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# Bibliothèque client étendue Amazon SNS pour Python
## Conditions préalables
Voici les prérequis à satisfaire pour utiliser la [bibliothèque client étendue Amazon SNS pour Python](https://github.com/awslabs/amazon-sns-python-extended-client-lib) :
+ Un AWS SDK. L'exemple de cette page utilise le SDK AWS Python Boto3. Pour installer et configurer le kit SDK, consultez la documentation [https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html](https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html).
+ Et Compte AWS avec les informations d'identification appropriées. Pour créer un Compte AWS, accédez à la [page d'AWS accueil](https://aws.amazon.com/), puis choisissez **Créer un AWS compte**. Suivez les instructions à l’écran.
Pour obtenir des informations sur les informations d'identification, consultez [Informations d'identification](https://boto3.amazonaws.com/v1/documentation/api/latest/guide/credentials.html) dans le *Guide du développeur AWS SDK pour Python*.
+ Python 3.x (ou version ultérieure) et pip.
+ Bibliothèque client étendue Amazon SNS pour Python (également disponible à partir de [PyPI](https://pypi.org/project/amazon-sns-extended-client/)).
## Configurer le stockage de messages
Les attributs ci-dessous sont disponibles sur Boto3 Amazon [SNS](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sns.html#client) Client[,](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sns/topic/index.html) Topic [PlatformEndpoint](https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sns/platformendpoint/index.html)et Objects pour configurer les options de stockage des messages Amazon S3.
+ **`large_payload_support`**— Le nom du compartiment Amazon S3 qui stockera les messages volumineux.
+ **`use_legacy_attribute`**— Dans `True` ce cas, tous les messages publiés utilisent l'attribut de message réservé Legacy (`SQSLargePayloadSize`) au lieu de l'attribut de message réservé actuel (`ExtendedPayloadSize`).
+ **`message_size_threshold`** – Seuil de stockage du message dans le compartiment de messages volumineux. Ne peut pas être inférieur `0` ou supérieur à`262144`. La valeur par défaut est `262144`.
+ **`always_through_s3`** – Si la valeur est `True`, tous les messages sont stockés dans Amazon S3. La valeur par défaut est `False`.
+ **`s3_client`**— L'`client`objet Boto3 Amazon S3 à utiliser pour stocker des objets sur Amazon S3. Utilisez-le si vous souhaitez contrôler le client Amazon S3 (par exemple, configuration Amazon S3 personnalisée ou informations d'identification). La valeur par défaut est utilisée `boto3.client("s3")` lors de la première utilisation si ce n'est pas déjà le cas.
## Exemple : publication de messages dans Amazon SNS avec la charge utile stockée dans Amazon S3
L’exemple de code suivant illustre comment :
+ Créez un exemple de rubrique Amazon SNS et de file d'attente Amazon SQS.
+ Joignez la politique à la file d'attente Amazon SQS pour recevoir le message de la rubrique Amazon SNS.
+ Abonnez la file d'attente pour recevoir des messages de la rubrique.
+ Publiez un message de test à l'aide du client étendu Amazon SNS, de la ressource Topic et PlatformEndpoint de la ressource.
+ La charge utile du message est stockée dans Amazon S3 et sa référence est publiée.
+ Imprimer le message publié depuis la file d'attente avec le message d'origine extrait d'Amazon S3.
Pour publier un message volumineux, vous pouvez utiliser la bibliothèque client étendue Amazon SNS pour Python. Le message que vous envoyez fait référence à un objet Amazon S3 contenant le contenu réel du message.
```
import boto3
from sns_extended_client import SNSExtendedClientSession
from json import loads
s3_extended_payload_bucket = "extended-client-bucket-store" # S3 bucket with the given bucket name is a resource which is created and accessible with the given AWS credentials
TOPIC_NAME = "---TOPIC-NAME---"
QUEUE_NAME = "---QUEUE-NAME---"
def allow_sns_to_write_to_sqs(topicarn, queuearn):
policy_document = """{{
"Version": "2012-10-17",
"Statement":[
{{
"Sid":"MyPolicy",
"Effect":"Allow",
"Principal" : {{"AWS" : "*"}},
"Action":"SQS:SendMessage",
"Resource": "{}",
"Condition":{{
"ArnEquals":{{
"aws:SourceArn": "{}"
}}
}}
}}
]
}}""".format(queuearn, topicarn)
return policy_document
def get_msg_from_s3(body,sns_extended_client):
"""Handy Helper to fetch message from S3"""
json_msg = loads(body)
s3_object = sns_extended_client.s3_client.get_object(
Bucket=json_msg[1].get("s3BucketName"), Key=json_msg[1].get("s3Key")
)
msg = s3_object.get("Body").read().decode()
return msg
def fetch_and_print_from_sqs(sqs, queue_url,sns_extended_client):
sqs_msg = sqs.receive_message(
QueueUrl=queue_url,
AttributeNames=['All'],
MessageAttributeNames=['All'],
VisibilityTimeout=0,
WaitTimeSeconds=0,
MaxNumberOfMessages=1
).get("Messages")[0]
message_body = sqs_msg.get("Body")
print("Published Message: {}".format(message_body))
print("Message Stored in S3 Bucket is: {}\n".format(get_msg_from_s3(message_body,sns_extended_client)))
# Delete the Processed Message
sqs.delete_message(
QueueUrl=queue_url,
ReceiptHandle=sqs_msg['ReceiptHandle']
)
