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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
EAI interfaces. That is not to say EAI platforms themselves 
cannot still provide useful services, from security to business 
process modeling, but certainly aspects of the proprietary 
formats for interface exposure will be commoditized in light of 
these new GML standards. The interoperation of distributed 
computers of different systems in different divisions of 
municipalities that web services enable falls into two primary 
categories: 
• Invoking Remote Procedures. Whenever one computer 
in a municipality division asks another computer to 
perform a function, that is known as a remote procedure 
call (RPC). RPCs are a staple of client-server 
architectures (Figueroa and Stusek, 2001). However, web 
services make RPCs dramatically simpler to carry out 
because they eliminate the need for the RPC to travel 
through any kind of proprietary interface that sits between 
the computers; and web services make it possible for 
computers to engage in RPCs even if they are running 
different operating systems and programming languages. 
• Exchanging Geospatial Data. Geospatial web services, 
because they use the universally accepted GML format for 
the transfer of geospatial data, are very good at helping 
distributed computers share data. For every transaction, 
the order-processing software (now itself a consumer of a 
separate service) sends a SOAP request asking for the 
exchange rates. In response, the provider computer sends 
back the exchange rates as another SOAP message. 
3. WHY SERVICE ORIENTED ARCHITECTURE? 
Traditionally, municipality’s information systems have been 
developed with a functional orientation often resulting in silos 
of services and information, preventing end-to-end business 
process visibility (Baptista and de Paiva, 2005). Enterprise 
application integration (EAI) and other traditional middleware 
solutions partially address this by enabling systems to 
communicate with each other, but they don’t fully solve the 
problem as they allow only limited business process 
adaptability (ESRI, 2007). Moreover, these traditional solutions 
come at a high cost, relying on proprietary technology and 
specialized and scarce skills. 
SOA helps address the fragmented IT landscape and addresses 
the difficulties associated with silos of IT infrastructure and 
applications (Panda D., 2007). There are three main benefits to 
adopting SOA approach for developing an EGIS for 
Municipalities (Figueroa and Stusek, 2001): 
• Using existing infrastructure. In the vast majority of 
cases, existing (legacy) applications have nothing wrong 
with them except for the fact that they do not interact 
easily with other applications, since their interfaces are 
typically closed and proprietary. Opening up applications 
with Web services and SOA generally means that the 
large amount of effort spent over many years enhancing 
legacy applications to support complex business rules 
does not need to be lost (Farrell, 2006; Sun, 2007). • 
• Reducing integration costs. Once an application is part 
of an SOA environment, it can easily be accessed by any 
other application, generally without change to the 
application. This allows a substantial savings to be 
realized in terms of redevelopment and integration costs 
(Farrell, 2006). 
• Increasing business agility. A business needs to be able 
to respond to changing market requirements quickly. SOA, 
by virtue of its self-defining, standardized nature, allows 
businesses to adapt by creating composite application 
functionality quickly (Liuand and Fan, 2007). 
However, critical success factors for an SOA implementation 
that alleviate and mitigate the challenges include defining 
coarse grained services and agile, loosely coupled business 
process (Shi, X., 2004). Furthermore, there is a need for SOA 
governance which provides a set of solutions, policies and 
practices which enable organizations to implement and manage 
an enterprise SOA. It is the SOA governance which makes it 
possible to realize ROI and the business benefits of loosely 
coupled services. In proposed methodology of this paper, GIS 
services grouped into three categories (Peng and Tsou, 2003): 
• Data Services: These types of services are tightly coupled 
with specific data sets and offer access to customized 
portions of that data. Web Feature Service (WFS), Web 
Mapping Service (WMS) and Web Coverage Service 
(WCS) can be considered in this group. WMS produces 
maps as two-dimensional visual portrayals of geospatial 
data. WCS provides access to un-rendered geospatial 
information. WFS provides geospatial feature data 
encoded in Geography Markup Language (GML) (OWS2, 
2004). 
• Processing Services: These types of services provide 
operations for processing or transforming data in a 
manner determined by user-specific parameters. They 
provide generic processing functions such as projection 
and coordinate conversion, rasterization and vectorization. 
Coverage Portrayal Service (CPS), Coordinate 
Transformation Service (CTS), and even WMS can be 
considered in this group (OWS2, 2004). 
• Registry or Catalog Service: These types of services 
allow users and applications to classify, register, describe, 
search, maintain, and access information about Web 
Services. Web Registry Service, Web Catalog Service, 
and our implementation of registry catalog service, Fault 
Tolerant High Performance Information Service, are 
considered in this group (OWS2, 2004). 
In order for SOA to work, interoperability standards related to 
all aspects of service operations are needed. Our proposed 
system uses the Open GIS Consortium (OGC) standards for the 
data finding and access, and OGC and W3C standards for the 
web services (W3C, 2004). In the geospatial web service area, 
OGC is modifying and extending W3C standards for the 
geospatial web services through the OGC web service initiatives 
(OWS2, 2004). 
4. ADAPTED SOA FOR DEVELOPING AN 
ENTERPRISE GIS FOR MUNICIPALITIES 
In this paper, we present some technical specifications of 
developed EGIS for the municipality of Tehran. Municipality of 
Tehran has already adopted by various desktop GIS as well as 
specific software with particular models and functionalities that 
deliver display of properties and services through web browsers. 
For this aim SOA used by flexible OGS standards and web 
services to be used in almost all applications and on all devices 
(Figueroa and Stusek, 2001). The core focus of this level of 
development is on the strategies available to managers of urban