Business process elements

A business process diagram is a graphical representation of a business process flow, which consists of a sequence of activity elements and flow controls elements. Rational® Requirements Composer supports a subset of elements from the core element set of Business Process Modeling Notation (BPMN) standard.
Four categories of elements are used in business process diagramming:

Explanations of the business process diagram elements are based on the Business Process Modeling Notation Specification, Object Management Group (OMG), www.omg.org.

Table 1. Business process swimlane dividers
Element Explanation Graphical Representation
Pool

A pool represents a participant in a business-to-business (Business2Business) process. A participant is a business entity (such as a company, company division, or customer) or a business role (such as a buyer or a seller), which controls or is responsible for a business process. High-level or complex processes can include multiple participants, each of whom controls their own processes within their organization. Each participant is associated with one pool.

Pools are not used in simple processes

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Lane A lane is a sub-partition within a pool in a business-to-business process or as a separate grouping of elements in a simple process. Lanes organize and categorize activities. Lanes are often used for internal roles (such as Manager, Associate), systems (such as an enterprise application), or an internal department (such as shipping, finance).
Table 2. Business process flow object elements
Element Explanation Graphical Representation
Event

An event is something that occurs during the course of a business process. Events affect the flow of the process and usually have a cause (trigger) and an impact (result). There are three types of events, which are based on when they affect the flow: start, intermediate, and end.

Start Event - None

Start Event - Message

Start Event - Timer

Start Event
Start events begin a process. There are three types of start events:
  • None. No type is specified. This is also used to start a sub-process when it is triggered by its parent.
  • Message. This is used when a message arrives from a participant and triggers the start of the process.
  • Timer. This is used as a single date and time or a repeating date and time that triggers the start of the process.

Start Event - None

Start Event - Message

Start Event - Timer

Intermediate Event
An intermediate event occurs during the process. It affects the flow of the process, but does not start or directly terminate the process. Intermediate events are used for two kinds of events:
  • Send events that "throw" or set off a trigger.
  • Receive events that "catch" or respond to a trigger.
There are four types intermediate events:
  • None. No type is specified. This is valid only in the main flow of the process and indicates some change of state within the process.
  • Message. This indicates that a message is sent or received, and prompts the continuation of the process.
  • Link. This connects two sections within a single level of a process. The sections cannot link from process to sub-process. They can also be used as "off-page" connectors or "go-to" objects.
  • Timer. This is used as a single date and time or a repeating date and time. In the main flow, it acts as a delay mechanism.

Intermediate Send/Receive Event - None

Intermediate Send Event - Message

Intermediate Send Event - Link

Intermediate Receive Event - Message

Intermediate Receive Event - Link

Intermediate Receive Event - Timer

End Event The end event ends the flow of a process and does not have any outgoing sequence flow. The following types of end events are supported:
  • None. No type is specified. This setting is also used for the end of sub-processes; flow returns to the parent process.
  • Message. This indicates that a message is sent at the conclusion of the process.
  • Terminate. This indicates that all activities of the process must end immediately. There is no subsequent compensation or event handling.
End Event - None

End Event - Message

Task

A task is a single activity that is included within a process. A task is used when the work in the process is not broken down to a finer level of process detail.

Sub-Process A sub-process is a single flow object element that represents a set of activities. A sub-process can be broken down into a finer level of detail (as a process) through a set of sub-activities.

Task types are stacked in the palette. To select a task type, click the down arrow on Tasks to select a subprocess.

Data Object Data objects do not have a direct affect on the Sequence Flow or Message Flow of the process, but they do provide information about functions within the process, such as how documents, data, and other objects are used and updated during the process. Data objects can provides information that is required or output by the process. They can be used to represent many different types of objects, both electronic and physical. All data objects must be contained by a process or a sub-process.
Decision Point (Gateway) A decision point (or gateway) controls the divergence and convergence of multiple sequence flows. It determines branching, forking, merging, and joining of paths. Icons within the diamond shape indicate the type of flow control behavior. The types of control include:
  • Decision Point (Exclusive) - A data-based exclusive decision and merging gateway. Data-based decisions represent a branching point where alternatives are based on conditional expressions that are contained within the outgoing sequence flow. An exclusive gateway restricts the flow so only one of a set of alternatives can be chosen during runtime.
  • Decision Point (Inclusive) - An inclusive (OR) decision and merging gateway. This decision represents a branching point where Alternatives are based on conditional expressions that are contained within the outgoing sequence flow. In some sense it is a grouping of related independent binary (Yes/No) decisions. Since each path is independent, all combinations of the paths can be taken, from zero to all. However, it should be designed so that at least one path is taken. A Default condition could be used to ensure that at least one path is taken.
  • Fork/Join - A parallel (AND) gateway that provides a mechanism to synchronize parallel flow and to create parallel flow. These gateways are not required to create parallel flow, but they can be used to clarify the behavior of complex situations where a string of gateways are used and parallel flow is required.

Each type of control affects both the incoming and outgoing Flow.

Gateway types are stacked in the palette. To select a type, click the down arrow on the Decision Point element and select a type.

Decision Point (Exclusive)

Decision Point (Inclusive)

Fork/Join

Table 3. Business process connector elements
Element Explanation Graphical Representation
Sequence Flow

A sequence flow is represented by a solid line with a solid arrowhead. Sequence flows show the order in which activities are performed in a single process. Flow connectors show the direction of flow from a source to a target. The sequence flow can cross the boundaries between lanes, but cannot cross the boundaries of a pool.

Exit sequence flows from Decision Point (Exclusive) or Decision Point (Inclusive) gateways are designated as default or non-default.

Sequence flow:

Default exit sequence flow from a gateway:

Message Flow

A message flow is represented by a dashed line with an open arrowhead. Message flows depict the contents of a communication and the flow of messages between two participants (in separate pools) that are prepared to send and receive the messages. Flow connectors show the direction of flow from a source to a target. A message flow crosses pool boundaries to show the interactions between these separate participants.

Message flows are not available in simple processes.

Message event:

Association An association is represented by a dotted line and is used to associate information in the form of text annotations with flow objects.
Table 4. Business process supportive elements
Element Explanation Graphical Representation
Group A group designates a collection of activities that does not affect the sequence flow. The grouping can be used for documentation or analysis purposes. Groups can also identify the activities of a distributed transaction that is shown across pools.
Note Notes are a mechanism for the designer to provide additional textual information for the reader of a business process diagram.

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