Yaojin Yang and Lasse Pajunen
Nokia Research Center, Nokia Corporation, P.O.Box 407, FI-00045 Nokia Group, Finland
Keywords: Mobile device, business process, Business Process Execution Language for Web Services
(BPEL/BPEL4WS), user interface development, Web Services, Service Oriented Architecture.
Abstract: Thanks to the increasing popularity of mobile devices, for accessing business process powered services
people now can use various devices for different circumstances or tasks in order to have optimized
performance. To support this kind of heterogeneous situation, user interfaces must be agile enough to adapt.
In our research, we have identified five key requirements and five design guidelines to help developers to
achieve this. Furthermore, we have introduced the concepts of user interface process and user interface
service, where user interface development for business processes is well positioned in a bigger picture of
Web Service and Service Oriented Architecture. Our research results have been presented by a case study
developing a group messaging system.
Supporting user interface agility, which is an ability
to accommodate present and future changes on user
interfaces, is becoming more crucial for developing
successful business processes. In business processes,
people and computer systems co-operate to achieve
common business goals. Due to the increasing
popularity of mobile devices, people tend to use
heterogeneous devices for executing their tasks.
Each business process usually involves multiple
people. Therefore, the types of devices used in
business processes are becoming quite extensive.
Every participating device requires an appropriate
user interface to provide as good as possible user
experience. In addition, a business process usually
involves more than one role. Each of these roles has
its own interaction logic for interactions between a
user and the process. Therefore, each role requires
its own user interface. The extensibility and
multiplicity of devices and business roles make the
support of user interface agility an important
requirement in developing business processes.
Offering a system or framework for
implementing user interfaces for business process
environments has been a topic of many research
projects. PerCollab (Chakraborty, 2004) is a system
that integrates business processes and various user
interface technologies. In that system, an interaction
controller manages all interaction with users. This
approach puts much weight on the interaction
controller. Therefore, it is suitable when a user
interaction is simple, a basic request (for example
filling in one form) from the user. However, we see
that more complex user interaction is often needed.
Other similar systems or frameworks have also been
made. GreenBSN (Liang, 2005) and WOSE
workflow framework (Lican, 2005) are some of the
examples, where a gateway is used to provide a most
suitable mobile interface for devices and to find a
most suitable service for a certain situation. In Lynx
(Velez, 2005), user interaction is implemented on
top of an email system.
However, our research has been concentrating
more on architectural issues of supporting user
interface agility rather than developing specific
techniques or systems. (Van Gurp, 2006) have also
been working on a rather similar field. But, they are
focusing on non-functional architectural
requirements in general. Our research results include
identified requirements for developing user interface
for heterogeneous devices enabled business
processes and proposed design guidelines that can be
used in designing such systems. Particularly, we
have introduced concepts of user interface process
and user interface service. The user interface process
is responsible for generating particular views for a
Yang Y. and Pajunen L. (2007).
In Proceedings of the Ninth International Conference on Enterprise Information Systems - SAIC, pages 179-184
DOI: 10.5220/0002379401790184
certain user interface. It runs in parallel with
business processes. In a Web Service enabled
environment, functions implemented by the user
interface process are published as a user interface
service, which is a first-class service. We verified
and evaluated the results by applying them to a
group messaging case.
The rest of the paper is organized as follows. In
Section 2, we will analyze typical situations in
heterogeneous devices enabled business processes
and will present requirements for suitable solutions.
In Section 3, we will propose a set of guidelines that
could be applied to a design and to an
implementation of the design. In Section 4, we will
use and analyze these guidelines in a group
messaging case study. Section 5 will identify some
future research topics, and finally in Section 6, we
will draw conclusions.
In heterogeneous devices enabled business
processes, user interfaces tend to change. A desktop
is no longer the only device for a user. Instead, the
interaction resource now consists of a dynamic set of
devices including both desktops and mobile devices.
A mobile device has different user interface
capabilities compared with a desktop and can also
have different capabilities compared with other
mobile devices in different models. Even the
capacities of the same device can vary when it is
operating in different context. The user interface
capabilities includes hardware capabilities such as
screen size, communication bandwidth, input
mechanisms etc., and software capabilities like a
browser capability, support of communication
protocols etc.
In addition, mobile devices introduce push style
interaction, where information is automatically
delivered to users instead of being manually
retrieved. This new type of interaction requires
customizing user interfaces to have different
interaction logic. On the desktop side, email based
applications have similar situation. Therefore, user
interface logic should be aware of the underlying
interaction model and also be adapt to that.
Furthermore, in business processes there are
usually more than one role in existence for
interaction between a user and a process. Each role
has its own interaction logic and one user could act
in one or more of these roles. That is, each role has
its own user interface and the user interface
provision needs to be role based.
