The SQS Transport never deletes any resource so it might happen that messages are routed to undesirable destinations if or when message handlers are moved to a different endpoint, or completely removed. Evolving an existing topologyĮvolving an existing topology needs to be handled with care. More information about the custom mapping API can be found in the configuration options documentation. The above snippet instructs the subscriber's subscription manager to create and subscribe to a topic named namespace-OrderAccepted when subscribing to the IOrderAccepted event. Transport.MapEvent("namespace-OrderAccepted") ĮndpointConfiguration.UseTransport(transport) However, if in the same system the publisher publishes the OrderAccepted message that implements IOrderAccepted from the Messages assembly it'll try to publish to the namespace-OrderAccepted topic and the message won't be delivered to the desired destination.įor the described inheritance scenario to work properly, a custom mapping must be defined at the subscriber: For example, if a subscriber is subscribed to the IOrderAccepted event defined in the Contracts assembly it will create and subscribe to a topic named namespace-IOrderAccepted. In case a subscriber needs to subscribe to a message type that is not the most concrete type as seen by the publisher, a custom mapping is needed. Inheritance at the subscriber level is not supported when using the automatically created topology. By default a subscriber will subscribe only to the most concrete type it knows about and a publisher will always publish the most concrete type it knows about. This has an impact on the way inheritance is supported by the transport. Message inheritance supportīy default topic names are generated using the message full type name and replacing characters that are not allowed in SNS. Refer to the transport operations section for more information. Topology deployment can be automated, or manually created, using the transport CLI tool. The topology (topics and subscriptions) is created automatically by the subscribing endpoints. Publishing events to multiple endpoints is achieved by publishing a single message to an SNS topic to which multiple destination queues are subscribed. The transport is a multicast-enabled transport and provides built-in support for publish-subscribe messaging using Amazon Simple Notification Service (SNS). ![]() ![]() When an endpoint scales out to multiple instances, each instance consumes messages from the same input queue. The transport initiates all network connections to SQS and S3 hence the endpoint itself does not need to be publicly accessible and can reside behind a firewall or proxy. Endpoints may access SQS queues whether they are deployed in AWS or not as long as the endpoint can reach both SQS and S3 via HTTPS it can use the transport. The topology used by the transport is composed of several AWS components.Īmazon SQS exposes queue endpoints that are publicly available via HTTPS.
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