A Transactional Metamodel For Business Process
Modeling With Support To Business Process Patterns
Lucinéia Heloisa Thom1, Cirano Iochpe1, Bernhard Mitschang2
1
Instituto de Informática – Universidade Federal do Rio Grande do Sul (UFRGS)
Caixa Postal 15.064 – 91.501-970 – Porto Alegre – RS – Brazil
2
Institute for Parallel and Distributed Systems (IPVS) – University of Stuttgart
Universitätstrasse 38, 70569 Stuttgart, Germany
{lucineia,ciochpe}@inf.ufrgs.br, mitsch@informatik.uni-stuttgart.de
Abstract. Currently, there are several metamodels for business process and
workflow process modeling. However, the limitations of these metamodels are
twofold: First, the use of organizational structure aspects is limited and
second they don’t support business (sub)process patterns based on
organizational structure aspects. These limitations may restrict the accuracy,
efficiency, and productivity of the workflow project. Thesis result specially
comprises a Transactional Metamodel of Business Processes (TMBP). TMBP
links organizational structure aspects with business (sub)process and makes it
feasible to create business (sub)process from the reuse of business
(sub)process patterns based on organizational structure aspects. An additional
feature of TMBP supports the generation of business subprocess patterns
through the Business Process Execution Language for Web Services
(BPEL4WS).
1. Introduction
Workflow management systems coordinate tasks, resources, and data according to the
formal representation of the business process executed in organizations [Mühlen 1999].
A business process can be understood as a partial order of tasks where each task
contributes in a stage of the process. At the end of the business process, the organization
should reach the objective of the business proposed. A workflow process model is a
representation of a business process and comprises all singularities required for the
business process automation.
Any organization should be modelled according to the business process it must perform.
Accordingly, first the business process must be defined and after this the organization
must be modelled to best operate it. Based on this definition and the study in [Thom,
2004], thesis conceptualization considers the existence of a strong relationship between
organizational structure aspects (e.g., centralization of decision-making, scalar chain and
coordination mechanisms) and business process modeling.
The main result of the thesis is a new approach for business process modeling. The
approach comprises a metamodel for business process modeling with support to
business (sub)process patterns based on organizational structure aspects. Additionally, a
methodology for business process modeling in the context of the metamodel is also
proposed.
In the remainder of section 1 the problem that motivates the thesis research as well as
corresponding proposal to solve the problem are presented. Section 2 shortly describes
the case study developed to discover the candidate patterns. This section also introduces
the metamodel for business process modeling. Section 3 briefly characterizes the
metamodel methodology for business process modeling. Last but not least, Section 4
gives conclusions and future work.
1.1. Problem Statement and Related Works
Recently, business process modeling and workflow process modeling became subject of
various specifications and standardization efforts. In the area of workflow patterns, the
proposal of Wil van der Aalst [Aalst 2000] is one of the most expressive. However, the
patterns are not related with organizational structure aspects. In which concerns
metamodels for business and workflow process modeling as presented in [Thom 2005],
different consortia including the Business Process Management Initiative (BPMI) as
well as the Workflow Management Coalition (WfMC), the World Wide Web
Consortium (W3C) and the Organization for the Advancement of Structured
Information Standards (OASIS) have proposed different approaches. However, these
metamodels present some limitations:
•
their submodels for organizational structure aspects representation show limited
power of expression. Most of them just consider the use of organizational structure
aspects in the assignment of task execution performer.
•
the use of business process patterns based on organizational structure aspects is not
considered in business process modeling. Accordingly, the reuse advantages of
patterns are not applied in the modeling phase of the workflow project. Therefore
the performance and quality of whole workflow project may not be guaranteed.
Nevertheless, the workflow process may not represent the real business process as it
is executed in the organization hence the organizational structure aspects are limited
related with business process modeling.
1.2. The Proposal
Aiming to solve the problems outlined in section 1.1, thesis proposal comprises:
•
1
Candidate patterns for business (sub)process modeling based on organizational
structure aspects1. We call candidate patterns because we agree with the pattern
community consensus that a pattern can be established after it is identified in at least
3 real cases. The approach presented in this paper considers only one workflow
application, although this application was implemented through a (large) set of
workflow process. Accordingly, two more workflow applications are becessary to
prove the candidate patterns. Nevertheless, in this papera business (sub)process
pattern is understood as a set (one or more) of recurring tasks that can be reused in
Examples of organizational structure aspects are: centralization of decision-making in high positions of the prganization and;
direct supervision of work (a superior supervises the work of a subordoinate). More examples are in [Thom 2005].
specific situations concerning related organizational structure aspects. The patterns
must be stored in the patterns catalogue of the metamodel in development.
•
Transactional Metamodel of Business Processes. TMBP is an extension of the
Transactional Model of the Workflow Processes - TMWP2 [Grefen 1999] with
support to organizational structure aspects. The extension mainly focus on: (a) to
increase the power of expression of the organizational submodels in business
process/workflow process metamodels and; (b) to provide a catalogue of patterns
based on organizational structure aspects to be used in business process modeling
and workflow process modeling.
•
Aiming implementation issues we also propose the TMBP methodology.
