.

Related: Message Filtering with SNS Subscription Filters - route only some messages to each queue.

Stack versions: This page was written for boto3 1.43.x (Python 3.10+) and the AWS SDK for JavaScript v3 (Node.js 18+).

Each example shows the same operation in both Python (boto3) and TypeScript (AWS SDK for JavaScript v3).

Prerequisites

Python: pip install boto3 (boto3 1.43.x, Python 3.10+). TypeScript: npm install @aws-sdk/client-sns @aws-sdk/client-sqs (Node.js 18+).
IAM permissions for sns:* and sqs:* on the resources you create.
A default region, set with AWS_REGION or passed per client.

Basic Examples

1. Create the Topic and Two Queues

Start with one SNS topic and two independent SQS queues that will each get a copy of every message.

# --- Python (boto3) ---
import boto3
 
sns = boto3.client("sns", region_name="us-east-1")
sqs = boto3.client("sqs", region_name="us-east-1")
 
topic_arn = sns.create_topic(Name="order-events")["TopicArn"]
billing_url = sqs.create_queue(QueueName="billing-queue")["QueueUrl"]
shipping_url = sqs.create_queue(QueueName="shipping-queue")["QueueUrl"]

// --- TypeScript (AWS SDK v3) ---
import { SNSClient, CreateTopicCommand } from "@aws-sdk/client-sns";
import { SQSClient, CreateQueueCommand } from "@aws-sdk/client-sqs";
 
const sns = new SNSClient({ region: "us-east-1" });
const sqs = new SQSClient({ region: "us-east-1" });
 
const { TopicArn } = await sns.send(new CreateTopicCommand({ Name: "order-events" }));
const billing = await sqs.send(new CreateQueueCommand({ QueueName: "billing-queue" }));
const shipping = await sqs.send(new CreateQueueCommand({ QueueName: "shipping-queue" }));

CreateTopic and CreateQueue are both idempotent for the same name and attributes.
Two separate queues means two separate consumers can process the same event differently.
Nothing is wired together yet - the topic and queues exist independently until subscribed.
Naming queues after the consumer (billing-queue, shipping-queue) keeps ownership obvious.

Related: SNS & SQS Together: Fan-Out Messaging - the pattern this builds.

2. Look Up Each Queue's ARN

Subscriptions need a queue's ARN, not its URL, so fetch it with GetQueueAttributes.

# --- Python (boto3) ---
billing_arn = sqs.get_queue_attributes(
    QueueUrl=billing_url, AttributeNames=["QueueArn"])["Attributes"]["QueueArn"]
shipping_arn = sqs.get_queue_attributes(
    QueueUrl=shipping_url, AttributeNames=["QueueArn"])["Attributes"]["QueueArn"]

// --- TypeScript (AWS SDK v3) ---
import { GetQueueAttributesCommand } from "@aws-sdk/client-sqs";
 
const billingAttrs = await sqs.send(new GetQueueAttributesCommand({
  QueueUrl: billing.QueueUrl, AttributeNames: ["QueueArn"],
}));
const shippingAttrs = await sqs.send(new GetQueueAttributesCommand({
  QueueUrl: shipping.QueueUrl, AttributeNames: ["QueueArn"],
}));

The URL identifies a queue for SendMessage/ReceiveMessage; the ARN identifies it for permissions and subscriptions.
GetQueueAttributes accepts a list of attribute names, so request only QueueArn when that is all you need.
Both queues' ARNs are required before you can grant SNS permission or create subscriptions.
ARNs are stable for the life of the queue, so cache them if you subscribe repeatedly.

Each queue must explicitly allow the SNS service to call SendMessage on it.

# --- Python (boto3) ---
import json
 
def allow_sns(queue_url, queue_arn, topic_arn):
    policy = {
        "Version": "2012-10-17",
        "Statement": [{
            "Effect": "Allow", "Principal": {"Service": "sns.amazonaws.com"},
            "Action": "sqs:SendMessage", "Resource": queue_arn,
            "Condition": {"ArnEquals": {"aws:SourceArn": topic_arn}},
        }],
    }
    sqs.set_queue_attributes(QueueUrl=queue_url, Attributes={"Policy": json.dumps(policy)})
 
allow_sns(billing_url, billing_arn, topic_arn)
allow_sns(shipping_url, shipping_arn, topic_arn)

// --- TypeScript (AWS SDK v3) ---
import { SetQueueAttributesCommand } from "@aws-sdk/client-sqs";
 
async function allowSns(queueUrl: string, queueArn: string, topicArn: string) {
  const policy = {
    Version: "2012-10-17",
    Statement: [{
      Effect: "Allow", Principal: { Service: "sns.amazonaws.com" },
      Action: "sqs:SendMessage", Resource: queueArn,
      Condition: { ArnEquals: { "aws:SourceArn": topicArn } },
    }],
  };
  await sqs.send(new SetQueueAttributesCommand({
    QueueUrl: queueUrl, Attributes: { Policy: JSON.stringify(policy) },
  }));
}
 
await allowSns(billing.QueueUrl!, billingAttrs.Attributes!.QueueArn, TopicArn!);
await allowSns(shipping.QueueUrl!, shippingAttrs.Attributes!.QueueArn, TopicArn!);

Without this policy, SNS's deliveries to the queue fail and the Publish call still reports success.
Scoping with aws:SourceArn restricts writes to this specific topic, not every SNS topic in the account.
This is a one-time setup step per queue, not something you repeat on every publish.
The policy attribute is a queue attribute like any other, set via SetQueueAttributes.

