What types of applications can you build with Application Express? |
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When to use Application Express? |
Due to its ease of use, Application Express is designed to build opportunistic and departmental applications quickly. These application are deployed on the web with superior performance. Historically, departments, prototypes, and small projects have relied on desktop databases to provide an agile development tool for these smaller scale SMB or departmental application development needs. Desktop databases can become very fragmented because they keep data in too many places, they can be vulnerable or inappropriate for use with sensitive information, and they are typically not web friendly. The browser based design time interface, the declarative programming framework, and simple wizards make Application Express a natural replacement for multi-user desktop databases applications such as Microsoft Access. SQL Savvy application developers also appreciate the ease with which you can create database applications with little or no web experience. You don't need to learn scripting languages or complex deployment frameworks, you simply write a few queries and choose from ready built user interface themes and form controls to create highly professional, secure, and scalable applications. |
Declarative Programming: |
With Application Express, coding is declarative. That means that no code is generated, no code is compiled, and you interact with wizards and property sheets. The SQL language is used to define reports and charts, so some knowledge of SQL is very helpful. You can optionally write snippets of code using PL/SQL, if procedural logic is needed. Declarative code yields fewer differences between developers and this consistency makes Application Express applications easy to maintain and manage. |
Architecture: |
The Application Express engine renders applications in real time from data stored in database tables. When you create or extend an application, Oracle Application Express creates or modifies metadata stored in database tables. When the application is run, the Application Express engine then reads the metadata and displays the application. Application Express lives completely within your Oracle database. It is comprised of nothing more than data in tables and large amounts of PL/SQL code. The essence of Oracle Application Express is approximately 215 tables and 200 PL/SQL objects containing 300,000+ lines of code. To provide stateful behavior within an application, Oracle Application Express transparently manages session state in the database. Application developers can get and set session state using simple substitutions as well as standard SQL bind variable syntax. To access the Oracle Application Express engine within the Oracle database you must configure the Oracle HTTP Server(Apache) containing the mod_plsql plug-in . The plugin functions as communication broker between the Web server and the Oracle Application Express objects in the Oracle database. This maps browser requests into database stored procedure calls. The following graphic illustrates the Oracle Application Express architecture using Oracle HTTP Server and mod_plsql. |
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