基于MDA的数据仓库抽取元数据交换规则

Mapping Rules of DW Metadata Exchange Based on MDA

参照模型驱动构架(MDA)的思想,为各类数据仓库工具元模型,建立符合CWM(公共仓库元模型)规范的平台无关模型映射规则,以便在统一的规范上自由交换元数据.以Informatica公司的Powermart抽取工具为例,建立PSM(平台相关模型)元模型,以CWM作为平台无关的PIM(平台无关模型)元模型,用OCL(对象约束语言)描述PSM与PIM之间的映射规则,实现了Powermart的DTD(文档类型定义)到CWM SQL(结构化查询语言)的元数据转换.

CWM(common warehouse metamodel) meta model is independent of any platform and products.Data warehouse tools are specific.Basing on the principles of MDA(model driven architecture) model transformation,CWM represents PIM(platform independent model),dw tools presents PSM(platform specific model),the mapping rules from PSM to PIM are set up,transformation rules from PIM to PSM are defined,metadata exchange between different tools is realized.According to above-mentioned,specific transformation rules are defined to implement the mapping between PowerMart.dtd(ETL(extract transform load) tool of informatica company) entity elements and CWM ones.And according to the semantics,the mapping is described formally so as to provide a solution for metadata interchange in the field of data warehouse.