SEKE 2012 Proceedings - Knowledge Systems Institute

ecause the system of C-net model is qu antification structure
which is similar with net system. “C” stands for computing and
communication. C-net describes token and variable separately
based on the basic principles of Petri net, so that C-net is
suitable to describe collaborative design workflow.
B. Collaboration mechanism description
To the description of coarse collaboration mechanism,
paper [4] integrates the branch of workflow and the object of
software engineering into Petri net, and builds the invoking
relationship, in which collaborate unit nets are collaborated
around process net. Paper [5] presents a m ethod of multiworkflow
interaction and coordination based on bus. The
research direction of these works is t o build coarse
collaboration mechanism to implement data translation and
progress control among processes, but it can’t reflect the
collaboration between tasks because its element is not task.
To the description of fine grit collaboration mechanism,
paper [6] presents the solution of workflow collaboration by
combing agent technology with ontology. Paper [7] describes
workflow based on Petri net, and uses an annotation language
to describe data exchange and process schedule between
processes. Both of these two works present the description of
fine grit collaboration mechanism, but they use different
modeling methods to describe the workflow and the
collaboration mechanism between workflows.
The inconsistency between workflow model and
collaboration mechanism model brings complexity to analysis
of the dynamic process data and execution state of workflow,
and there are also some researches on the unified formalization
of collaboration design process. Paper [8] uses Pi-Calculus
technology to formally define the inter-organizational business
process structure, and use the special mechanism of Pi-
Calculus to describe parallel processes and their
communication. But its problem is th at the process model
based on Pi-Calculus is too complex and abstract to let designer
understand the process and conduct the implementation of
specific design process. Paper [9] provides a set process
modeling mechanism of pub/sub system based on color net,
which adopts Petri net model to describe pub component so as
to realize process collaboration and only focus on the
description of control flow. So according to the feature of
collaborative design, it n eeds a k ind modeling method which
can describe both design process and design collaboration of
collaborative design by the data exchange of fine grit task level.
The collaboration at task level asks for more requirements to
process modeling, which mainly is reflected in the description
of the process and collaboration between processes.
III. DATA COLLABORATION DESCRIPTION OF
COLLBORATIVE DESIGN
Through C-net model, we can describe the basic process of
dataflow oriented collaborative design, and we conclude three
main process collaboration patterns in the scene of data
collaboration between collaborative design processes. Then we
use C-net to build model for process collaboration patterns.
A. C-net model
The formal definition of C-net is as follow:
, , ; , , to stand for
r
C_netand xV,t T,
p P. P, V and T separately stand
for the token set, variable set and transition set of CN and F,
R and Wr separately stand for flow relationship, read
relationship and write relationship.
Definition 1 Use CN PV T F RW
It is critical to realize the communication between
processes by the collaboration between tasks and support the
description of parameters exchange between tasks and
constraints between parameters in collaborative design. C-net
support parameters passing of collaborative design, because C-
net introduces variable set which can make some
corresponding extensions so as to provide the description of
data flow and control flow between design tasks.
B. Data collaboration model of collaborative design
According the features of collaborative design, including
inter-organization, data flow oriented, parallel and iterative
execution, we conclude three major parameter interaction
patterns to describe the complex data collaboration between
design processes, including task interaction between superior
process and subordinate process, task interaction between
parallel processes and task interaction between iterative
processes.
Pattern 1 : task interaction between superior process
and subordinate process
In this pattern, the relationship between superior process
and subordinate process are reflected into parameter passing
from one or more tasks of subordinate process to the task of
superior process. This pattern often is used in the level
structure to describe the interaction between the tasks which
belong to the processes of different level. These interactions
include the monitoring, collection, statistics and analysis of
superior process to subordinate process, and the specific
abstract process is as follow:
Figure 1. Task interaction pattern between superior and subordinate process
In figure 1, transition T strands for the task of superior
process which implements the interaction with subordinate
process. It shows that T collects parameters from T2, T3 and Ti.
T2
T3
T
Ti
Tj
Pattern 2 : task interaction between parallel processes
In this pattern, the tasks of different parallel processes
interact with each other based on parameters, which is reflected
into two scenes: one is that some tasks can pass parameters to
multi tasks from other parallel processes; the other is that some
tasks can receive parameters from multi-tasks from other
parallel processes. In collaborative design process, this pattern
is mainly used to describe data collaboration process in the
form of parameter which is c aused by the dependence of the
design contents among different design teams. This pattern also
describes the parameter interaction caused by multidisciplinary
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