=Paper=
{{Paper
|id=Vol-61/paper-7
|storemode=property
|title=Software Agent Technology in Mobile Service Environments
|pdfUrl=https://ceur-ws.org/Vol-61/paper7.pdf
|volume=Vol-61
|dblpUrl=https://dblp.org/rec/conf/mservices/SesslerKV02
}}
==Software Agent Technology in Mobile Service Environments==
https://ceur-ws.org/Vol-61/paper7.pdf
Software Agent Technology in Mobile Service
Environments1
Ralf Sesseler, Alexander Keiblinger, Nicolas Varone
DAI-Lab at Technische Universität Berlin
Sekretariat FR 6-7, Franklinstraße 28/29, 10587 Berlin, Germany
{sesseler, keiblin, nvarone}@dai-lab.de
Abstract. The demand for mobility in modern societies leads to the develop-
ment of smaller and wireless networked computational devices. The resulting
service environments for future mobile service networks will be complex. The
individual character of future services requires highly flexible service infra-
structures and development frameworks. We propose agent technology for the
implementation of mobile services to reduce the complexity of mobile service
infrastructures. We present JIAC IV, a Java-based agent framework designed
with the service as a modelling abstraction. JIAC IV delivers a highly inte-
grated set of tools for the analysis, design, and development of agent-based
software services. Utilising the JIAC IV agent toolkit, a service developer fo-
cuses on application logic using agent services and the co-operation between
agents. This will lead to faster service development cycles despite the increas-
ing complexity of the environments. Encapsulation and communication be-
tween independent functional units can be a way to manage future complexity
of service networks, and software agents are its technological implementation.
1 Introduction
The digital economy has been driven by two main phenomena: the tremendous suc-
cess of networked services powered by the Internet protocol family and the need for
mobility in modern societies, addressed by the equally successful mobile telephony.
Mobile services (m-services) are positioned just at the crossroads of these two hetero-
geneous worlds. The next generation of electronic services does not only rely on the
smart integration of technologies, it also needs identification and handling of a new
array of arising business opportunities. Making the most of these opportunities will
require new approaches and tools.
Agent technology [1] is a promising way to realise the basic infrastructure for the
supply of m-services. Agents perform their tasks autonomously and flexibly by inte-
grating reactive, goal-driven, and interactive behaviour. Agent societies are open and
dynamic and may be distributed logically as well as physically. Thus, multi-agent
systems provide the flexibility and openness required for m-commerce. Our approach
extends agent technology by a service concept that enhances the interoperability of
agents and maps services to the agent level. In addition, our agent toolkit JIAC IV
1
This work was funded by T-Systems-Nova Deutsche Telekom Innovationsgeselschaft mbH.
(Java Intelligent Agent Componentware, Version IV) offers a comprehensive frame-
work for the development and deployment of multi-agent systems.
In this paper, we consider the particularities of m-services compared to e-services
and examine the requirements for m-services successively from a user and a provider
point of view. We will introduce the JIAC IV agent framework and outline how its
features meet m-service specific requirements. In more detail, we describe the
mechanisms of JIAC IV that enable a high degree of flexibility and dynamics in pro-
viding and using services.
2 Scope and Definition of M-Services
A common and broad definition of m-services is the act of providing and consuming
services through wireless handheld devices such as cellular phones, personal digital
assistants (PDA), laptops, or any other wireless enabled device. Usually expected to
be the next wave of electronic services, mobile services (m-services) enable users to
access networked services anywhere and anytime. From all the numerous aspects
characterising any e-service solution, such as availability, reliability, ubiquity, instan-
taneity, and usability, we have identified the latter two as the main properties
differentiating between e- and m-services.
Usability describes the comfort in the utilisation of devices and services regarding
size (device, keys, screen), multimedia capabilities (colour, sound, CPU), and user
interfaces (input capabilities, menus). Usability is also affected by the access method
(dial-in or always-on) and the network performance parameters. Handheld devices
used to access m-services have to get along with a smaller set of resources in terms of
memory, processing power, storage capacity, and display size in comparison to the
devices used in e-services. Technology is pushing the limits in the field of stationary
and mobile technology simultaneously, while bandwidth differences persist.
The second main aspect to consider is instantaneity, which indicates how quickly
and efficiently a transaction can be performed. It also enables impulsive and un-
planned user activities. Consider a car driver listening to his favourite song in the
radio. At this moment, the user may have the desire to buy the CD of the artist. In a
conventional e-commerce scenario, the user has to delay his transaction until he has
access to a networked computer. In the upcoming m-services world, the user will be
able to place an order directly, resulting in a higher factor of instantaneity.
