Business Process Modelling

Tokens

once a process instance has been spawned (started), we use the notion of token to identify the progress (or state) of that instance. At which stage this case currently is.

Business Process modeling languages

1. Petri net - traditional, used in research, not user friendly

2. UML activity diagram - popular for programming

3. Event-driven Process Chains (EPC)

4. Business-Process Model and Notation (BPMN) - used in this lass, imperaive process modelin languages

5. DECLARE - declarative language. Defines rules/constraints between activities instead of a fixed sequence.

6. CMMN - case management model and notation: standardized used for one time disaster. States resources and roles, and suggest the path to follow (but not strict depends on circumstances).

Imperative vs Declarative languages

Imperative (BPMN) = HOW to do things. tells exact steps

Declarative = WHAT is allowed/not allowed, sets the rules,not fix the order

WHY BPMN

1. Standard & widely used

• International standard (OMG)

• Used by many companies/tools  (multi-vendor support)

 

2. Easy to understand

• Business-friendly

• Three basic shapes + specialisations within shapes (simple visually)

 

3. Clear process structure

• Shows full process from start to end

• Can hide/show details (sub-processes)

 

4. Good for communication

• Distinguishes:

  • Sequence flow (steps inside process)

  • Message flow (communication between parties)

 

5. Handles complexity

• Can model:

  • Multiple interacting processes (choreography)

  • Events (triggers, exceptions)

Process diagrams

1. Private (internal processes)

• non-executable (only for understanding, high-level)

• executable - can be run by a sytem (automated)

2. Public (shows interactions with external participants without internal process details)

• Interacion between a private business process and another process or participant

• Activities of the private process model are not shown

BPMN diagram types

1. Process Diagrams

2. Collaboration Diagrams

3. Choreography Diagrams

4. Converstion Diagrams

Collaboration diagram

Depicts the interaction between two or more entities:

• Featuers usually - includes internal activities, in contrast to choreography diagram, like two or more pools and message flows

Choreography Diagram

Procedural contract between participants

Contains:

• Interactions between participants instead of activities

• Interections represent set of Message exchanges

Conversation Diagram

• Particular usage of and informal descriptio of a Collaboration diagram

• Pools do not contain process

• Shows conversations between pools

Process decomposition

Process may be too large to be understood at once

Readability can be improved by using sub-processes that hide certain parts of the process

Sub-process - mini-process inside the proces: self-contained, composite activity

Collapsed or Expended view

Value of sub-processes:

• allows to visualise end-to-end process on the single page

• enable top-down modeling (hierarchy)

• clarify governnce boundaries (who responsible for what)

• scope event anding by adding events to a sub-process

Call-activity

In case a sub-process is used in more than one proces

Define sub-process as a global process model (the content of sub-process can be defined)

Call sub-process from each process that uses it by means of he Call Activity (thick border)

Rework and repetition

For that we use XOR-split with two branches one allowing to continue the rest of the process, and the second goes back

Alternative way is to use subprocesses

Rework and repetition with sub-processes

Loop activity or cycle

A loop activity is just a shorthand for a cycle — but you can only use that shorthand when the cycle is clean enough (1 entry, 1 exit). If not, you're stuck with drawing the full cycle manual (here two exit points - so cycle)

If it is a cycle not a loop - hard to demonstrate it as a subprocess

Multi-instance activity

An activity executed multiple times for a collection of items (e.g., one execution per supplier or customer), often in parallel. The BPMN symbol is three vertical lines at the bottom of the activity.

Ad-hoc sub-process

You do not know the order of the activities (start point or end point). The process continues until the goal is achieved (the order is paid in this case)

!!! All other sub-processes must have start and end events

BPMN events

Timer - if the event starts periodically

Signal - can be caught by multiple processes (message only by one)

Error Event - something goes wrong and an exception path is triggered; the process may continue.

Terminate event - something goes wrong and an exception path is triggered; the process may continue.

Intermediate events - happens during the process

Boundary events - events put on the side of the activity - during the implementation of a certain activity you get a cancellation request or any other thing that interruprs your process

Boundary interrupting - stops the whole process

Boundary non-interrupting - additional process is running in parallel

Sending and receiving message events

Racing events: Event-based decision events

XOR split gateway - you decide based on the case

• a branch is chosen based on conditions that evaluate over available data

• the choice can be made immediately after the token arrives from the incoming flow

Event-driven XOR split - it happens from outside (approval or disapproval from client), or timer

• Sometimes the choice must be delayed until and event happens

• The choice is based on a race among events

Exception handling

• Exception handling - stopping a sub-procss and performing a special activity

• Types of exceptions for an activity (task/sub-process):

All these are cathing and interrupting intermediate events. They stop the enclosing activity and start an exception handling routine.

Conditional events

To capture business rules:

A conditional event keeps checking over and over until the rule becomes true