Introduction To BPMN

Structure of the course • Introduction • Basic BPMN Introduction to BPMN  Just enough to get you started modelling • Core BPMN  Might be enough for up to 80% of your needs • Extended BPMN  Filling in the gaps! • Exercises  An opportunity to use what you have learned as you go along • Laboratory Work  An extended process modelling exercise © 2009 Clear View Training Limited 2

What is a business process? • There is no standard definition of a business process, so we define it as: A sequence of Introduction to BPMN activities performed by one or more business participants in order to deliver value to the business • This definition emphasizes the following points:  The process can be broken down into a sequence of simpler activities  These activities have to be performed by someone or something (a participant)  The ultimate goal is to deliver value to the business whether directly or indirectly © 2009 Clear View Training Limited 5

Types of business process • Management processes Management Introduction to BPMN  Govern the operation of a business • Operational processes  Constitute the core business activities and create the Operational primary value stream • Supporting processes Supporting  Support the core processes © 2009 Clear View Training Limited 6

Why model processes? “You can’t control what you don’t understand” Introduction to BPMN • Understand and control current processes  Measure time, cost, resources • Improve current processes  Streamline, identify missing steps, rationalize • Design new processes  Realize business requirements with new processes • Communicate existing and new processes  Process models are a very effective way to communicate existing and new processes • Automate processes  Apply a process execution engine © 2009 Clear View Training Limited 7

What is BPMN? • Business Process Modelling Notation  Human oriented industry standard graphical notation Introduction to BPMN for modelling business processes  Based on flow charts (these are already widely used)  Has a mapping to BPEL4WS • Scope:  Organizational structures and resources  Functional breakdowns  Data and information models  Strategy  Business Rules © 2009 Clear View Training Limited 8

BPMN structure • BPMN has a relatively simple high-level structure BUT complexity arises because BPMN has: Introduction to BPMN  2 types of Activity (but with many variants)  10 types of Event (with throw & catch semantics)  5 types of Gateway  3 Connecting Objects  3 Artifacts © 2009 Clear View Training Limited 10

Managing BPMN complexity • Divide and conquer! • We define 3 levels of BPMN Introduction to BPMN  Basic - just enough to create some simple models  Core - enough for about 80% of your modelling needs  Extended - features that are rarely needed Extended Core and Extended are Core defined in the BPMN specification Core Basic We have added Basic to make it easier to learn BPMN © 2009 Clear View Training Limited 11

Summary • BPMN – Business Process Modeling Extended Notation Introduction to BPMN Core • Model processes so that you can understand and improve existing Core Basic processes, and create new processes • We can categorize processes into Management, Operational and Support © 2009 Clear View Training Limited 12

Exercise – your processes • Consider the business in which you are currently working... Introduction to BPMN  List the key business processes  Categorize these processes as Management, Operational or Support  Which of these processes do you think could be improved? Suggest some possible improvements © 2009 Clear View Training Limited 13

Contents • What is Basic BPMN? Introduction to BPMN • Some Basic BPMN Elements:  Swimlanes  Flow Objects  Connecting Objects • The Business Process Diagram (BPD) • BPD semantics – the Token Game © 2009 Clear View Training Limited 15

What is Basic BPMN? • It is the simplest possible subset of BPMN that we consider to be useable Introduction to BPMN • The goal of Basic BPMN is to be:  Just enough BPMN to get you creating very simple diagrams!  Easy to learn  Easy for non-technical stakeholders to understand  Good enough for rough sketches and informal diagrams © 2009 Clear View Training Limited 16

Basic BPMN structure • Basic BPMN comprises the simplest useable subset of elements: Introduction to BPMN  Swimlanes - Pools and Lanes  All types of connecting object  1 type of Activity – the Task  2 types of Event – None Start and End Events  2 types of Gateway – Exclusive and Parallel Gateway  1 Artifact – the Annotation © 2009 Clear View Training Limited 17