Office computers are likely to have a broader bandwidth and to be continuously
on-line, but suffer from restrictions on privacy depending on the employer’s policy
with respect to usage and system configuration. Home computers provide a higher
degree of usability because the user has full administrative control. Public Internet
access points have no or few advanced personalisation functions, but tend to become
more and more widely available enabling a higher degree of instantaneity. Laptops
and PDAs cope with these notions of privacy and personalisation, but have a narrower
bandwidth due to air network access constraints and limited multimedia capabilities.
Handhelds have even more restricted multimedia capabilities, but they offer a higher
degree of portability and can be used instantly in many situations.
E-Services
home
desktops
office
public
usability
laptops
M-Services
pda
handsets
instantaneity
Figure 1. Relationship between usability and instantaneity
M-services are usually represented as a subset of all e-services, implying that any
e-service could be made available from a wireless device. Instead, we see an inverse
relationship between usability and instantaneity spanning a gradual transition from
e-services to m-services (Figure 1). Therefore, m-services should be recognised as a
unique business opportunity with its own unique characteristics and constraints and
not just an extension of an organisation’s Internet-based e-services channel.
2.1 M-Services: A User Perspective
A typical e-service usage takes more time than a typical m-service usage. Usually, an
e-service user wants to compare competing offers and to switch between them. He
processes much more information before proceeding. M-services fulfil a spontaneous
need or desire, accomplishing a well-defined task in a well-defined context. The
respective process and the user interface should be designed to enable a simple
utilisation. Automated mechanisms that are easily accessible have to be provided to
complete the task efficiently.
Certain similarities between e- and m-services, especially the following common
issues should be addressed: security, personalisation, service aggregation, high avail-
ability, and network and terminal independence. Security is a fundamental challenge
any m- or e-business project is faced with. It is a topic extensively documented in the
literature with solutions implying the utilisation of standardised encryption, authenti-
cation, authorisation, and non-repudiation mechanisms. Personalisation mechanisms
should drive and assist the user experience and save time in the navigation and input
of data. New business models require the flexible assembling of services. The goal is
to enable a smart collaboration between actors of the value chain and to lead the crea-
tion of transversal services. The aggregation of services will provide the user with a
homogenous view on his m-commerce experience.
Another common constraint is availability. Systems have to guarantee high avail-
ability, be robust with respect to hardware and software failures, and also enable
smooth maintenance operations such as on-the-fly reconfiguration or component
replacement. Maintaining a high level of reliability will create trust and loyalty rela-
tionships between business partners. The user interfaces have to be flexible and adap-
tive enough to fit the targeted device. Applications have to be aware of the kind of
terminal used and provide user interfaces and content accordingly. Due to the possi-
bility of intermittent wireless network coverage, applications have to be able to work
in an off-line mode and to make use of methods to restore the user context after an
interruption.
2.2 M-Services: A Provider Perspective
The user experience with current Internet-based e-commerce will set the basic de-
mand for the level of security, usability, personalisation, and availability of
m-commerce services. The service providers in the mobile environment will have to
catch up with these standards, but also integrate the location and situation awareness
in a consistent manner. This awareness needs to be invisible to the end user or be
easily accessible from the user interface of the end user device. The service providers
need to integrate information regarding the location, price, availability, and content of
services as selection criteria into the service infrastructure. These constraints result in
a demand for context sensitivity and user adaptivity of mobile devices.
There are some fundamental commodities an m-service provider infrastructure
needs to offer. The upcoming world of dynamically selected services needs support
for short and overall savvy service development cycles to reduce costs.
Capabilities for dynamic maintenance, management, and extension of the infra-
structure as well as of single services have to be supplied. Distributed accounting and
billing mechanisms are needed which are easily scalable in a highly dynamic service
environment. Special precautions have to be taken with respect to the security of
services, accounting, and user data.
Additional data sets with user and community profile data and location data have
to be merged into an integrated, user-adaptive data model. Given the high cost for
content, infrastructure support for content exchange or recycling between different
media channels is required. Acting on the assumption that complex services will
become aggregations of sub-services from different providers, mechanisms for billing
between service providers are needed. These have to be supported within the overall
mobile network infrastructure.
Considering the technological and social challenges described earlier, we recom-
mend agent technology as a well-suited software paradigm for the upcoming service
environments. Agent technology has been designed for complex, distributed, and
open environments. Decentralisation helps to cope with the complexity problem of
service infrastructures. Software agents are encapsulated entities, which interact at a
level of formal semantics. Mobile agents are able to travel between platforms to fulfil
their tasks at different locations. The agents can reside within the provider network
infrastructure or on the end user device. Stemming from decades of research in the
field of artificial intelligence, agent technology has the additional benefit of operating
at a higher level of abstraction than procedural or object-oriented techniques.
