ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS", Bangkok, May 23-25, 2001
A COMMON DATA MODEL AND REQUESTING LANGUAGE FOR SPATIAL INFORMATION MARKETPLACES
Matthew Y. C. PANG , Wenzhong SHI, Geoffrey SHEA
Department of Land Surveying and Geo-informatics
The Hong Kong Polytechnic University
Hung Horn, Kowloon, Hong Kong
Fax: (852) 2330 2994
e-mail: matthew.pang@polyu.edu.hk
Keywords: Spatial Internet marketplace, mediator, g-Commerce
Abstract
This paper investigates Spatial Information Marketplaces, its technical issues and applicability in the GIS industry. To facilitate
g-Commerce (Geographical Commerce), this paper adopted a well-known business model in e-Commerce, namely electronic
marketplace, into the market of geographical information (Gl) and geographical information services (GIServices). This new version of
electronic marketplace is termed as Spatial Information Marketplaces. This paper discusses the essential characteristics and components
in the marketplace. Follows that, the paper investigates the current developments and standards in geographical information
interoperation. Accordingly, based on the structure of mediating server, a possible architecture of the marketplaces is proposed. The
architecture makes use to the currently available standards developed by OpenGIS Consortium (OGC). Moreover, to cope with the needs
in manipulating different service providers in the marketplace, the OGC’s simple feature model is extended and a common requesting
language is developed accordingly.
1. INTRODUCTION
This paper investigates Spatial Information Marketplaces and its
applicability and technical barriers in the GIS industry. Spatial
Information Marketplaces consists of extremely devising services
and applications. This paper examines an architecture for
integrating heterogeneous service providers. The proposed
architecture extends the available standards in the industry.
According to a proposed architecture, a common data model and
requesting language that manipulate services from the
heterogeneous service providers are proposed.
Electronic marketplaces have been used extensively in
contemporary e-commerce applications. In an electronic
marketplace, huge amounts of data and services are traded
though the Internet. Both customers and providers in the
marketplace usually interest in a same market area, for example,
construction material. Improvements on efficiency, reduce
overhead for both buyers and suppliers, speed up business
process are advantages of electronic marketplaces [1].
Spatial Information Marketplaces is a spatial version of the
electronic marketplace. In the Spatial Information Marketplaces,
customers and providers trade in the market of geographical
information (Gl) and geographical information services
(GIServices). Since the Gl and GIServices are requested by
customers on demand, costs spent on GIS developing and
maintaining are greatly reduced. Moreover, the marketplace
offers huge number of services from which users can choice at
one single place in the Internet. GIService providers, such as
traditional software vendors, Gl providers, and specialized spatial
service providers expose themselves to an extremely large group
of customers locating all over the world. Costs spent on
advertisement and marketing are greatly reduced. Thus, the
marketplace provides a win-win situation to both GIS software
vendors and GIS users.
The concept of spatial information marketplace is a step forward
in the development of geospatial interoperability. Currently, the
GIS industry focuses geoprocessing interoperability on sharing of
geographic data set within and among geo-information
communities (2]. The concept of spatial information marketplace
facilitates a channel for delivering not only a sharable geographic
data set but also a total solution of geoprocessing services. The
new concept of geographic interoperability will absolutely prompt
the uses of geographic information technology [3]. Although the
spatial information marketplace is a new concept to the GIS
community, these technologies and standards developed in the
community are worthy foundations to its successful
implementation.
2. COMPONENTS OF SPATIAL INFORMATION
MARKETPLACE
A Spatial Information Marketplace shall consist of at least two
major components, namely, service providers, and infrastructure.
In a Spatial Information Marketplace, customers select services
from a huge number of service providers. These providers can
either offer on-line spatial data services (e.g. digital maps at
various re-solutions) or computational services (e.g. overlay,
digital terrain modelling, map production service) to users on
receiving their orders [4]. Data service is understood as a
collection of distributed geographic data sets that can be invoked
in a uniform manner and in a single location [4]. For example, a
spatial information marketplace can provide a unique requesting
mechanism for demographic data and land use data are
maintained in different data service providers. Computational (or
functional) services refers tc a collection of geographic data
manipulate functions those can be invoked from a single location
[4]. Actual implementations of the functions are installed at the
servers of their service providers. In the point of view of
customers, instead of purchasing these complex and infrequently
used functions, they can invoke the services whenever the
services are needed. Furthermore, since services are maintained
by professional persons, general users are benefited from the
high quality services with minimum expenditure. Examples of
computational services include noise-modelling service,
three-dimensional surface modelling, optimal route finding
service, marketing area analysis, and map coordinates
transformation.
Infrastructure of a Spatial Information Marketplace includes a
standardized users interface, from which various services can be
invoked. The interface should be user-friendly in order to maintain
willingness for customers to purchase services. Moreover, the
interface should possess a unique logical structure and a
common requesting language for different types of services.
Another element of the infrastructure is catalogue service in which
services are descried in a logical order. Customers search and
select services based on the descriptions provided in the
catalogue. An additional software component of the infrastructure
is mobile agent. The agent corporate the operation of GIService
from multiple service providers, in order to accomplish a complex
requirement from customer. Due to limited length of this paper,
mobile agent will not be addressed in this paper.
3. GEOGRAPHICAL INFORMATION INTEROPERATION
Geographical information interoperation refers to openness,
ability to exchange and commonality in user interaction in
manipulating geographic information in a distributed computing
environment. The technology is the backbone of Spatial
Information Marketplaces. Successful implementation of the
marketplace relies on a standard of geographical information
interoperability among the customers and the service providers.