BPMN Elements • BPMN elements may have attributes. These are slots that store information Task attributes Introduction to BPMN about the element • Attributes store the semantic \"meat\" of the model • BPMN tools allow you to inspect and change attributes a Task © 2009 Clear View Training Limited 18

The Business Process Diagram • A Business Process Diagram (BPD) is a type of flowchart written in BPMN that comprises Flow Introduction to BPMN Objects connected by Connecting Objects • To understand a BPD, imagine tokens flowing around the diagram via the Connecting Objects and being affected by the Flow Objects  This is often known as the token game - we'll say a lot more about this shortly! Flow Object Connecting Object © 2009 Clear View Training Limited 19

Swimlanes • Organize the BPD into:  Pools – represent a participant in the process Introduction to BPMN  Lanes – group related Activities • If a BPD has a single Pool and no Lanes, then the Pool boundary rectangle may be omitted This Lane is where we would Pool representing draw the Catalog Management the Librarian part of the process participants This Lane is where we would draw the Loan Management part of the process © 2009 Clear View Training Limited 20

Participants • Use Pools in conjunction with Message Flows to show communication between two or more business Introduction to BPMN participants: Pool representing the Sales Department Message Flow Pool representing the Warehouse © 2009 Clear View Training Limited 21

Flow Objects • A process is defined as a sequence of Flow Objects: Introduction to BPMN  Events – something that happens during the process  Activities – work performed in the process  Gateways – split/merge flow through the process • There are many types of Flow Object! Exclusive Start Gateway Event End Task Event (a type of Activity) © 2009 Clear View Training Limited 22

Connecting Objects • Connect Flow Objects together:  Sequence Flows – determine the sequence of Activities Introduction to BPMN  Message Flows – messages between process participants  Associations – associate text or data with modelling elements Sequence Flow Association Message Annotation Flow © 2009 Clear View Training Limited 23

BPD semantics - token game • Token game – a token is an imaginary focus of control that you imagine flowing around the BPD Introduction to BPMN • Tokens traverse from a source Flow Object to a target Flow Object via a Sequence Flow • A Flow Object executes when it has tokens on one or more of its input flows  When a Flow Object starts to execute it takes tokens off its input flows  When a Flow Object has finished executing it offers tokens on one or more of its output flows Start Event End Event © 2009 Clear View Training Limited 24

Process instances • Each time a process receives a new Start Event, a new instance of that process begins executing Introduction to BPMN • We say that a process may have many process instances instance 3 instance 2 instance 1 © 2009 Clear View Training Limited 25

Simple definitions... • Event – something of note that happens to the business Introduction to BPMN • Activity – a piece of work performed in a business process • Gateway – controls the flow through the business process • Artifact – an Annotation, Group or Object © 2009 Clear View Training Limited 29

What is an Event? • All businesses are subject to notable occurrences that we call Events: Introduction to BPMN  An Event is something of note that happens to the business  Events may optionally have Triggers that cause the Event to happen, and Results that are the result of the Event. These are indicated by a symbol inside the Event icon (see later) • There are three categories of Event: Start events - begin the process Intermediate events - happen during the process (see later) End events - terminate all or part of the process © 2009 Clear View Training Limited 30

Basic Events Introduction to BPMN None Start Event None End Event • The None Start Event begins the business process in an undefined way by emitting a token  It is called the None Start Event, because the Trigger for the Event is unspecified • The None End Event terminates the business process by consuming the token  It is called the None End Event because the Result of the process is unspecified • There are 6 types of Start Event and 8 types of End Event that we will look at later © 2009 Clear View Training Limited 31

More than one start event • Sometimes a process is different depending on how it is started Introduction to BPMN • This example shows a simple order process that may be started by an Email, Phone Call or Letter requesting items Trigger (see later) © 2009 Clear View Training Limited 32

