The Concurrency Control On Web's Terrace And Its Application In ERP

The ERP system on Web's terrace is a completely open system, which is based on the Web's environment and is dynamicly expansible. On Web's terrace, applications are divided into the presentation layer, the business layer and the service layer. The presentation layer is constructed in accordance with the form of HTML. The business layer is encapsulated to components. The service layer is deployed in according to the distribution pattern. Application modules are totally departed with system integration frame and communicate with each other through the frame. The system have plenty of integration ways with the exterior. The combination of Web and distributed system also brings concurrency control some new characters. In Professional work, operations often include several connections. Therefore operations include multi-transaction. It is insufficient to merely gurrantee the completeness of the database physical transaction. Although COM+'s technique supplies transaction management mechanism, it can not guarrantee the atomicity of a deal. This paper proposes a timestamp-based concurrency control protocol to resolve this problem. Moreover it suggest to make timestamp according to the deal in term of ERP. By means of control the granularity of timestamp, conflicts between multi-users can be decreased and the concurrency degree may be increased.The XML stands for Extensible Markup Language (The abbreviation of extensible Markup Language, The meaning is the mark language that may be extended). The XML is a set of semantic mark definition regulations. These marks separate the file into many components and identify them. It is also a meta-marked language, i.e. it defines what is used to define other semantic and structural marked languages related with special fields. XML technique is applied to ERP on Web's terrace in this paper. As a kind of medial data carrier, XML files can be encapsulated into data islands when downloaded to clients. HTML elements can be binded to them. Data are transfered by means of XMLHTTP instead of FORM, and this becomes a common pattern of batch updating. The strong points rest with the better organized submitted data and the richer data quantity. Furthermore this data submitting pattern reduces the mutual between the server and the client and decreases the frequency of page switching, so brings convenience to the users.