Oracle JDeveloper Tip

 

Most Commonly Used Methods in ADF Business Components

Author: Steve Muench, ADF Development Team
Date: January 19, 2006
Revision 1.9 ( Revision History)

Abstract

This paper provides a high-level description of the key ADF Business Components classes in the Oracle Application Development Framework, summarizing the methods that ADF developers write, call, and override most frequently.


Contents

Overview
Logical Architecture of Services Built with ADF Business Components
Most Commonly Used Methods in the Client Tier
ApplicationModule Interface
Transaction Interface
ViewObject Interface
RowSet Interface
RowSetIterator Interface
Row Interface
StructureDef Interface
AttributeDef Interface
AttributeHints Interface
Most Commonly Used Methods In the Business Service Tier
Controlling Custom Java Files For Your Components
ApplicationModuleImpl Class
DBTransactionImpl2 Class
EntityImpl Class
EntityDefImpl Class
ViewObjectImpl Class
ViewRowImpl Class
Setting Up Your Own Layer of Framework Base Classes
Conclusion

Overview

Service-oriented J2EE Applications built using the ADF framework encapsulate their business logic into one or more business services. Clients access these business services either as web services or, when the client is a user interface, using the ADF data-binding layer that implements the Data Controls and Bindings from JSR-227. The data controls abstract the back-end business service implementations and binding objects link front-end user interface controls in a declarative way to back-end data.

ADF supports business services implemented as simple Java objects, web services, EJB Session beans, and framework-based Java objects that inherit built-in functionality from the ADF Business Components base classes. These ADF Business Components are business-tier building-block classes, and related design-time extensions to JDeveloper, that give you a prescriptive architecture for building richly-functional and cleanly layered J2EE business services with great performance. This paper offers a high-level description of the key components that comprise ADF Business Components, and provides a summary of the methods that developers leveraging ADF BC base classes write, call, and override most frequently while building their J2EE-compliant business services.

Logical Architecture of Services Built with ADF Business Components

You can use business services you build with ADF Business Components in one of three ways:

  1. As lightweight local Java service classes,
  2. As EJB session beans, or
  3. As stateless web services

In all three cases, there is a clean separation between the client tier code that invokes the service and the business service tier where the service's implementation details reside.

With the J2EE web service option, your web service client interacts with the service using a web service proxy class generated by the client tool environment based on the service's WSDL service description. The methods that appear on your web service are the custom methods you've written on your business service component.

With the local Java service class and the EJB session bean options, your Java client code interacts with either the base ADF component interfaces or custom component interfaces that JDeveloper 10g generates for you automatically after indicating which custom methods should appear on the component's client interface.

Since ADF adopts this best-practice approach of having your client work with interfaces instead of directly with implementation classes, it offers the additional benefit of allowing you to change between deploying your business service as a local Java class or an EJB session bean without changing your client code. Along with the custom service interface, JDeveloper generates appropriate client-side proxy implementation classes that implement your custom interface. As such, it's an implementation detail you don't need to worry about yourself. With either 2-tier or 3-tier deployment of your application modules, thing just work...which is nice.

Figure 1 shows the relationships between the key components in the Oracle Application Development Framework. The dashed vertical line in the diagram represents the clean separation of component interfaces that are available on the client, and which ones are only available in the business tier implementation.

Relationship Between Key ADF Business Components Classes
Figure 1: Relationship Between Key ADF Business Components Classes

Whenever you deploy an ADF Business Components project using a Business Components deployment profile in JDeveloper 10g, two separate JAR files get created, further emphasizing this logical separation between business tier and client tier:

  • YourProjectNameCSMT.jar

    This archive contains all of the implementation classes that comprise your project's business service application module components and other ADF BC components that your application modules use. We picked the MT suffix in the name to represent Middle Tier. When deploying your application module as an EJB Session Bean, this JAR file lives on the EJB middle tier. It never is downloaded to the remote client.

