Middleware design for integrating relational database and NOSQL based on data dictionary

With the rapid development of WEB2.0 or the Social Web as well as the maturing of Internet retail, the traditional relational database is increasingly incompatible with the demands of availability, scalability for massive data, fast data backup and recovery. With the original purpose of large-scale web applications, NOSQL concept, abbreviation of “not only structured query language”, is proposed, which is a broad class of database management systems that differ from classic relational database management systems. NOSQL databases generally do not require a fixed formal schema and usually avoids join operations, so its efficiency for simple query is very high but not for complex query. In this article, a method is proposed to integrate these two types of database by adding middleware between application layer and database layer. We mainly design the detailed implementation of two modules which are data dictionary module and SQL processor module of middleware. The middleware would provide an unified interface and shield underlying data distribution for the applications, meet the need of horizontal scalability without affecting the application logic implementation.