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)
1
Part 1: Foundations
4
Part 2: Real-World DDD
12
Part 3: Evolution Patterns

Chapter 8: Implementing Long-Running Workflows

In the long run, the pessimist may be proven right, but the optimist has a better time on the trip.

— Daniel Reardon

In the previous chapters, we looked at handling commands and queries within the context of a single aggregate. All the scenarios we have looked at thus far have been limited to a single interaction. However, not all capabilities can be implemented in the form of a simple request-response interaction, requiring coordination across multiple external systems or human-centric operations, or both. In other cases, there may be a need to react to triggers that are non-deterministic (occur conditionally or not at all) and/or are time-bound (based on a deadline). This may require managing business transactions across multiple bounded contexts that may run over a long duration of time while continuing to maintain consistency (saga).

There are at least two common patterns to implement the saga pattern:

  • Explicit...