### Write access, principles

Connecting an application to a database by establishing a connection between client and database server:

So JDBC™ is just one among a whole bunch of protocol implementations connecting database servers and applications. Consequently JDBC™ is expected to appear in the lower layer of multi-tier applications. We take a three-tier application as a starting point:

We may add an additional layer. Web applications are typically being build on top of an application server (WebSphere, Glassfish, Jboss,...) providing additional services:

Opening a connection to a database server requires:

Items 1 - 4 will be encapsulated into a so called JDBCURL. We consider a typical example corresponding to the previous parameter list:

Writing JDBC™ based applications follows a simple scheme:

From a programmer's point of view the java.sql.DriverManager is a bootstrapping object: Other objects like Connection instances are being created from this central and unique object.

Figure 823, “JDBC™ architecture ” does not show details about the relations between java.sql.Connection, java.sql.Statement and java.sql.ResultSet objects. We start by giving a rough description of these three interfaces' tasks and responsibilities: