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Author: Bruce Silver
Publisher: Cody-Cassidy Press
Publication Date: May 2020
Pages: 130

Overview

Case management is a branch of business process management dealing with unstructured and event-driven processes. CMMN is a business-oriented diagramming language standard for creating case models, for both case logic description and execution. This book follows the author’s popular BPMN Method and Style and DMN Method and Style, showing how to use CMMN to create case models where the logic is clear from the printed diagrams and executable on a business automation platform.

Unlike BPMN for structured processes, which adopts the familiar look of swimlane flowcharts, CMMN diagrams may seem unfamiliar to most modelers. CMMN employs a declarative logic, where each task and stage in the model independently defines its own prerequisites. Aimed at business users, the book explains how to use the diagramming notation across various modeling styles, including**:

  • User-driven: In which the next steps are determined primarily by knowledge worker decisions.

  • Event-condition-action (ECA): In which the next steps are determined primarily by business events.

  • Hierarchical: In which CMMN stages are used as exclusive states of the case, with a top-level diagram describing the overall case logic and child-level diagrams detailing the logic of each stage.

Additionally, the book introduces extra conventions called Method and Style, which aim to ensure the case logic is apparent from the printed diagrams. Many details necessary for understanding the logic are only visible to those with access to the design tool, not to stakeholders who only see the printed diagrams. Method and Style prescribes various additional connectors and labeling conventions that make these logic details visible to all. These conventions are formulated as “style rules” that can be validated in a CMMN tool.

The book provides a detailed explanation of CMMN’s declarative logic patterns, illustrated with examples from the field of Social Care. It also includes an exhaustive list of CMMN Method and Style patterns alongside their BPMN Method and Style equivalents, making it a valuable resource for modelers who need to navigate beyond BPMN’s structured process constraints and for implementers interested in using this standard language in their business automation offerings.

Key Learning Objectives

  1. Understanding Case Management Concepts: Gain a solid foundation in the principles of case management, how it differs from traditional process management, and where CMMN (Case Management Model and Notation) is applicable.

  2. Learning CMMN Notation: Become proficient in using CMMN’s visual notation to model case processes, including key elements like case plans, tasks, milestones, stages, and event listeners.

  3. Modeling Case Logic: Learn to model flexible, non-linear case logic where steps and tasks depend on evolving conditions and events, accommodating the variability of real-world case management.

  4. Applying Method and Style Rules: Understand the best practices and stylistic guidelines to create clear, consistent, and executable CMMN models that are both technically correct and easily understood by business stakeholders.

  5. Integrating CMMN with BPMN and DMN: Learn how to integrate CMMN models with BPMN (for process workflows) and DMN (for decision logic), creating a comprehensive approach to handling dynamic, knowledge-driven case work.

  6. Building Executable Models: Focus on creating CMMN models that are not only descriptive but also ready for execution in a case management system, bridging the gap between modeling and implementation.

Topics include:

  • Introduction to Case Management and CMMN
  • CMMN Notation Basics
  • Case Plan Structure and Design
  • Task Types and Their Usage
  • Event Listeners and Sentries
  • Planning and Case Control
  • Case File Management
  • CMMN Method and Style Guidelines
  • Integrating CMMN with BPMN and DMN
  • Executable CMMN Models
  • Real-World Case Studies
  • Advanced CMMN Concepts

Preface

Those familiar with the author’s previous work may find it surprising that they have authored a book on the Case Management Model and Notation (CMMN) standard, given their initial skepticism when CMMN was launched in 2014. At that time, BPMN 2.0 was already a widely adopted standard for both business and technical modelers. The rationale behind CMMN, as maintained by its creators, was that it addressed many types of processes that BPMN could not. Although BPMN could have been adapted to handle these, such changes never materialized. The author acknowledges a shift in perspective due to CMMN’s ability to manage processes that BPMN finds challenging due to its narrow conception of a process.

A second motivating factor for the author’s change of heart has been the adoption of CMMN by leading innovators in business process technology. Organizations like Trisotech, Flowable, and FICO have begun to incorporate CMMN, alongside BPMN and DMN, into their business automation solutions, demonstrating the utility and increasing relevance of CMMN in modern business process management.

