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Rapid application development of Oracle Web systems

Michael Cunningham and Kent Crotty
There are many ways to implement a Web-enabled Oracle database using complex tools such as XML and PHP. However, these are not easy tools for deploying complex Oracle Web systems, and Oracle Application Express (HTML-DB) opens up a whole new world for Rapid Application Development (RAD).

This book excerpt provides step-by-step examples for getting started building Web-enabled applications. Oracle Application Express (Apex, or HTML-DB) is Oracle's latest tool for fast deployment of Web-based Oracle systems, and this excerpt will get you started, fast.

This is an excerpt from the bestselling book

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Easy HTML-DB Oracle Application Express: Create Dynamic Web Pages with OAE by Michael Cunningham and Kent Crotty. Click here to download the full chapter.

Introduction to Apex (HTML-DB)

This chapter serves two main purposes. The first is to introduce the HTML DB development environment, and the second is to provide a reference for topics that are not specifically mentioned in other chapters.

The Application Builder is complex, and this book will not cover it all. The book is written for the beginning to intermediate-level HTML DB developer, so the most common things any user should know when starting out will be covered.

Instead of taking up space in the individual chapters describing the HTML DB pages used to edit the attributes of various components, they will be included in this chapter. When applicable, more detailed explanations will be included in the other chapters.

Access to the Application Builder is gained from the Workspace home page. While on the workspace home page, click on the Application Builder icon. This will bring up the Application Builder home page.

Editing an application

From the Application Builder home page, click on the Conference RSVP application. This will bring up the Application's home page.

There are several options available from the Application's home page. The Pages region shows a list of the pages in the application as well as some key attributes of each page, such as page id, the last time and by whom it was updated, and whether the page is locked for development. The application can be run by clicking on the Run Application icon or run a single page by clicking on the run stoplight icon.

Run Application

This icon can be used to run the application just as if it were being entered in the browser as a URL. This simulates what a visitor to the web application would encounter upon entering the application.

Edit Attributes

This is used to modify global Application Attributes and is described in greater detail in the Application Attributes section later in this chapter.

Shared Components

Shared Components are parts of an application intended for use on many pages of an application. They are reusable components. Many of the shared components can participate in what is called Publish and Subscribe. For example, a List of Values (LOV) such as Products could be defined in one application and published to other applications. If the LOV were to be modified, the changes can be published to all the subscribing applications. There is also more detail for this option later in the Shared Components section.

Export/Import

This function is used to export the entire application making it easy to deploy to another HTML- DB database, or to export various pieces of the application such as Themes, Pages and User Interface Defaults.

Standard attributes

The Application Attributes are where the global properties are set for the application. Navigate to the Edit Application Attributes page by clicking on the down arrow in the Edit Attributes icon and then click on the Edit Definition menu item. The standard attributes are explained in the following sections.

Name

This is where the name of the application is set. It is also the name displayed in the Application Builder home page.

Application Alias

The text entered here can be used in the URL to the application. The application alias can be used in lieu of the application id. For example: if the application id is 102 as in the Conference RSVP application, the application alias can be set to HELLOWORLD. Either of the following can be used on the URL's to get to the application.

http://localhost:7777/pls/hdb20/f?p=102
http://localhost:7777/pls/hdb20/f?p=helloworld

NOTE: Use the Application Alias cautiously. These should be unique in the HTML DB engine. If the same alias name is used more than once, it may confuse the HTML DB engine.

Version

The version field provides a place to set a version that can be used in page templates to indicate the version on every page of the application if the user chooses. To add the version to a page template, use the #APP_VERSION# substitution string in the templates.

Image Prefix

This is set to /i/ by default and represents the same setting as is in the dads.conf file as presented in the section of this book on Database Access Descriptor (DAD). The value here must be the same as in the DAD file.

Logging

This allows the activity to be recorded in activity logs. Each page view will be logged allowing the workspace administrators to monitor the application activity. The activity reports will be covered in the chapter on advanced HTML DB administration.

Parsing Schema

The parsing schema is very important to the application. All SQL statements and PL/SQL are executed as a specific database user known as the parsing schema. This is also the schema that will own the tables, indexes, PL/SQL, etc. that will be created through the SQL Workshop. Although this can be modified for the application, EASYHDB will be used for the parsing schema throughout the book. The EASYHDB parsing schema was created when the easy workspace was created earlier in this book.

Status

This option is used to set the current status and availability of the application. This can be handy when in a development mode for an application or when it is necessary to make an application unavailable during maintenance.

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This was first published in April 2007

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