NOTE: All Message Flows MUST connect two separate Pools. They MAY connect to the Pool boundary or to Flow Objects within the Pool boundary. They MUST NOT connect two objects within the same Pool.

An Activity MAY be the target of a Message Flow; it can have zero (0) or more incoming Message Flows. An Activity MAY be a source of a Message Flow; it can have zero (0) or more outgoing Message Flows.

10.3.1 Resource Assignment

The following sub clauses define how Resources can be defined for an Activity. Figure 10.7 displays the class diagram for the BPMN elements used for Resource assignment.

Figure 10.7 – The class diagram for assigning Resources

Resource Role

The ResourceRole element inherits the attributes and model associations of BaseElement (see Table 8.5). Table 10.5 presents the additional model associations of the ResourceRole element.

Table 10.5 – Resource Role model associations

Expression Assignment

Resources can be assigned to an Activity using Expressions. These Expressions MUST return Resource entity related data types, like Users or Groups. Different Expressions can return multiple Resources. All of them are assigned to the respective subclass of the ResourceRole element, for example as potential owners. The semantics is defined by the subclass.

The ResourceAssignmentExpression element inherits the attributes and model associations of BaseElement (see Table 8.5). Table 10.6 presents the additional model associations of the ResourceAssignmentExpression element.

Table 10.6 – ResourceAssignmentExpression model associations

Parameterized Resource Assignment

Resources support query parameters that are passed to the Resource query at runtime. Parameters MAY refer to Task instance data using Expressions. During Resource query execution, an infrastructure can decide which of the Parameters defined by the Resource are used. It MAY use zero (0) or more of the Parameters specified. It MAY also override certain Parameters with values defined during Resource deployment. The deployment mechanism for Tasks and Resources is out of scope for this document. Resource queries are evaluated to determine the set of Resources, e.g., people, assigned to the Activity. Failed Resource queries are treated like Resource queries that return an empty result set. Resource queries return one Resource or a set of Resources.

The ResourceParameterBinding element inherits the attributes and model associations of BaseElement (see Table 8.5). Table 10.7 presents the additional model associations of the ResourceParameterBinding element.