【正文】 附錄 外文資料翻譯英文原文A platform for municating construction material information between emerce systems[16]Emerce systems are being increasingly important in the Hong Kong construction material procurement market. Currently，however, many etrading marketplaces have been developed, owned, and/or hosted by different panies. Each of the etrading marketplaces forms a closed system with their unique customers and clients. The totality of these etrading marketplaces appears to be islands in the sea, as they are isolated with no interoperation between them. Since material information in each etrading marketplace is limited，buyers usually cannot find all the required materials from one marketplace. This paper introduces a platform ，named ‘EUnion’, that enables interoperation between etrading marketplaces. The ability of marketplaces to interoperate extends the idea of liquidity and network effect by joining more buyers with more suppliers，without sacrificing the ability of each marketplace to be highly specific to the supplychain node or target buyer group it serves． This paper first discusses problems in a noninteroperable Emerce marketplace environment. Then two approaches for enabling interoperation between marketplaces，the mobile agent approach and the Web services approach， are introduced．The third part presents the concept, system architecture and functions of the EUnion platform．1 Problems in NonInteroperable ETrading Marketplace EnvironmentThe Webbased etrading marketplace contains two major functions：providing trading information and facilitating trading transactions. Users may log into the system as either buyers or sellers of construction materials. Sellers can upload their product information and find out summary information about their customers and their transactions. Buyers can search certain types of products，providing requirements such as brand，model, quality, price，etc.，or they can browse the products on display. When the products requested by a buyer are found，the information will be displayed to the buyer and the contact information of an agent closest to the buyer’s location will also be sent to the buyer. The buyer can negotiate with the agent about the price，or send an order to the agent by pleting some forms online. If the user could not find the desired products，the system will keep the inquiry in storage for access by the sellers.In recent years，several other construction etrading sites have appeared on the Web. They are operated by different organizations and attract different client groups．They specialize in trading materials from suppliers in different regions. From time to time, however，clients of one etrading system would like to buy materials that are not available in that system but are offered on other sites. One way to solve this problem is to let the client register with several etrading marketplaces and search these sites one by one.The variety and heterogeneity of different etrading sites create problems for material purchasers. Finding materials in these sites requires material purchasers to acquire and maintain a list of web addresses, to interpret and understand the semantics and navigation methods in different sites，and to integrate product information in these sites for evaluation manually. These kinds of material finding jobs can be time consuming and the material purchaser is required to keep abreast of new etrading sites as they e online．To provide better valueadded services to the clients，the concept of EUnion is presented by linking together relevant etrading marketplaces so that cooperation between the etrading marketplaces can be facilitated. In the etrading union, when an etrading site does not have the material requested by one of its registered clients，the site will send a request to other etrading sites in the union. The remote etrading site will treat the request as one from an associated client. An associated client cannot directly make use of the service of the etrading marketplace as its registered client. When the material requested is found, the remote site will inform the requesting etrading site, which will decide whether to submit an order on behalf of its client. Once a deal is made between the two etrading sites，the requesting site will inform the remote site of the contact information of an agent to whom the material should be delivered. It will also display the material information to the buyer along with the contact information of the agent closest to the buyer’s location. The remote etrading site will charge some extra amount of money，usually a certain percentage of the normal price, for providing the service． 2 Approaches for Enabling Interoperation between ETrading MarketplacesSince individual etrading systems are developed based on different putational architectures，platforms and software, it is not a trivial task to make them interoperable. Several issues need to be addressed in order to realize the eUnion concept. The first issue is how an individual etrading system finds the service from other sites and municates with each other. The second issue is how systems understand the various kinds of data from other systems，such as the query，order，and product information. Specifically，the data may be in different formats and databases for representation and storage. This section discusses two approaches for achieving interoperation between etrading marketplaces，the mobile agent approach and the Web services approach． The Mobile Agent ApproachA mobile agent is a puter program that can autonomously migrate between network sites，.，it can execute at a host for a while，halt execution，dispatch itself (together with its data and execution state) to another host, and resume execution thereall under its own control. It has been found that mobile agent is especially suitable for structuring and coordinating distributed applications running in a