Azure Service Fabric - Service intercommunication and coupling

Question

I'm in the process of learning about Service Fabric and many resources seem to promote inter-service communication using Service Fabric remoting.

Yet many other resources about microservice architecture state that inter-service communication should be avoided and if needed should ideally occur only in an asynchronous fashion (e.g. via an event hub or service bus). In this way services are only loosely coupled.

Wouldn't Service Fabric remoting therefore promote tighter coupling between services, potentially negating some of the benefits of a microservice architecture and introducing fragility? Or are these drawbacks mitigated in someway when using Service Fabric?

Answer 1

Coupling services together with a run-time dependency leads to problems if one of the targeted services becomes unavailable or unhealthy.

SF has built-in strategies to deal with unhealthy-ness and can perform rolling upgrades, thereby reducing the risk of downtime.

Another aspect is that services calling services, share a schema. This is also a form of coupling. Changing the schema of a service can require its callers to also change. This problem is not mitigated by SF.

Services & Actors that work together inside a bounded context usually change together, so in this scope some tight coupling could be acceptable.

When communicating across domains, I'd still recommend using an Event Driven approach. Either within the cluster, or using an external broker like Azure Service Bus.