Package software.amazon.smithy.mqtt.traits

Class TopicBinding<T extends Trait>

java.lang.Object
software.amazon.smithy.mqtt.traits.TopicBinding<T>
public final class TopicBinding<T extends Trait> extends Object
Contains computed information about the resolved MQTT topic bindings of an operation.

Smithy models can contain a number of MQTT topics that are formed by the publish and subscribe traits. Each of these traits resolves to a single MQTT topic.

This class abstracts away the process of computing the payload of an MQTT operation. Each topic binding provides the following information:

  • The operation in the model that created the binding.
  • The MQTT topic.
  • The payload shape that forms the payload of the topic.
  • The optionally present input structure of the operation, which provides information like topic label bindings.

@smithy.mqtt#publish topics

Operations marked with @smithy.mqtt#publish resolve to a single topic that is defined by topic property of the trait.

subscribe topics

Operations marked with subscribe resolve to a single topic that is defined by the topic property of the trait.

Payload resolution

The payload binding of a topic binding can be resolved to either no payload (e.g., publish operations with no input shape), a structure payload, or a member of a structure. The target of a specific event shape member can be used as a payload in subscribe operations where an event member is marked with the eventPayload trait.

  • Method Details

    • getOperationMqttTrait

      public static Optional<? extends Trait> getOperationMqttTrait(Shape operation)
      Finds the MQTT binding trait associated with an operation.
      Parameters:
      operation - Operation to check.
      Returns:
      Returns the optionally found MQTT binding trait.

    • getMqttTrait

      public T getMqttTrait()
      Gets the trait that formed the binding of the operation to MQTT for this topic.

      The provided trait will be either an instance of PublishTrait or SubscribeTrait.

      Returns:
      Returns the MQTT trait binding.

    • getOperation

      public OperationShape getOperation()
      Gets the operation shape related to the topic bindings.
      Returns:
      Returns the operation that has topic bindings.

    • getTopic

      public Topic getTopic()
      Gets the resolved topic of the binding.
      Returns:
      Returns the resolved topic.

    • getInput

      @Deprecated public Optional<StructureShape> getInput()
      Deprecated.
      Use getInputShape instead.
      Gets the input shape related to this operation.
      Returns:
      Returns the optional input shape.

    • getInputShape

      public StructureShape getInputShape()
      Gets the input shape related to this operation.
      Returns:
      Returns the input shape.

    • getPayloadShape

      public Optional<Shape> getPayloadShape()
      Gets the payload shape of the topic.

      The payload shape is either a structure for a single-event event stream, or a union for a multi-event event stream.

      Returns:
      Returns the optional payload target.

    • conflictsWith

      public boolean conflictsWith(TopicBinding<?> other)
      Returns true if the topic binding conflicts with another.

      A topic binding is considered conflicting if both bindings have conflicting topics determined through Topic.conflictsWith(software.amazon.smithy.mqtt.traits.Topic) and the topic bindings utilize a different payload. If both topics do not have a payload then they are not conflicting. If both topics have a payload, but they target the same shape, then they are not conflicting.

      Parameters:
      other - Other topic binding to compare against.
      Returns:
      Returns true if the topic bindings conflict.

    • equals

      public boolean equals(Object o)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object