Microservices – µSOA vs. SCS vs. DDDD vs. FaaS

Comparison of Technologies

The following table compares four important types of microservice architectures. They all try to achieve high cohesion and low coupling within the system landscape. However, the different approaches rely on different levels of granularity and different techniques.

 

 µSOASCS
(Self-Contained System)
DDDD
(Distributed Domain-driven Design
FaaS
(Function as a Service)

Size

Very smallMedium, may consist of multiple smaller microservices, independent system (including data storage and UI)SmallAs small as possible (a few hundred lines), definition of the interface first, only possible if decomposition can be reached.

Demarcation

One task (within a domain)One domainOne bounded context / domainOne function

Independence

Independent development of tasksIndependent development of domainsIndependent development of bounded contexts / domainsIndependent development of functions

Communication

Mostly synchronous communication (REST), resilience for calls (e.g. Hystrix)), often combined with streaming (e.g. Apache Kafka)Lightweight integration (ideally via UI), can answer requests independently, asynchronous communication with other systems (if necessary)Asynchronous communication (for better stability), business events, redundant data storage (CQRS)Asynchronous communication, event-based

Coupling

Orchestration for a common goalLow coupling of domainsBounded context, ubiquitous language, low coupling of the contextsCollaboration for common goal, common interfaces, emergent behavior

Team

2-3 persons per microservice1 Scrum team per SCS as main team (but possibly also several Scrum teams for different Microservices with scaled Scrum1 Scrum team per system1-2 persons per function

Infrastructure

Common infrastructureNo special infrastructure requiredCommon infrastructure for professional eventsDependence on common infrastructure

Scalability

For very high scalability requirementsGood scalabilityGood scalabilityFor extreme scalability requirements

Examples

Netflix, TwitterAmazon, Otto.de, Galeria Kaufhof Serverless architecture, AWS Lambda, Azure Functions

µSOA

SCS

DDDD

FaaS

Contact

Christoph Ehlers

+49-89-45841-100