What is an Activity? • Activity - a piece of work performed in a business process Introduction to BPMN • There are two types of Activity:  Task - this is an Activity that is considered atomic within this business process  Sub-Process - an Activity that can be decomposed hierarchically into other activities Task collapsed Sub-Process (an atomic Activity) (a compound Activity) © 2009 Clear View Training Limited 33

Expanded Sub-Process • Sub-Processes may be expanded (usually by double clicking on the + icon) to show the Tasks Introduction to BPMN and Sub-Processes contained within them  A Sub Process may only begin with a None Start Event and end with a None End Event expanded Sub-Process © 2009 Clear View Training Limited 34

Activity semantics • An Activity may have zero or more input flows and zero or more output flows Introduction to BPMN  It executes when gets a token on any input flow  After completion it offers tokens simultaneously on all of it's output flows race condition Pick And Pack Order executes when it gets a token on any of its input flows © 2009 Clear View Training Limited 35

What is a Gateway? • Gateways split and merge the flow through a business process Introduction to BPMN • You control the flow through the business process by choosing the appropriate Gateways • There are 5 types of Gateway. Each type has specific splitting and merging behaviour controlled by:  Conditions on the incoming and outgoing flows  Events on the outgoing flows  A single condition on the Gateway itself • Basic BPMN has two Gateways - the Exclusive Gateway and the Parallel Gateway © 2009 Clear View Training Limited 36

Basic Gateways • Gateway semantics depend on events and conditions on incoming and outgoing flows Introduction to BPMN • Exclusive Gateway – allows you to express decisions • Parallel Gateway – allows you to express parallelism Type Input - merging Output - splitting Exclusive Passes on each Single token to outgoing flow incoming token whose condition is true Parallel Waits for token on all Token to all outgoing flows incoming flows © 2009 Clear View Training Limited 37

Exclusive Gateway • The Exclusive Gateway has one or more input flows, and two or more output flows. When it accepts a token on Introduction to BPMN one of it's input flows it emits a single token on a single output flow:  Each output flow has a condition and the set of conditions must be mutually exclusive  A token is emitted on the output flow whose condition is true condition default - if none of the other conditions are met © 2009 Clear View Training Limited 38

Parallel Gateway • The Parallel Gateway has one or more input flows, and two or more output flows Introduction to BPMN • It waits for a token on all of it's input flows (join), then emits a token on all of it's output flows (fork) fork flow join flows see later see next slide © 2009 Clear View Training Limited 39

Artifacts • BPMN provides three Artifacts that allow Introduction to BPMN you to add extra information to models: Text Annotation - text added to a diagram to increase its comprehensibility. Use liberally! Group - a way to group together parts of the process Data Object - a way to show data and documents that are manipulated by the process © 2009 Clear View Training Limited 40

Exercise - assumptions • Using Basic BPMN model the following processes: Introduction to BPMN  Making a cup of tea  Reading your email  Applying for a training course • Before you can model any of these processes, you will first need to make some assumptions about the context in which the process runs  For each process, list all of the assumptions you are making © 2009 Clear View Training Limited 43

What is Core BPMN? • Includes all of Basic BPMN plus:  More Start Events, Intermediate Events and Introduction to BPMN Gateways  Activities – Task and Sub-Processes types  Artifacts – Data Objects and Groups • Core BPMN is the essential set of BPMN modelling elements for Business Analysts!  Basic BPMN is only good for sketches  Extended BPMN is used less frequently © 2009 Clear View Training Limited 45

Contents • We know from Basic BPMN that Activities may be Tasks or Sub-Processes Introduction to BPMN  Tasks are atomic with the context of a particular process model  Sub-Processes may be decomposed hierarchically into nested Sub-Processes and Tasks • In this section we look at TaskTypes and SubProcessTypes  These allow you to be more specific about the semantics of the Activities in your process models © 2009 Clear View Training Limited 48

