Proposal of a Framework to Workflow Process Automation Systems
based on .NET Framework and XML Web Service
NASCIMENTO, R.P.C. DO; MARTINS, J.A.C.; PINTO, J.M.S.
Departamento de Electrônica e Telecomunicações
Universidade de Aveiro
Instituto de Engenharia Eletrônica e Telemática de Aveiro
Campus Universitário de Santiago, 3810-193
PORTUGAL
rogerio@ieeta.pt http://www.ieeta.pt/~rogerio
Abstract: Our main goal is the interrelation amongst the new metadata paradigm - the XML family - and the
Workflow Process Automation, and its integration and interaction with database legacy systems. We intend to
answer two fundamental subjects: the granularity of XML documents that support the framework, and the crossreference capacity with other files or databases in a system, being both supported by XML databases. We used
TEXTML Server as a back end system for intermediating and recovering information from binary and XML files. In
out case study, we implemented a multimedia and heterogeneous distributed system based on Web Services, SOAP
and WSDL. The main idea in the proposal of the framework was separate the process logic from the application
components. For that, we used workflow process management techniques and XML Web Services to the process
logic. For the application components we built XML Schemas to generated XML files, indexes for TEXTML Server
and XSL files that will be used to format data for each system front-end like PDA’s, third generation mobile phones
(GPRS, UMTS) and personal computers. We are testing a workflow process automation prototype (based on WfMC
reference model) to be used in our case study: the information management system of legislative data of the
portuguese parliament. All this was embedded in the new Microsoft’s platform for software components: the .NET
Framework.
Key-Words: Workflow Process Automation, XML, TEXTML Server, SOAP, Web-Services, .NET Framework
1 Introduction
Through the proposal of a generic framework we intend to
analyze the workflow processes and metadata of a organization
to infer the benefits that can be extracted and, also, to
implement a multimedia system based on this framework.
Concepts related with WPA – Workflow Process
Automation, e-commerce and XML – eXtensible Markup
Language can be found in [1], [2] and [3], but we didn’t find a
solution based on open patterns using XML Web Services and
XML databases.
In [1], the XML Nets are proposed, a new type of high level
Petri Nets to support interorganization business processes. In
[2], a XML architecture is discussed for distributed workflow
management whose key is called XML Mediator. It is based on
XSQL of Oracle and uses XML messages over HTTP to
change data between the workflow and the business object
servers and, on the other hand, between the workflow and the
customers' activities. And [3] describes an infrastructure
composed by dynamic agents based on Java for the ecommerce automation. XML is the message format chosen for
the communication among that agents.
We found in [4] and [5] related works that use XML to make
the business logic independent from the mechanisms that
support them. [4] discusses the integration of the documents
inside of an organization and it’s based on Ultimus Workflow
solution ([6]). [5] describes an architecture to supports
interorganization workflows through XML messages and it is
based on the open pattern Wf-XML specified in the Interface 4
of Reference Model of WfMC – Workflow Management
Coalition.
In the next sections we discuss about the three main pillars
of our work: the WPA, the technologies XML and the .NET
Framework.
2 Workflow Process Automation
Our study is fundamentally based in WPA that can be
defined as a sequence of structured tasks (or semi-structured)
executed in series or in parallel for two or more individuals to
obtain a common goal.
When we began the investigation of concepts, myths and
solutions of current workflow systems we saw that the majority
of existing solutions in the industry (Diamond, icXpert
Solution Suite, HighView Workflow, W4 Architecture and
Ultimus Workflow [6] ) confuse the essence of WPA with
other concepts like cooperative and colaborative work, process
digitalization, integration of the applications inside a company,
re-engineering or even with the own operating system.
We investigated some proposed models for standardization
of WPA and we chose the Workflow Reference Model [7] of
the group WfMC as this model more readly adapted to generic
solutions.
Thus we discarded others standardization proposals like the
complex proposal of OMG, the limited proposal of BPMI–
Business Process Management Iniciative [8] and the SWAP –
Simple Workflow Access Protocol [9][KAI99] of IETF
Working Group, that, in fact, didn't become a pattern although
it has its merits.
3 XML Family
We used XSL – Extensible Stylesheet Language files and
XSLT to do style sheets of the information based on XML
documents. An XSL file should be created necessarily for the
corresponding format of the XML elements that you want to
show in a specific front-end.
The XSL files generated in our framework will be used in
the communication with mobile devices front-ends, including
PDA’s [10], the third generation of mobile phones, and, also,
with browsers of laptops and/or desktops computers.
3.1 Search Engines
We analyzed some intermediary systems for the recovery of
information in XML files. Specifically, we looked at the
following solutions: Sgrep, XYZFind, eXist and TEXTML
Server [11]; the Kweelt [12], an academic proposal from the
University of Pennsylvania; and we also discussed some
solutions with the REDIS Group of the University of Vigo.
We chose TEXTML Server as a back-end system to store,
index and look for information in a great number of XML
documents. We highlighted the main reasons: quite efficient
query language, safe support for commercial applications and
100% XML database.
