broker, as in this infrastructure, not only data but services are to
be provided. The service broker for the Virtual Lang Agency
(Figure 4), supports the creation, execution. control and man-
agement of business virtual processes. It is composed of the
components explained in Section 5; the Workflow Service Cata-
logue, Workflow definition tool, Workflow rule engine and Ad-
ministration and control tool.
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its participating organizations
The proposed GSI broker is an Inter-workflow Management
System based on the work of Hayami and Katsumata, [4] and
the interoperability standards developed by the Workflow Man-
agement Coalition (WfMC), [1], with the main components of a
regular WFMS: a process definition tool, a workflow engine
and the administration and monitoring tool. Using the inter-
workflow method, the process is defined in hierarchy. One top-
level definition of the cooperative process is made in the Inter-
workflow definition tool and internal process definitions are
made in the enterprises.
The communication can be achieved using gateways as de-
scribed in the WfMC Interoperability, [1]. A gateway is a
mechanism that allows specific workflow products to move
work between each other.
7. QUALITY-AWARE SERVICE CHAINING
The previous sections have outlined the eminent evolution of
the GDI into a to take advantage of ICT advances and novel
business paradigms. The GSI is rooted in web services
technology, particularly dynamic chaining of geographic
information services to deliver functionality of value to the
user.
Dynamic chaining of services presents a novel model for
delivering geospatial solutions, products and services to diverse
communities of users. With state of the art standards for
business-to-business integration, GI services offer a real
opportunity for disparate GI enterprises (service nodes) to
dynamically discover each other, negotiate innovative business
propositions and collaboratively execute common business
processes to address a market opportunity and meet strategic
mission.
198
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
However, as the technology becomes mundane, the services
will proliferate and the number of users will explode.
Furthermore, the emergence of exciting but quality sensitive
applications like wireless and mobile location-based services,
and increased integration of GI services in mission critical
business processes, quality of service (QoS) emerges as a
critical concern and a major factor of competition on the
geographic services infrastructure.
Sustainable exploitation of GI services therefore demands
careful consideration of diverse user requirements and the
quality related constraints of service chaining in view of the
limitations of Web computing. Given the potentially large
number of services, each with distinct non-functional quality
characteristics, a first and necessary step towards providing
QoS guarantees in service chains will thus be to enforce QoS-
aware discovery and composition of services, in which services
are selected from a community to participate in a business
process based on their non-functional quality properties. Once
selected, the services can then be choreographed in their correct
sequence and their execution managed by a QoS-aware
workflow management system to ensure adherence to QoS
specifications.
Clearly, mechanisms to enable QoS-aware discovery and
composition of services, orchestration and execution service
chains in workflows become necessary. Similarly, a QoS model
defining important non-functional quality characteristics is
needed. These constraints can be imposed and managed by the
service broker shown in Figure 3.
Its notable however, that the notion of quality being advanced
here is beyond classical spatial data quality and extends to
include systemic and business process quality criteria like cost,
performance, reliability etc. QoS-aware service chaining, while
not providing hard QoS guarantees, will greatly enhance the
quality perceived by the user or Internet Gl applications, [13].
8. CONCLUDING REMARKS
Geo-information production services can be offered in a market
place, using the Web and Internet as the network environment
that can reach more customers at lower prices and taking
advantage of the efforts and advances on existing GDI concept
which will be improved to a Geo-information Service
Infrastructure (GSI), that as its name suggest, can offer data
plus services for all the geomatics players, including direct
contact with customers and their requirements, all together in a
virtual environment, composed of a collection of independent
enterprises offering their core competences and joining together
in a dynamic way to offer and produce complex products.
By using the concept of the virtual enterprise, the GSI has been
outlined. Such an enterprise can extend its share in the ever-
growing information mark by providing access to a variety of
GIS services and to be a tool to support the generation of
'complex' products/services. Such view will enhance the
existing geo-spatial data infrastructure concept. The geo-
information ‘service’ infrastructure opens new business
opportunities for service delivery, facilitating service search and
execution, and increasing the interest of organisations to
participate in geo-information infrastructure initiatives. It also
provide huge entry opportunities for "small niche players to
enter the market with specific offering. However. these
opportunities are limited by the availability of data/service
repositories and catalogues in the market.
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