Symboly BPMN
Každá značka, ktorú vie BPMN 2.0 dať na papier, a k čomu tým proces zaväzuje: značky činností, tri okraje udalostí, päť kosoštvorcov, dva druhy čiar, ktoré nie sú zameniteľné, a dátové symboly, ktoré takmer nikto nekreslí správne.
9 min čítaniaBPMN 2.06 z 6
01Activities: the work
One shape - a rounded rectangle - carries every kind of work BPMN can describe. What changes is the marker in the corner or on the bottom edge, and those markers are where most of the meaning lives.
| Element | Notation | What it means |
|---|---|---|
| Task | rounded rectangle, no marker | Atomic work. The process does not model anything inside it, which is a claim about this diagram rather than about reality - a task here can be a fortnight of work somebody else models elsewhere. |
| Subprocess | small square plus on the bottom edge | Contains a process of its own. Collapsed, the plus is all you see; expanded, the box grows and the child process is drawn inside it. The plus is the only difference from a task, and the one people miss. |
| Call activity | thick border, plus marker | A subprocess defined once and reused. The thick outline says the definition lives somewhere else, so changing it changes every caller - which is exactly the property that makes it worth the extra symbol. |
| Task type markers | small icon, top-left corner | An envelope for send and receive, a person for user, gears for service, a script scroll for script. They say who or what executes the task, and they are the difference between a picture and something an engine can run. |
| Loop and multi-instance | circular arrow, or three bars | A circular arrow repeats the activity while a condition holds. Three vertical bars run one instance per item in a collection, three horizontal bars run them one after another. |
| Transaction | double-line border | A subprocess whose steps either all complete or are all compensated. Rare in hand-drawn models and load-bearing in executable ones. |
Markers stack: one activity can legitimately carry a subprocess plus, a multi-instance bar and a loop arrow at once.
02Events: the border carries the meaning
Every event is a circle. Two things vary independently: the border, which says when in the process it sits, and the glyph inside, which says what kind of thing happened.
| Element | Notation | What it means |
|---|---|---|
| Start event | thin single outline | Where a token appears. A process with no start event is legal and almost always a mistake in a diagram meant to be read by a person. |
| Intermediate event | double outline | Something happens partway through - the process waits for it (catching) or announces it (throwing). Placed on the boundary of an activity, it interrupts that activity. |
| End event | thick single outline | A token is consumed. Several end events on one process are normal and good: they name the distinct ways it can finish. |
| Message | envelope glyph | Something arrived from, or was sent to, another participant. |
| Timer | clock glyph | A date, a duration or a recurring schedule fired. |
| Error | lightning bolt glyph | Something failed in a way the process has a plan for. On an activity boundary it is the notation's exception handler. |
Filled glyphs throw, hollow glyphs catch, and the full set runs to a dozen triggers. They have an article of their own: BPMN events covers the two axes, boundary events and the interrupting distinction in detail.
03Gateways: the rhombi
A gateway never does work. It only decides how many of the paths leaving it carry a token, and the marker inside it is the whole statement.
| Element | Notation | What it means |
|---|---|---|
| Exclusive | X, or an empty rhombus | Exactly one outgoing path. The blank rhombus means the same thing, which is why an empty one is never ambiguous, only less explicit. |
| Parallel | plus | Every outgoing path, always, no conditions. As a join it waits for all incoming paths before continuing. |
| Inclusive | circle | One or more paths, whichever conditions hold. The most expressive of the five and the easiest to deadlock. |
| Event-based | pentagon in a double ring | Decides nothing. It waits, and whichever of the events downstream fires first takes the token. |
| Complex | asterisk | An escape hatch for conditions the other four cannot express. If you need it, write the rule in an annotation beside it - nobody reads an asterisk the same way twice. |
Splitting and merging, default flows and the classic inclusive deadlock are in BPMN gateways.
04Connecting objects: three lines, never interchangeable
This is the shortest table on the page and the one that decides whether a diagram is correct. Two of these lines look similar at a glance and mean entirely different things.
| Element | Notation | What it means |
|---|---|---|
| Sequence flow | Solid line, filled arrowhead. The order of steps within one pool. It may never cross a pool boundary, and that single rule is what makes pools mean anything. | |
| Message flow | Dashed line, open circle at the tail, hollow arrowhead. Communication between pools. It says nothing about order inside either one. | |
| Association | Dotted line. Ties an annotation or a data object to whatever it is about. Carries no control flow whatsoever. | |
| Default flow | sequence flow with a slash at the tail | Taken when no other outgoing condition holds. The notation's guarantee that a token is never stranded at a gateway. |
| Conditional flow | sequence flow with a hollow diamond at the tail | Taken only if its condition is true. Redundant leaving a gateway, which already carries conditions - it earns its place leaving an activity directly. |
A sequence flow crossing a pool boundary is not a stylistic slip. It is invalid BPMN, and an engine will reject it.
05Pools, lanes and the black box
A pool is a participant - an organisation, or any process with control flow of its own. A lane subdivides one pool, usually by role or department. The difference is not cosmetic: steps in two lanes of one pool are joined by sequence flow, and steps in two pools can only exchange messages.
