from Hacker News

Coupling between services is one of the most significant difficulties associated with microservices. Conventional architecture is a “don’t ask, don’t tell” architecture in which data is collected only when requested. Suppose there are three services in issue, A, B, and C. Service A asks the other services, “What is your present state?” and assumes they are always ready to respond. This puts the user in a position if the other services are unavailable.

Retries are utilized by microservices as a workaround to compensate for network failures or any negative impacts brought on by changes in the network topology. However, this ultimately adds another layer of complexity and increases the expense.

In order to address the problems with the conventional design, event-driven architecture adopts a “tell, don’t ask” philosophy. In the example above, Services B and C publish Continuous Streams of data, such as Events, and Service A subscribes to these Event Streams. Then, Service A may evaluate the facts, aggregate the outcomes, and locally cache them.

Utilizing Event Streams in this manner has various advantages, including:

-Systems are capable of closely imitating actual processes. -Increased usage of scale-to-zero functions (serverless computing) as more services are able to stay idle until required. -Enhanced adaptability