IskaWeb: A Web-Based Information System for the ...

IskaWeb: A Web-Based Information System for the Classification of Industrial Wastes J. O. Dada (corresponding author and presenter of the paper), H.-D. Kochs & J. Petersen Universität Duisburg-Essen - Campus Duisburg Fakultät für Ingenieurwissenschaften/Institut für Informationstechnik Bismarckstr. 90, D-47057 Duisburg, Germany (dada, kochs, joerg.petersen) @uni-duisburg.de Tel.: +49 203 379 3623, Fax: +49 203 379 2205

Abstract Industrial wastes must be classified at least two times on the way from the owner of the waste to the waste disposal facility in order to ensure that waste handling is in conformity with the law. Wastes classification as dangerous goods is up to now very difficult because they consist of many components with diverse dangerous properties. This paper presents the results of the IskaWeb project; a web-based information system we developed for the classification of waste products using branch specific expert knowledge. IskaWeb consists of many integrated software modules. The Web Interface is a collection of dynamic Hypertext Mark-up Language pages integrated into a rule-based expert system module with the help of Java Servlet technology. Building the information system required knowledge and expertise from several disciplines.

Keywords: Information System, Web application, Web Interface, Java Servlet Technology, Expert System 1. Introduction According to the law, industrial waste must be classified at least two times on the way from the owner of the waste to the waste disposal facility in order to ensure that waste handling is in conformity with the law. The classification takes place first of all when allocating the waste key number according to the “Europäische Abfallartkatalog (EAK)” [1] in the context of the creation of the disposal proof, and secondly with the allocation of packaging and transport regulations in accordance with “Gefahrgutverordnung Straße und Eisenbahn (GGVSE)” [2]. Since GGVSE is only designed for pure substances and compound substances with limited number of pure substances as components, the classification of wastes as dangerous goods is up to now very difficult because they consist of many components with diverse dangerous properties. The dangerous properties also depend very much on the waste production process i.e. waste origin. The rapid growth of the Internet and the Web provides highly customised, accessible, and interactive sources of information. It has a very good potential to serve as efficient means of communication of waste classification results to waste producing industries as well as the law enforcement agents. The main objective of the IskaWeb project presented in this paper is to join the branch specific expert knowledge and the capabilities of the Web to provide solutions to the difficulty presently faced with the classification of industrial wastes. Users can interact with the system web site anytime anywhere to classify waste. The user will contribute information about the origin, the compositions and other characteristics of the waste for the classification of production-specific waste. Classification will be a stepwise process where waste is considered to be a preparation consisting of several components (i.e. physical and chemical compounds), each of them contributing to relevant waste properties. For the classifications, a set of standard output parameters describing the industrial waste is used. The output parameters can either be taken from the system database or analytically determined. The system combines information received from the user through the Internet with the information in the database for the purpose of classification. The followings are some of the functionalities provided by the IskaWeb: • • • •

A comprehensive waste classification according to the new EAK [1], A secured and objective waste classification according to GGVSE [2] using a scientifically secured methodology, A general improvement for work protection during transportation, storage, disposal and utilisation of the industrial waste as well as Promotion of the exchange and spreading of information and knowledge about the problems of the waste disposal and recycling of waste.

Waste classification provides a general improvement for work protection during transportation, storage, disposal and utilisation of the industrial wastes, as well as a promotion of the exchange and spreading of information and knowledge about the problems of the waste disposal and recycling.

2. Waste Classification Method Waste classification is based on laws [1,2,3,4,5,6]. The method adopted for the waste classification in this project is based on rule-based expert system using a simple if then rules. The regulations for the classification, which are contained in the laws, are interpreted and formulated into decision rules by experts. The domain experts based on the IskaWeb rule syntax for writing rules developed the classification rules using a forward chaining approach. The classification rules are organized in a tree like structure. The tree represents the conceptual structure of classification rules as shown in figure 1. There are three kinds of nodes in the tree: Root, Node, and Leaf. Root is the starting point of the knowledge base. Node represents one section of laws/regulations. Law section may have many sub-sections, as shown in the diagram. Leaf means final result will be made at that part of the law. Each classification rule corresponds to a node in the tree structure. Laws/regulations

Root Node Leaf

Fig. 1. Tree structure of classification rules [11] For automatic compilation of the classification rules into Java source codes, we developed a rule compiler using object-oriented methods with Universal Modelling Language [7,8] and Java Compiler Compiler (JavaCC) [9]. The Java source codes are then compiled into Java byte code i.e. Knowledge Base (KB) module, which we used to develop an expert system. The steps involved for the compilation of rules into KB module are shown in figure 2.

Law Text

Interpretation into Rules by Expert

Rules

Rules in JavaByte-Code (KB) Fig. 2. Generation of knowledge base module from rules

Rule Compiler

Rules as Java Classes (Source Files)

We compiled the components of the waste based on the survey conducted on some selected industries that produces wastes. The waste components together with waste physical and chemical properties, and the components properties are then used for the classification of waste in IskaWeb. Waste classification start with the extraction of facts – preparation (i.e. waste) with properties and compositions from the database. Facts are then saved in the memory. Rules are applied upon these data. As soon as some rules fire, new facts (data) will be derived during the classification process. These new facts (data) will also be saved in the memory. Rules are applied on the updated data, and derive again new facts. The process goes on and on, until a limit has been reached. The limit signifies the end of classification process i.e. the rules have examined all the properties involved in GGVSE or EAK classification. The classification rules determine basically the preparation’s dangerous properties, transport class properties, and precedence of hazards etc. of a given waste.

