Microservices vs. Service-Oriented Architecture

Chapter 2. Comparing Service Characteristics

The OASIS Reference Model for Service Oriented Architecture defines a service as “a mechanism to enable access to one or more capabilities, where the access is provided using a prescribed interface and is exercised consistent with constraints and policies as specified by the service description.” In other words, a service has some business capabilities and has a well-defined interface and well-defined contract to access that service. What this definition does not specify, however, is how services are further defined based on classification, organizational ownership, and granularity (i.e., service size). Understanding these service characteristics helps define the context of a service within a particular architecture pattern.

Although microservices and SOA both rely on services as the main architecture component, they vary greatly in terms of service characteristics. In this chapter I compare microservices and SOA by focusing on how the services are classified within each pattern (i.e., service taxonomy), how services are coordinated based on the service owner, and finally the difference in service granularity between microservices and SOA.

Service Taxonomy

The term service taxonomy refers to how services are classified within an architecture. There are two basic types of service classifications—service type and business area. Service type classification refers to the type of role the service plays in the overall architecture. For example, ...