Reading-Notes
Class 14 Summary :
What’s the difference between a FIFO and a standard queue?
- “Standard queues provide at-least-once delivery, which means that each message is delivered at least once. FIFO queues provide exactly-once processing, which means that each message is delivered once and remains available until a consumer processes it and deletes it”.
How can the server be assured a message was properly received?
- “Messages are stored on the queue until they are processed and deleted. Each message is processed only once, by a single consumer”.
What classic design pattern is best represented by event driven programming?
- Event-driven from end to end.
How do you test an event driven system?
- “tests for event-driven systems operate on events for inputs and events for outputs. Another by-product of a decoupled architecture is often an absence of mocks and stubs in the service test code, which stems from inherent ‘unawareness’ the service has of other services”.
Document the following Vocabulary Terms :
| Term | |
|---|---|
| FIFO Queue | FIFO (First-In-First-Out) queues are designed to enhance messaging between applications when the order of operations and events is critical, or where duplicates can’t be tolerated. |
| Pub/Sub | enables you to create systems of event producers and consumers, called publishers and subscribers. |
AWS SNS and SQS :
-
SNS : “ is a web service that makes it easy to set up, operate, and send notifications from the cloud. It provides developers with a highly scalable, flexible, and cost-effective capability to publish messages from an application and immediately deliver them to subscribers or other applications”.
- SNS benefits:
- nstantaneous, push-based delivery (no polling)
- Simple APIs and easy integration with applications
- Flexible message delivery over multiple transport protocols
- Inexpensive, pay-as-you-go model with no up-front costs
- SQS : “is a message queue service used by distributed applications to exchange messages through a polling model, and can be used to decouple sending and receiving components” .