3 The JIAC IV Agent Toolkit
Before going into detail about some specific aspects of JIAC IV, we will give an
overview of the whole toolkit in this section and motivate some of its features by their
relation to the requirements for the realisation of e- and m-services we stated above.
JIAC IV is intended as a comprehensive toolkit for developing and deploying
multi-agent systems. The metaphor of a service is used as an abstraction of interac-
tions between agents as well as of interactions between the user and the system. It
allows a service developer to focus on his business logic in terms of modelling the
content of a service, of the processes of providing and using a service, and of the
relationships between agents. The level of the operation of the services, the interac-
tions between agents, and the end user access is realised by the capabilities of the
agents, the functionality of the agent infrastructure, and the generic access scheme,
which are part of the JIAC IV system. Already integrated are also mechanisms for
security and management functionality. In addition, the toolkit delivers an integrated
set of tools for developing agent-based software services. The implementation of the
toolkit has reached a stable working state and will be publicly available soon.
The toolkit covers design methodology and tools, component and control architec-
ture, agent languages, a FIPA compliant infrastructure, management and security
functionality, and a generic scheme for user access (Table 1). For a detailed over-
view, see [2]. Though it is a generic agent toolkit, JIAC IV has many features suit-
able for the realisation of platforms for e- and m-services. These features are outlined
in the following. We also refer to [3] regarding the relation between our toolkit and
electronic marketplaces.
Table 1. The JIAC IV Agent Toolkit
JIAC IV Agent Toolkit
Architecture Development Run-Time
component control methodology tools infrastructure administration
architecture architecture
components knowledge analysis configuration platforms configuration
roles reactivity design compilers migration fault manage-
messages deliberation implementation debugger white pages ment
interaction evaluation yellow pages end user
security access
A crucial aspect of e- and m-services is the interoperability in the context of an
open and dynamic environment. The service scheme of JIAC IV allows interactions
to be established and performed dynamically. Required information and support for
interactions are provided by the agent infrastructure based on the specifications of
FIPA [4]. To exploit the dynamics of the environment, the agents require the ability
to act in a flexible and autonomous way. Therefore, the control architecture of agents
in JIAC IV integrates reactive, deliberative, and interactive behaviour [5]. Reactivity
allows dealing with opportunities and other suddenly changing circumstances that
may occur. The deliberation process uses the set of available capabilities to flexibly
perform the given tasks. The integration of interactivity includes the capabilities of
other agents into these single-agent control processes. By combining dynamic selec-
tion of services and flexible control of agents, services may be provided, accessed,
and assembled from more basic services automatically or in collaboration of the user
and his agents. Thus, particular e- and m-services do not remain separated, but are
integrated into larger interoperating service environments. This reduces the develop-
ment effort and increases the benefit for the user.
The special requirements of commercial applications on the reliability, trustwor-
thiness, and maintenance of the system are addressed by several management and
security functionalities. Management services include configuration, fault manage-
ment, and the logging of system processes, which may be used for analysis as well as
for accounting. Security issues are handled by an integrated infrastructure supporting
authorisation, authentication, and privacy mechanisms [6].
Additional functionalities for management, security, and others may be integrated
and adapted easily due to the overall modularity of JIAC IV. At the agent level, the
modularity is attained by a component system allowing the rapid creation and recon-
figuration of agents, since they are assembled of reusable and exchangeable compo-
nents and knowledge elements [5]. It is for example possible to add new communica-
tion transport facilities, to exchange the planning mechanism, or to replace a compo-
nent by an improved version at run-time. At the society level, modularity is a result
of the openness realised by the agent infrastructure. Thus, the implementation of a
service may be modified and extended without affecting its permanent availability.
Finally, the process of developing and deploying complex systems is supported by
an agent-oriented software engineering model. It is supported by tools for agent
specification and tools to analyse and debug the running system. Furthermore, the
toolkit includes a generic scheme for user interfaces, which translates agent function-
ality into services accessible by humans in multiple formats. Thus, JIAC IV allows a
rapid development of complex, distributed systems for service provisioning.
