The Design On Syntax Analyzer In Data Flow Query Language

As a great number of real-time data are generated, there are great needs for operation on those data during the running process. The present database systems cannot meet the needs of operating on real-time data. Even the real-time database systems are lack of real-time and accuracy during the running process of dealing with data flow. As a result, a new form of data processing appeared, which is called data stream.Data steam processing needs continuous query. As the generation of data, the result of data processing should be output constantly.The present database technology is suitable for processing and storing static recordset databases. It cannot be used in constant and rapid processing of data flow, and does not support continuous queries. So, after studying on the technology of data flow processing, based on PowerStream prototype systems, the paper suggested constructing PSL editor and syntax analysis systemThe main innovations are as following:1. Employed C++ and MFC technology to develop PSL editor and syntax analysis system, and realize the functions of editing, code generation and analysis and testing the system in Windows environment.2. Designed PSL language which has the features of easy-writing, simplicity and semantic clearness. Expended the traditional SQL language. Realized the function of operating on data flow. Supported continuous queries and real-time update on the dataflow. Meanwhile, the paper improved data definition language and data operation language.3. Used the technology of C++ program to call Lex and Yacc to realize the functions of syntax and Lexical analysis on PSL language. Supported PQL language which is used by Power Stream prototype systems, and lowered the difficulty when employed Power Stream system to design and using4. Used the C++ technology to realize syntax analyzer, to realize the functions of syntax and Lexical analysis on PSL grammar; Improved the fLexibility and self-definition in syntax analysis.5. Conducted testing on PowerStream prototype systems. The output result of PSL edior and syntax analysis system had been used in PowerSteam and proved that the PSL system is practical and usable.