Tham khảo tài liệu 'enterprise service computing from concept to deployment_9', kinh doanh - tiếp thị, quản trị kinh doanh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 252 Yan Klein The so-called context driver defines the environment where the business process is engaged. The specific business-information entities that are contained by a business document can be derived contextually from the more generic core components. Example When a business process or document contains a date of order item its North American ISO International Organization for Standardization representation will be YYYY-MM-DD where each Y is a digit in the year M is a digit in the month and D is a digit in the day while the European representation of the same component will be DD-MM-YYYY. A context driver can translate the date of order core component into the proper format according to whether the geographical context is Europe or North America. Being able to use core components to create new documents that are mutually understandable is a very powerful semantic instrument. This flexible tool can help diminish the semantic gap of EDI technologies but only if it is globally accepted and widely adopted. At the same time the EDI history suggests that core components alone might not be able to close the semantic gap entirely Kelz 2004 . Since the WSDL standard for Web services only defines syntax and does not include any semantic definitions it is the responsibility of the service provider to deal with the resulting problems. To close this semantic gap one can use the recent OASIS standard UBL universal business language which is based on xCBL XML common business library and is harmonized with ebXML core-component specifications OASIS 2004 . UBL defines a set of standard business documents that build a common business vocabulary. Those documents can be used as a semantic layer for existing technologies such as Web services even though the EDI history suggests that it is unlikely that UBL will be the lingua franca of e-business. Nevertheless UBL can be used to add interoperability to Web services Gertner 2002 or to migrate from Web services to ebXML. .
