Custom Application Development
using Oracle Application Express (APEX)
Oracle Application Express (APEX) is a fully supported "no-cost" option of the Oracle Database. Using only a web browser, you can develop sophisticated browser-based applications utilizing your skills in SQL and PL/SQL.
Powerful Page Functionality
Page content is organized into regions. Regions can contain text, custom PL/SQL, reports, charts, maps, calendars, web service references or forms. Forms are made up of fields (called items) which can be selected from the multitude of built-in types (such as text fields, text areas, radio groups, select lists, check boxes, date pickers, and popup list of values) or a developer can create their own types using plug-in support. Table update functionality is built-in and PL/SQL can be used to process data. Session state (or application context) is transparently managed and the user interface presentation is separated from the application logic so that the look and feel of an application can be changed simply by selected a different theme.
Features of APEX
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Forms - APEX can be used to build robust data entry forms that
feature client-side (Javascript) and server-side (PL/SQL) validation. Forms
are generated using a wizard which also generates the corresponding SQL for
the intended DML operation (query/insert/update/delete).
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Reports - The tool features dynamic reports that allows end users to
customize standard reports. Interactive reports allows the end user to
select desired columns, filter, sort, group, highlight, aggregate, compute
and many other operations without involving the IT department.
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Charting - The tool has the ability to create stunning charts,
dials, graphs, Gantt charts using "Flash" technology.
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Access Migration Tool - APEX has a built-in tool for migrating
Microsoft Access applications to APEX. On average the tool can automatically
migrate about 80 percent of an Access application.
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Calendars - The tool has built-in calendars for reporting purposes
with month/week/day views. There are also date picker calendars that are
fully customizable.
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Logic Processing - APEX contains many built-in computations,
validations and processing that accelerate the development process.
Developers can also create their own custom computations, validations and
processing.
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Session State Management - APEX automatically manages session state without maintaining a persistent database sessions for the duration of the
user session.
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Websheets - Websheets allow the end users to publish content and to
manage who has access to the content. Using websheets, end users can create
their own ad hoc reports and publish them for others to view.
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Authentication & Authorization - APEX has several built-in
authentication and authorization schemes that can be used to build a secure
application. Developers can also create custom authentication and
authorization schemes. Authorizations can easily be based on "Roles" created
in the database or a LDAP server.
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Conditional Processing - In APEX, everything (pages, items, buttons,
etc) has conditional logic that determines visibility to the end user.
Conditional processing can be combined with an authentication scheme to
manage access in an APEX application.
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REST Web Services - REST Web Services uses a much simpler
architecture than SOAP style web services and it is easy to build forms and
reports based on a web service. Web Services extends the functionality of
APEX applications.
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Logging & Monitoring - APEX has its own built-in logging and
monitoring services. Both developer and end user activities are
automatically logged and are viewable by querying the internal APEX tables.
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Quality Assurance - APEX is a self-documenting, declarative
development tool that stores all definitions and development efforts in the
database in the form of metadata. The metadata is mostly used to dynamically
generate HTML pages, but they can also be used as a source of documentation
and as a quality assurance tool. The APEX Advisor uses the metadata to
generate quality checks reports to ensure quality in the application.
Metadata Driven
Oracle Application Express is an integrated feature of the Oracle database. The Oracle Application Express engine renders pages dynamically in real time from the data contained within the Oracle Application Express metadata repository thereby eliminating the need for a complicated application server middle tier.
When you create or extend an application, Oracle Application Express creates or modifies the metadata stored in its database tables. When the application is run, the Oracle Application Express engine then reads the metadata and displays the requested page or processes page submissions.
Simplified Middle Tier
Oracle Application Express Listener
The Oracle Application Express Listener is a Java based alternative to Apache mod_plsql. The Oracle Application Express listener is supported to run on Oracle WebLogic Server and OC4J.
Apache MOD_PLSQL
One way to access the Oracle Application Express engine is to 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. Images are stored on the file system and served by Apache. Using Apache allows the web listener to be placed on the same physical machine as the database, or on a separate physical machine.
Embedded PL/SQL Gateway
The Embedded PL/SQL Gateway (EPG) runs in the XML DB HTTP server in the Oracle database and includes the core features of mod_plsql, but does not require the Oracle HTTP Server powered by Apache. The EPG stores and serves all files, including images, CSS, and JavaScript from the database. The EPG is convenient for smaller configurations. The EPG is not recommended for larger scale production use cases or Internet facing applications.
Conclusion
If you need to build robust browser based applications quickly and do not have the need for a more complex JavaEE
infrastructure then APEX might just be the solution you are looking for. Let DesTech be your guide to successfully building systems using this sophisticated technology.
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