BPMN

BPMN stands for Business Process Model and Notation. It is used to describe lower-level processes and depicts a detailed sequence of process steps and information flows needed to perform a process. Each process can be decomposed in either BPMN or EPC notation. When you decompose a BPMN process that is placed on the SADT diagram, no arrows are migrated from the SADT diagram to the BPMN diagram.

There are five basic categories of elements in BPMN:

• flow objects (events, tasks/sub-processes, and gateways);
• data (data objects and databases);
• connecting objects (sequence flows, message flows, and associations);
• swimlanes (pools and lanes);
• artifacts (text annotations).

See Table 1 for the description of the BPMN shapes:

Element	Button	Shape	Description
Task, Sub-process			Activity is an action or a set of actions performed over an object (document, material object, etc.) in order to produce a given result. The types of BPMN activities are tasks and sub-processes. A Task is a simple action without further decomposition. Tasks are subdivided into types, each type (excluding an Abstract task) has its own marker in the left upper corner of the task shape. A Sub-process is a decomposed process, which is described in detail in its diagram. The subprocess is indicated by a block with a plus sign at the center of the bottom of the shape. Sub-processes are subdivided into types.
Event			An Event is something that "happens" during the course of a process. Events affect the flow of a process and usually have a cause (trigger) or an impact (result). Events are circles with open centers to allow internal markers to differentiate triggers or results. There are three types of Events, based on when they affect the flow: Start, Intermediate, and End. The Start and some Intermediate Events have "triggers" that define the cause for the Event. There are multiple ways that these events can be triggered. End Events MAY define a "result" that is a consequence of a Sequence Flow path ending. Start Events can only react to ("catch") a trigger. End Events can only create ("throw") a result. Intermediate Events can catch or throw triggers. For the Events, triggers that catch, the markers are unfilled, and for triggers and results that throw, the markers are filled. Additionally, some Intermediate Events can be attached to the boundary of an activity. These events are called boundary events, some of them interrupt the process flow and some don’t.
Gateway			Gateways are used to control how the process flows (how tokens flow) through Sequence Flows as they converge and diverge within a process. If the flow does not need to be controlled, then a Gateway is not needed. The term "gateway" implies that there is a gating mechanism that either allows or disallows passage through the Gateway; that is, as tokens arrive at a Gateway, they can be merged together on input and/or split apart on output as the Gateway mechanisms are invoked. Exclusive gateway can be displayed with or without a marker inside the shape. You can change default settings in the All Users Settings (Main Menu → Home → All Users Settings) on Models tab.
Sequence Flow			A Sequence Flow is used to represent the order of flow elements in a process. Each Sequence Flow has only one source and only one target. A sequence flow may be named, if necessary. Figure 1 Figure 2 Figure 3
Conditional Sequence Flow			A Sequence Flow can define a condition Expression, indicating that the token will be passed down the Sequence Flow only if the Expression evaluates to true. This Expression is typically used when the source of the Sequence Flow is a Gateway or an Activity. A conditional outgoing Sequence Flow from an Activity MUST be drawn with a mini-diamond marker at the beginning of the connector (Figure 4). Conditional outgoing Sequence Flows from a Gateway MUST NOT be drawn with a mini-diamond marker at the beginning of the connector. Figure 4
Default Sequence Flow			A Sequence Flow that has a Gateway or an Activity as its source can be defined with as default. Such a Sequence Flow will have a marker to show that it is a default flow. The default Sequence Flow is taken (a token is passed) only if all the other outgoing Sequence Flows from the Activity or Gateway are not valid (i.e., their condition Expressions are false). A default outgoing Sequence Flow MUST be drawn with a slash marker at the beginning of the connector (as seen in Figure 4).
Message Flow			A Message Flow is used to show the flow of Messages between the current process and the external process. If necessary, a message flow can be named. Figure 5
Association			An Association is used to associate information and Artifacts with Flow Objects. Figure 6 shows how Data Associations are used to represent inputs and outputs of Activities. Figure 6 Data objects may be directly associated with a Sequence Flow connector (Figure 7). Figure 7 Also, data objects may be associated with a Message Flow (Figure 8): Figure 8
Pool			Represents the process steps. A diagram contains one pool only.
Swimlane			Represents activity actors (org units or functional objects).
Collapsing Pool			External activity. Is used to represent interaction between the current activity and the external activity. Figure 9 Figure 10. Process 1 diagram
Documents			Documents that are created, manipulated, and used when executing a Process.
Applications Databases Material objects Other functional objects			Applications, databases, material objects, and other functional objects that are created, manipulated, and used when executing a Process.

Table 1. BPMN Elements