sns_extended_client = boto3.client("sns", region_name="us-east-1")
create_topic_response = sns_extended_client.create_topic(Name=TOPIC_NAME)
sns_topic_arn = create_topic_response.get("TopicArn")
# create and subscribe an sqs queue to the sns client
sqs = boto3.client("sqs",region_name="us-east-1")
demo_queue_url = sqs.create_queue(QueueName=QUEUE_NAME).get("QueueUrl")
sqs_queue_arn = sqs.get_queue_attributes(
QueueUrl=demo_queue_url, AttributeNames=["QueueArn"]
)["Attributes"].get("QueueArn")
# Adding policy to SQS queue such that SNS topic can send msg to SQS queue
policy_json = allow_sns_to_write_to_sqs(sns_topic_arn, sqs_queue_arn)
response = sqs.set_queue_attributes(
QueueUrl = demo_queue_url,
Attributes = {
'Policy' : policy_json
}
)
# Set the RawMessageDelivery subscription attribute to TRUE if you want to use
# SQSExtendedClient to help with retrieving msg from S3
sns_extended_client.subscribe(TopicArn=sns_topic_arn, Protocol="sqs",
Endpoint=sqs_queue_arn
, Attributes={"RawMessageDelivery":"true"}
)
sns_extended_client.large_payload_support = s3_extended_payload_bucket
# Change default s3_client attribute of sns_extended_client to use 'us-east-1' region
sns_extended_client.s3_client = boto3.client("s3", region_name="us-east-1")
# Below is the example that all the messages will be sent to the S3 bucket
sns_extended_client.always_through_s3 = True
sns_extended_client.publish(
TopicArn=sns_topic_arn, Message="This message should be published to S3"
)
print("\n\nPublished using SNS extended client:")
fetch_and_print_from_sqs(sqs, demo_queue_url,sns_extended_client) # Prints message stored in s3
# Below is the example that all the messages larger than 32 bytes will be sent to the S3 bucket
print("\nUsing decreased message size threshold:")
sns_extended_client.always_through_s3 = False
sns_extended_client.message_size_threshold = 32
sns_extended_client.publish(
TopicArn=sns_topic_arn,
Message="This message should be published to S3 as it exceeds the limit of the 32 bytes",
)
fetch_and_print_from_sqs(sqs, demo_queue_url,sns_extended_client) # Prints message stored in s3
# Below is the example to publish message using the SNS.Topic resource
sns_extended_client_resource = SNSExtendedClientSession().resource(
"sns", region_name="us-east-1"
)
topic = sns_extended_client_resource.Topic(sns_topic_arn)
topic.large_payload_support = s3_extended_payload_bucket
# Change default s3_client attribute of topic to use 'us-east-1' region
topic.s3_client = boto3.client("s3", region_name="us-east-1")
topic.always_through_s3 = True
# Can Set custom S3 Keys to be used to store objects in S3
topic.publish(
Message="This message should be published to S3 using the topic resource",
MessageAttributes={
"S3Key": {
"DataType": "String",
"StringValue": "347c11c4-a22c-42e4-a6a2-9b5af5b76587",
}
},
)
print("\nPublished using Topic Resource:")
fetch_and_print_from_sqs(sqs, demo_queue_url,topic)
# Below is the example to publish message using the SNS.PlatformEndpoint resource
sns_extended_client_resource = SNSExtendedClientSession().resource(
"sns", region_name="us-east-1"
)
platform_endpoint = sns_extended_client_resource.PlatformEndpoint(sns_topic_arn)
platform_endpoint.large_payload_support = s3_extended_payload_bucket
# Change default s3_client attribute of platform_endpoint to use 'us-east-1' region
platform_endpoint.s3_client = boto3.client("s3", region_name="us-east-1")
platform_endpoint.always_through_s3 = True
# Can Set custom S3 Keys to be used to store objects in S3
platform_endpoint.publish(
Message="This message should be published to S3 using the PlatformEndpoint resource",
MessageAttributes={
"S3Key": {
"DataType": "String",
"StringValue": "247c11c4-a22c-42e4-a6a2-9b5af5b76587",
}
},
)
print("\nPublished using PlatformEndpoint Resource:")
fetch_and_print_from_sqs(sqs, demo_queue_url,platform_endpoint)
```
**Sortie**
```
Published using SNS extended client:
Published Message: ["software.amazon.payloadoffloading.PayloadS3Pointer", {"s3BucketName": "extended-client-bucket-store", "s3Key": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"}]
Message Stored in S3 Bucket is: This message should be published to S3
Using decreased message size threshold:
Published Message: ["software.amazon.payloadoffloading.PayloadS3Pointer", {"s3BucketName": "extended-client-bucket-store", "s3Key": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"}]
Message Stored in S3 Bucket is: This message should be published to S3 as it exceeds the limit of the 32 bytes
Published using Topic Resource:
Published Message: ["software.amazon.payloadoffloading.PayloadS3Pointer", {"s3BucketName": "extended-client-bucket-store", "s3Key": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"}]
Message Stored in S3 Bucket is: This message should be published to S3 using the topic resource
Published using PlatformEndpoint Resource:
Published Message: ["software.amazon.payloadoffloading.PayloadS3Pointer", {"s3BucketName": "extended-client-bucket-store", "s3Key": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"}]
Message Stored in S3 Bucket is: This message should be published to S3 using the PlatformEndpoint resource
```