By analyzing mobilized business processes, we
have discovered following requirements for
supporting user interface agility in developing the
heterogeneous devices enabled business processes.
R1: Providing customized user interfaces for
each type of devices with a unique set of capabilities
participating in business processes. This enables
users using devices with different capabilities to
interact with the same service provided by the
business process.
R2: Providing customized user interfaces based
on an available communication channel. This
enables users in any context to access the same
services using the same device. Switching between
different user interfaces should be supported when
the communication channel has been changed. The
selection could be made by users or automatically by
a system. For example, user interfaces for a Web
browser is provided when a high-speed channel is
available. However, when a high-speed channel is
not available, SMS based user interfaces can still be
provided to access the service. In addition, off-line
user interfaces could be offered where no
connectivity is available or allowed.
R3: Providing new customized user interfaces for
new types of devices after business processes have
already been deployed. When new types of devices
are used, users should be able to use them to
participate in processes immediately with a
minimum user effort required. Also, there should
not be any effect to the existing and running system.
R4: Supporting both pull and push approaches
with different interaction logic implemented in user
R5: Providing user interfaces based on users’
roles in business processes. Different roles conduct
interaction with services in different logics. An
appropriate user interface should be provided once a
certain role is initialized. Switching between
different user interfaces should also be supported
when the user’s role has been changed.
Based on the requirements above, we can say that a
system of heterogeneous device enabled business
processes should have a clear separation between its
user interface and business logic. Then, user
interface variation will not have any impact on
business logic. In addition, the system should have a
clear separation between its user interface
presentation and data that is going to be presented in
order to facilitate the user interface customization.
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Furthermore, the system should offer a flexible and
standard based deployment mechanism, so that it is
able to dispatch role based user interfaces or
customized user interfaces for new types of devices
after deployment time.
Finally, because the system aims for providing
and executing business process based services, it is
straightforward to implement it as a Web Service
based system, which secures the system to be an
open and standard-based environment.
Hence, we have outlined the following
guidelines that we should take into account when
designing such systems. However, the outlined
guidelines do not aim at providing specific
techniques for satisfying the identified requirements.
Instead, the guidelines aim at building a framework
for facilitating the development that is going to
realize the requirements. As a result, there is no one-
to-one mapping between the guideline and the
G1: Model-View-Controller (MVC) is the
general design pattern for designing a system of
heterogeneous device enabled business processes,
because of its supporting of loose coupling between
user interface components and business processes.
G2: In the MVC model, View module needs to
be further decomposed into the components of
presentation and the components of view generation.
Each device has its own user interface infrastructure.
The components of presentation are part of that
infrastructure; the components of view generation
are independent of that infrastructure and
responsible for generating views. The component of
view generation is the place where the user interface
customization is realized. Customization includes
both presentation customization and the user
interface logic customization. The set of components
for generating views for certain customized user
interface could be a stand alone deployment unit.
For instance, a set of components responsible for
generating HTML views and a set of components
responsible for generating XForms views are two
deployment units. Inside a View module, a client-
server structure and messaging based
communication can be adopted as design patterns for
achieving loose coupling between presentation and
view generation. This is necessary if the components
of view generation are deployed on a server side
instead of on a device side, which is a similar case
compared to Web application development.
G3: Model module consists of business
processes that control dynamic nature of the data,
which are independent of user interfaces.
G4: Controller module deals with user inputs and
manages view generation components according to
the results of service invocation, and it also takes
care of interpreting user inputs, determining which
service to invoke, and then invoking that service. It
is used as a communication hub between the view
module and the model module.
G5: There are three types of component-level
communication in existence in the system: device
internal communication, server-side internal
communication and cross boundary communication.
The device internal communication makes use of the
device’s native communication infrastructure for a
better performance. The server-side internal
communication adopts standard messaging
mechanisms in order to achieve maximum
interoperability. Cross boundary communication
should adopt a standard mechanism if possible. A
bottleneck may be lacking support for the standard
mechanism from mobile devices. Therefore, it might
need to have adaptation components for enabling the
standard-based device-to-server communication.
4.1 Introduction
We have designed and implemented a system of a
group messaging process by taking the design
guidelines into account.
In the group messaging process, a person can
send messages to a group of people, and any person
on the recipient list can receive and read the message
and then send acknowledgement to the sender. The
messages can be either plain textual messages or
textual messages with binary attachments. One
typical scenario is that (Figure 1). Firstly, all users
who are going to send and receive group messages
need to join the process and register their devices.
Then, the sender composes a message, and sends the
message. The system delivers the message to a
group of recipients. The delivery can be performed
in either push or pull style. It is decided by the
specific type of device that the recipient is using.