TaskType • Each Task may have an TaskType attribute that determines its detailed semantics: Introduction to BPMN TaskType Semantics None The default Task Type Send Sends a Message to an external participant on completion Receive Waits for a Message from an external participant Manual A Task performed entirely manually User A Task performed by a human with the assistance of automation Service A service such as a web service or automated application Script A script executed by a business process engine Reference A reference to a pre-existing Activity © 2009 Clear View Training Limited 49

User and Service TaskTypes • The User and Service TaskTypes involve Participants outside of the current process: Introduction to BPMN  User – a user external to the process  Service – a system external to the process • Because of this, Tasks of these types must be started by receiving a Message  When they end they will often send a Message back to the process that started them © 2009 Clear View Training Limited 50

SubProcessType • Each Sub-Process may have an SubProcessType attribute that determines its detailed semantics: Introduction to BPMN SubProcessType Semantics Embedded The Sub-Process is embedded in the parent process. It is activated by it, and can access all of it's global data. May be AdHoc (see next slide) Reusable The Sub-Process is in a different BPD. It has no access to, nor dependency on, it's parent Reference A reference to an existing Sub-Process. All inputs, outputs and data must match. A cross between Reusable and Embedded. In a different BPD, BUT has dependencies on it's parent © 2009 Clear View Training Limited 51

AdHoc Embedded SubProcess • If and only if the SubProcess is AdHoc it has the following attributes: Introduction to BPMN  AdHocOrdering - determines if it's Activities can be performed in Parallel (the default) or must be Sequential. Often determined by resource constraints  AdHocCompletionCondition - an expression that tells you when the AdHoc SubProcess will end © 2009 Clear View Training Limited 52

SubProcessType syntax • The tilde is tilde BPMN standard Introduction to BPMN notation for AdHoc • The adornments in the top right- hand corners are tool specific (BizAgi) © 2009 Clear View Training Limited 53

Summary • Activities may be Tasks (atomic) or Sub- Processes (non-atomic) Introduction to BPMN • Task and SubProcess types allow you to model Activity semantics more precisely • TaskTypes:  None, Send, Receive, Manual, User, Service, Script, Reference • SubProcessTypes:  Embedded (may be AdHoc), Reusable, Reference © 2009 Clear View Training Limited 54

Event Triggers • Events may have a Trigger that specifies what causes the Event Introduction to BPMN • The Trigger is shown as an icon inside the Event symbol  There are many different types of Trigger! • Events may: Trigger  Catch a Trigger See next slide  Throw a Trigger © 2009 Clear View Training Limited 57

Catching and Throwing • There are two Event behaviours:  Catching - the Event waits for it's trigger and then Introduction to BPMN emits a token. The Trigger is outline  Throwing - the Event waits for a token then emits a trigger. The Trigger is filled in • Start Events can only catch and End Events can only throw. Intermediate Events (see later) can both catch and throw Message Message Message Start Event - Message End Event - waits for receipt of a Message waits for receipt of a token (see later) then emits a token then emits a Message © 2009 Clear View Training Limited 58

Start Event semantics • A Start Event begins a new instance of a business process Introduction to BPMN  It has a single outgoing Sequence Flow and no incoming flows • When triggered, it emits a token on it’s single outgoing flow  The Trigger is the cause of a Start Event e.g. a timer going off, a message or signal being received or None e.g. a Message Start Event emits a Token on receipt of a specific Message (see later) © 2009 Clear View Training Limited 59

Core Start Events • There are 3 Core Start Events each with a Introduction to BPMN different Trigger Emits a token when the time Timer Start Event condition becomes true Emits a token when a specified Message Start Event Message is received Emits a token when a specified Signal Start Event Signal is received Start Events can only catch! © 2009 Clear View Training Limited 60

Timer Start Event • Timer Start Events are triggered when a time condition becomes true e.g. Introduction to BPMN  \"At End Of Week\" - a specific point in time  \"After 2 Weeks\" - after a duration in time  \"Every Tuesday\" - a repeating condition • Note: using a specific time or date (e.g. 1st Feb. 2009) may inhibit the reusability of the process • It is crucial to be very clear and precise when stating time conditions! © 2009 Clear View Training Limited 61