Create the subscriptions using each queue's ARN as the endpoint.

# --- Python (boto3) ---
sns.subscribe(TopicArn=topic_arn, Protocol="sqs", Endpoint=billing_arn)
sns.subscribe(TopicArn=topic_arn, Protocol="sqs", Endpoint=shipping_arn)

// --- TypeScript (AWS SDK v3) ---
import { SubscribeCommand } from "@aws-sdk/client-sns";
 
await sns.send(new SubscribeCommand({ TopicArn, Protocol: "sqs", Endpoint: billingAttrs.Attributes!.QueueArn }));
await sns.send(new SubscribeCommand({ TopicArn, Protocol: "sqs", Endpoint: shippingAttrs.Attributes!.QueueArn }));

SQS subscriptions confirm automatically - there is no PendingConfirmation state to wait out.
Order does not matter: subscribe before or after granting the queue policy, as long as both exist before you publish.
Subscribe returns a SubscriptionArn you can use later to set a filter policy or unsubscribe.
A topic can have any mix of SQS, email, HTTPS, and Lambda subscriptions at once.

5. Publish Once, Receive From Both Queues

A single publish reaches both queues; drain each independently.

# --- Python (boto3) ---
sns.publish(TopicArn=topic_arn, Subject="Order placed", Message="order o-100 placed")
 
for url in (billing_url, shipping_url):
    resp = sqs.receive_message(QueueUrl=url, WaitTimeSeconds=5)
    for m in resp.get("Messages", []):
        print(url, "got", m["Body"])
        sqs.delete_message(QueueUrl=url, ReceiptHandle=m["ReceiptHandle"])

// --- TypeScript (AWS SDK v3) ---
import { PublishCommand } from "@aws-sdk/client-sns";
import { ReceiveMessageCommand, DeleteMessageCommand } from "@aws-sdk/client-sqs";
 
await sns.send(new PublishCommand({ TopicArn, Subject: "Order placed", Message: "order o-100 placed" }));
 
for (const url of [billing.QueueUrl, shipping.QueueUrl]) {
  const resp = await sqs.send(new ReceiveMessageCommand({ QueueUrl: url, WaitTimeSeconds: 5 }));
  for (const m of resp.Messages ?? []) {
    console.log(url, "got", m.Body);
    await sqs.send(new DeleteMessageCommand({ QueueUrl: url, ReceiptHandle: m.ReceiptHandle! }));
  }
}

Each queue receives its own independent copy of the message with its own message id.
The default SNS-to-SQS delivery wraps your message in a JSON envelope with Message, MessageId, and TopicArn fields.
Deleting from one queue does not affect the copy sitting in the other queue.
A slow or crashed billing worker never blocks the shipping queue from being drained.

Intermediate Examples

By default the queue body is a JSON wrapper around your message; raw delivery removes it.

# --- Python (boto3) ---
sub_arn = sns.subscribe(TopicArn=topic_arn, Protocol="sqs", Endpoint=billing_arn)["SubscriptionArn"]
sns.set_subscription_attributes(
    SubscriptionArn=sub_arn, AttributeName="RawMessageDelivery", AttributeValue="true")

// --- TypeScript (AWS SDK v3) ---
import { SetSubscriptionAttributesCommand } from "@aws-sdk/client-sns";
 
const sub = await sns.send(new SubscribeCommand({ TopicArn, Protocol: "sqs", Endpoint: billingAttrs.Attributes!.QueueArn }));
await sns.send(new SetSubscriptionAttributesCommand({
  SubscriptionArn: sub.SubscriptionArn, AttributeName: "RawMessageDelivery", AttributeValue: "true",
}));

With raw delivery on, Body in the receive response is your original message text, not an SNS envelope.
Turn this on when a consumer expects a specific payload shape and should not need to parse SNS metadata.
Message attributes still travel with the message and remain usable for filtering either way.
Set this per subscription, so one queue can get raw delivery while another keeps the envelope.

7. Clean Up Topic and Queues

Delete subscriptions implicitly by deleting the topic, then delete the queues.

# --- Python (boto3) ---
sns.delete_topic(TopicArn=topic_arn)
sqs.delete_queue(QueueUrl=billing_url)
sqs.delete_queue(QueueUrl=shipping_url)

// --- TypeScript (AWS SDK v3) ---
import { DeleteTopicCommand } from "@aws-sdk/client-sns";
import { DeleteQueueCommand } from "@aws-sdk/client-sqs";
 
await sns.send(new DeleteTopicCommand({ TopicArn }));
await sqs.send(new DeleteQueueCommand({ QueueUrl: billing.QueueUrl }));
await sqs.send(new DeleteQueueCommand({ QueueUrl: shipping.QueueUrl }));

Deleting a topic removes its subscriptions too; you do not need to unsubscribe first.
Deleting a queue does not touch the topic or other queues subscribed to it.
Queue deletion can take up to 60 seconds to fully propagate before the name is reusable.
Always clean up test topics and queues to avoid confusing them with production resources of the same name.

Related: Message Filtering with SNS Subscription Filters - route only some messages to each queue.

Stack versions: This page was written for boto3 1.43.x (Python 3.10+) and the AWS SDK for JavaScript v3 (Node.js 18+).

Messaging Deep Dive Basics

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Messaging Deep Dive Basics