Once the recipients receive the message, they read it
and then send acknowledgement to the sender. The
system delivers the acknowledgement to the sender
in the same way of the message delivery. The sender
then checks the acknowledgement status from all
recipients. If acknowledgement has already been
received from all recipients, the sender tells the
system to delete the message. If not, the sender
continues to wait for new incoming
acknowledgement. Finally, all users quit the group
messaging process.
Figure 1: Group messaging sequence chart.
In this case study, there are three different types
of devices that are going to be supported: desktop
computers, high-end mobile devices with a decent
HTML browser, and low-end mobile devices with
SMS as the only messaging application.
4.2 Design
The design of the system is based on the framework
exposed by the guidelines (Figure 2). The system is
an application of the MVC pattern (G1).
Figure 2: High-level design of the system of group
messaging process.
In the View module, the class of Presentation
represents a collection of related components for
rendering device specific user interfaces; the class of
View generation is a collection of related
components for creating user interface views that are
then going to be presented locally in each device
(G2). Multiple instances of View generation will be
deployed onto the system. Each of them will be
deployed separately as a stand alone deployment
unit and will take care of one certain type of user
interface. Based on the types of devices that are
going to be used in this case study, desktop
computers, high-end mobiles with HTML browser
and low-end mobiles with SMS support only, we
decided to support two different types of user
interfaces, HTML-based and SMS-based. The
HTML-based user interface will serve both desktop
computers and high-end mobiles with pull style
interaction; the SMS-based user interface will serve
low-end mobiles with push style interaction.
Consequently, there will be two instances of View
generation deployed separately onto the system.
The instances could be deployed on device if the
device’s capability allows, but, in our cases, they
will be deployed on server in order to achieve better
performance and impose centralized control on view
The Controller module serves as a
communication hub between the View module and
the Model module (G3). It will take user inputs from
user interfaces, then interpret the inputs to requests
of invoking certain operations on a data model, and
finally manage the view generation to produce new
views of the user interface according to results from
In the Model module, the class of Business
process represents a set of related components that
implements group messaging related functions listed
in Section 4.1; the class of Data encapsulates the
data repository of the system and any data-related
lower-level services for accessing and manipulating
raw data (G4). In a message delivery procedure, the
message is firstly sent to and saved in the data
repository, and then retrieved from the data
repository and sent to recipients.
As proposed by the last guideline (G5), the
server side and device-to-server communication will
be based on a standard mechanism, while the device
side communication will be performed in the
devices’ native ways. About the standard
mechanism, we naturally choose the Simple Object
Access Protocol (SOAP) over other protocols as the
primary communication protocol, because it is a de
factor standard. However, since lacking SOAP
support from mobile devices or considering
performance issues, it is necessary to have additional
adapters to convert protocols between HTML and
SOAP and between SMS and SOAP.
4.3 Implementation
Figure 3 is the actual implementation of the system,
which takes advantage of several technologies.
We use the Business Process Execution Language
for Web Services (BPEL/BPEL4WS) (Curbera,
2003) as the implementation language of our
processes due to several reasons. Firstly, our system
is a business process-oriented system and all tasks
can be modeled and implemented as processes.
Secondly, the system is a long-running system,
Sender Recipients
System of
1.1. join group messaging and register device
2. compose and send message
3. deliver message
4. read and acknowledge message
5. deliver acknowledgement
6. delete message
1.2. join group messaging and register devices
7.1. quit group messaging
7.2. quit group messaging
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which especially requires compensation actions and
scoping to support failure recovery.
Figure 3: Implementation of the system of group
messaging process.
Thirdly, the system needs to rely on a flexible
deployment mechanism in order to be able to deploy
components even after initial deployment. Last but
not least, the system is a Web service based system.
Due to the flexible deployment mechanism
supported by BPEL implementations, we decide to
implement the instances of view generation,
presented in the design, as BPEL processes as well
and call those processes user interface processes.
Therefore, in the implemented system there are three
BPEL processes, HTML-based user interface
process, SMS-based user interface process, and
messaging process. The first two processes are
responsible for view generation and also act as
Controller role to connect the device to the
messaging process. The last process is where the
actual messaging related business logic is
implemented. We use ActiveBPEL BPEL
implementation to execute these three processes.
The HTML-to-SOAP adapter is implemented as
a Java Servlet, which can convert messages between
HTTP and SOAP. The SMS-to-SOAP adapter is
based on the Kannel, an open source SMS gateway,
which can convert messages between SMS and
Relational database, MySQL, is used as the Data
repository, which the messaging process can access
to through the Data service implemented on Java
Table presents realization relations from the
implementation component to the logical component
in design, and deployed-onto relations from the
implementation component to the deployment unit.
Table 1: Mapping table between implementation and
logical components, and between implementation
component and deployment unit.