2. Case Study
The candidate patterns for business process modeling were discovered through the
development of a case study in a governmental organization. The technique used to
discover the patterns is described in [Thom 2003]. In the case study, 3 patterns were
discovered [Thom 2003]. Each pattern represents a relationship between one or more
aspects of the organization and its more than 60 workflow sub-processes. Next
subsection presents an example of pattern described with Buschmann notation
[Bushmann 1996] and illustrated with action semantics [Object Management Group
2003].
2.1. Candidate pattern for document approval
The document approval process (see Figure 1) is a sequence of agreements. Each
agreement is performed by one organizational role (e.g., manager, director, president of
a company). The process ends when all organizational roles performed theirs
evaluations or one of then does not agree with the document content.
Name: Document Approval
Context: In this paper to approve means to make a decision about something that needs to be
evaluated (e.g., the evaluation of a document content). Based on it the approval process
includes at least two parameters: an item (e.g., document) and an organizational role
responsible for the decision task execution.
Problem: Depending on the level of decision-making (more or less centralized in the high
positions of the organization) the structure of the document approval process may vary.
Solution: The document approval pattern is recommend when these two situations are
identified: (1) an approval process must be modeled and; (2) the process is executed in a
context with high centralization of decision-making and direct supervision of the work (one
person responsible for the work of another). The process is composed of four tasks:
ToReviewItem;
ToRecordSignature;
ToGetNumberOfrecordedSignatures;
ToAnnulPreviousSignatures. The loop is repeated in the number of organizational roles
received via input parameter or one of the organizational roles does not agree with the
document content. In this case all performed signatures are annulled and the process must end.
Figure 1: Candidate pattern for document approval
2
The Transactional Model of Workflow Processes was developed in the context of WIDE Project. The WIDE Model is composed
by three models called: Process Model, Information Model and Organizational Model [Grefen 1999].
OrganizationalRole
Item
ToReviseItem
approve
ToRecordSignature
ToAnnulPreviousSignature
disapprove
ToGetNumberOfSignatures
Number of signatures
Figure 2: An organizational role performs a document review (item). In case it
agrees with the document content its signature is recorded. In case it
disagrees, all previous signatures (in case they exist) are annulled and the
process must end. The actions inside the dashed line are repeated in the
number (represented by the four small squares in the dashed line) of
organizational roles given by input parameters or a disapproval occurs.
2.2. Introduction to TMBP
TMBP is described through the Unified Modeling Language notation. Accordingly, the
metamodel is a package composed of five subpackages: PBusinessProcess,
POrganizational, PResource, PRouting and PCatalogue (Figure 1).
Transactional Model of Business Process (TMBP)
POrganizational
PResource
PCatalog
PBusinessProcess
PRouting
Figure 3: Transactional metamodel of business process
Due to space limitation in this paper not all packages of TMBP are described. The
description is restricted for those classes instantiated in the specification of the pattern
introduced in Section 2.1. A full characterization of the metamodel is in [Thom 2005].
OraganizationalRole in Figure 3 is an instance of the class
OrganizationalRole of POrganizational package (Figure 3). This class is
linked with Actor (task performer). Additionally, it is associated with
OrganizationalUnit (e.g., department, division). Nevertheless, it is a
generalization of functional role. A functional role is associated with Skill (e.g., to
know how to program in Java) and competence (e.g., may sign orders > than $ 20.000).
Organization
Actor
subordinated of
0.. *
0..*
0..*
0..*
0..*
OrganizationalRole
0..*
Functional
Competence
0..*
StructuralAspect
0.. *
Figure 4: Organizational package
OrganizationalUnit
0..*
0..* 0..*
0..*
Skill
Item in Figure 2 is an instance of the class ItemType of PResource package. A
resource (see Figure 5) is an artefact required for a task execution. It can be: a tool
(e.g., word processor, printer) or an item type (e.g., document). Depending on its type
an item can have a more complex structure (class SructuredItemType in Figure 5).
In this case it is recursively composed of sub-items
e.g., an environment process
composed of several documents (sub-itens).
Resource
Tool
ItemType
StructuredItemType
Figure 5: Resource package
An instance of the class
BusinessProcess
(see Figure 6) of
PBusinessProcess package transforms an item from an initial state into a final
state. Transformations may be decomposed in smaller transformations, where each of
them corresponds to a change in the item state. When there are no more
transformations to be performed, the item reaches its final state and the organization
reaches the aim of its business (in the example of Figure 2, the document is approved or
disapproved).
Due to its possible high complexity, a business process can be recursively decomposed
in to business subprocess, up to the business transaction level. Under the organization’s
point of view, a business transaction is the smallest business process unit of work. Each
business transaction is responsible for one of the item transformations.
