Topics and Events - Concepts

Content-based deduplicationLink to this anchor

Content-based deduplication is a setting available for FIFO topics. Enable content-based deduplication if the message body is guaranteed to be unique for each message. A unique hash value is generated from the body of each message, which is used as its deduplication ID. This avoids the need to set a deduplication ID when sending messages. Read more in our dedicated documentation on creating topics.

CredentialsLink to this anchor

Credentials give services and platforms access to Topics and Events, enabling them to connect to the host system. Credentials for Scaleway Topics and Events define whether the bearer is allowed to write, and/or read, and/or manage topics and subscriptions. Refer to our credentials documentation for more information.

FIFOLink to this anchor

FIFO stands for First In First Out, and represents a type of topic where the exact order of messages is preserved, and duplicate messages are not tolerated. As well as these specificities, FIFO topics support all the same features as the Standard type. Consider using FIFO topics for any use cases where the order of messages is critical, such as e-commerce order management systems, systems where one action should not happen until another has been completed, or first-come-first-served ticketing systems.

FilteringLink to this anchor

In a topic-based system, where topics handle the logic, filtering is similar to routing. Messages are sent to defined topics, which can be thought of as filters, as subscribers can subscribe only to the topics they are interested in. In a content-based system, filtering is carried out more directly by subscribers, who define filters for messages based on the content/attributes they want to receive.

Message brokerLink to this anchor

A message broker is a piece of software that allows applications, systems, and services to communicate with each other and send/receive data. It facilitates the exchange of information by receiving messages from a producer and transmitting them to a consumer. Scaleway Topics and Events is a message broker tool based on the AWS SNS messaging system.

Messaging and QueuingLink to this anchor

Previously, Scaleway Messaging and Queuing was a single product that grouped together three different messaging protocols. It has now been split into three distinct products: NATS, Queues, and Topics and Events.

Publish/SubscribeLink to this anchor

Also known as “pub/sub”, the publish/subscribe model provides a pattern or framework for the exchange of messages between publishers and subscribers. It contrasts with the queuing model. The key feature of publish/subscribe is that messages are not sent to defined recipients. Instead, subscribers define the types of message they are interested in, and only receive messages matching their criteria. The publisher sends the message without knowing exactly who will receive it.

RegionLink to this anchor

Topics and Events is available in multiple regions. A region designates the geographical area where the service is hosted. Refer to the product availability table to check which regions are available for Topics and Events.

When creating topics, you need to do this on a region-by-region basis. The region drop-down in the console allows you to switch between available regions.

SNSLink to this anchor

Scaleway Topics and Events is based on the AWS SNS protocol. Simple Notification Service, or SNS, is a publish/subscribe notification service for the mass delivery of messages. SNS acts as a single message bus that can be sent to a variety of devices and platforms through a single code interface. It is also possible to adapt message formats to the particular needs of each platform.

StandardLink to this anchor

Standard-type topics represent the default topic type, and offer an at-least-once message delivery system. Unlike FIFO topics, standard topics provide only best-effort attempts to deliver messages in order. At-least-once delivery means that it is possible under rare circumstances that the same message may be received more than once.

SubscriberLink to this anchor

In Topics and Events, a subscriber is the entity (e.g. a queue, function, or URL) that messages from topics are pushed to. Subscribers can filter messages based on their topic or content.

SubscriptionLink to this anchor

A subscription is a connection between a client or endpoint, and a topic. By creating a subscription, the subscribed endpoint receives messages and notifications published to the topic. You can create subscriptions for HTTP/S endpoints, Scaleway queues, and Scaleway Serverless Functions and Containers.

Subscription protocols and endpointsLink to this anchor

A subscription protocol refers to the communication method used to deliver messages to a subscriber. Different types of subscribers require different protocols. When you create a new subscription to a topic with Scaleway Topics and Events, the following options are available:

TopicLink to this anchor

A topic is a communication channel used to send messages and notifications to subscribed endpoints or clients. Publishers send messages to topics, and those messages are received by subscribers. Subscribers can include Serverless Functions, Scaleway Queues and HTTP/HTTPS endpoints. As such, topics decouple the publishing and the receiving of messages, allowing for flexibility and scalability in building loosely-coupled systems.

Topic typesLink to this anchor

When creating topics with Scaleway Topics and Events, two topic types are available. Standard topics provide at-least-once delivery, while FIFO topics offer first-in-first-out delivery, and (unlike Standard topics) guarantee that messages are delivered in order and without duplication. Content-based deduplication is only available for FIFO topic types. Find out more about creating topics with our dedicated documentation.

Topic volumeLink to this anchor

Topic volume is one of the factors affecting the billing of Scaleway Topics and Events. Topic volume is calculated as the total sum of the sizes of all messages sent from a topic to its subscriptions.

Topics and EventsLink to this anchor

Scaleway Topics and Events is a product for creating managed messaging topics based on the SNS protocol. Previously, it was part of the Messaging and Queuing product.