# AWS SQS

SQS queues - sending, receiving and deleting messages and creating queues from Python services.

Zato lets you work with Amazon SQS queues directly from your Python services. You create an [AWS connection](https://zato.io/docs/dev/examples/cloud/aws/index.html) in the Dashboard, and the SQS client is available under `conn.sqs` - the same client that `boto3.client('sqs')` returns, with credentials and configuration managed for you.

## Sending messages {#sending-messages}

```python
# -*- coding: utf-8 -*-

# stdlib
import json

# Zato
from zato.server.service import Service

class SendOrderEvent(Service):

    input = 'order_id'

    def handle(self):

        # Get the connection by its Dashboard name
        conn = self.aws['My AWS']

        # Look up the queue ..
        queue_url = conn.sqs.get_queue_url(QueueName='orders')['QueueUrl']

        # .. and publish the message.
        message = json.dumps({'order_id': self.request.input.order_id})
        conn.sqs.send_message(QueueUrl=queue_url, MessageBody=message)
```

## Receiving messages {#receiving-messages}

Received messages stay invisible to other consumers for the queue's visibility timeout - delete each one after processing it, otherwise it will reappear.

```python
# -*- coding: utf-8 -*-

# Zato
from zato.server.service import Service

class ProcessOrderEvents(Service):

    def handle(self):

        conn = self.aws['My AWS']

        queue_url = conn.sqs.get_queue_url(QueueName='orders')['QueueUrl']

        # Receive up to ten messages, waiting up to two seconds for them
        response = conn.sqs.receive_message(
            QueueUrl=queue_url,
            MaxNumberOfMessages=10,
            WaitTimeSeconds=2,
        )

        # There is no Messages key at all if the queue was empty
        messages = response.get('Messages', [])

        for message in messages:

            # Process the message ..
            self.logger.info('Processing order event: %s', message['Body'])

            # .. and delete it so it is not delivered again.
            conn.sqs.delete_message(QueueUrl=queue_url, ReceiptHandle=message['ReceiptHandle'])

        self.response.payload = {'processed': len(messages)}
```

## Creating queues {#creating-queues}

```python
# -*- coding: utf-8 -*-

# Zato
from zato.server.service import Service

class CreateOrderQueue(Service):

    def handle(self):

        conn = self.aws['My AWS']

        # Create the queue - the call also succeeds if the queue already exists
        # with the same attributes, returning its URL.
        response = conn.sqs.create_queue(
            QueueName='orders',
            Attributes={'VisibilityTimeout': '60'},
        )

        self.response.payload = {'queue_url': response['QueueUrl']}
```

## More resources {#more-resources}

- [AWS integrations overview](https://zato.io/docs/dev/examples/cloud/aws/index.html)
- [AWS tutorial](https://zato.io/docs/dev/examples/cloud/aws/tutorial.html)
- [boto3 SQS reference](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sqs.html)

## Learn more {#learn-more}

- [Development documentation](https://zato.io/docs/dev/) - The complete reference for writing services
- [Requests and responses](https://zato.io/docs/dev/request-response/) - What a service receives, what it returns and how both are structured
- [Integration examples](https://zato.io/docs/dev/examples/) - Ready-made code for the systems you are likely to connect to
- [IDE and debugging](https://zato.io/docs/dev/ide/) - Write services in the Dashboard or in your own editor
- [Data models](https://zato.io/docs/dev/model/) - Declare inputs and outputs and have them validated for you
- [In-depth API tutorial](https://zato.io/tutorials/main/01.html) - The full platform tutorial, from installation to production patterns