CMMN Method and Style

The author’s approach with CMMN is to make the case logic complete and unequivocal. For this, it is necessary to define variables and executable expressions for the entry and exit conditions of case model elements, known as plan items, details that are typically not visible in the diagrams. CMMN Method and Style implements conventions that imply the presence of certain variables and condition expressions based on the labels of diagram elements such as milestones and sentries. Through these conventions, a diverse array of case behaviors can be clearly and unambiguously conveyed just from the printed diagrams.

Given that CMMN’s declarative logic paradigm may be unfamiliar to many users, diagrams are susceptible to modeling errors, like endlessly repeating tasks with no termination except by manual intervention, or deadlocked stages that cannot complete. The style rules can also help detect many of these errors.

Tools such as those from Trisotech offer automated model validation based on these style rules. The enforcement of Method and Style’s rules through model validation, based on the author’s extensive experience in BPMN and DMN training, has proven to significantly enhance model quality and clarity. Thus, this book not only explains CMMN from the specifications’ perspective but also elaborates on the Method and Style conventions, including the style rules.

In the process of writing this book, the author uncovered occasional inconsistencies and ambiguities within the CMMN specification itself, prompting a series of discussions with representatives from both Trisotech and Flowable about the intended meanings and solutions to problematic areas of the spec. CMMN Method and Style captures the consensus reached through these discussions, reflecting a comprehensive understanding and application of the CMMN standard.

Structure of the Book

The book elucidates the concepts of CMMN, its foundational elements, and the utilization of these elements in various styles of case management models. Additionally, it delineates the Method and Style conventions, the rationale behind them, and how they are represented in the diagrams.

The author recommends that readers progress through the chapters sequentially, although Chapter 8, “Declarative Modeling Patterns,” may serve as a valuable reference for specific behaviors illustrated in earlier chapters, as well as those that modelers may encounter in practice.

Chapter 1: What Is CMMN? This chapter explores how case management integrates within the business process management framework. It details how cases differ from the “structured” processes of BPMN and provides examples of typical case management scenarios. The genesis of the CMMN standard is discussed, particularly as a response to the limitations of BPMN.

Chapter 2: Case Plan Elements. This chapter explains the building blocks of a CMMN diagram or Case Plan Model. It describes the various actions possible within each state of the case and how the completion of these actions, combined with other events, drives the overall behavior of the case. The chapter covers the types of tasks, the actions of a case, and stages, which are containers for the case plan elements available in a particular state. It also explains CMMN’s declarative logic paradigm, based on the lifecycle state of tasks, stages, and other model elements, as well as the event-condition-action mechanism.

Chapter 3: Case File Model. This chapter discusses the case data elements, collectively known as case file items. Not all case file items are visualized in the diagrams, but file item standard events—such as create, update, or delete—are shown in the diagram if they trigger the advancement of the case plan. It introduces the Method and Style concept of implicit file items that capture the state of a task or milestone for use in condition expressions in event-condition-action logic.

Chapter 4: Modeling Case Logic. This chapter shows how various diagram elements are combined to describe activity flow in a declarative manner. It discusses the conditions under which a CMMN task or stage starts and completes, and the advantages of using BPMN and CMMN together. The concept of end states from BPMN Method and Style is extended to tasks and stages in CMMN, including their visual representation in the diagrams.

Chapter 5: Styles of Case Modeling. This chapter illustrates the three basic styles used in CMMN models**: user-driven, event-condition-action (ECA), and hierarchical. Typically, a CMMN model incorporates a mix of all three styles. The user-driven style progresses based on manual user actions, the ECA style advances automatically based on declarative logic, and in the hierarchical style, stages represent exclusive states of the case with logic determining active stages displayed at the top level.

Chapter 6: CMMN by Example**: Social Care. Presents a detailed real-world example from the social care sector in Europe, utilizing elements of all three case modeling styles discussed.

Chapter 7: Style Rules. This chapter explains the Method and Style model validation rules. These style rules, which are the author’s own recommendations, aim to clarify the case logic from the diagrams and guard against logic that could lead to unintended behaviors such as deadlocked models.

Chapter 8: Declarative Modeling Patterns. Explains various ECA “micropatterns” in CMMN, with references to equivalent BPMN patterns using Method and Style. This chapter serves as a reference for understanding models within the book and real scenarios encountered by modelers. Those familiar with BPMN are advised to read this chapter before Chapter 6.

Chapter 9: Executable CMMN with Method and Style. Explains how executable CMMN tools can integrate Method and Style by automatically generating variables and condition expressions implied by the labels of diagram elements. This integration facilitates the communication of the underlying logic directly through the diagrams.