Friday, July 31, 2009

Business Process Management (Part-2 Business Process Modelling[Chapter III Business Process Modelling Foundation ] ) Sec G -- By Mathias Weske

Process Interactions

Business processes reside in single organizations. Since enterprises cooperate
with each other, it is essential to consider the interaction between enterprises.
Since all activities that an enterprise conducts are part of some business process, the interaction between enterprises can be described by the interaction
of business processes of these enterprises. These interactions typically
occur in a peer-to-peer style, following an agreed-upon process choreography.
These enterprises are reflected by the
respective value chains. Within these value chains are the business functions
realized by the business processes.
The buyer value chain contains an order product business function, and
the reseller value chain contains an order management business function. The
business process models that realize this interaction are shown in Figure 3.21.
The order product business function of the buyer starts by his placing
an order. This placing of an order is realized by a message to the reseller;
the task place order is responsible for sending this message. On the reseller
side, this message is received by a receive order activity. The processes continue
as specified. Since the message flow occurs between multiple activities
in both directions, the value chain level representation of the interacting business
processes—from buyer to reseller—is not complete in the sense that it
does not hold all possible orders of interaction.
Interacting process instances can be visualized adequately by event diagrams.
The distributed nature of interacting processes is represented by introducing
a horizontal line for each participant, on which the events of that
participant appear in an ordered fashion. Participants communicate by send ing and receiving messages. In event diagrams, a one-way message interaction
is represented by a send event, a corresponding receive event, and an arc connecting
the two events. Participants can communicate only by sending and
receiving messages.
It abstracts
from events regarding the initiating, enabling, starting, and terminating of
activities. Instead, it concentrates on message events. Each message send event
is marked by the activity instance during which the send occurs, and each
receive event is marked by the activity instance during which the receive
occurs. It is valid to assume that messages are sent on termination of the
respective activity instance and an arrival of a message triggers the enable
event for the receiving activity instance.

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