Book Image

Domain-Driven Design with Java - A Practitioner’s Guide

By : Premanand Chandrasekaran, Karthik Krishnan
Book Image

Domain-Driven Design with Java - A Practitioner’s Guide

By: Premanand Chandrasekaran, Karthik Krishnan

Overview of this book

Domain-Driven Design (DDD) makes available a set of techniques and patterns that enable domain experts, architects, and developers to work together to decompose complex business problems into a set of well-factored, collaborating, and loosely coupled subsystems. This practical guide will help you as a developer and architect to put your knowledge to work in order to create elegant software designs that are enjoyable to work with and easy to reason about. You'll begin with an introduction to the concepts of domain-driven design and discover various ways to apply them in real-world scenarios. You'll also appreciate how DDD is extremely relevant when creating cloud native solutions that employ modern techniques such as event-driven microservices and fine-grained architectures. As you advance through the chapters, you'll get acquainted with core DDD’s strategic design concepts such as the ubiquitous language, context maps, bounded contexts, and tactical design elements like aggregates and domain models and events. You'll understand how to apply modern, lightweight modeling techniques such as business value canvas, Wardley mapping, domain storytelling, and event storming, while also learning how to test-drive the system to create solutions that exhibit high degrees of internal quality. By the end of this software design book, you'll be able to architect, design, and implement robust, resilient, and performant distributed software solutions.
Table of Contents (17 chapters)
Part 1: Foundations
Part 2: Real-World DDD
Part 3: Evolution Patterns

Handling deadlines

Thus far, we have looked at events that are caused by human (for example, the applicant submitting an LC application) or system (for example, the auto-approval of an LC application) action. However, in an event-driven system, not all events occur due to an explicit human or system stimulus. Events may need to be emitted either due to inactivity over a period of time or on a recurring schedule based on prevailing conditions.

For example, let’s examine the case where the bank needs submitted LC applications to be decided on as quickly as possible. When applications are not acted upon by the trade finance managers within 10 calendar days, the system should send them reminders.

To deal with such inactivity, we need a means by which to trigger system actions (read: emit events) based on the passage of time—in other words, perform actions when a deadline expires. In a happy path scenario, we expect either the user or the system to take a certain action...