The Oracle EBS Architecture provides a multi-tiered, distributed computing framework that supports Oracle EBS products. It consists of the following three tiers:
- Client Tier
- Application Tier
- Database Tier
Figure 1. Oracle EBS three tier architecture
The Client Tier, also referred to as the Desktop Tier, provides the client interface through HTML for HTML-based applications, and through Java applets for the Forms-based applications. It consists of four service components:
- The Forms Client Applet: a general-purpose presentation applet for all Oracle EBS Forms-based products that are packed as a collection of Java Archive (JAR) files that are downloaded from the web server at the beginning of the client's first session.
- Desktop Java Runtime Environment: a Java Virtual Machine (JVM) on the desktop client where the forms Client Applet runs.
- Java Web Start: which launches Oracle EBS Java-based functionality.
- Java Plug-in: Oracle EBS supports launching Java applets using the Java Plug-in for browsers that support it.
Each of these components is downloaded from the application tier once the client first time connects to the Oracle EBS.
The Application Tier hosts the various service groups that process the application business logic and manages the communication between the client tier and the database tier. The Application Tier is composed of the following services groups or servers:
- HTTP services
- Java services
- Forms services
- Concurrent Processing server
Note: In Oracle EBS Release 12.2, Web services and Forms services are provided by Oracle Application Server and Oracle Fusion Middleware.
The Application Tier supports load balancing among multiple servers on the following services:
- Web Services: This component of Oracle Application server process requests from the desktop clients over the network. It has two major components: Web Listener (Oracle HTTP server powered by Apache) and Java Servlet Engine (Oracle WebLogic Server (WLS). Web Listener accepts incoming HTTP requests from client browsers and routes the requests to the Oracle WebLogic server that runs JSP. The JSP obtains the content from the Oracle EBS database table, and constructs the HTML page with the information, passes the HTML page back to the client browser.
- Forms Services: Forms services in Oracle EBS Suite Release 12.2 are provided by the Forms listener servlet, The Forms listener servlet is a Java servlet that allows to run Oracle Forms applications over HTTP or HTTPS connections. It hosts Oracle EBS forms and the associated runtime engine. It facilitates the communication between the client and the Oracle database server by:
- Communicating with the desktop client using either a standard HTTP network connection or secure HTTPS network connection.
- Communicating with the Oracle database server using the Oracle database Net service.
- Concurrent Processing Server: processes non–interactive and potentially long-running functions efficiently alongside interactive operations and ensures that resource-intensive concurrent processing operations do not interfere with interactive operation. Concurrent requests are the processes that run on the Concurrent Processing Server. When users submit a concurrent request through HTML-based or forms-based applications, a row is inserted into a database table that specifies the program to run. The concurrent manager receives a request by reading this request in the table and initiates the associated concurrent program.
The Database Tier consists of the Oracle database servers that store and manage the data of Oracle EBS system. The Oracle database servers are installed with Oracle Grid Infrastructure and Automatic Storage Management (ASM) and Oracle Database Software. The Oracle database contains the application schemas for various Oracle EBS application modules. The database also serves the metadata repository for the Oracle EBS configuration.