User interface
generation and
BPEL engine
on server side
or user device
Group messaging
BPEL engine
on server side
Data service Data
Java runtime
on server side
Data repository Data
Database on
server side
Java Servlet
container on
server side
4.4 Experiences
First, having unique user interfaces for all types of
devices is impossible. Depending on screen size,
bandwidth, and interaction model, customized user
interfaces are required. However, HTML is a proper
technology for implementing user interface for most
types of devices, since a decent Web browser has
already been equipped in most mobile devices. From
most of the developers’ point of view, implementing
user interfaces in HTML is also less complicated if
compared with other technologies.
Second, user interface processes is a good means
to separate presentation from business logic and to
offer flexibility to interface customization.
Implementing a new type of user interfaces is just a
task of implementing another process. Different
types of user interfaces can be developed by
different people in parallel and deployed at the same
time. By this way, user interfaces could also be seen
as a service provided by the process. The user
interface service is a first class service in a Web
Service enabled environment.
Third, BPEL is good technology for
implementing Web service based, long-running and
process-oriented systems. Especially, the
deployment mechanism supported by BPEL
implementations offers a very flexible way to deploy
various customized user interfaces.
Fourth, since lacking SOAP support from mobile
devices or considering performance issues,
conversion between SOAP and other protocol is still
needed. Communication adapters are crucial parts in
the whole system.
Fifth, a controller is not necessary to be
implemented as a separate component. Combining a
controller and view generation into a single process
is usually more practical.
A) User interface as a service. As demonstrated in
the case study, user interfaces can be implemented
and published as a service. So far, we have only
presented the concept of user interface services, but
it will be more valuable to investigate and evaluate
this concept in the context of the ecosystem of Web
Service and Service Oriented Architecture.
B) Applying new user interface technologies of
mobile devices. Nowadays, many new user interface
technologies are emerging and maturing. For
example, AJAX, XForms, SVG, and Flash Lite
could be used in the future. However, from the
developers’ perspective, applying those new
technologies also brings new challenges. One of the
challenges we are particularly interested in,
regarding mobile business processes, is how flexible
an end-to-end architecture should be in order to
embrace those technologies? The architecture should
be able to support both centralized and distributed
user interaction logic and be able to help designers
and developers to make decisions on how to
distribute the interaction logic according to certain
C) Methodology and tool support for modeling
process-oriented system. A business process system
is a process-oriented system, which consists of
processes and collaboration among processes. There
are already methodologies and tools in existence for
modeling such systems, like Pi calculus (Smith,
2003). However, we still need to investigate whether
there are new requirements or what kind of
requirements are for the process modeling
technologies, when user interfaces can also be
implemented in processes or even when the
processes can be deployed on mobile devices.
In this paper, we have focused on how to provide
user interfaces agility for developing heterogeneous
device enabled business processes by identifying
key requirements and proposing five guidelines for
designing such business process systems. The
highlights from the presented research are the
architectural guidelines for developing systems of
heterogeneous device enabled business processes
and the introduction of concepts of user interface
process and user interface service.
Andrews T., Curbera F., Dholakia H., Goland Y., Klein J.,
Leymann F., Liu K., Roller D., Smith D., Thatte S.,
Trickovic I. and Weerawarana S. Business Process
Execution Language for Web Services. 5 May 2003.
Chakraborty, D. and Hui Lei. 2004. Pervasive Enablement
of Business Processes. Pervasive Computing and
Communications, 2004. PerCom 2004. Proceedings of
the Second IEEE Annual Conference on 2004
Page(s):87 – 97
Van Gurp Jilles, Karhinen Anssi, Bosch Jan. 2006. Mobile
Service Oriented Architectures (MOSOA). DAIS
2006, LNCS 4025, pp. 1 – 15, 2006.
Liang, Z. L. and Wong, R. K. 2005. A lightweight mobile
platform for Business Services Networks. Proceedings
of the IEEE Eee05 international Workshop on
Business Services Networks (Hong Kong, March 29 -
29, 2005). ACM International Conference Proceeding
Series, vol. 87. IEEE Press, Piscataway, NJ, 12-12.
Lican Huang, David W. Walker, Omer F. Rana and Yan
Huang. 2005. Dynamic Invocation, Optimization and
Interoperation of Service-oriented Workflow. Work-
in-Progress Section, the 5th International Symposium
on Cluster Computing and Grid Computing, Cardiff,
Wales, U.K. May 2005
Velez, I.P. and Velez, B. 2005. Lynx: An Open Email
Extension for Workflow Systems Based on Web
Services and its Application to Digital Government.
Telecommunications, 2006. AICT-ICIW '06.
International Conference on Internet and Web
Applications and Services/Advanced International
Conference on19-25 Feb. 2006 Page(s):160 - 160
Smith, H. and Fingar, P. 2003. Workflow is just a pi
ICEIS 2007 - International Conference on Enterprise Information Systems