BPMN 2.0 Analysts Razvan

Parallel Event-Based Gateway⌘

• All events must occur before a process can start

Complex Gateway⌘

• The Complex Gateway can be used to model complex synchronization behavior
• For example, it could specify that tokens on three out of five incoming Sequence Flows are needed to activate the Gateway.

Link Events⌘

• A Link is a mechanism for connecting two sections of a Process.
• Link Events can be used to avoid long Sequence Flow lines.
• The use of Link Events is limited to a single Process level (i.e., they cannot link a parent Process with a Sub-Process or one pool to another pool).

Error Events⌘

• An Error is generated when there is a critical problem in the processing of an Activity or when the execution of an Operation failed
• An Error indicates that a named Error should be generated.
• 3 types of error events:
  • Start Event Sub-Process Interrupting
  • Intermediate Boundary Interrupting
  • End
• Process can't wait for an error or rise an error in itermediate event (only in Boundary Intermediate)
• Process can't be instantiated using error event (only in Event Sub-Process)

Error Events Example 1⌘

Error Events Example 2⌘

Error Events Example 3⌘

Escalation Events⌘

• An Escalation identifies a business situation that a Process might need to react to.
• In contrast to an Error, an Escalation by default is assumed to not abort the Activity to which the boundary Event is attached.

Escalation Example⌘

Escalation Example 2⌘

Compensation⌘

• Compensation is undoing steps that were already successfully completed, because their results and possibly side effects are no longer desired and need to be reversed.
• If an Activity is still active, it cannot be compensated, but rather needs to be canceled.
• Compensation is not an error handling

Compensation Example⌘

Transaction⌘

• Is a specialized type of Sub-Process that will have a special behavior that is controlled through a transaction protocol.
• Transaction verifies if all of the participants have successfully completed their end of the transaction or have been restored to the equivalent of their original state.
• ACID model describes transactions:
  • Atomic - transaction is "all or nothing": if one part of the transaction fails, the entire transaction fails, and the system state is left unchanged.
  • Consistent - any transaction will bring the system from one valid state to another.
  • Isolatated - concurrent execution of transactions results in a system state that would be obtained if transactions were executed serially, i.e. one after the other.
  • Durable - once a transaction has been committed, it will remain so, even in the event of power loss, crashes, or errors.

Transaction in BPMN⌘

Three basic outcomes of a Transaction:

• Succes
• Cancel
• Error

Cancel Events⌘

• Cancel Events are only used in the context of modeling Transaction Sub-Processes
• Activities indicated by sequence flow from error event will be executed after transaction is rolled back

Loops and multi-instance⌘

Standard Loop ⌘

• The Activity will loop as long as the boolean loopCondition is true
• The condition is evaluated for every loop iteration, and MAY be evaluated at the beginning or at the end of the iteration (testBefore = true lub testBefore = false)
• In addition, a numeric cap can be optionally specified - loopMaximum
• Loop activity instances are sequentially executed - one after another.
• Loop Activity is similar to DO WHILE loop.

Multi-Instance Activity⌘

Multi-Instance parallel

Multi-Instance sequential

• The instances MAY execute in parallel or MAY be sequential.
• Multi-Instance Activities are used with collection of items
• Multi-Instance Activity is similar to FOR EACH loop

Multi-Instance Activity Example⌘

Loop Exercises ⌘

Process, Collaboration, Choreography and Conversation in BPMN 2.0⌘

Process - again⌘

A Process describes a sequence or flow of Activities
in an organization with the objective of carrying out work.

• Process is depicted as a graph of Flow Elements, which are a set of Activities, Events, Gateways, and Sequence Flows that define finite execution semantics.
• BPMN uses the term Process specifically to mean a set of flow elements
• It uses the terms Collaboration and Choreography when modeling the interaction between Processes

Types of BPMN Processes ⌘

• There are three basic types of BPMN Processes:
  1. Private Non-executable (internal) Business Processes
  2. Private Executable (internal) Business Processes
  3. Public Processes

Collaboration⌘

• Collaboration is a collection of Participants shown as Pools, their interactions as shown by Message Flows, and MAY include Processes within the Pools and/or Choreographies between the Pools
• A Choreography is an extended type of Collaboration

Collaboration Example⌘

Choreography⌘

• Choreography looks like Private Business Process
• Choreography formalizes the way business Participants coordinate their interactions.
• The focus is not on orchestrations of the work performed within these Participants, but rather on the exchange of information (Messages) between these Participants.

Choreography Example 1⌘

Choreography Example 2 from spec⌘

Business Process Model and Notation (BPMN), Version 2.0, pages 318-319

Conversations⌘

• The Conversation diagram is particular usage of a Collaboration diagram (simplified version of Collaboration)
• Pools usually are empty.
• A Conversation is a logical grouping of Message exchanges

Conversation Example⌘

Annex

Business Process Model and Notation, v2.0, page 261