Keyword Geographical Information; System Integrating Method; GIS Software Integration
Abstract Component integrating model was brought up for integrating GIS software based
on component object model (COM) and Active X technique; The paper was also discussed the
creating methods and major technical point of component integration and repeatable class
objects; And finally, a clue and methods were furnished to the integrating GIS software with
two case studies of Land Management Information System and Monitoring and Evaluating
System of Coastal Reclaiming Lands.
1. Introduction
The information highway and “digital earth” plan has been becoming an actions of many
governments in the world under the current tendency. The geographical information system
(GIS) has its favorable developing circumstances and prospect as the wideness and the deepness
of GIS applications are appeared a trend in changing with each passing day depending on the
rapid development of computer development and great increasing of geo-information demands
from society. But, the acquiring, storing, analyzing, processing and presenting results of geo-information
need to be supported by GIS software. With the improving theory of GIS, and the
founding and the developing of geomatics, GIS software platform was rapidly passed a
developing procedure from GIS software packet to OpenGIS, WebGIS. As the diversity and the
structure differentiae, various commercial GIS softwares are not compatible with each other.
Due to the demands pushing forward the GIS software market, numerous function module were
brought forth to the market by many well-known GIS software companies. The integrating
issues are gradually becoming prominent between modular developed by users themselves and
commercial ones, different commercial software, different modular but same commercial
software. It is a “bottleneck” in applying GIS and GIS engineering construction.
There are usually two main integrating demands in developing applied geographical
information systems (AGISs) and building geographical information Projects (GIPs). One is to
create a friendly user interface, according to user’s requirements, by “inherent platforms”
supporting with one of commercial GIS software. It was intensified some analyzing, processing,
and output functions etc. and was developed to be a flexible and practical system; Another is
integrated the superior components selected from various commercial GIS software in order to
adapt the demands in building AGISs or GIPs. For the former one, it can not be satisfied to
different user’s typical requirements like some simulating models etc. even if each of the
commercial GIS software provided their own developing language or modular. And developed
programs can not be adapted to each other and have no repeatibility to the other systems.
Therefore, integrated techniques became a hot point with the GIS applications going on
advance. This paper was discussed briefly the integrated issues through the experience.
II.Approaches to integrate the software
With the characteristics of geo-information being the regionalism, delamination,
distribution, dynamic role and synthesis, it has been going into the departments of government
and enterprises passed over geo-science but widely spatial information service through network.
The main tendency of GIS applications is turned into the developing and integrating system
according to the user’s demands with the support of GIS software.
The software integration can be divided into two aspects: data integration and
components (functions) integration. Distributed database system and open database connection
(ODBC)are furnished the significant approaches for relative attribute data; For spatial data, the
data integration is mostly used the Import/Export for file exchange between different modular
in a GIS or in various GISs. Object oriented technique and Component Object Model (COM),
they are the technical fundament of integrated functions between the GIS software.
2.1 Component Object Model
Component object model (COM) is an object model of Client/Server and a standard form
of processing interface between various components of the software and applying programs.
According to the COM, a much more complicated and huge system can be set up by several
components integration.
COM standard is included structure standard and Dynamic-Link Library
(COMPOBJ.DLL) for executing. The first part is defined the mechanism of object creation and
communication between objects; The second part is provided inner service of COMPOBJ.DLL.
Communications between objects are implemented through COM connector that it keeps a
logical and semantic relation with a function sets. Component object can not only be a client
object but also be a server object. Even it can be both. COM is given a designing model of
object oriented. The component integration is implemented through the models that they set up
the complicated components and implement in coordination with software components in other
systems.
2.2 Active X technique
The purpose of using object linking and embedding (OLE) technique is to integrate data
from different applying programs or software easily and to coordinate the implementing
simultaneously between client programs and server programs with friendly user interface.
Automatic programming of OLE 2.0 allows the applying program detached from standard
macro-language but using script completely or macro driving. The essence of OLE is the
component software. The component, which developed by the other projects, controller or
applying programs, do not have to redeveloping and just use them in the applying program. The
combination of OLE and OLE controller techniques together were named Active X technique
by Microsoft.
ActiveX is a component technique based on distributed COM. It can make operating each
other between software components through network in spite of component programmed in
different languages. And ActiveX is an assembly of Open techniques that it is provided a
standard frame to create, to manage and to call the controllers based on the Object Oriented.
Through the connector of events, methods, and attributes etc., it is interchanged with applied
programs and built up an applied system which every GIS controller and non-GIS controller
integrated easily with using visual develop tools.
Now, the component technique is a main current of GIS software development. For
example, MapObjects, from ESRI, is provided 35 OLE (Object Linking & Embedding) objects.
GeoMedia Professional, from INTERGRAPH, is provided 11 group and 30 controllers as
programming objects. GeoMap, from GeoStar Information Project Company of Wuhan, is
composed of one OLE controller and nearly 20 OLE Auto objects by using Windows
developing environment. Hence, it is reasonable that to implement GIS software integrated
method based on OLE/ActiveX component. Under the support of visualization development
environment, any integrated target can be implemented by optimal composed of OLE/ActiveX.
And for the typical functions, the Application Programming Interface (API) functions can also
be integrated to it as repetitious class object composed.
