Processes vs cases: prescribed flow vs available work

Motto — BPMN says “do this, then this”; CMMN says “while the case is open, these things may happen” — one models a route, the other a workspace.

Part of Phase 06 — CMMN: case management. Concept lesson — no code required. Concept reading: Principle 8.

The Problem

Try to model a fraud investigation in BPMN and watch it fight you. The investigator might request statements, interview the customer, call the bank, or escalate — in any order, some steps never happen, others repeat, and judgment drives the choice. Your diagram becomes a hairball of loops and inclusive gateways. It tries to prescribe work that is inherently discretionary. That is not a modelling skill gap. It is a paradigm mismatch. BPMN assumes a knowable happy path, and that assumption does not hold for knowledge work. CMMN exists for exactly this kind of work.

The Concept

The inversion, side by side:

	BPMN process	CMMN case
Core metaphor	a route: tokens move along flows	a workspace: plan items become available/active/completed
Order	the model decides	the case worker decides, within guardrails
“Next step”	whatever the token faces	whatever is enabled — possibly several, possibly none
Guardrails	sequence flows, gateways	sentries: “X becomes available when Y completes / when data says so”
Completion	tokens reach end events	required items done, nothing active — or worker closes it
Home turf	origination, payments, onboarding — the whole course so far	investigations, disputes, complex claims, advisory work

The litmus test is one question: who owns the order? If the organisation owns it (“KYC before decision, always” — every capstone step), it’s a process. If the practitioner owns it (“interview first or statements first? it depends on the case”), it’s a case. Most real systems are processes with a few discretionary pockets. That is why lesson 03’s mixing pattern — cases calling processes, and processes calling cases — matters more than pure CMMN. It is also why lesson 04 warns you how rarely pure CMMN is the right answer.

Here is a mental bridge from what you’ve already built. A CMMN case behaves like a scope full of Phase 7 event subprocesses — units of work that arm when their condition holds — but the human is the event source. The engine machinery underneath is the same (Phase 2’s rows, Phase 3’s tasks). Only the authority over sequencing changes.

Ship It

This lesson ships outputs/process-or-case-guide.md — the litmus test and the traps on both sides.

Check Yourself

Q1. The question that sorts process from case is…

A) how many steps there are
B) who owns the order — the organisation (process) or the practitioner within guardrails (case)
C) whether humans are involved
D) data volume

<details><summary>Answer</summary>B — humans appear in both (Phase 3 is all process-side humans). Discretion over sequencing is the divider.</details>

Q2. In CMMN, sequencing pressure (“escalation only after evidence complete”) is expressed by…

A) sequence flows
B) sentries gating a plan item’s availability on other items’ completion or case data
C) gateway conditions
D) it can’t be expressed

<details><summary>Answer</summary>B — sentries are guardrails on availability, not a route. The worker still chooses among whatever is enabled.</details>

Q3. Loan origination (the capstone) is a process, not a case, because…

A) it has service tasks
B) the order is organisationally mandated — KYC before decision before offer; no case worker may reorder it
C) it’s too long for CMMN
D) CMMN lacks timers

<details><summary>Answer</summary>B — the litmus test applied. The capstone’s one discretionary pocket (fraud referral) is exactly where lesson 03’s mixing would enter.</details>

Challenge. Take three “too dynamic for BPMN” claims you’ve heard, or make them up: dispute handling, hardship restructuring, high-value client onboarding. Run the litmus test on each step, not each flow. The typical finding: 80% of the “dynamic” flow is prescribed, with one genuinely discretionary stage. That one stage is the shape lesson 03 models.

Next: Plan items, stages, milestones, sentries
The warning label: lesson 04

Processes vs cases: prescribed flow vs available work

The Problem

The Concept

Ship It

Check Yourself

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