SOA – Service-Oriented Architecture

is an architectural style that allows different software systems to communicate and interact with each other as services.

Commonly composed of the following components:
Service Provider – A web service, application, with a service interface
Service Registry – To discover the services
Service Bus – It routes messages between different components: Protocol transformation, message transformation, message routing, etc.
Business Process Execution Engine – It coordinates the execution of various services.
Enterprise Service Bus (ESB) – Provides integration with legacy systems, data transformation, mediation, security enforcement, etc.
Orchestration Engine – Controls the flow of execution in complex scenarios
Pros: scalability, modularity, fault tolerance
Cons: deployment, cost, simplicity, testability, performance, reliability