Oracle Apex Part 1 Introduction

 Introduction

Oracle APEX is a rapid web application development tool for the Oracle database. Using only a web browser and limited programming experience, you can develop professional applications that are both fast and secure. Thanks to built-in features such as user interface themes, navigational controls, form handlers, and flexible reports, Oracle APEX accelerates the application development process.

From the end user's perspective, the deployed applications require only a browser and access to an Oracle database running APEX.

APEX Architecture

Oracle APEX installs with your Oracle database and is composed of data in tables and PL/SQL code. Whether you run the Oracle APEX development environment or an application you built using Oracle APEX, the process is the same. Your browser sends a URL request that is translated into the appropriate Oracle APEX PL/SQL call. After the database processes the PL/SQL, the results are sent back to your browser as HTML. This cycle happens each time you request or submit a page. The application session state is managed in the database tables within Oracle APEX. It does not use a dedicated database connection. Instead, each request is made through a separate database session, consuming minimal CPU resources.

Listeners in APEX

Oracle HTTP Server uses the mod_plsql plug-in to communicate with the Oracle APEX engine within the Oracle database. Oracle APEX Listener communicates directly with the Oracle APEX engine, thus eliminating the need for the mod_plsql plug-in. Both Oracle HTTP Server and the Oracle APEX Listener function as communication brokers between the web server and the Oracle APEX objects in the Oracle database. More specifically, they map browser requests into database stored procedure calls over an Oracle Net Services connection. The following graphic illustrates the Oracle APEX architecture using Oracle HTTP Server and mod_plsql.

This three-tier architecture has the following components:

  1. A web browser
  2. Oracle HTTP Server (Apache) with mod_plsql or Oracle APEX Listener
  3. An Oracle database containing Oracle APEX

Advantages of the embedded PL/SQL gateway:

  1. Ease of configuration
  2. Included in the database
  3. No separate server installation

About the APEX Engine

The APEX engine renders and processes pages. It also performs these tasks:

  1. Session state management
  2. Authentication services

 

About the Oracle APEX Environment

Oracle APEX enables a single Oracle database to become a shared workgroup database service. Multiple users can access it using a web browser without installing additional software.

About Workspaces

The area where you develop applications is called a workspace. A workspace is a virtual private database that enables multiple users to work within the same Oracle APEX installation while keeping their objects, data, and applications private.

In a typical development environment, you might create a single workspace for all your developers to share. However, you can also create dedicated workspaces for specific developers or projects. Creating a dedicated workspace limits access to the workspace objects to only those users associated with the workspace.

The following graphic shows the relationships between users and developers, workspaces, and database schemas.

When you create a workspace, you associate it with a new or existing schema. A schema is a logical container for database objects such as tables, views, and stored procedures. A single schema can be associated with one or more workspaces.

About Oracle APEX User Roles

When setting up APEX users at a large organization, you assign roles and privileges to specific users. The roles within Oracle APEX include the following:

·       End users are application users without any access to development or administrative capabilities.

·       Developers are users who create and edit applications and modify database objects. Developers can have their own workspaces or share a workspace.

·       Workspace administrators are developers who perform administrator tasks specific to a workspace such as managing user accounts, monitoring workspace activity, and viewing log files.

·       Instance administrators are superusers who manage an entire hosted instance using the APEX Administration Services application.

The following graphic shows multiple users with various roles accessing the Oracle APEX development environment, APEX Administration Services, and the published applications.

For this guide, you must have the privileges usually associated with three roles: Instance Administrator, Workspace Administrator, and Developer. The following graphic shows an Oracle APEX instance with a single user.

 

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