4 Dynamic Interactions Based on Services
The main objective of the service concept of JIAC IV is to gain a high degree of
flexibility and dynamics of interactions between agents. A crucial prerequisite of this
is interoperability, which is achieved by standardisation at different levels allowing
mutual understanding. For that purpose, all interactions are described as services in a
uniform manner and are performed by a generic protocol. Apart from interoperabil-
ity, this also enables the integration of interactions into the knowledge-based control
scheme according to the service descriptions. The agent infrastructure facilitates
communications and interactions between agents by providing information about
agents and their services dynamically. Finally, the user access translates services
from the agent level to the user level by mapping services and protocols onto user
interfaces. The details of this service concept are the topic of the next two sections.
4.1 Interoperability by Standardisation
Standardisation is a common technique to attain interoperability between agents. A
well-known example is the effort of FIPA [4] to provide a framework for the interop-
erability between different agent systems. But in open, dynamic, distributed systems,
interoperability is already required within an agent system of a single architecture,
because it lacks fixed, predefined boundaries and dependencies.
Since they use communications as the basis of interactions, most agent systems
employ standards for the format, the content, and the course of communications.
Agents in JIAC IV communicate by exchanging speech acts according to the FIPA-
ACL format [4]. The content of these speech acts is expressed in the knowledge
representation language of the agents using ontologies to define shared vocabularies.
Protocols facilitate the processing of communicative acts by prescribing the possible
courses of valid conversations in advance.
At the society level, interactions between agents are facilitated by an agent infra-
structure. Again, this infrastructure has to rely on standardisation to ensure access to
its functionality for all agents. Therefore, the agent infrastructure of JIAC IV utilises
the corresponding FIPA management specifications [4].
To bridge the gap between the agent level and the society level, the service con-
cept of JIAC IV introduces an additional layer of standardisation for describing and
performing interactions. From the society point of view, services specify interde-
pendencies between abstract roles of agents in an open manner. From the point of
view of a single agent, services allow flexible access to additional capabilities and
resources provided by the society. Thus, services standardise interactions in a similar
way as speech acts and protocols do for communications and as the infrastructure
does for agent societies.
4.2 Integrating Agent Control and Interactions by Services
As in many agent systems, the behaviour control mechanisms of JIAC IV [5] are
based on well-known knowledge-based techniques in the style of BDI [7]. Reactivity
is ensured by a rule-based situation assessment and goal-oriented behaviour is real-
ised by planning mechanisms. The usage of formal logics for knowledge representa-
tion allows the description and the control of agent behaviour at an abstract level in a
uniform manner.
The first step to integrate interactions into the behaviour control mechanisms of
the agents is to describe interactions in the same way single-agent actions are repre-
sented. Agents that rely on AI planning techniques usually describe actions in the
form of operators stating the conditions and effects of their execution to allow a goal-
directed behaviour control. In JIAC IV, interactions are therefore also expressed by
operators, while the execution of these operators is delegated to other agents. These
operators are called services because they express an action that the provider of the
service performs in order to reach an effect for the customer. Therefore, the service
operators have to describe the interactions from the point of view of the customer who
uses them in its decision process. The service provider handles services in a more
reactive manner, since it is permanently waiting for requests.
To represent interactions as operators has many advantages. Conditions and ef-
fects of the usage of a service are described explicitly in a familiar way. Interactions
may be selected by the agents dynamically as any other action, and the combination
of services or their integration into sequences of actions exploits the planning capa-
bilities of the agent. Thus, service operators allow flexible and automated interactions
between agents.
5 An Open, Generic Protocol for Service Access
A service operator only describes the circumstances of an interaction, but not how to
perform the interaction. The latter part is done by conversation protocols. Since all
interactions between agents in JIAC IV exploit services, they may be performed by a
common scheme, which is prescribed by the service meta-protocol with the provider
and the customer as roles.
customer start accept-
proposal
request
provider
propose
refuse agree reject-
proposal
end
(multiple providers) (single provider)
negotiation service
protocol protocol
reject accept failure done
end failure success
Figure 2. The Service Meta-Protocol
The meta-protocol of JIAC IV (Figure 2) for accessing services consists of three
phases. The customer initiates the protocol by requesting the service from one or
several providers. After negotiation of generic parameters, the provider agrees or
refuses the request. Then, the customer chooses the best provider based on service-
specific negotiations. Finally, this provider supplies the service. To retain openness,
negotiation and service supply are handled by embedded protocols that may be freely
defined for a service. For negotiation, common auction protocols may be used.
The meta-protocol is tightly bound to the concept of a service operator. On execu-
tion of such an operator, an agent initiates the meta-protocol as the customer and
hands over to the provider the instantiation of the operator as given by its conditions.
The result sent back by the provider contains the achieved effect of the operator.
Thus, the meta-protocol implements the process of delegating the execution of a ser-
vice operator from the customer to the provider.
