The Sustainability of GIS Services in The Framework of E-Government



3. The role of spatial data and gis services in the e-government initiatives

3.1 The E-Government Initiatives
The term E-Government is generally agreed to derive from electronic government. E- Government introduces applications to support various dimensions and ramifications of government and has the following general service areas:
  • The delivery of public services, where there is an online, Internet based, or electronic aspect to the delivery of the services
  • The conduct of government business where the activities of those involved in the process of government itself (such as legislators and the legislative process) where some electronic or online aspect is under consideration. E-Government provides many opportunities to improve the quality of services to the citizen (G2C), to business (G2B, B2B) as well as to government institutions (G2G), as detailed in [9] and many Web- pages about e-government initiatives in many countries.
The evolution of E-Government initiative went through 4 stages of development (the Economist, 2000):
  • The 1st Stage: Public and private institutions publishing information about themselves (the emerge of Web pages)
  • The 2nd Stage: Two-way communication, allowing citizen to provide new information about themselves
  • The 3rd Stage: Multi-purpose citizen portal, providing quantifiable services; the delivery of geo-information and geo-services can be included
  • The 4th Stage: Portal personalization; portal that integrates complete range of services and based on needs and functions, not on department or agency. The portal will perform the task of ‘brokering’ to locate, request and chain services from various service nodes, according to the specifications set by service requestors. The proposed on-line cadastre portal eCAD in this paper falls in such category.
3.2 The Role Of Location-based Services In The E-Government.
The Cadastre register and topographic base maps are amongst the Base Registers that are essential for the information infrastructure of the society, such as population, building, and enterprises corporation registers. Many identifiers of base register objects are generated from real estate identifier. The spatial description of real estates provides the opportunity to integrate real estates and objects inside them with other GISs.

Most of documentation for basic topographic features as well as for land administration in many countries, however, is still in paper form which makes it difficult to search and access to the required information in these documents. Modern GIS and ICT technologies offer the opportunity to computerized records (base maps, registers, plans, deeds, index map) as well as the integration of new medias (maps, pictures, balances). Further, the Internet and Web technologies found its way in the cadastre business and several initiatives took place in many countries to improve the delivery of cadastre services over the Internet, as reviewed in [10], such as:
  • Land Register On-line for the delivery of data and cadastre service on the Internet.
  • Provide National Land Information Service Electronically.
  • Electronic conveyance via electronic official seal and signature implemented to replace the paper documents and bridging the process of registration and conveyance.
This paper is proposing a supplementary functionality to these initiatives, a customized, on-stop, portal for on-line delivery of location-based services, focusing on cadastre services. Such services can be either simple (i.e. services provided by a single organization in the cadastre business) or a complex one (i.e. a service composed by the chaining of several functionalities in various organizations). In this respect it is important to develop policies for standardisation, legal aspects, pricing, distribution, etc. in the environment of a National Spatial Data Infrastructure NSDI. Data from different sources and with will be integrated; several GIS functionalities can be invoked and used in all kind of new combinations.

4. On-line GIS services portal, eGIS portal

4.1 The eGIS Architecture
The goal of the proposed eGIS Portal, as shown later in Figure (4), is to provide a single place where agencies in the cadastre business can post metadata that describe their resources (data and services) and where they clients can go to discover and request services from these resources through brokerage service. The Portal is a means for agencies (private and public) to share existing resources through web services. The Portal also includes the necessary services, which are needed to coordinate, chain and control the execution of identified services. Several technologies are needed to perform these tasks such as Web services providing GIS functionalities, workflow management services, service brokers, etc., as shown in figure (2).

Service brokers maintain registries containing relevant service metadata to aid the discovery of required services. Workflow management services control and coordinate the execution of service chains, both intra- and inter-enterprise, negotiate and enforce adherence to quality of service specifications (service level agreements) while shielding the client from the complexities of the chaining process. The service broker and WFMS are thus central components of the proposed eGIS Portal. Other essential tools to extract and harmonize data sets as well as to invoke a service from the participating agencies, are embedded in the under laying layer of protocols for networking distributed databases and service nodes and achieving interoperability amongst them. The current form for the spatial data infrastructure architecture can realize such layer.

The functionalities required realizing such portal, as shown in figures (1) and (2), are:
  • Data brokering functionality to analyze requests and locate spatial data and cadastre data and services, and delivery of services.
  • Services to create and search data and service registers.
  • Chaining functionality to chain services from various organizations.
  • Web services to access wide range of GIS functionalities.
  • An integrated framework for data and service interoperability.
  • Spatial data infrastructure functionalities to support access to spatial data and geo-services.
In the following, some of these functionalities are described in details.


Figure 2 eGIS architecture overview


4.2 State-of-Art for Web Services
Web services are a new breed of Web application. They are self-contained, self-describing, modular applications that can be published, located, and invoked across the Web. Web services perform functions, which can be anything from simple requests or complicated business processes. In other words, web services are interoperable building blocks for constructing applications. Further, responds to requests can be immediate (synchronous web service) or delayed depending on complexity of processes (asynchronous web services). Web services and consumers of Web services are typically businesses, making Web services predominantly business-to-business (B-to-B) transactions. An enterprise can be the provider of Web services and also the consumer of other Web services.

The Web Services Description Language (WSDL), an XML language, is used to define Web services (as a set of operations, messages and binding protocols) and describe how to access them in a specific format. More details can be found in [2], [5].

4.3 Chaining Service
The proposed eGIS architecture, figure (2) supports Business Process Management (BPM) technologies to facilitate adaptive enterprise functionality. The Workflow Chaining Service (WFCS) executes workflow processes and correlates and coordinates synchronous interactions into collaborative and transactional business flows. It is an infrastructure service for modeling, connecting, deploying and managing and executing business processes. The Workflow Manager:
  • Allows composite web services to be defined
  • Integrates asynchronous services
  • Coordinates multi-step business processes
  • Publishes business processes as Web Services
  • Invokes automated processing flows
For each process, the WFCS takes a BPM script (written by Business Process Execution Language BPEL, a language enables task-sharing for distributed computing) that describes the workflow or processing chain to be executed, a WSDL document that describes the interface that the process will present to clients, and the WSDL documents that describe the service instances that the process may invoke during its execution. From this information, the process is made available as a Web Service (or called Service Chaining) that can take place across the Web in such a way that any cooperating entity (a participating agency or service node) can perform one or more steps in the process the same way. Farther, the programmer might describe a business protocol that formalize what pieces of information is needed for such step (for the generation of a product for instant) and what exceptions may have to be handled (such as technical constraints, data heterogeneity, business constraints). Further details can be found in [1], [2], [4], [5].

As described in ISO 19119, there are many possible approaches to composing chains of processing services into aggregate or compound service components. General patterns can be used to describe these approaches based on, for example, the visibility of the services to the user (or client application) as well as the difference in how control of the services is managed. Using these criteria, Figure (3) shows several patterns.


Figure (3). Service Chaining Cases (from ISO 19119, OGC Topic 12)


These chaining patterns include:
  1. User defined (transparent) chaining: the client application manages the workflow and control of the chain is exclusively with the user of the client application
  2. Workflow-managed (translucent) chaining: in which the client application invokes a Workflow Management service that controls the chain and the user is aware of the individual services; a workflow service controls the chain execution, perhaps with oversight by the human user of the client application
  3. Aggregate service (opaque): in which the client application invokes a service that carries out the chain, with the user having no awareness of the individual services; the aggregate service exclusively performs the control function with no visibility by the client application.
Page 2 of 3
| Previous | Next |