Summary

Java's strength for distributed network computing, which when augmented with database access, gives systems developers features they have lacked before, such as:

• Easy object to relational mapping
• Database independence
• Distributed network computing

A Java based two-tiered model will not work well in complex applications because the database is required to be on the same machine as the Web server. This is mainly due to the Java Applet security model which prevents an Applet from making arbitrary connections to other servers. For sensitive corporate applications on the Internet, you probably will not want sensitive databases outside your corporate firewall where they are vulnerable.

A three tiered approach allows you to isolate your database connection so that the presentation layer does not care how or where the data is stored. The browser client then talks to objects on the Web server, which can then talk to data objects on the database server. Database connectivity becomes an issue hidden in the middle tier. [10] [15]