/*
* Copyright 2013-2014 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package com.amazonaws.services.sns.util;
import java.util.HashMap;
import java.util.Map;
import com.amazonaws.AmazonClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.auth.policy.Policy;
import com.amazonaws.auth.policy.Principal;
import com.amazonaws.auth.policy.Resource;
import com.amazonaws.auth.policy.Statement;
import com.amazonaws.auth.policy.Statement.Effect;
import com.amazonaws.auth.policy.actions.SQSActions;
import com.amazonaws.auth.policy.conditions.ConditionFactory;
import com.amazonaws.services.sns.AmazonSNS;
import com.amazonaws.services.sns.model.SubscribeRequest;
import com.amazonaws.services.sns.model.SubscribeResult;
import com.amazonaws.services.sqs.AmazonSQS;
import com.amazonaws.services.sqs.model.GetQueueAttributesRequest;
import com.amazonaws.services.sqs.model.QueueAttributeName;
import com.amazonaws.services.sqs.model.SetQueueAttributesRequest;
/**
* Set of utility methods for working with Amazon SNS topics.
*/
public class Topics {
/**
* Subscribes an existing Amazon SQS queue to an existing Amazon SNS topic.
* <p>
* The specified Amazon SNS client will be used to send the subscription
* request, and the Amazon SQS client will be used to modify the policy on
* the queue to allow it to receive messages from the SNS topic.
* <p>
* The policy applied to the SQS queue is similar to this:
* <pre>
* {
* "Version" : "2008-10-17",
* "Statement" : [{
* "Sid" : "topic-subscription-arn:aws:sns:us-west-2:599109622955:myTopic",
* "Effect" : "Allow",
* "Principal" : {
* "AWS":["*"]
* },
* "Action" : ["sqs:SendMessage"],
* "Resource":["arn:aws:sqs:us-west-2:599109622955:myQueue"],
* "Condition" : {
* "ArnLike":{
* "aws:SourceArn":["arn:aws:sns:us-west-2:599109622955:myTopic"]
* }
* }
* }]
* }
* </pre>
* <p>
* <b>IMPORTANT</b>: If there is already an existing policy set for the
* specified SQS queue, this operation will overwrite it with a new policy
* that allows the SNS topic to deliver messages to the queue.
* <p>
* <b>IMPORTANT</b>: There might be a small time period immediately after
* subscribing the SQS queue to the SNS topic and updating the SQS queue's
* policy, where messages are not able to be delivered to the queue. After a
* moment, the new queue policy will propagate and the queue will be able to
* receive messages. This delay only occurs immediately after initially
* subscribing the queue.
* <p>
* <b>IMPORTANT</b>: The specified queue and topic (as well as the SNS and
* SQS client) should both be located in the same AWS region.
*
* @param sns
* The Amazon SNS client to use when subscribing the queue to the
* topic.
* @param sqs
* The Amazon SQS client to use when applying the policy to allow
* subscribing to the topic.
* @param snsTopicArn
* The Amazon Resource Name (ARN) uniquely identifying the Amazon
* SNS topic. This value is returned form Amazon SNS when
* creating the topic.
* @param sqsQueueUrl
* The URL uniquely identifying the Amazon SQS queue. This value
* is returned from Amazon SQS when creating the queue.
*
* @throws AmazonClientException
* If any internal errors are encountered inside the client
* while attempting to make the request or handle the response.
* For example if a network connection is not available.
* @throws AmazonServiceException
* If an error response is returned by AmazonSNS indicating
* either a problem with the data in the request, or a server
* side issue.
*
* @return The subscription ARN as returned by Amazon SNS when the queue is
* successfully subscribed to the topic.
*/
public static String subscribeQueue(AmazonSNS sns, AmazonSQS sqs, String snsTopicArn, String sqsQueueUrl)
throws AmazonClientException, AmazonServiceException {
Map<String, String> queueAttributes = sqs.getQueueAttributes(new GetQueueAttributesRequest(sqsQueueUrl)
.withAttributeNames(QueueAttributeName.QueueArn.toString())).getAttributes();
String sqsQueueArn = queueAttributes.get(QueueAttributeName.QueueArn.toString());
Policy policy = new Policy().withStatements(
new Statement(Effect.Allow)
.withId("topic-subscription-" + snsTopicArn)
.withPrincipals(Principal.AllUsers)
.withActions(SQSActions.SendMessage)
.withResources(new Resource(sqsQueueArn))
.withConditions(ConditionFactory.newSourceArnCondition(snsTopicArn)));
System.out.println("Policy: " + policy.toJson());
queueAttributes = new HashMap<String, String>();
queueAttributes.put(QueueAttributeName.Policy.toString(), policy.toJson());
sqs.setQueueAttributes(new SetQueueAttributesRequest(sqsQueueUrl, queueAttributes));
SubscribeResult subscribeResult =
sns.subscribe(new SubscribeRequest()
.withEndpoint(sqsQueueArn)
.withProtocol("sqs")
.withTopicArn(snsTopicArn));
return subscribeResult.getSubscriptionArn();
}
}