3. IskaWeb Structure IskaWeb (figure 3) is implemented in a distributed computer environment using client/server technology. The system follows a three-tier architecture and consists basically of 5 main components/modules: System Database, Expert System, Servlet Web Interface and Database Tables Interface modules. These modules are briefly explained in this section.

Web Browser (Clients / Users)

Web Browser (System Admin)

Web Browser (Domain Engineers) Internet

HTTPS

Apache Web Server

Servlet Engine Expert System Module

Servlet Web Interface Module (SWIM)

Database Tables Interface Module (DTIM)

JDBC/Oracle Call Level Interface

System Database Fig. 3. IskaWeb structure

3.1 System Database Located at the heart of the IskaWeb is the system database. The system database consists of the following three logical modules: • • •

Material database – contains materials data and properties as contained in [1, 2], Waste database – contains waste and waste components data with their properties, branch specific information and waste keys and Knowledge Base – contains rules written by expert.

The system database resides on Window NT platform running the Oracle 8i Database Server. Oracle 8i has support for SSL over HTTP connection to the database with a strong authentication and data integrity over the network, and possible encryption for Java Database Connectivity (JDBC) [10] connections to the database.

3.2 Expert System Module We implemented the Expert System (ES) as web application. The ES module consists basically of two main components; the KB module i.e. Java byte code and the inference engine, which are invisible from the outside world. The inference engine is able to infer conclusions or solutions from the KB based on the user-supplied or stored facts. The user interface requests information from the user and outputs results with explanation. The inference engine implements the reasoning mechanism or capabilities of the KB. An inference consists of three stages: matching, conflict resolution and execution. The inference engine has a working memory, a repository of classification rules, and it executes the rules. Figure 4 shows the components of the expert system module and their interfaces with other modules in IskaWeb.

KB-Servlet Module

Rule Objects

Working Memory

Database Interface

Inference Engine

Object Instantiation

System Database

Rules in JavaByte-Code (KB Module)

Fig. 4. Components of the expert system modules

3.3 Servlet Web Interface Module (SWIM) SWIM implements the web interface for the IskaWeb. Users use the web browser to communicate with the system. SWIM establishes the communication and interchange information between the system and the users

through the web browser (Internet Explorer/Netscape Navigator). It maintains and controls the flow of data between the user and the system. SWIM is based on Java Servlets technology [10]. Servlets are applications running on the web server to manage client’s requests. The Servlet serves as interface between the remote user and the inference engine through the web server. The communication between the web browser (client) and the Apache web server used in our project is over a Secure Socket Layer (SSL) i.e. HTTPS. Since the system is multi-users system, there is need to manage individual session. We achieved this with help of Servlet session tracking. When a user makes a request, a session ID is created for the user, which identifies the user throughout user interactions with the expert system. There are three categories of users: The domain experts, the system administrator and the general users. SWIM consists of 3 sub-modules: Knowledge Acquisition (KQ) Servlet, KB-Servlet and Administrator (AD) Servlet modules) for each of the user categories. The general users use Knowledge Base (KB) Servlet to interact with the expert system. The user begins consultation with the expert system using web browser. In some part of the consultation, the expert system could need information from the users, when user gives the information, the expert system modifies its working memory and stores this value that will be available until the end of the consultation. The KB-Servlet module handled the web server interactions with the inference engine. The domain expert uses the KQ-Servlet module for interacting with the system while the system administrator uses the AD-Servlet module for system administration through a web browser.

3.4 Database Table Interface Module (DTIM) We used relational database for the persistence layer but the programming language used is object-oriented. The DTIM implements the object-oriented interface for the relational Database. It interfaced the expert system module and the SWIM to the database. DTIM uses JDBC for connection into the database.

4. IskaWeb Prototype A prototype of the IskaWeb has been implemented and can be assessed through the web site "http://IskaWeb.de" (Password protected). Figure 5 shows a sample of waste classification result. Various steps that are involved before the result of the classification is presented to the user are in http://IskaWeb.de.

Fig. 5. Sample waste classification result

5. Conclusion Waste classification is not only a legal issue but also has economic meaning. It provides a general improvement for work protection during transportation, storage, disposal and utilisation of the industrial waste, as well as a promotion of the exchange and spreading of information and knowledge about the problems of the waste disposal and recycling. In this paper, we have presented a web-based information system - IskaWeb for the classification of industrial and commercial wastes. Our method for waste classification in IskaWeb is based on rule-based expert system. We implemented the expert system as web application, which we integrated into the Apache web server using Java Servlet technology. Initial tests carry out by the industrial partners and other users confirmed the suitability of IskaWeb for the classification of wastes. However, the present knowledge base for IskaWeb is based on some selected waste producing branches. Future work will be to extend the knowledge base to other branches. The interface for the knowledge acquisition also needs to be improved upon to incorporate more operators and to guide the domain expert in writing rules.

6. Acknowledgment We acknowledge with thanks the financial support from Deutsche Bundesstiftung Umwelt for the project work presented in this paper.

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[2]

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[3]

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[4]

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[5]

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[6]

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[9]

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[10]

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[11]

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