4 Software Components Models
Recently, Microsoft© launched a new product unto the
market for visual development called Visual Studio.NET™
that includes, among others, an architecture for Web
applications –ASP.NET [13] – much better than previous ASP
and new resources for Visual Basic, creating the VB.NET [14].
We began the research on ASP.NET and VB.NET for the
prototype implementation of the workflow system based on
XML, with database managed by TEXTML Server.
Thus, we could use the new integrated concepts, such as
XML Web Services and .NET Framework [15] (platform
independence, debugging, security services, inheritance,
garbage collection, etc).
Web Services are the emerging pattern for distributing
functionality over Internet. They are built over open patterns
and protocols like HTTP, XML and SOAP – Simple Object
Access Protocol (defined by W3C).
The functions that a Web Service makes available are
defined by another pattern: the language WSDL – Web
Services Description Language. These patterns allow the
software components to communicate each other, in spite of
the operating system in which they reside.
.NET Framework supplies types and services to support the
creation and distribution of Web Services. For example, the
namespace System.Web.Services supplies such types like
WebService, a class to access the ASP.NET functionalities.
5 Proposal Framework Architecture
We used the classic logical model of three layers (Data,
Logic and Presentation) to define the architecture of the
proposed framework (see fig. 1):
In the Data Layer are located the storage services and data
indexes. We used TEXTML Server as the back-end system.
They are necessary for integration and interaction of the
Document Base with legacy files of data.
For example, in our case study we crossed referenced
information with the digital library [16] of the Portuguese
Parliamentary meetings [17]. These services didn't modify the
stored files, maintaining the integrity of the database.
The logic business services are located in the Logic Layer
for the WPA. These services also include the rules and logic
of the business that will generate specific ASP.NET forms.
We decided to use the metadata outline of the XPDL – XML
Process Definition Language [21] defined in the Workflow
Process Definition Interface of Workflow Reference Model.
We used, in that way, a DTD that contained generic
information to model all the elements that compose the process
of a typical workflow: Participants, Activities, Transitions,
Applications and Important Data of Workflow. We created,
thus, a generic XML Schema based on this DTD.
5.1.3 XML Web Services
We used XML Web Services to offer for the framework the
functionality of a ubiquitous systems (anywhere, anytime,
anymedia, anydevice syndrome and context-aware). Because
each front-end needs a different view of the data and has a
different hardware architecture, it can have guaranteed access
to the system thanks to Web Services's interoperability.
Fig. 1: Architecture of the Proposal Framework
Finally, we have the Presentation Layer that contains the
services to establish the interface with the users and manipulate
the input data. Here we used specific XSL files to transform
the return XML document in an HTML file adapted to the
browser of the used front-end (PDA, mobile telephone, laptop).
5.1 Framework’s Elements
XML technologies are significantly different from classic
procedural programming languages both in structure, syntax
and nature. XML application development is also a completely
different process. XML application development begins with
developing the content model using XML Schema or DTD's
[18].
The proposal framework is composed by a interface API, a
generic XML Schema and the XML Web Services, as follows:
5.1.1 TEXTML Server Client API
We discovered that TEXTML Server can provide us
intelligent (dynamic) indexes that will facilitate the search and
the necessary cross-references for a generic multimedia system.
The documents are reconstituted from the repository, that also
collaborates with the bi-directional integration among the base
of XML data and the other types of binary files such as audio,
video and images. For this we use the TEXTML Server Client
API, desined by Ixiasoft [11].
5.1.2 Generic XML Schema
We investigated the WfMC metamodel and the XRL –
eXchangeable Routing Language proposed in [19] and [20].
6 Case Study: Portuguese Parliament
Starting from the generic XML Schema and based on
Potuguese Parliamentary rules [22], we generated an XML
document. This vision relates the infrastructure of the
workflow with each process<999>.xml document regarding
the hundreds of processes that will be generated in a
Legislative Session.
The workflow is also related with the Commission or
Commissions assigned to the Portuguese Parliament President
responsible for the path of those processes. Thus, we can infer
cross-references in the Processes, its Activities, and its
responsible Commissions.
For each Activity of the Common Legislative Process, is
also associated with an Activity Performer, its Description and
other elements like the Restrictions to the Transitions (postconditions and pre-conditions for its accomplishment),
Simulation Data, Time Limits, etc.
A Process XML Schema was created to generate XML
documents that will keep the referring data to each/any process
type that can be appreciated by the Portuguese Parliament.
Emphasizing the multimedia characteristic of the proposed
framework, each element of this XML Schema called
DocumentType can be a binary file (audio, video, image, text)
that are added and indexed dynamically in the TEXTML
Server database.
We discussed here about the limit wanted for the system
granularity. Another element called Debates, for example, it
could be a simple text data - the proceedings of the meetings or another sequence of rich documents involved in the
Commission Debates as, for example, presentations done in
MS Powerpoint©, video and/or audio of the meetings,
journalistic staff (newspapers, magazines, TV) presented, etc.
Summarizing, any information that can be coded digitally.
That discussion helps to solve the first great objective of
our research: the degree of granularity of the XML documents
used for the definition of a WPA system.