BusinessProcess
ItemType
work item
0..*
(from PResource)
1
Actor
Subflow
(from POrganizational)
1
responsible
0..*
SubProcess
BusinessTransaction
inputs
0..*
0..*
responsible
0..*
OrganizationalUnit
0..*
Resource
(from PResource)
(from POrganizational)
Task
Skill
SimpleTaskType
(from POrganizational)
0..*
0..1
0..*
0..*
Routing
(fro m PRo uting )
0..1
next
msg
SimpleTask
SuperTask
0..*
0..*
0..1
previous
Manual
Figure 6: Business process package
Automatic
3. Methodology for Business Process Modeling Based On TMBP
TMBP methodology is proposed aiming to achieve implementation issues needed for
automatic generation of business (sub)process based on business subprocess patterns
stored in TMBP catalogue. Considering the methodology proposed by Electronic
Commerce Modeling (ECOMOD) project3, TMBP methodology for business process
and workflow process modeling and implementation was developed. The methodology
is still subject of discussion and research. Until now it is composed of three steps:
•
Creation of business process models based on TMBP. The task of this step is the
creation of business process models as described in Section 2.1.
•
Automatic generation of BPEL4WS [Andrews 2003] processes corresponding to the
business process models defined in step 1. This step should results in process
description as the one presented in Figure 7.
•
Execution of BPEL4WS process through whatever workflow engine.
3.1. Mapping TMBP business process to BPEL4WS process
This section presents some rules for mapping a TMBP process example (as shown in
Figure 2) to a correspondent BPEL4WS process. These rules are to be used in the
context of the second step of TMBP methodology.
Rule for “parameter” mapping: In Figure 2 an organizational role (responsible for a
document approval) is received as input parameter. In BPEL4WS this situation is
represented with an invoke activity (as shown number 1 of Figure 7).
Mapping rule for “decision task”: The decision node (illustrated in Figure 2 as a
diamond) is mapped to BPEL4WS as a switch statement.
Mapping rule for “record task”: According with Figure 2, the result of a decision can
be an approval or a disapproval. If approved the signature or an indication of it needs to
be recorded. In BPEL4WS this situation is mapped through an operation
(recordsignature). A variable counts the number of signatures to be used in
case of disapproval (see number 2 in Figure 7).
Mapping rule for “cancel performed task”: If disapproval occurs all previous
signatures (in case they exist) must be cancelled. In BPEL4WS this situation can be
expressed through a while
statement
and through an operation
(“anulSignature” as shown number 3 and 4 of Figure 7).
Process Description (port type description and message description are left out).
3
ECOMOD project was funded by the German National Research Foundation. The project focuses on the development of
enterprise models as well as conceptual foundation for cross-organizational business processes and corresponding versatile
platforms for electronic trading [Frank 2004]. The Multi-Perspective Enterprise Modeling (MEMO) was created in ECOMOD
context. MEMO is a method for the modeling of organizations according to different views as well as different levels of abstraction
[Jung 2004].
<process name=“documentApproval”>
(1)<invoke partnerLink=“reviewer”
portType=“itemReviewerPT”
operation=“reviewItem”
variable=“review”
<correlations>
<correlation set= “itemID” initiate=“yes”/>
</correlations> </invoke>
<switch>
<case condition =
“bpws:getVariableProperty(‘review’)=“true”
<sequence>
(2)
(3)
(4)
<invoke partnerLink=“requester”
portType=“signaturePT”
operation= “recordSignature”
from expression=
“bpws:getVariableData(‘signatureCount’) +
bpws:getVariableProperty(‘auxSignatureCount’
)to variable=‘signatureCount’/> </invoke>
</sequence> </case>
<otherwise>
<while condition =
“bpws:getVariableProperty(‘signatureCount’)>0
<sequence>
<invoke partnerLink=“requester”
portType=“signaturePT”
operation= “annulSignature”
from expression=
bpws:getVariableData(‘signatureCount’) bpws:getVariableProperty(‘auxsignatureCount’
) “/></invoke></sequence></while>
“bpws:getVariableData(‘signatureCount’)= 0
</otherwise>
from expression=
“bpws:getVariableData(‘numberOfOrganizationalRoles’) bpws:getVariableProperty(‘auxnumberOfSuperiorPositions’)
“/></switch></process>
Figure 7: TMBP process as BPEL4WS process
4. Conclusions and Future Work
With an example of business subprocess patterns identified through the development of
a case study in a governmental organization, the transactional metamodel for business
process modeling (TMBP) was introduced. The main goal with the metamodel is to
provide a bridge between OSA and business (sub)process, minimizing the complexity of
business process modeling and at the same time improving the efficiency and quality of
it. Furthermore, through business pattern reuse, the productivity within the workflow
modeling process is expected to increase.
The final remark demonstrated how BPEL4WS might be used in the description of
executable business subprocess patterns that support organizational structure aspects.
BPEL4WS will become the execution language for business (sub)processes with tool
support and platform independency. The thesis approach automatically maps TMBP
processes to BPEL4WS processes by generating executable BPEL4WS from TMBP
specifications. Last, but not least, TMBP provides a high level specification that
supports semi-automatic selection of patterns.
As future work TMBP must be extended with different kind of process (technology
dependent process versus informational subprocess) and respectively related
organizational structure aspects. Additionally to deeper investigate the way patterns
should be represented as well as stored, and queried in the pattern catalogue of TMBP as
well as to look for adequate inference engines that can answer queries to the catalogue
with minimum human interference. Furthermore, to validate TMBP through the
application of the metamodel in real study cases.
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