Database Access Through Java Technologies

As a high level development environment, the Java technologies offer support to the development of distributed applications, independent of the platform, providing a robust set of methods to access the databases, used to create software components on the server side, as well as on the client side. Analyzing the evolution of Java tools to access data, we notice that these tools evolved from simple methods that permitted the queries, the insertion, the update and the deletion of the data to advanced implementations such as distributed transactions, cursors and batch files. The client-server architectures allows through JDBC (the Java Database Connectivity) the execution of SQL (Structured Query Language) instructions and the manipulation of the results in an independent and consistent manner. The JDBC API (Application Programming Interface) creates the level of abstractization needed to allow the call of SQL queries to any DBMS (Database Management System). In JDBC the native driver and the ODBC (Open Database Connectivity)-JDBC bridge and the classes and interfaces of the JDBC API will be described. The four steps needed to build a JDBC driven application are presented briefly, emphasizing on the way each step has to be accomplished and the expected results. In each step there are evaluations on the characteristics of the database systems and the way the JDBC programming interface adapts to each one. The data types provided by SQL2 and SQL3 standards are analyzed by comparison with the Java data types, emphasizing on the discrepancies between those and the SQL types, but also the methods that allow the conversion between different types of data through the methods of the ResultSet object. Starting from the metadata role and studying the Java programming interfaces that allow the query of result sets, we will describe the advanced features of the data mining with JDBC. As alternative to result sets, the Rowsets add new functionalities that enhance the flexibility of the applications. These are analyzed and the approach is described. Next, we will describe Java Data Objects (JDO) Application Programming Interface, which is a way to store persistent data in databases, using plain old Java objects (POJO) to represent persistent data. The approach makes possible separation between data manipulation and database manipulation.