Messages and Signals • Messages and Signals are packets of data stored as Properties (see notes) Introduction to BPMN Messages are sent 1 to 1 and include Message references to the sender and receiver Signals are broadcast 1 to many and neither the sender nor the receiver Signal are specified © 2009 Clear View Training Limited 62

Message Start Event • Message Start Events are triggered by receipt of a message from a business participant external Introduction to BPMN to the current process  A message is simply a direct communication between exactly two business participants - we'll see how to send messages later © 2009 Clear View Training Limited 63

Signal start event • Signal start events are triggered by receipt of a signal from a business participant or process Introduction to BPMN external to the current process  A signal is broadcast from an external business participant or process to many others © 2009 Clear View Training Limited 64

End Event semantics • End Events may:  End a particular path through a business process Introduction to BPMN  End the whole process (Terminate End Event)  Generate a Result (e.g. a Message or Signal being sent) • They have incoming flows and no outgoing flows because they consume their input tokens e.g. a Message End Event Result - sends a Message © 2009 Clear View Training Limited 65

Core End Events • There are 3 Core End Events each with a different Trigger: Introduction to BPMN Terminate thread and Message End Event send a Message Terminate thread and Signal End Event send a Signal Terminate all threads in Terminate End Event the process End Events can only throw! © 2009 Clear View Training Limited 66

Message End Event • When this Event receives a Token it emits a Message that is sent to a particular participant or Introduction to BPMN process  Can only send the Message to a different participant or process - targets within the same Pool are not allowed (use Signals for that!) See next slide © 2009 Clear View Training Limited 67

Signal End Event • When this Event receives a Token it broadcasts a Signal to every process set up to receive it Introduction to BPMN  Unlike a Message, a Signals attributes specify neither it's Source nor it's Target Sends the Newsletter Any process that is waiting for a Newsletter can receive this Signal © 2009 Clear View Training Limited 69

Terminate End Event • When this Event receives a Token all Activities in the process stop! Introduction to BPMN  A common use for a Terminate End Event is to stop a process after an interrupt or non-recoverable error wait for Intermediate terminate all threads Events (see later) © 2009 Clear View Training Limited 70

Summary • Events may have Triggers that they may catch or throw Introduction to BPMN • Core Start Events:  Timer – when time condition becomes true  Message – on receipt of a Message  Signal – on receipt of a Signal • Core End Events:  Message – throws a Message  Signal – throws a Signal  Terminate – terminates the process © 2009 Clear View Training Limited 71

Contents • What is an Intermediate Event? Introduction to BPMN • Intermediate Event semantics • Intermediate Events as Interrupts • Core Intermediate Events  None  Timer  Message & Signal © 2009 Clear View Training Limited 73

What is an Intermediate Event • Intermediate Events occur during a business process Introduction to BPMN • They do not spawn a new process instance! • Intermediate Events may catch or throw:  Catch - waits for the Event Trigger then emits a token  Throw - throws the Event Trigger then emits a token catch throw © 2009 Clear View Training Limited 74

Intermediate Event Semantics • Catch: Introduction to BPMN  If there is an input flow: • Wait for a token  Wait for the Event Trigger  Emit a token on the single output flow • Throw:  Wait for a token on the single input flow  Emit the Event Trigger  If there is an output flow: • Emit a token on the single output flow © 2009 Clear View Training Limited 75

Intermediate Events as interrupts • Intermediate Events are often placed on Activity boundaries to act as interrupts Introduction to BPMN • If the Event Trigger occurs before the Activity is completed, the Activity is interrupted, and the Intermediate Event emits a token If the Intermediate Event is Triggered before Task 1 finishes, perform Task 3, else Intermediate perform Task 2 Event on Task Boundary © 2009 Clear View Training Limited 78