  • YourProjectNameCSCommon.jar

    This archive contains any custom client interfaces, generated custom remote client proxy classes, custom domains, and message bundles that are accessible by both the client-tier and the business service tier. We picked the suffix Common in the archive name to remind you that this jar is common to both tiers. This file is generally relatively quite small compared to the middle-tier JAR.

The following sections briefly explain each component and give tips about the methods J2EE developers using ADF Business Components will use most frequently for each kind of component.

Most Commonly Used Methods in the Client Tier

All of the interfaces described in this section are designed for use by client-layer code and are part of the oracle.jbo.* package.


NOTE:

The corresponding implementation classes for these oracle.jbo.* interfaces are consciously designed to not be directly accessed by client code. As we'll see in the Most Commonly Used Methods In the Business Service Tier section below, the implementation classes live in the oracle.jbo.server.* package and generally have the suffix Impl in their name to help remind you not to using them in your client-layer code.


ApplicationModule Interface

The ApplicationModule See Javadoc for ApplicationModule is a business service component that acts as a transactional container for other ADF components and coordinates with them to implement a number of J2EE design patterns important to business application developers. These design pattern implementations enable your client code to work easily with updateable collections of value objects, based on fast-lane reader SQL queries that retrieve only the data needed by the client, in the way the client wants to view it. Changes made to these value objects are automatically coordinated with your persistent business domain objects in the business service tier to enforce business rules consistently and save changes back to the database.

If you want to... Call this ApplicationModule interface method...
Access an existing view object instance by name findViewObject()
Creating a new view object instance from an existing definition createViewObject()
Creating a new view object instance from a SQL Statement createViewObjectFromQueryStmt()

Note:

This incurs runtime overhead to describe the "shape" of the dynamic query's SELECT list. We recommend using this only when you cannot know the SELECT list for the query at design-time. Furthermore, if you are creating the dynamic query based on some kind of custom runtime repository, you can follow this tip to create (both read-only and updateable) dynamic view objects without the runtime-describe overhead with a little more work. If only the WHERE needs to be dynamic, create the view object at design time, then set the where clause dynamically as needed using ViewObject API's.

Access a nested application module instance by name findApplicationModule()
Create a new nested application module instance from an existing definition createApplicationModule()
Find a view object instance in a nested application module findViewObject()

Note:

To find an instance of a view object belonging to a nested application module you use a dot notation nestedAMInstanceName. VOInstanceName

Accessing the current transaction object getTransaction()

In addition to generic ApplicationModule access, JDeveloper 10g can generate you a custom YourApplicationModuleName interface containing service-level custom methods that you've chosen to expose to the client. You do this by visiting the Client Interface tab of the Application Module editor, and shuttling the methods you'd like to appear in your client interface into the Selected list. JDeveloper will also generate an appropriate YourApplicationModuleNameClient client proxy implementation class that is used automatically by your remote client in the case that you deploy your application module as an EJB Session Bean or whenever you use your application module in Batch Mode.

Transaction Interface

The Transaction See Javadoc for Transaction interface exposes methods allowing the client to manage pending changes in the current transaction.

If you want to... Call this Transaction interface method...
Commit pending changes commit()
Rollback pending changes rollback()
Execute a one-time database command or block of PL/SQL executeCommand()

Note:

Commands that require retrieving OUT parameters, that will be executed more than once, or that could benefit by using bind variables should not use this method. Instead, expose a custom method on your application module class as described here.

Validate all pending invalid changes in the transaction validate()
Change the default locking mode setLockingMode()

Note:

You can set the locking mode in your configuration by setting the property jbo.locking.mode to one of the four supported values: none, optimistic, pessimistic, optupdate. If you don't explicitly set it, it will default to pessimistic. For web applications, we recommend using optimistic or optupdate modes.

Decide whether to use bundled exception reporting mode or not. setBundledExceptionMode()

Note:

ADF controller layer support sets this parameter to true automatically for web applications.

