by Debasish Ghosh

## Functional Domain Modeling

• Domain
  • The area of interest in the business.
  • A blueprint of the relationships between the various entities of the problem domain and sketches out other important details (objects, behaviours, language, context...).
  • Example: personal banking business.
• Bounded context
  • One complete functionality within your system.
  • Example: tax reports, deposit management...
• Entities
  • Items with an identity that has to be managed in the course of its entire lifetime within the system.
  • Semantically mutable.
  • Example: account.
• Value objects
  • Items identified entirely based on the value it contains.
  • Semantically immutable.
  • Example: address.
• Services
  • Encapsulate behavior involving value objects and entities.
  • Example: account service.
• Aggregates
  • Group of related objects defining a consistency boundary.
  • Can consist of one or more entities and value objects.
  • One of the entities is the aggregate root. It...
    • Ensures consistency boundary of business rules and transactions within the aggregate.
    • Prevents the implementation of the aggregate from leaking out to its clients acting as a façade for all the operations that the aggregate supports.
  • Example: account, containing bank, address, dates...
• Repositories
  • Interface to persist entites.
  • Example: AccountRepository, implemented by AccountRepositoryPostgresql and AccountRepositoryInMemory.