The advanced management system of agricultural resources has been developed in GIS environment as a new means to manage a number of agricultural resources about agricultural production. This paper discusses the basic method for designing and implementing the system. The system includes also other key techniques of information sciences such as expert system and simulation. Otherwise, the system is also a user-friendly decision support system based on ARCVIEW 2.1 and designed to help the managers of agricultural resources sort and rank the resource application. The system includes a number of predefined categories for evaluating the decisions to use the agricultural resource. The work is concerned with the system modeling and integration in GIS environment. The problems of system architecture and O-O design are considered, and a brief description of some key techniques of the system. The system is ideally suited to solving complex and important management decisions about how to use agricultural resource and would seem to have great potential for aiding agricultural resource decision makers. However, both developers and commissioning organizations should be aware of the amount of effort that is required in order to elevate the working prototype to proven, commercially reliable systems. The principles used to establish the system could be applied for any other area in the world where is an appropriate information base and GIS to build advanced agricultural resource management system.
1. INTRODUCTION Advanced management system of agricultural resources is one of the most important tools to implement high efficient management of modernization agricultural production and makes more and more influence to the production. However, most of early management systems of agricultural resources were developed mainly in the environment of data base system, which makes the efficient management for agricultural resource that includes a lot of geographic information become very or extremely difficult problem because of the lack of advanced graphic processing function about geographic information in those systems. Otherwise, the user interfaces of those systems were usually very poor and unsatisfactory, so that they have been facing many difficulties in their practical applications. Latterly, GIS was used to introduce its function into those systems so as to largely improve and increase their performance and function, respectively. However, many application examples shown that the performance of those improved systems was not still satisfactory in most of practical applications. Major reasons resulting in this situation can further be discussed as follows. 1)Operation speed and function of various user interfaces designed and implemented by each user are not usually satisfactory because of the application of some unsuitable programming languages and methods, 2)User must spend a lot of time to integrate data base system, GIS and other support systems because of the low efficiency of codes of the above complex user interfaces and the lack of suitable framework for the integration, 3)It is very difficult in the above environment to fast build and implement the system model of complex application with the advanced object-oriented technique. However, our research shown that Esri�s ARCVIEW 2.1 provides a very satisfactory GIS environment and framework for redesigning the traditional management system of agricultural resources and implementing a management system of agricultural resources that has total new functions based on ARCVIEW 2.1 environment. This paper discusses mainly our new advances and partial achievements in the process to design and implement a district-level management system of agricultural resources. The main objective of this study is to develop a prototype system for implementing the management system of agricultural resources in ARCVIEW environment. The study is also aimed at providing practical experiences and management tools for building larger management system of agricultural resources and training managers of some important agricultural resources. The remainder of the paper is organized as follows. First, a brief review of the layered architecture model relevant to the design and implementation of management system of agricultural resources is provided. Next, the methods associated with the development and implementation of the model are described. Some experiences and results from application of ARCVIEW 2.1 with Avenue are presented to illustrate how to integrate a complex application system having several subsystems. Finally, some important conclusions are offered. 2. ARCHITECTURE MODEL Although management systems of agricultural resources have been widely used in agriculture production for many years, their application relevant to GIS in agriculture production is recent, and how to build a reasonable architecture model for designing and implementing the management systems based on GIS environment has been being a very difficult problem, so that the architecture model is rare to date. The management system described in this paper utilizes a layered model of architecture which involves the seven different layers shown in Fig. 1. The model is in practice a
widely accepted structuring technique. The functions of management system of agricultural resources are partitioned into a vertical set of layers. Each layer performs a related subset of the functions required to exchange information with another similar system which has the architecture. It relies on the next lower layer to perform more primitive functions and to conceal details of those functions. It provides services to the next higher layer. Ideally, the layers should be defined so that changes in one layer do not require changes in the other layers. Thus, we have decomposed one complex problem about how to construct management system of agricultural resources into a number of more manageable subproblems. The task of our research team was to define a set of layers and the services performed by each layer. The partitioning should group functions logically, should have enough layers to make each layer manageable small, but should not have so many layers that the processing overhead imposed by the collection of layers is burdensome. Further, we discuss briefly each of the layer. The environment data layer (first layer) provides the mechanism for managing the environmental data about the resource management, which include the data relevant to land, water, weed, crop, tree and other natural resources. While the first layer provides only the basic management for environmental natural resources, the second layer (weather data layer) attempts to make use of the services from the first layer and provides the means to manage the historical and current weather data about the agricultural resources. The basic service of the production data layer ( the third layer) is to provide the management for production data about agricultural resources, which includes various data about production tools, materials and facilities. The purpose of layer 4 (decision data layer) is to provide a mechanism to generate various data to support the decision about agricultural resource management. The layer complexity depends on the type of service it can get from layer 3. The decision layer provides a mechanism for making various decisions for agricultural resource management with the help of a number of decision models. The management layer is concerned with the integrated management decision for a number of special groups of agricultural resources. Its purpose is to define various standard application-oriented management decisions. The application layer about application of agricultural resource management provides a means for various users or application processes to access the management system. This layer contains management functions about the application and some useful mechanisms to support local and remote applications. 3. ARCHITECTURE IMPLEMENTATION According to the architecture model, the management system implementation can be divided into three subsystems. The first is basic resource management subsystem shown in Fig. 2, which encompasses the model�s layers 1, 2 and 3. The subsystem is
