xoEPC - Jan Mendling

3.4. EPC Semantics 53
a decision has to be made: whether to perform it in every process instance during run
time (ON), or whether to exclude it permanently (OFF), i.e. it will not be executed in any
process instance, or whether to defer this decision to run time (OPT), i.e. for each process
instance, it has to be decided whether to execute the function or not. Configurable con-
nectors subsume build-time connector types that are less or equally expressive. Hence,
a configurable connector can only be configured to a connector type that restricts its
behavior. A configurable OR-connector may be mapped to a regular OR-, XOR-, AND-
connector, or to a single sequence of events and functions (indicated by SEQn for some
process path starting with node n). A configurable AND-connector may only be mapped
to a regular AND-connector. A configurable XOR-connector may be mapped to a regular
XOR-connector or to a single sequence SEQn. Interdependencies between configurable
EPC nodes can be specified via configuration requirements, i.e. logical expressions that
define constraints for inter-related configuration nodes. Configuration guidelines formal-
ize recommendations and best practices (also in the form of logical expressions) in order
to support the configuration process semantically. Additional work formalizes C-EPC
syntax [RA07], its mapping to EPCs [MRRA06], and its identification from existing sys-
tems [JVAR06].
3.4 EPC Semantics
In addition to related work on the syntax of EPCs, there are several contributions towards
the formalization of EPC semantics. This section first illustrates the semantical problems
related to the OR-join. Then it gives a historical overview of semantical definitions, and
provides a formalization for EPCs, that is used in this thesis. Furthermore, we present
an implementation of these semantics as a ProM plug-in that generates the reachability
graph for a given EPC.
3.4.1 Informal Semantics as a Starting Point
Before discussing EPC formalization problems, we need to establish an informal un-
derstanding of state representation and state changes of an EPCs. Although we provide