Starting application development with Oracle ADF and ADF Faces, some
concepts may be hard to grasp at the beginning. Using Oracle ADF and ADF
Faces, the following terminologies are used in the context of reuse of
components and processes
JSF fragments
JSF page fragments are page definitions that run embedded in another JSF
page. Fragments are like page includes in JavaServer Pages, with the
difference that in Oracle ADF Faces they are usually used in the context
of ADF regions or dynamic declarative components. You can also
reference page fragments directly from a JSP includes tag added to a
JavaServer Faces document (JSPX). However, in this case, and only if a
page fragment has ADF bound content, you need to make sure the content
of the page fragments ADF binding file (PageDef) is copied to the
PageDef file of the parent page. Otherwise ADF queried data will not
show.
ADF regions
ADF regions consist of an ADF Faces af:region tag, an ADF bounded task
flow and page fragments. Page fragments that are used in a bounded task
flow don't need to copy their ADF binding references to the parent
container, which is a huge difference between JSP includes and ADF
regions. ADF regions define an interactive area on a view, a JSF
document or another JSF page fragment, that developers use to show a
single view or a complete, multi-step, process. ADF regions can be
statically or dynamically defined. In either way they require a PageDef
file and a bounded task flow to reference. ADF regions help building
desktop like web applications in which users stay for long on a single
page while working on a business task.
Declarative components
Declarative components allow developers to build a composite component
out of existing ADF Faces components. Declarative components exist in
two flavors: library driven and dynamic declarative components (ddc).
The tag library driven components are declaratively built from the File |
New menu option. In the JSF view option you find a declarative
component menu option that steps you through building your own ADF F
aces component from existing ADF Faces components. You use tag library
driven declarative components to build custom components with behavior,
like a tool bar or a custom file-upload handler. The goal of building
declarative components is to build re-usable components that simplify
development and administration by avoiding duplicate page codes. Dynamic
declarative components (DDC) are used within the scope of the web
application they are defined in and cannot be re-used across
applications. Their main usage is to build reusable layout artifacts or
page area components. For example, a custom tab canvas is what you would
build using DDC components.
Page templates
Page templates are layout definitions that you use as a starter when
building new pages to enforce consistent page layouts throughout
applications and enterprises. Best practices are to build a page
template using the ADF Faces Quick start templates. You cannot nest page
templates, but you can use page templates on parent and child views
(page fragments). A page template is the page level equivalent to a DDC
component.
ADF Library
ADF libraries are special Oracle ADF archive files that you use to reuse
bounded task flows (regions), page templates and declarative
components. They are standard JAR files with extra information in the
archive manifest file that allows you to import the library files into
the Oracle JDeveloper Resource Palette for declarative reuse.
When designing an application you best start planning reuse of components and page segments. If you have an application wide look and feel that you can define as page template(s) then do this first. If you can identify areas within pages that you may need more often on other pages as well, without the pages to be identical from their layout, you use dynamic declarative components. For functionality like global toolbars or common and composite user interface logic, you build tag library based declarative components, which then can be used across applications too. An ADF region is an interactive and optionally also data centric page are that you use to show complete business processes in place. ADF regions are a friend for building rich Internet application interfaces and business centric web desktops. ADF libraries are the vehicle to deploy your reusable work.
