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13 The Business Process Modeling Notation 351
There are several types of subprocesses in BPMN, including embedded subpro-
cess and independent subprocess. An embedded subprocess is part of the parent
process, while an independent subprocess exists independently of the parent pro-
cess. This chapter does not go into the details of these nuances and instead treats
both embedded and independent subprocesses equally.

13.2.2 Data

There are two ways in which the manipulation of data by processes and tasks can
be specified in BPMN: by means of data objects and by means of properties.
Data objects represent documents, data, or other objects that are used in the pro-
cess. They have a name and, optionally, a state. Data objects can be associated with
activities, showing that they are input for (by an arrow pointing to that task) or out-
put of that activity (by an arrow originating in that task). They can also be associated
with flows, showing that they are transferred from one activity to another via that
flow. Figure 13.3 illustrates these cases, annotating the business process diagram
from Fig. 13.1 with data objects. In the BPMN standard, data objects are used only
informally for documentation purposes. According to the BPMN specification, they
provide additional information for the reader of the BPMN Diagram, but do not
directly affect the execution of the process. Therefore, data objects do not play any
role when mapping BPMN to an executable workflow language. Indeed, in the map-
ping from BPMN to the Business Process Execution Language (BPEL) presented
in an appendix of the BPMN specification, data objects are simply not mapped.
Properties in BPMN can roughly be equated to variables in YAWL. They have
a name and a type and can be associated with (sub-)processes and tasks (and data

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Fig. 13.3 Example of a business process model with data in BPMN