Operators and protocols for services provide the agent only with the ability, but
not the opportunity to interact. The latter is the purpose of the agent infrastructure,
which constitutes a society of agents and facilitates interactions. As mentioned be-
fore, the agent infrastructure of JIAC IV draws from concepts of the FIPA manage-
ment specification [4]. Agent platforms are the organisational unit that constitute
societies of agents. Each platform has an Agent Management System (AMS) to ad-
minister its agents, a Message Transport System (MTS) as the default communication
channel, and one or several directory facilitators (DF) to manage available services.
Several platforms may be connected by mutual acquaintance.
The combination of service operators, meta-protocol, and agent infrastructure al-
lows highly dynamic interactions between agents. The DF provides up-to-date infor-
mation about available services and providers. It may be accessed on demand and in
a goal-driven manner due to the operator character of services. In addition, the cus-
tomer may choose a provider in the selection phase of the meta-protocol. Thus, the
service concept enables a dynamic access to available services and providers as well
as a dynamic selection of appropriate services and providers. Agents share their ca-
pabilities and may utilise the total functionality of an agent society to fulfil their tasks.
The only prerequisite is the ability to use the required ontologies and embedded pro-
tocols that have to be standardised in advance.
Another advantage of modelling interactions as services is the possibility to map
services from the human level to the agent level and vice versa. In the former direc-
tion, service parameters like costs, quality of service, and security requirements can
be integrated into the service descriptions and used as selection criteria. Functionality
such as accounting and billing may be supported by additional infrastructure services.
In the latter direction, services at the agent level may be made accessible to hu-
mans by translating the user role of the protocols to a user interface. The JIAC IV
toolkit encloses a generic scheme for these translations based on intermediary agents.
By separating the user interface and the service functionality in that way, some
specific restrictions of m-services may be addressed. The user interface can be
adapted to the capabilities of the device appropriately. The limited resources of the
mobile device are only used to run the interface and to handle data exchange to the
agent in the network.
6 Summary
We identified usability and instantaneity as the main aspects to be considered for
m-service solutions and found an inverse relationship between e-services and m-
services that form a gradual transition. Therefore, it is not sufficient to simply extend
the concepts and business models of e-services into the m-services world. M-services
have to be recognised as technically challenging but also as interesting new business
opportunities with unique characteristics and constraints. Aspects of services like
security, personalisation, service aggregation, availability, and network/terminal in-
dependence have to be considered in a new way. The individual character of future
services demands for highly flexible service infrastructures and development frame-
works.
Designed with complex service environments in mind and the service as a central
concept, the JIAC IV agent framework constitutes a toolkit for developing and de-
ploying multi-agent systems covering design methodology and tools, agent languages,
component and control architecture, and an infrastructure with integrated manage-
ment and security functionality.
We described the service concept that bridges the single agent level and the multi
agent level by providing a standardised but open way to describe and perform interac-
tions. At the single agent level, the integration of interactions into the behaviour
control allows the dynamic selection and combination of services. The service con-
cept of JIAC IV enables the agents to profit from the openness and dynamics of the
service supply. The usage of agent technology for the realisation of e- and m-services
allows the transition from the static, stand-alone services of today to the dynamic,
interconnected service environments of tomorrow.
7 Related Work
BDI-style agent architectures are based on the work of Bratman [8]. Like other BDI
architectures, JIAC IV draws from the conceptual framework of BDI in a pragmatic
way without implementing a belief-desire-intention logic. The modular structure of
JIAC IV is comparable to component-based architectures (e.g. [9]). The use of tool-
kits in order to support the development process of agent-based systems is widespread
(e.g. ZEUS [10], AgentBuilder [11]).
The basic idea of software agents as mediators has been described by Guttman et
al. [12] for the domain of e-commerce. We focused mainly on the user adaptivity as
the main difference to e-services. The model of [12] consists of six steps: Need iden-
tification, product brokering, merchant brokering, negotiation, purchase and delivery,
and finally product service and evaluation. They argue that agents are of benefit
mainly for product and merchant brokering and for negotiation because of their
autonomy.
Our view of mobile services has been inspired by the European perspective of cur-
rent mobile GSM services and the upcoming UMTS services as represented in [13].
Although security issues are commonly regarded as very important in the context
of mobile agents, architectures with enhanced security features are sparse. Mole [14],
another mobile agent platform, deals mainly with life-cycle aspects, localisation, and
transactions. Access control lists are a well-known feature of Aglets [15]. In the
Ajanta framework [16] security is managed similar to our approach by use of creden-
tials and authentication protocols. Additionally, it provides a proxy-based mechanism
for protected resource access.
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