FESCA 2011
Design of a Distributed Case Management System
using Dynamic Condition Response Graphs 1
Thomas Hildebrandt 2, Raghava Rao Mukkamala 3, Tijs Slaats 4
IT University of Copenhagen, Rued Langgaardsvej 7, 2300 Copenhagen, Denmark
Abstract
We present a case study of a design of a distributed case management system using Dynamic Condition Re-
sponse (DCR) Graphs, a recently proposed declarative notation for distributed processes. The case study was
carried out jointly with our industrial partner Exformatics, a danish provider of knowledge and workflow man-
agement systems. We present an early prototype design and simulation tool and outline the proposal for the
continued work of the two last authors towards the PhD degree, developing the model, technologies and tools
further to make it applicable to component and model based design of distributed systems.
Keywords: Case Study, Declarative Workflow, Model and Component Based Design, Verification
1 Introduction
The purpose of a Case Management System (CMS), as used in for instance Human
Resource (HR) departments, hospitals, financial, and governmental institutions, is
to guide case workers to perform the right tasks and to record the history of the
case. Handling of a case often involves the coordination of tasks of many different
case workers and interaction with several it systems, e.g. for document handling.
Since the initial work on workflow systems in the 1980s it has been advocated to
implement CMSs as so-called process-aware or process-oriented it systems which
1 Authors listed alphabetically. This research is supported by the Danish Research Agency
through a Knowledge Voucher granted to Exformatics (grant #10-087067, www.exformatics.com),
the Trustworthy Pervasive Healthcare Services project (grant #2106-07-0019, www.trustcare.eu)
and the Computer Supported Mobile Adaptive Business Processes project (grant #274-06-0415,
www.cosmobiz.dk).
2 Email:hilde@itu.dk
3 Email:rao@itu.dk
4 Email:tslaats@itu.dk
This paper is electronically published in
Electronic Notes in Theoretical Computer Science
URL: www.elsevier.nl/locate/entcs

Hildebrandt and Mukkamala and Slaats
are based on explicit work process descriptions described in some high-level pro-
cess notation such as UML activity diagrams and business rules. This allows the
system to be more easily adapted to different and changing work processes and also
makes the rules governing the system more visible to the users.
The rise of web service standards such as SOAP, WSDL and WS-BPEL gave
new momentum to process-oriented it systems. SOAP and WSDL standardized
how to access external it systems as web services in a service oriented architecture
and WS-BPEL provided a standard high-level programming language for combin-
ing individual service calls into process flows, also referred to as a process or-
chestration. Following WS-BPEL, the BPEL4People [1] and WS-HumanTask [16]
specifications were the first attempt to standardize the inclusion of human tasks
into BPEL to encompass workflows. Moreover, W3C started in 2004 develop-
ing the Web Services Choreography Description Language (WS-CDL) [25] which
can be used to provide a global view of the intended interactions between dif-
ferent actors of a system, similar to the view of interactions provided by UML
sequence diagrams. Within the last 5 years focus has moved from WS-BPEL
(and BPEL4People) to the development of Business Process Model and Notation
(BPMN) [15] which standardizes the graphical notation used for business pro-
cesses, encompassing both human and automated tasks, and including both no-
tations for orchestrations and choreographies.
However, as pointed out in [23], the imperative process notations with explicit
control and message flows underlying both WS-BPEL and BPMN are best fit to de-
scribe rigid flows of service invocations and human tasks. Moreover, it has proven
to be non-trivial to support changes of the processes on-the-fly [22]. This does not
match well the typical more ad-hoc nature of case work where it is often needed to
redo and skip tasks and possibly adapt the set of tasks and their mutual constraints
dynamically [21]. An alternative approach studied by several research groups is the
use of declarative process models [3,6,18,19,23,24] which describe the constraints
on process flows, not how to fulfill them.
As part of the PhD project of the second author within the Trustworthy Per-
vasive Healthcare Services (TrustCare) research project [8] we have developed a
declarative process model called Dynamic Condition Response Graphs (DCR Graphs) [9–
11, 13]. The model is a both a generalization of the Process Matrix model [12, 14]
developed by Resultmaker, a danish provider of workflow and case-management
systems and the classical event structure model for concurrency [26, 27]. It dif-
fers crucially from BPMN and BPEL in describing temporal constraints instead of
describing the control and message flow.
In the present paper we first describe an application of DCR graphs in the design
phase of the development of a distributed, inter-organizational case management
system. We then give a brief description of a set of tools for designing, simulating
and verifying DCR graphs which have been developed during the last year. Fi-
nally we briefly outline the proposal for the continued work of the two last authors
2