7 Conclusion And Future Works
The effective interrelation between the XML family and the
WPA facilitates a great variety of data queries in XML
documents or any indexed binary file stored in a XML
database, like the TEXTML Server Document Base.
The resolution of these subjects leads us to the key point of
our research: the capacity of cross-reference in XML
documents with other files or legacy databases. For the
specific problem of our case study we will test this with the
Portuguese Parliament (http://debates.parlamento.pt) legacy
system.
We are in the final phase of the study of XPDL API,
TEXTML Server Client API and the definition of the
ASP.NET webforms. These elements are the main ones of the
constitute the framework here proposed. At the moment we
have not found any academic work that uses XML Web
Services nor XML databases to implement solutions in WPA
systems.
Our next step is the effective integration of the proposed
framework with ubiquitous applications [23] and front-ends
[24] of the new mobile world, mainly PDA’s and the third
generation of mobile phones that already facilitate the use of
MP3 audio files, images and video.
As a future work project, we intend to analyse the use of
XML database versus relational database and describe the
inherent aspects of the integration of heterogeneous systems
based on XML Web Services.
References:
[1] Kirsten Lens: Modeling Interorganizational Workflows
with XML Nets. Proceedings of IEEE International
Conference on System Sciences, 2001.
[2] German Shegalov: XML-enable Workflow Management
for E-Services across Heterogeneous Platforms.
The
VLDB(Very Large Data Bases) Journal, Vol 10, Issue 1, pp
91-103, 2001.
[3] Qiming Chen et ali: Dynamic-agents, Workflow and XML
for E-Commerce Automation. Proceedings of Electronic
Commerce Automation, pp 314-323, 2000.
[4] Lerina Aversano et ali: Integrating Document and
Workflow Management Tools using XML and Web
Technologies: a Case Study. 6th European Conference on
Software Maintenance and Reengineering, 2002.
[5] Michael zur Muehlen: A Framework for XML-based
Workflow Interoperability – The AFRICA Project. Americas
Conference on Information Systems, 2000.
[6] Ultimus, Inc.: Groupware, Workflow and the role of
Ultimus. www.workflowzone.com, 2001.
[7] WfMC – Workflow Management Coalition: WfMC
Workflow Reference Model. www.wfmc.org/standards, 2001.
[8] BPMI – Business Process Management Initiative: BPML
Specification. http://BPMI.org, 2001
[9] Gail Kaiser and G. A. Bolcer: SWAP: Leveraging the Web
to Manage Workflow.
IEEE Internet Computing.
http://computer.org/internet, jan-fev, 1999.
[10] A. Riera et ali: Entorno Docente Basado en PDA (PDA
based Learning Environment).
Actas del Simposio en
Informática y Telecomunicaciones, 2001.
[11]
IXIASOFT,
Inc.:
IXIASOFT
White
Paper.
www.ixiasoft.com, 2001.
[12] Arnaud Sahuguet: Kweelt, the Making-of: Mistakes Made
and Lessons Learned. http://db.cis.upenn.edu/Publications/,
2000
[13] Dave Sussman et ali: Professional ASP.NET, Wrox
Press, 2001.
[14] Craig Utley: A Programmer’s Introduction to Visual
Basic.NET. Sams Publisher, 2001.
[15] Microsoft, Inc.: Microsoft Visual Studio.NET
Professional. DVD-ROM, 2002.
[16] Joaquim S. Pinto et ali.: Modelização e Concepção de
uma Biblioteca Digital (Concepts and Modeling of A Digital
Library). 2º Congresso Luso-Moçambicano de Engenharia,
FEUEM/FEUP, 2001.
[17] Joaquim S. Pinto et ali.: Portuguese Parliamentary
Records Digital Library. ICEIS’2001 International IEEE
Conference on Enterprise Information Systems, 2001.
[18] Larry Kim. XML integrated development Environments,
White Papers and Analyst Reports at www.xmlspy.com, 2002.
[19] W.M.P. van der Aalst et ali.: XRL/Woflan: Verification
and extensibility of an XML/Petri-net based language for interorganizational workflows, Proceedings of the 6th Informs
Conference on Information Systems and Technology , 2001.
[20] W.M.P. van der Aalst et ali.: XML Based Schema
Definition for Support of Inter-organizational Workflow,
University of Colorado and Eindhoven University of
Technology Report, 2001.
[21] WfMC – Workflow Management Coalition. XML Process
Definition Language. www.wfmc.org, 2001.
[22] Assembéia da República de Portugal. Regimento da
Assembléia da República (Portuguese Parliament Laws).
Assembléia da República – Divisão de Edições, 2000.
[23] Anthony C.W. Finkelstein et ali.: Ubiquitous Web
Application Development – A Framework for Understanding.
6th World Multiconference on Systemics, Cybernetics and
Informatics, 2002.
[24] Richard Han et ali. WebSplitter: A Unified XML
Frameworl for Multi-Device Collaborative Web Browsing.
ACM Conference on Computer Supported Cooperative Work,
pp221-230, 2000.