primarily intended to provide the "raw" management service of agricultural resources which is directly used by an end user and is the lack of decision support. Two main components such as GIS environment and data base management system support its major operation. The second is advanced resource management subsystem shown in Fig. 3, which is used to perform an analysis of basic management data from the first
subsystem and to recommend the best basic management decisions or strategies for the application subsystem. The management models, expert system and simulation models are used to support its major operation. The simulation models generate a complete data for each basic management decision of the expert system. In general, the expert system is capable of integrating the knowledge of several disciplines into a single knowledge based system of decision support. The properly developed expert system is a powerful tool for providing managers or users of agricultural resources with the day-to-day decision support need to use or assign those resources. The management models in the subsystem are some object-oriented programs designed to analyze alternatives over both numeric and non- numeric decision criteria. According to various different application requirements, the programs form the final recommendation for the best resource management decision given to an user�s preferences and perceptions about the set of management decision. The third is application subsystem of resource management shown in Fig. 4, which provides a
means for application processes or users to access the management system of agricultural resources. The subsystem is composed of three classes of models: local application models, which handle various services for local users, remote application models, which handle various services for remote users, and models for testing system functions, which provide for the testing of the system components and assist in fault isolation and identification. 4. ARCVIEW INTEGRATION The above subsystems can be regarded as collections of tools or methods that serve a special role in the decision of agricultural resource management. Rather than viewing these subsystem as black box entities, one can view them as collections of methods that are part of the application domain, which is called a real world model of resource management. Thus, we can use the real world model as the joining tool in systems integration. However, our research and experiences shown that ARCVIEW 2.1 provides a very satisfactory GIS environment and framework for implementing the integration. The object-oriented management model of agricultural resource based on the above architecture and ARCVIEW 2.1 is shown in Fig. 5. The O-O design does
not allow subsystems to communicate directly. All communication is governed by the real world model of the application domain which consists of ARCVIEW 2.1 kernel. Subsystems would communicate with the real world and not with each other. The advantage to this approach was that the management system would not be committed to or built around any specific type of subsystem, making the management system compatible with more application environments. Fig. 6 shows the class
hierarchy for real world model based on ARCVIEW 2.1. Considerations were given to a design that supports any management system of agricultural resources to satisfy various practical application requirements. The real world was constructed bottom up, which starts with objects that were known to be required for the decision and simulation as well as management entity of particular part in the real world was the presence of classes that represented collections of objects and of multiple inheritance. Our experiences have shown that the concept of ARCVIEW kernel is a viable approach to systems integration under the object-oriented paradigm. The user and manager�s view of the world and its behavior is the focal point of the entire management system. All special processing functions provided by subsystems such as GIS, simulation models and expert system are methods to ARCVIEW real world objects. In the practical implementation of the management system, the Microsoft�s VISUAL BASIC 4.00 and VISUAL C++ 2.00 as well as Esri�s AVENUE were used to implement the object-oriented model in ARCVIEW environment with the help of the architecture model. Especially, a number of scripts developed by AVENUE plaid very key role during integration of the management system, which make the design and implementation of some complex user interfaces become very simple. This integration process is shown in Fig. 7.
5. CONCLUSION The work in this paper described some major advantages of management system of agricultural resource designed and implemented by our new method. The scientific management of agricultural resource will become a very important part of modern agricultural production in next century and a new research direction in domain of agricultural engineering. The wide application of advanced management system of agricultural resource will reduce the huge loss of the resource due to poor management and use of the resource. The work to develop more efficient management system of agricultural resource will become a future challenge in modern agricultural production. However, our success and full experiences had shown that our current work and outcomes related to the research of management system of agricultural resource based on GIS environment provided a satisfactory ground and open a wider research domain for the development of future advanced management system of agricultural resource. 7. ACKNOWLEDGMENTS The authors wish to acknowledge the valuable contributions of other members of our research team to the research. They also acknowledge funding of the research by China National Foundation of Natural Sciences 8. REFERENCES Coad, P. And Yourdon, E. (1990) Object-Oriented Analysis. Prentice- Hall, Englewood Cliffs, NJ, 232 pp. Law, A. M. And Kelton, W. D. (1991) Simulation Modeling and Analysis. McGraw-Hill, Inc., New York, N. Y. Plant, R. E. And Stone, N. D., 1991. Knowledge-based systems in Agriculture. McGraw-Hill, New York, 364 pp. Martin, J.(1993) The Principles of Object-Oriented Analysis and Design. Prentice-Hall, Englewood Cliffd, NJ. 412 pp. Power, J. M. (1993) Object-riented design of decision support systems in natural resource management. Comput. Electron. Agric., 8: 301- 324. Anderson, J. R., Dillon, J. L. And Hardaker, J. B. (1977) Agricultural Decision Analysis. The Iowa State University Press, Iowa City, Iowa, 344 pp. Dent, J. B. And Blackie, M. J. (1979) Systems Simulation in Agriculture. Applied Science Publishers Ltd., London, 180 pp. Esri, 1994. Introducing ARCVIEW. Environmental Systems Research Institute Ltd., Redlands, CA, 98 pp. Esri, 1994. Introducing Avenue. Environmental Systems Research Institute Ltd., Redlands, CA, 120 pp.