aws-sns

SNS Component

The SNS component allows messages to be sent to or consumed from an Amazon Simple Notification Topic. The implementation of the Amazon API is provided by the AWS SDK.

Prerequisites

You must have a valid Amazon Web Services developer account, and be signed up to use Amazon SNS. More information are available at Amazon SNS.

URI Format

sns://topicName/yourTopicName?options

The "topicName/" path is a flag that the value following the slash is a topic name that should be created or one that already exists. Alternatively, you can access existing topics by their Amazon Resource Name (ARN) as follows:

sns://arn:aws:sns:us-east-1:123456789012:yourTopicName?options

You can append query options to the URI in the following format, ?options=value&option2=value&...

Endpoint Properties

Common Properties

Property	Required	Default	Description
accessKey	yes	-	AWS access key
secretKey	yes	-	AWS secret key
amazonSNSClient	yes	-	Amazon AWS SNS Client
amazonSQSClient	yes	-	Amazon AWS SQS Client
deleteTopicOnStop	-	false	Deletes the topic when the component stops

Consumer Only Properties

Property	Required	Default	Description
queueName	-	-	Name of the queue to use for the callback
queueArn	-	-	SQS ARN to use for the callback
idempotent	-	false	If true, consumer will avoid processing messages that it has already processed
delay	-	500	Frequency of polling on the queue to check for new messages
deleteQueueOnStop	-	false	Deletes the queue when the component stops
verify	-	false	Verifies each of the messages using the signature in the message. Invalid messages are deleted

Producer Only Properties

Property	Required	Default	Description
subject	-	-	default subject to use for the message being sent if not overridden in the camel message header with "SNS:Subject"

Consumer Use Cases

Subscribing to a topic

Topic	Subscription Endpoint	Test Case
topic name	SQS name	SubscribeByTopicNameAndQueueNameTest.java
topic name	SQS ARN	SubscribeByTopicNameAndQueueArnTest.java
topic ARN	SQS name	SubscribeByTopicArnAndQueueNameTest.java
topic ARN	SQS ARN	SubscribeByTopicArnAndQueueArnTest.java

Required SNS component options

You have to provide the amazonSNSClient and amazonSQSClient (consumer only) in the Registry or your accessKey and secretKey to access the Amazon's SNS.

Topic Permissions

If the topic is referenced by its name then the caller is assumed to be the owner of the topic. The create topic API call is used to create the topic by name or return the topic if it already exists.

If the topic is referenced by its Amazon Resource Name (ARN) then it is assumed that the caller has access to subscribe to the topic.

Queue Permissions

The only supported subscriber endpoint at the moment is an Amazon Simple Queue Service (SQS). If the queue is referenced by its name, then the caller is assumed to be the owner of the queue. The create queue API call is used to create the queue by name or return the queue if it already exists. When the queue is created, its default policy is overridden to allow the SNS ARN to send messages to the queue.

Note that the documentation for SQS states that the policy may take up to 60 seconds to propagate although in practice it appears to be taking over 90 seconds. The result is that the SQS endpoint will not begin receiving messages until the policy is propagated. The unit tests that alter the policy of a queue sleep for 2 minutes to ensure that the policy has been applied. This will be revisited when the SQS service changes.

If the queue is references by its ARN then it is assumed that the queue exists and has sufficient permissions on it to receive messages from the topic.

Unsubscribing

The consumer will automatically unsubscribe from the topic once it is stopped.

Topic/Queue deletion

The consumer will optionally delete the topic or queue when it is stopped. See the above for info on controlling this and other behavior with endpoint properties. See DeleteQueueOnStopTest.java and DeleteTopicOnStopTest.java for examples.

Message Mapping between SNS and Camel

The component will unwrap the message payload from its JSON format and put the message field into the camel message payload and add all of the other fields as headers prefixed with "SNS:". The available properties on the message are as follow:

SNS:MessageId	A Universally Unique Identifier, unique for each notification published
SNS:Timestamp	The time (in GMT) at which the notification was published.
SNS:TopicArn	The topic to which this message was published
SNS:Type	The type of the delivery message, set to “Notification” for notification deliveries.
SNS:UnsubscribeURL	A link to unsubscribe the end-point from this topic, and prevent receiving any further notifications.
SNS:Message	The payload (body) of the message, as received from the publisher
SNS:Subject	The Subject field – if one was included as an optional parameter to the publish API call along with the message.
SNS:Signature	Base64-encoded “SHA1withRSA” signature of the Message, MessageId?, Subject (if present), Type, Timestamp, and Topic values.
SNS:SignatureVersion	Version of the Amazon SNS signature used.

These properties can be used to filter messages in the route.

Producer Use Cases

Publish by topic name
Publish by topic ARN

AWS Unit Tests

The unit tests that invoke the AWS services require valid credentials in order to work. These credentials are set in a file in the test directory (src/test/resources/awscreds.properties). Either modify this file to contain the correct accessKey and secretKey or pass these values in via the command line or export as system properties.

awscreds.propertiesaccessKey=${env.accessKey}
secretKey=${env.secretKey}

Sample command line:

mvn clean install -DaccessKey=YOUR-ACCESS-KEY -DsecreteKey=YOUR-SECRET-KEY

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