Decide whether entity caches will be cleared upon a successful commit of the transaction. setClearCacheOnCommit()

Note:

Default is false

Decide whether entity caches will be cleared upon a rollback of the transaction. setClearCacheOnRollback()

Note:

Default is true

Clear the entity cache for a specific entity object. clearEntityCache()

ViewObject Interface

A ViewObject See Javadoc for ViewObject encapsulates a database query and simplifies working with the RowSet of results it produces. You use view objects to project, filter, join, or sort business data using SQL from one or more tables into exactly the format that the user should see it on the page or panel. You can create "master/detail" hierarchies of any level of depth or complexity by connecting view objects together using view links. View objects can produce read-only query results, or by associating them with one ore more entity objects at design time, can be fully updateable. Updateable view objects can support insertion, modification, and deletion of rows in the result collection, with automatic delegation to the correct business domain objects.

Every ViewObject aggregates a "default rowset" for simplifying the 90% of use cases where you work with a single RowSet of results for the ViewObject's query. A ViewObject implements all the methods on the RowSet interface by delegating them to this default RowSet. That means you can invoke any RowSet methods on any ViewObject as well.

Every ViewObject implements the StructureDef interface to provide information about the number and types of attributes in a row of its rowsets. So you can call StructureDef methods right on any view object.

If you want to... Call this ViewObject interface method...
Set an additional runtime WHERE clause on the rowset setWhereClause()

Note:

This WHERE clause augments any WHERE clause specified at design time in the base view object. It does not replace it.

Set a dynamic ORDER BY clause setOrderByClause()
Create a Query-by-Example criteria collection createViewCriteria()

Note:

You then create one or more ViewCriteriaRow objects using the createViewCriteriaRow() method on the ViewCriteria object you created. Then, you add() these view criteria rows to the view criteria collection and apply the criteria using the method below.

Apply a Query-by-Example criteria collection applyViewCriteria()
Set a query optimizer hint setQueryOptimizerHint()
Access the attribute definitions for the key attributes in the view object getKeyAttributeDefs()
Add a dynamic attribute to rows in this view object's rowsets addDynamicAttribute()
Clear all rowsets produced by a view object clearCache()
Remove view object instance an its resources remove()
Set an upper limit on the number of rows that the view object will attempt to fetch from the database. setMaxFetchSize()

Note:

Default is -1 which means to impose no limit on how many rows would be retrieved from the database if you iterate through them all. By default they are fetched lazily as you iterate through them.

In addition to generic ViewObject access, JDeveloper 10g can generate you a custom YourViewObjectName interface containing view-object level custom methods that you've chosen to expose to the client. You do this by visiting the Client Interface tab of the View Object editor, and shuttling the methods you'd like to appear in your client interface into the Selected list. JDeveloper will also generate an appropriate YourViewObjectNameClient client proxy implementation class that is used automatically by your remote client in the case that you deploy your application module as an EJB Session Bean or whenever you use your application module in Batch Mode.

RowSet Interface

A RowSet See Javadoc for RowSet is a set of rows, typically produced by executing a ViewObject's query.

Every RowSet aggregates a "default rowset iterator" for simplifying the 90% of use cases where you only need a single iterator over the rowset. A RowSet implements all the methods on the RowSetIterator interface by delegating them to this default RowSetIterator. This means you can invoke any RowSetIterator method on any RowSet (or ViewObject, since it implements RowSet as well for its default RowSet).

If you want to... Call this RowSet interface method...
Set a where clause bind variable value setWhereClauseParam()

Note:

Bind variable ordinal positions are zero-based

Avoid view object row caching if data is being read only once setForwardOnly()
Force a rowset's query to be (re)executed executeQuery()
Estimate the number of rows in a view object's query result getEstimatedRowCount()
Produce XML document for rows in View Object rowset writeXML()
Process all rows from an incoming XML document readXML()
Set whether rowset will automatically see new rows based on the same entity object created through other rowsets setAssociationConsistent()
Create secondary iterator to use for programmatic iteration createRowSetIterator()

Note:

If you plan to find and use the secondary iterator by name later, then pass in a string name as the argument, otherwise pass null for the name and make sure to close the iterator when done iterating by calling its closeRowSetIterator() method.

RowSetIterator Interface

A RowSetIterator See Javadoc for RowSetIterator is an iterator over the rows in a RowSet. By default it allows you to iterate both forward and backward through the rows.

If you want to... Call this RowSetIterator interface method...
Get the first row of the iterator's rowset first()
Test whether there are more rows to iterate hasNext()
Get the next row of iterator's rowset next()
Find row in this iterator's rowset with a given Key value findByKey()

Note:

It's important that the Key object that you pass to findByKey be created using the exact same datatypes as the attributes that comprise the key of the rows in the view object you're working with.

Create a new row to populate for insertion createRow()

Note:

The new row will already have default values set for attributes which either have a static default value supplied at the entity object or view object level, or if the values have been populated in an overridden create() method of the underlying entity object(s).

Create a view row with an initial set of foreign key and/or discriminator attribute values createAndInitRow()

Note:

You use this method when working with view objects that can return one of a "family" of entity object subtypes. By passing in the correct discriminator attribute value in the call to create the row, the framework can create you the correct matching entity object subtype underneath.

Insert a new row into the iterator's rowset insertRow()

Note:

It's a good habit to always immediately insert a newly created row into the rowset. That way you will avoid a common gotcha of creating the row but forgetting to insert it into the rowset.

Get the last row of the iterator's rowset last()
Get the previous row of the iterator's rowset previous()
Reset the current row pointer to the slot before the first row reset()
Close an iterator when done iterating closeRowSetIterator()
Set a given row to be the current row setCurrentRow()
Remove the current row removeCurrentRow()
Remove the current row to later insert it at a different location in the same iterator. removeCurrentRowAndRetain()
Remove the current row from the current collection but do not remove it from the transaction. removeCurrentRowFromCollection()
Set/change the number of rows in the range (a "page" of rows the user can see) setRangeSize()
Scroll to view the Nth page of rows (1-based) scrollToRangePage()
Scroll to view the range of rows starting with row number N scrollRangeTo()
Set row number N in the range to be the current row setCurrentRowAtRangeIndex()
Get all rows in the range as a Row array getAllRowsInRange()

Row Interface

A Row See Javadoc for Row is generic value object. It contains attributes appropriate in name and Java type for the ViewObject that it's related to.

If you want to... Call this Row interface method...
Get the value of an attribute by name getAttribute()
Set the value of an attribute by name setAttribute()
Produce an XML document for a single row writeXML()
Eagerly validate a row validate()
Read row attribute values from XML readXML()
Remove the row remove()
Flag a newly created row as temporary (until updated again) setNewRowState(Row.STATUS_INITIALIZED)
Retrieve the attribute structure definition information for a row getStructureDef()
Get the Key object for a row getKey()

In addition to generic Row access, JDeveloper 10g can generate you a custom YourViewObjectNameRow interface containing your type-safe attribute getter and setter methods, as well as any desired row-level custom methods that you've chosen to expose to the client. You do this by visiting the Client Row Interface tab of the View Object editor, and shuttling the methods you'd like to appear in your client interface into the Selected list. JDeveloper will also generate an appropriate YourViewObjectNameRowClient client proxy implementation class that is used automatically by your remote client in the case that you deploy your application module as an EJB Session Bean or whenever you use your application module in Batch Mode.

StructureDef Interface

A StructureDef See Javadoc for StructureDef is an interface that provides access to runtime metadata about the structure of a Row .

In addition, for convenience every ViewObject implements the StructureDef interface as well, providing access to metadata about the attributes in the resulting view rows that its query will produce.

If you want to... Call this StructureDef interface method...
Access attribute definitions for all attributes in the view object row getAttributeDefs()
Find an attribute definition by name findAttributeDef()
Get attribute definition by index getAttributeDef()
Get number of attributes in a row getAttributeCount()

AttributeDef Interface

An AttributeDef See Javadoc for AttributeDef provides attribute definition information for any attribute of a View Object row or Entity Object instance like attribute name, Java type, and SQL type. It also provides access to custom attribute-specific metadata properties that can be inspected by generic code you write, as well as UI hints that can assist in rendering an appropriate user interface display for the attribute and its value.

If you want to... Call this AttributeDef interface method...
Get the Java type of the attribute getJavaType()
Get the SQL type of the attribute getSQLType()

Note:

The int value corresponds to constants in the JDBC class java.sql.Types

Determine the kind of attribute getAttributeKind()

Note:

If it's a simple attribute, it returns one of the constants ATTR_PERSISTENT, ATTR_SQL_DERIVED, ATTR_TRANSIENT, ATTR_DYNAMIC, ATTR_ENTITY_DERIVED. If it is an 1-to-1 or many-to-1 association/viewlink accessor it returns ATTR_ASSOCIATED_ROW. If it is an 1-to-many or many-to-many association/viewlink accessor it returns ATTR_ASSOCIATED_ROWITERATOR

Get the Java type of elements contained in an Array-valued attribute getElemJavaType()
Get the SQL type of elements contained in an Array-valued attribute getElemSQLType()
Get the name of the attribute getName()
Get the index position of the attribute getIndex()
Get the precision of a numeric attribute or the maximum length of a String attribute getPrecision()
Get the scale of a numeric attribute getScale()
Get the underlying column name corresponding to the attribute getColumnNameForQuery()
Get attribute-specific custom property values getProperty(), getProperties()
Get the UI AttributeHints object for the attribute getUIHelper()
Test whether the attribute is mandatory isMandatory()
Test whether the attribute is queriable isQueriable()
Test whether the attribute is part of the primary key for the row isPrimaryKey()

AttributeHints Interface

The AttributeHints See Javadoc for AttributeHints interface related to an attribute exposes UI hint information that attribute that you can use to render an appropriate user interface display for the attribute and its value.

If you want to... Call this AttributeHints interface method...
Get the UI label for the attribute getLabel()
Get the tool tip for the attribute getTooltip()
Get the formatted value of the attribute, using any format mask supplied getFormattedAttribute()
Get the display hint for the attribute getDisplayHint()

Note:

Will have a String value of either Display or Hide.

Get the preferred control type for the attribute getControlType()
Parse a formatted string value using any format mask supplied for the attribute parseFormattedAttribute()

Most Commonly Used Methods In the Business Service Tier

The implementation classes corresponding to the oracle.jbo.* interfaces described above are consciously designed to not be directly accessed by client code. They live in a different package named oracle.jbo.server.* and have the Impl suffix in their name to help remind you not to using them in your client-layer code.

In your business service tier implementation code, you can use any of the same methods that are available to clients above, but in addition you can also:

  • Safely cast any oracle.jbo.* interface to its oracle.jbo.server.* package implementation class and use any methods on that Impl class as well.
  • Override any of the base framework implementation class' public or protected methods to augment or change its default functionality by writing custom code in your component subclass before or after calling super. methodName() .

This section provides a summary of the most frequently called, written, and overridden methods for the key ADF Business Components classes.

Controlling Custom Java Files For Your Components

Before examining the specifics of individual classes, it's important to understand how you can control which custom Java files each of your components will use. When you don't need a customized subclass for a given component, you can just let the base framework class handle the implementation at runtime.

Each business component you create comprises a single XML component descriptor, and zero or more related custom Java implementation files. Each component that supports Java customization has a Java tab in its component editor in the JDeveloper 10g IDE. By checking or unchecking the different Java classes, you control which ones get created for your component. If none of the boxes is checked, then your component will be an XML-only component, which simply uses the base framework class as its Java implementation. Otherwise, tick the checkbox of the related Java classes for the current component that you need to customize. JDeveloper 10g will create you a custom subclass of the framework base class in which you can add your code.


NOTE:

You can setup global IDE preferences for which Java classes should be generated by default for each ADF business component type by selecting Tools | Preferences... | Business Components and ticking the checkboxes to indicate what you want your defaults to be.


A best practice is to always generate Entity Object and View Row classes, even if you don't require any custom code in them other than the automatically-generated getter and setter methods. These getter and setter methods offer you compile-time type checking that avoids discovering errors at runtime when you accidentally set an attribute to an incorrect kind of value.

