The structure of OAF
contains:-
·
MODEL
·
VIEW
·
CONTROLLER
MODEL:-
The entire database
related transactions in OAF pages will be taken care by the MODEL. Model is where the application implements business logic.
The major components of Model are:-
Application Module(AM).
Entity Object(EO).
View Object(VO).
Application Module:-
Application module serves as a container for related BC4J objects.
Application module provides transaction context.
Application module establish database connection.
Entity Object:-
Entity object encapsulates business rules and logic.
Entity objects are mainly
used by any program that inserts, updates or deletes data.
Entity object provides
consistent data validation across all application.
Entity objects may be
linked to other entity objects by
entity association objects.
Entity Object map to a database table or other data source.
Entity Objects can be
created on database objects like Table,
View, Synonym etc or other Entity Objects.
View Object:-
View object encapsulates a database query.
View object provide
iteration over the query result set.
View object primarily based on Entity Objects (EO) or may
be based on plain SQL or may be based on multiple Eos.
View object provides
single point of contact for getting and setting Eos values.
VIEW:-
View is nothing but the OAF page output.
Each UI (User Interface)
widget corresponds to one or more java objects (Beans).
The java objects are used create HTML at run time.
Customers and third
parties use Page Personalization to modify pages to fit business needs and user
preferences.
CONTROLLER:-
Controller controls the UI behavior.
Controller classes define how your java beans behave.
Controller classes subclass OAControllerImpl.
OAPageBean is the
main OA Framework page processing class.
There
are methods in the Controller class to handle GET and POST requests.
processRequest.
processFormData.
processFormRequest.
The OAPageBean calls the processRequest method when a browser
issues a GET request.
The OAPageBean then calls processFormData for pages that insert or
update data.
The OAPageBean calls the processFormRequest method when a browser
issues a GET request.
More About Entity Objects
Entity Objects are mainly
used for insert, update or delete the records from database.
Entity Object will take
care of business logic and validation related to a table.
Entity Object Encapsulate
the attribute level and entity level validation.
OA Framework supports
both Java and PL/SQL entity objects
If we want to perform the DML operations on the standard (Seeded)
table then we go for PL/SQL based Entity Object.
If we want to perform the DML operations on the custom table then we
go for Java Based Entity Object
All the entity objects that you create are subclass of
oracle.apps.fnd.framework.server.OAEntityImpl
class.
While Creating the Entity
Object always generate accessors (setters/getters).
EO should have following
attributes(WHO COLUMNS):-
CreationDate
CreatedBy
LastUpdateDate
LastUpdatedBy
LastUpdateLogin
AAfter creating the entity
object always attach that to VO
Entity Association:-
Define a relationship between
entity objects.
Facilitate
access to data in related entity objects, May be based on database constraints,
May be independent of database constraints
Consist of a source (master) and a destination (detail) entity.
There
are two types of Entity Associations:-
Reference Association.
Composition Association.
Reference Association:-
Used for weak association
between entities such as foreign keys for lookups.
Ex:- Requisition
- Supplier association
Composition
Association:-
Used
for composite objects with strong "owning" relationship
Use if:
child entity cannot exist without parent;
Child
is deleted when parent is deleted
Example:
RequisitionHeader – RequisitionLine association
Behavior of Composition
Association:-
When child is dirtied, parent is dirtied
automatically
When child is locked, parent is locked first
automatically
Validation order is child first, parent second.
parent has final veto power on child modifications
Insert/Update order is parent first, child second
Delete order is child first, parent second
View Object (VO):-
View Object is mainly
used for Manage collection of data and to display them in OAF page.
View Object represents a
query result.
View Objects are used for
joining, filtering, projecting and sorting your business data.
View Object can be
created in three ways:-
Generated SQL based on Eos.
Expert Mode custom SQL with no underlying Eos.
Expert Mode custom SQL manually mapped to Eos.
View Object can be
created on the bases of Single Entity Object or more than one Entity Object.
View
Object can also be created from SQL statements.
A VO controls many view rows.
Each view row represents
a row of the data that is queried from the database.
When you want aliases in
the query, make sure that the attribute settings in the VO wizard include the
alias names.
All the view objects that
you create are subclass of
oracle.apps.fnd.framework.server.OAViewObjectImpl class.
While creating always
create View Row Java class (ViewRowImpl) and
accessors (setters/getters).
Each VO should have:
<YourName>VO.xml
<YourName>VOImpl.java (optional)
<YourName>ViewRowImpl.java (required)
After
creating the view object always attach that to AM.
View Link:-
A view link is a link between view objects.
You can
create view links by providing the following:
Source and destination views
Source and destination attributes
Use a view link to create
a master-detail relationship between view objects.
Allows dynamic synchronization between parent and
child VO.
Child rowset is ‘refreshed’ when the current parent
row changes.
Application
Module (AM):-
Application module serves as a container for related BC4J
objects.
AM defines the logical
data model and business methods needed support an application task.
AM is the interface
between the Client transactions and Data Base transactions.
Types of AM:-
Root AM (The AM attached to main region is called
Root AM).
Nested AM(The AM attached to child region is called
Nested AM).
All the pages are
attached to the AM.
The entire application
module that you create is subclass of
oracle.apps.fnd.framework.server.OAApplicationModuleImpl class.
Path classes for EO , VO, AM on server
EO-related (business logic) .java and .xml files in
oracle.apps.<application
shortname>.<module>.schema.server
Example: oracle.apps.xxx.po.schema.server.______________
AM
and VO (UI-related logic) .java and .xml files in
oracle.apps.<application
shortname>.<module>.server
Example: oracle.apps.xxx.po.server.______________
Poplist-
and LOV-related VO and AM .java and .xmlfiles in
oracle.apps.<application
shortname>.<module>.poplist.server
and
oracle.apps.<application
shortname>.<module>.lov.server
