Domain-Driven Design basics in LLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Bounded Context

In Domain-Driven Design, what best describes a Bounded Context?

A A clearly defined boundary within which a particular domain model applies and has consistent meaning.

B A database schema shared by all parts of the system to ensure data consistency.

C A user interface component that handles all user interactions for the domain.

D A network boundary that separates microservices physically.

💡 Hint

Think about where a domain model's rules and language stay consistent.

A Bounded Context defines a clear boundary where a specific domain model is valid and consistent. It helps avoid confusion when different parts of a system use the same terms differently.

❓ Architecture

intermediate

Identifying Aggregates

Which of the following best represents an Aggregate in Domain-Driven Design?

A A UI form that collects user input for multiple entities.

B A database table that stores all entities of a domain.

C A cluster of domain objects treated as a single unit for data changes, with one root entity controlling access.

D A microservice that handles all domain logic.

💡 Hint

Think about grouping domain objects to maintain consistency.

An Aggregate is a group of related domain objects that are treated as a single unit for data changes. It has a root entity that controls all access to the group to maintain consistency.

❓ scaling

advanced

Scaling with Bounded Contexts

When scaling a large system using Domain-Driven Design, what is the best practice regarding Bounded Contexts?

A Split the system into multiple Bounded Contexts that can be developed and deployed independently.

B Combine all domain models into one large Bounded Context to reduce communication overhead.

C Use Bounded Contexts only for UI components, not for backend services.

D Ignore Bounded Contexts and focus on database normalization for scaling.

💡 Hint

Think about how to reduce complexity and allow teams to work independently.

Splitting a large system into multiple Bounded Contexts allows teams to work independently, reduces complexity, and enables independent deployment and scaling.

❓ tradeoff

advanced

Tradeoffs in Using Entities vs Value Objects

In Domain-Driven Design, what is a key tradeoff when choosing between Entities and Value Objects?

A Entities are used only in UI layers; Value Objects only in database layers.

B Entities have identity and lifecycle but add complexity; Value Objects are simpler but immutable and lack identity.

C Entities cannot be persisted; Value Objects must be stored in separate tables.

D Entities are always immutable; Value Objects always have a unique ID.

💡 Hint

Consider identity and mutability differences.

Entities have a unique identity and lifecycle, which adds complexity in tracking changes. Value Objects are simpler, immutable, and identified by their attributes rather than identity.

❓ estimation

expert

Estimating Capacity for Event-Driven Domain Model

You design a system using Domain-Driven Design with multiple Bounded Contexts communicating via events. If each context emits 1000 events per second and there are 5 contexts, what is the minimum event processing capacity your event bus must support to avoid bottlenecks?

A At least 10000 events per second

B At least 1000 events per second

C At least 2000 events per second

D At least 5000 events per second

💡 Hint

Multiply events per context by number of contexts.

The event bus must handle the total events emitted by all contexts combined, which is 5 contexts * 1000 events/sec = 5000 events/sec minimum capacity.