Understanding Connectivity

1.1.1 Understanding Connectivity

Oracle Net, a component of Oracle Net Services, enables a network session from a client application to an Oracle Database server.

When a network session is established, Oracle Net acts as the data carrier for both the client application and the database. It is responsible for establishing and maintaining the connection between the client application and database, as well as exchanging messages between them. Oracle Net is able to perform these jobs because it is located on each computer in the network.

Parent topic: About Oracle Net Services

1.1.1.1 About Client/Server Application Connections

Oracle Net enables connections from traditional client/server applications to Oracle Database servers. Figure 1-1 shows how Oracle Net enables a network connection between a client and a database server. Oracle Net is a software component that resides on both the client and the database server. Oracle Net is layered on top of network Oracle protocol support, rules that determine how applications access the network and how data is subdivided into packets for transmission across the network. In the following figure, Oracle Net communicates with TCP/IP to enable computer-level connectivity and data transfer between the client and the database.

Figure 1-1 Client/Server Application Connection

Description of "Figure 1-1 Client/Server Application Connection"

Specifically, Oracle Net is comprised of the Oracle Net foundation layer, which establishes and maintains connections, and Oracle protocol support, which maps the foundation layer technology to industry-standard protocols.

Java Client Application Connections

Parent topic: Understanding Connectivity

1.1.1.1.1 Java Client Application Connections

Java client applications access an Oracle database through a Java Database Connectivity (JDBC) Driver, a standard Java interface for connecting from Java to a relational database. Oracle offers the following drivers:

JDBC OCI Driver for client-side use with an Oracle client installation.
JDBC Thin Driver, a pure Java driver for client-side use without an Oracle installation, particularly with applets.

These drivers use Oracle Net to enable connectivity between a client application and an Oracle database.

The following figure shows a Java client application using a JDBC OCI driver and an Oracle Database server. The Java client application makes calls to the JDBC OCI driver, which translates the JDBC calls directly into the Oracle Net layer. The client then uses Oracle Net to communicate with Oracle Database that is also configured with Oracle Net.

Figure 1-2 Java Application Connection

Description of "Figure 1-2 Java Application Connection"

1.1.1.2 About Web Client Application Connections

Internet connections from client web browsers to an Oracle Database server are similar to client/server applications, except that the connection request goes to an application web server.

Figure 1-3 shows the basic architecture for web client connections, including a client web browser, an application web server, and an Oracle Database server. The browser on the client communicates with HTTP to the web server to make a connection request. The web server sends the request to an application where it is processed. The application then uses Oracle Net to communicate with the Oracle Database server that also is configured with Oracle Net.

Figure 1-3 Web Client Connections through Application Web Server

Description of "Figure 1-3 Web Client Connections through Application Web Server"

The basic components have the following characteristics:

HyperText Transport Protocol (HTTP)

HTTP provides the language that enables web browsers and application web servers to communicate.
Application Web Server

An application web server manages data for a website, controls access to that data, and responds to requests from web browsers. The application on the web server communicates with the database and performs the job requested by the web server.

Parent topic: Understanding Connectivity

1.1.1.2.1 Web Client Connections Through Java Application Web Server

An application web server can host Java applications and servlets, as shown in Figure 1-4. Web browsers make a connection request by communicating through HTTP to an application web server. The application web server sends the request to an application or a servlet, which uses a JDBC OCI or a JDBC Thin driver to process the request. The driver then uses Oracle Net to communicate with the Oracle Database server that also is configured with Oracle Net.

Figure 1-4 Web Client Connections Through Java Application Web Server

Description of "Figure 1-4 Web Client Connections Through Java Application Web Server"

Parent topic: About Web Client Application Connections

1.1.1.2.2 Web Client Connections Without an Application Web Server

Web clients that do not require an application web server to access applications can access Oracle Database directly, for example, by using a Java applet. In addition to regular connections, the database can be configured to accept HTTP protocol, FTP, or WebDAV protocol connections. These protocols are used for connections to Oracle XML DB in the Oracle Database instance.

The following figure shows two different web clients. The first web client makes an HTTP connection to the database. The second web client uses a web browser with a JDBC Thin driver, which in turn uses a Java version of Oracle Net called JavaNet to communicate with the Oracle Database server that is configured with Oracle Net.