Core Intermediate Events Introduction to BPMN Intermediate Name Semantics Throw Catch Interrupt None No Trigger - fires immediately Fire when time condition Timer Yes becomes true Message Yes Send/wait for a Message Signal Yes Send/wait for a Signal © 2009 Clear View Training Limited 79

None Intermediate Event • This doesn’t really do anything – it has no Trigger, so it fires immediately on receiving a Introduction to BPMN token • Use it as documentation to indicate that the process has reached an important intermediate state or milestone © 2009 Clear View Training Limited 80

Timer Intermediate Event • Triggers when a time condition becomes true • They can be used in two ways: Introduction to BPMN  Time-out – when placed on an Activity boundary, they act as a time-out because the Activity is interrupted when the time condition becomes true  Delay – when they are placed inline in a Sequence Flow, they cause the flow to pause until the time condition becomes true See example on next slide... © 2009 Clear View Training Limited 81

Summary • Intermediate Events occur during a business process Introduction to BPMN  They may catch or throw  They do not spawn a new process instance Intermediate Name Semantics Throw Catch Interrupt None No Trigger - fires immediately Fire when time condition Timer Yes becomes true Message Yes Send/wait for a Message Signal Yes Send/wait for a Signal © 2009 Clear View Training Limited 84

Event-Based Exclusive Gateway • This is a type of Exclusive Gateway where, instead of conditions on its two or more outgoing Introduction to BPMN flows, it has Intermediate Events (see later) • When it accepts a token on one of it's input flows it emits a token on each of its output flows:  Each of these tokens is received by an Intermediate Event which waits for its trigger  Whichever of these Events is triggered first \"wins\", and the token passes through that Event - all the other waiting tokens are consumed © 2009 Clear View Training Limited 87

Event Gateway example • This example shows a simple log on process that illustrates the Event-Based Exclusive Gateway Introduction to BPMN (Event Gateway for short) Intermediate Event-Based Events Exclusive Gateway © 2009 Clear View Training Limited 88

Core Artifacts • The two Core Artifacts are:  Groups - a way to organize and highlight Introduction to BPMN parts of the model  Data Objects - indicate data (often documents) flowing through the process Group Data Object © 2009 Clear View Training Limited 89

Groups • Groups are simply a way to organize and highlight parts of the model in order to increase its comprehensibility Introduction to BPMN  They have no semantics beyond a simple organizing role • In the example below, the Groups indicate phases in the process © 2009 Clear View Training Limited 90

Data Objects • Data Objects indicate data (often documents) flowing through the process, and possibly being transformed by it Introduction to BPMN • They may have a state state © 2009 Clear View Training Limited 91

Data Object semantics • Data Objects may have a state – \"A condition or situation during the life of an Introduction to BPMN object during which it satisfies some condition, performs some activity or waits for some event“  In UML the states an object may go through are modelled by creating State Machine  The example on the previous slide shows the states the Product Specification document goes through • Data Objects have no effect on the flow!  They are connected to other elements by Associations not by Sequence Flows © 2009 Clear View Training Limited 92

Summary • The Event-Based Exclusive Gateway offers a token on the first outgoing flow to Introduction to BPMN receive an Event • Groups allow you to organize your model by grouping related Activities together • Data Objects allow you to show how information flows around the business process  Use States to show how Data Objects are transformed by the Activities © 2009 Clear View Training Limited 93

Contents • Activity behaviour Introduction to BPMN  Internal looping, Repetition • Extended Events  Conditional Events  Link Events  Multiple Events  Error Events - error handling  Compensation Events - compensation  Cancel Events - Transactions © 2009 Clear View Training Limited 96

Activity internal looping • You can specify that an Activity loops internally - there are two types of internal loop: Introduction to BPMN  While loop - the loop condition is checked at the beginning of the Activity. The activity executes if the loop condition is true then repeats while the loop condition is true  Until loop - the loop condition is checked at the end of the Activity. The Activity always executes once then repeats if and only if the loop condition is true • It's good style to show the loop condition as an annotation on the diagram! loop indicator © 2009 Clear View Training Limited 97

Multi Instance Activities - repetition • In repetition, a new Activity instance is created each time Introduction to BPMN  Compare this to a loop where the same Activity instance executes over and over again • These new Activity instances may execute in sequence or in parallel In this example, we have not specified whether the execution is in sequence or in parallel because this is an Multi Instance implementation issue that Activity indicator doesn't impact this business process! © 2009 Clear View Training Limited 98

Extended Events • There are many different types of Extended Event: Introduction to BPMN  Conditional Events  Link Events  Multiple Events  Error Events - error handling  Compensation Events - compensation  Cancel Events – Transactions • These are summarized on the next slide... © 2009 Clear View Training Limited 99

Extended Events Summary Intermediate Name Start End Throw Catch Interrupt Introduction to BPMN Conditional Yes Link Multiple Yes Error Yes Transactions Compensation Yes Cancel Yes © 2009 Clear View Training Limited 100

Conditional Events • A Conditional Event is triggered when a Boolean condition becomes true e.g. Introduction to BPMN  \"Overdue\" - a Boolean value  \"Overdue & !First Offence\" - a Boolean expression  \"Balance < 0.0\" - a Boolean relation • It is edge triggered, on the false->true transition so it always catches • There are Conditional Start and Intermediate Events true false © 2009 Clear View Training Limited 101

Link Intermediate Events • Link Events allow the connection of two or more parts of the same process at the same level - they can’t cross process boundaries e.g. Introduction to BPMN Process to Sub-Process • Multiple source Link Events (throw) can link to a single target Link Event (catch) • Use them to break long Sequence Flow lines and connect parts of a Process across different pages of a print-out © 2009 Clear View Training Limited 102

Multiple Events • Multiple Events have two or more Triggers • It's essential to describe the Triggers in an annotation! Introduction to BPMN Name Icon Triggers Semantics Message, Timer, Catch: wait for any of Start Conditional, Signal the Triggers then emit Message, Timer, Error, a token Cancel, Compensation, Intermediate Conditional, Link, and Throw: wait for a Signal token then throw all of Message, Error, Cancel, the Triggers End Compensation, Signal, T erminate © 2009 Clear View Training Limited 103

Example: Multiple Start Event • The Multiple Start Event has two or more triggers any of which may trigger the Event Introduction to BPMN  Triggers may be Timer, Conditional, Message or Signal  The set of Triggers is listed in the Multiple Start Event attributes • The triggered process is the same for all Triggers Without this Annotation the model would be unreadable! © 2009 Clear View Training Limited 104

Error Handling • Error End and Intermediate Events work in pairs to provide a simple error handling mechanism: Introduction to BPMN  Use an Error End Event to end an Activity and raise a named error  Catch the error with an Error Intermediate Event attached as an interrupt to the Activity boundary  This Error Intermediate Event emits a token to another Activity that handles the error Example on the next slide © 2009 Clear View Training Limited 105

Compensation • Sometimes you need to undo the effects of a business process. You do this by Introduction to BPMN rolling it backwards, one completed Activity at a time • There are three options for undoing each completed Activity: 1. Do nothing - there are no data changes to undo 2. Overwrite - restore all data to its original state 3. Undo - perform a specific Activity to undo the data changes - this is known as compensation © 2009 Clear View Training Limited 107

A compensated Activity • If the goods are Out Of Stock, the Accept Payment Activity must be compensated so that the customer gets their refund! Introduction to BPMN • If the Compensation Event specifies a compensatable Activity only that Activity is compensated. Otherwise, all compensatable Activities in the process are compensated Association Compensation Intermediate Event (catch) Compensation Compensation End Activity Event (throw) © 2009 Clear View Training Limited 108

