Queue

The cloud.Queue resource represents a data structure for holding a list of messages. Queues are typically used to decouple producers of data and the consumers of said data in distributed systems. Queues by default are not FIFO (first in, first out) - so the order of messages is not guaranteed.

Usage

Setting a Queue Consumer

bring cloud;

let q = new cloud.Queue();

q.setConsumer(inflight (m: str) => {
  log("message ${m} consumed");
});

new cloud.Function(inflight () => {
  q.push("message a");
  q.push("message b");
});

Using Queue inflight api

Pusing messages, popping them, and purge

bring cloud;

let q = new cloud.Queue();

new cloud.Function(inflight () => {
  q.push("message a");
  q.push("message b", "message c", "message d");
  log("approxSize is ${q.approxSize()}");
  log("popping message ${q.pop()}");
  log("popping message ${q.pop()}");
  log("approxSize is ${q.approxSize()}");
  q.purge();
  log("approxSize is ${q.approxSize()}");
});

Target-specific details

Simulator (sim)

The sim implementation of cloud.Queue uses JavaScript's Array

AWS (tf-aws and awscdk)

The AWS implementation of cloud.Queue uses Amazon Simple Queue Service.

Azure (tf-azure)

🚧 Not supported yet (tracking issue: #617)

GCP (tf-gcp)

🚧 Not supported yet (tracking issue: #616)

API Reference

Queue

A queue.

Initializers

bring cloud;

new cloud.Queue(props?: QueueProps);

Name	Type	Description
props	QueueProps	No description.

---

props^Optional

• Type: QueueProps

---

Methods

Preflight Methods

Name	Description
setConsumer	Create a function to consume messages from this queue.

Inflight Methods

Name	Description
approxSize	Retrieve the approximate number of messages in the queue.
pop	Pop a message from the queue.
purge	Purge all of the messages in the queue.
push	Push one or more messages to the queue.

---

setConsumer

setConsumer(handler: IQueueSetConsumerHandler, props?: QueueSetConsumerProps): Function

Create a function to consume messages from this queue.

handler^Required

• Type: IQueueSetConsumerHandler

---

props^Optional

• Type: QueueSetConsumerProps

---

approxSize

inflight approxSize(): num

Retrieve the approximate number of messages in the queue.

pop

inflight pop(): str

Pop a message from the queue.

purge

inflight purge(): void

Purge all of the messages in the queue.

push

inflight push(...messages: Array<str>): void

Push one or more messages to the queue.

messages^Required

• Type: str

Payload to send to the queue.

---

Properties

Name	Type	Description
node	constructs.Node	The tree node.

---

node^Required

node: Node;

• Type: constructs.Node

The tree node.

---

Structs

QueueProps

Options for Queue.

Initializer

bring cloud;

let QueueProps = cloud.QueueProps{ ... };

Properties

Name	Type	Description
retentionPeriod	duration	How long a queue retains a message.
timeout	duration	How long a queue's consumers have to process a message.

---

retentionPeriod^Optional

retentionPeriod: duration;

• Type: duration
• Default: undefined

How long a queue retains a message.

---

timeout^Optional

timeout: duration;

• Type: duration
• Default: undefined

How long a queue's consumers have to process a message.

---

QueueSetConsumerProps

Options for Queue.setConsumer.

Initializer

bring cloud;

let QueueSetConsumerProps = cloud.QueueSetConsumerProps{ ... };

Properties

Name	Type	Description
env	MutMap<str>	Environment variables to pass to the function.
memory	num	The amount of memory to allocate to the function, in MB.
timeout	duration	The maximum amount of time the function can run.
batchSize	num	The maximum number of messages to send to subscribers at once.

---

env^Optional

env: MutMap<str>;

• Type: MutMap<str>
• Default: No environment variables.

Environment variables to pass to the function.

---

memory^Optional

memory: num;

• Type: num
• Default: 128

The amount of memory to allocate to the function, in MB.

---

timeout^Optional

timeout: duration;

• Type: duration
• Default: 1m

The maximum amount of time the function can run.

---

batchSize^Optional

batchSize: num;

• Type: num
• Default: 1

The maximum number of messages to send to subscribers at once.

---

Protocols

IQueueSetConsumerHandler

• Extends: IResource

• Implemented By: IQueueSetConsumerHandler

Inflight client: @winglang/sdk.cloud.IQueueSetConsumerHandlerClient

A resource with an inflight "handle" method that can be passed to Queue.setConsumer.

Properties

Name	Type	Description
node	constructs.Node	The tree node.

---

node^Required

node: Node;

• Type: constructs.Node

The tree node.

---

IQueueSetConsumerHandlerClient

• Implemented By: IQueueSetConsumerHandlerClient

Inflight client for IQueueSetConsumerHandler.

Methods

Name	Description
handle	Function that will be called when a message is received from the queue.

---

handle

inflight handle(message: str): void

Function that will be called when a message is received from the queue.

message^Required

• Type: str

---