A pool drawn with nothing inside it is a black box, and it is a deliberate statement rather than an omission. It says this participant matters, we exchange these messages with it, and how it works internally is none of this diagram's business. Modelling a customer's decision-making as though you could observe it is the failure this shape exists to prevent.
06Data objects and artifacts
The family that gets left off most diagrams, sometimes rightly. These symbols carry no control flow - a process runs identically with every one of them deleted - so they earn their place only when the reader's question is about information rather than order.
| Element | Notation | What it means |
|---|---|---|
| Data object | page with a folded top-right corner | Information an activity produces or needs. A small arrow in the corner marks it as a data input or output. |
| Data store | cylinder | Something that outlives the process instance - a database, a filing cabinet. The distinction from a data object is lifetime, not technology. |
| Text annotation | open bracket with text beside it | A note tied to any element by a dotted association. Where the rule a symbol cannot express gets written down, and the most underused mark in BPMN. |
| Group | dashed rounded rectangle | A visual bracket around related elements. Crosses pools freely because it means nothing to the execution - purely for the reader. |
07The subset worth memorising
BPMN 2.0 defines well over a hundred distinct marks, and no working modeller uses more than a fraction. The specification itself acknowledges this by defining a descriptive conformance class, and it is close to the list below.
- Task - rounded rectangle. Work happens here.
- Start and end events - thin circle, thick circle. Where tokens appear and are consumed.
- Exclusive gateway - rhombus with an X. One path out.
- Parallel gateway - rhombus with a plus. All paths out.
- Sequence flow - solid arrow. Order within a pool.
- Message flow - dashed arrow. Communication between pools.
- Pool and lane - who does the work.
Everything else is reached for when a specific question demands it. A diagram built from those seven is readable by anyone who has seen BPMN once, and that is worth considerably more than a diagram that is technically richer and gets skipped.
In one line each
- 01One rounded rectangle is every kind of work; the marker on it says which kind.
- 02Event border says when - thin start, double intermediate, thick end. Glyph says what.
- 03The marker in a rhombus says how many outgoing paths carry a token, and nothing else.
- 04Solid arrow inside a pool, dashed arrow between pools. Crossing a boundary with a solid one is invalid.
- 05A plus in a rhombus and a plus on a box edge are unrelated marks.
- 06An empty pool is a black box: a participant deliberately not modelled.
- 07Seven symbols cover almost every diagram worth drawing.
These symbols on real processes are in the worked BPMN examples, and the order to put them down in is in how to draw a BPMN diagram.
08Časté otázky
Koľko symbolov má BPMN?
BPMN 2.0 ich definuje výrazne vyše sto, ak sa každý spúšťač udalosti, značka činnosti a variant brány počítajú zvlášť. Číslo, na ktorom záleží, je oveľa menšie: zhruba tucet tvarov nesie drvivú väčšinu skutočných diagramov a kto pozná úlohu, tri okraje udalostí, výlučnú a paralelnú bránu, dva druhy tokov a bazén, prečíta takmer čokoľvek.
Aký je rozdiel medzi úlohou a podprocesom v BPMN?
Úloha je atomická - proces vnútri nej nič nemodeluje. Podproces obsahuje vlastný proces a kreslí sa ako ten istý zaoblený obdĺžnik s malým štvorčekom so znamienkom plus na spodnej hrane. Zbalený ten detail skrýva, rozbalený sa box zväčší a podriadený proces sa nakreslí dovnútra. Plus je jediný vizuálny rozdiel, a preto ho ľudia tak často prehliadnu.
Čo znamená znamienko plus vnútri tvaru BPMN?
Závisí to výhradne od tvaru, ktorý ho nesie, a je to najčastejší zdroj zmätku v celej notácii. Plus v kosoštvorci je paralelná brána, ktorá rozdelí jeden token na niekoľko. Plus v malom štvorčeku na spodnej hrane zaobleného obdĺžnika je značka podprocesu, ktorá hovorí, že činnosť má vnútri vlastný proces. Tie dve veci spolu nesúvisia.
Čo znamená lomka na sekvenčnom toku v BPMN?
Krátka šikmá lomka pri začiatku sekvenčného toku ho označuje ako predvolený tok. Je to cesta, ktorá sa zvolí, keď žiadna iná odchádzajúca podmienka na danej bráne či činnosti neplatí, a je to spôsob, akým notácia zaručuje, že token nikdy neuviazne. Malý prázdny kosoštvorec na začiatku je opačná značka: podmienený tok, ktorý sa použije len ak podmienka platí.
Ktoré symboly BPMN sa treba naučiť ako prvé?
Šesť, a unesú prvý skutočný diagram: zaoblený obdĺžnik pre úlohu, tenký krúžok pre počiatočnú udalosť, hrubý krúžok pre koncovú udalosť, kosoštvorec s X pre výlučnú bránu, plnú šípku pre sekvenčný tok a bazén pre účastníka. Pridajte paralelnú bránu a prerušovanú šípku toku správ a zvládnete väčšinu spoluprác.
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