Transactions • Transactions are Sub-Processes that have ACID properties: Introduction to BPMN  Atomic - the Transaction Activities are treated as a discrete unit of work. All the Activities in the Transaction are performed or none of them are  Consistent - the Transaction always leaves the system in a consistent state  Isolated - data in intermediate states are hidden from all other Activities  Durable - on success, the changes are persistent © 2009 Clear View Training Limited 109

Transactions in BPMN Success BPMN defines Introduction to BPMN three possible Cancel outcomes for Transactions Hazard • Success - everything works as planned. Exits via a Sequence Flow when all paths have succeeded • Cancel - the Transaction is cancelled. Exits via a Cancel End Event. All Transaction Activities are rolled back and compensated if possible • Hazard - something has gone wrong! Exits on an Error End Event on any path. No roll-back possible! © 2009 Clear View Training Limited 110

Summary • We have looked at Activity internal looping and repetition Introduction to BPMN • Introduced the Extended Events:  Conditional, Link, Multiple, Error, Compensation, Cancel • Considered:  Error handling  Compensation  Transactions © 2009 Clear View Training Limited 112

Extended Gateways • There are only 2 Extended Gateways: Introduction to BPMN Type Input - merging Output - splitting Inclusive Waits for token on one to all Token to one to all outgoing incoming flows depending flows depending on flow on flow conditions conditions Complex Waits for token on one to all Token to one to all outgoing incoming flows depending flows depending on Gateway on Gateway condition condition © 2009 Clear View Training Limited 114

Inclusive Gateway • The Inclusive Gateway has a complex splitting and merging behaviour Introduction to BPMN  Because of this, Inclusive Gateways are generally only used in pairs with each split being closely followed by a corresponding merge • Splitting - each output flow has a condition and a token is emitted on all the output flows whose conditions are true  This is a logical inclusive OR • Merging - all the tokens generated by a corresponding upstream Inclusive Gateway split are synchronized and merged © 2009 Clear View Training Limited 115

Inclusive Gateway Example • This example is from a photo player system:  You Choose Media (music, slideshow or both) Introduction to BPMN  Depending on what you have chosen, the system Play(s) Music, Play(s) Slideshow or both  When all media has finished playing, the process ends © 2009 Clear View Training Limited 116

Complex Gateway • These have no default semantics!  Splitting - modeller provides an Introduction to BPMN IncomingCondition  Merging - modeller provides an OutgoingCondition • They must be supported by Text Annotations that describe their semantics, otherwise the BPD is unreadable! • They are often used to combine many Gateways into a single Gateway © 2009 Clear View Training Limited 117

Complex Gateway example • Notice the IncomingCondition on the Complex Gateway split and OutgoingCondition on the Introduction to BPMN Complex Gateway merge Can you simplify this? © 2009 Clear View Training Limited 118

Summary • The two Extended Gateways have quite complex semantics so always look for Introduction to BPMN simpler solutions if possible! Type Input - merging Output - splitting Inclusive Waits for token on one to all Token to one to all outgoing incoming flows depending flows depending on flow on flow conditions conditions Complex Waits for token on one to all Token to one to all outgoing incoming flows depending flows depending on Gateway on Gateway condition condition © 2009 Clear View Training Limited 119

Next steps... • Contact Clear View Training (www.clearviewtraining.com) for BPMN and UML Introduction to BPMN consultancy and training • Check out our books: Secrets of Introduction Analysis to BPMN (4Q 2009) (2Q 2010) © 2009 Clear View Training Limited 122

Orne Library Automated System (OLAS) • The Laboratory Work will be interleaved with the course material at the discretion of Introduction to BPMN the lecturer • Read the “Orne Library Automated System (OLAS)” document • Model the As-Is Orne Library processes • Model the To-Be OLAS processes © 2009 Clear View Training Limited 125

Introduction To BPMN

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