ApplicationModuleImpl Class

The ApplicationModuleImpl See Javadoc for ApplicationModuleImpl class is the base class for application module components. Since the application module is the ADF component used to implement a business service, think of the application module class as the place where you can write your service-level application logic. The application module coordinates with view object instances to support updateable collections of value objects that are automatically "wired" to business domain objects. The business domain objects are implemented as ADF entity objects.

Methods You Typically Call on ApplicationModuleImpl

 

If you want to... Call this method of the ApplicationModuleImpl class
Perform any of the common application module operations from inside your class, which can also be done from the client See the ApplicationModule Interface section above.
Access a view object instance that you added to the application module's data model at design time get ViewObjectInstanceName()

Note:

JDeveloper 10g generates this type-safe view object instance getter method for you to reflect each view object instance in the application module's design-time data-model.

Access the current DBTransaction object getDBTransaction()
Access a nested application module instance that you added to the application module at design time get AppModuleInstanceName()

Note:

JDeveloper 10g generates this type-safe application module instance getter method for you to reflect each nested application module instance added to the current application module at design time.

Methods You Typically Write in Your Custom ApplicationModuleImpl Subclass

 

If you want to... Write a method like this in your custom ApplicationModuleImpl class
Invoke a database stored procedure someCustomMethod()

Note:

Use appropriate method on the DBTransaction interface to create a JDBC PreparedStatement. If the stored procedure has OUT parameters, then create a CallableStatement instead.

See this sample project for a robust code example of encapsulating a call to a PL/SQL stored procedure inside your application module.

Expose custom business service methods on your application module someCustomMethod()

Note:

Select the method name on the Client Interface panel of the application module editor to expose it for client access if required.

JDeveloper 10g can generate you a custom YourApplicationModuleName interface containing service-level custom methods that you've chosen to expose to the client. You do this by visiting the Client Interface tab of the Application Module editor, and shuttling the methods you'd like to appear in your client interface into the Selected list.

Methods You Typically Override in Your Custom ApplicationModuleImpl Subclass

 

If you want to... Override this method of the ApplicationModuleImpl class
Perform custom setup code the first time an application module is created and each subsequent time it gets used by a different client session. prepareSession()

Note:

This is the method you'd use to setup per-client context info for the current user in order to use database Oracle's Virtual Private Database (VPD) features. It can also be used to set other kinds of PL/SQL package global variables, whose values might be client-specific, on which other stored procedures might rely.

This method is also useful to perform setup code that is specific to a given view object instance in the application module. If instead of being instance-specific you want the view object setup code to be initialized for every instance ever created of that view object component, then put the setup logic in an overridden create() method in your ViewObjectImpl subclass instead.

Perform custom setup code after the application module's transaction is associated with a database connection from the connection pool. afterConnect()

Note:

Can be a useful place to write a line of code that uses getDBTransaction().executeCommand() to perform an ALTER SESSION SET SQL TRACE TRUE to enable database SQL Trace logging for the current application connection. These logs can then be processed with the TKPROF utility to study the SQL statements being performed and the query optimizer plans that are getting used.

Perform custom setup code before the application module's transaction releases its database connection back to the database connection pool. beforeDisconnect()

Note:

If you have set jbo.doconnectionpooling to true, then the connection is released to the database connection pool each time the application module is returned to the application module pool.

Write custom application module state to the state management XML snapshot passivateState()
Read and restore custom application module state from the state management XML snapshot activateState()

DBTransactionImpl2 Class

The DBTransactionImpl2 See Javadoc for DBTransactionImpl2 class — which extends the base DBTransactionImpl class, and is constructed by the DatabaseTransactionFactory class — is the base class that implements the DBTransaction interface, representing the unit of pending work in the current transaction.

Methods You Typically Call on DBTransaction

 

If you want to... Call this method on the DBTransaction See Javadoc for DBTransaction object
Commit the transaction commit()
Rollback the transaction rollback()
Eagerly validate any pending invalid changes in the transaction validate()
Create a JDBC PreparedStatement using the transaction's Connection object createPreparedStatement()
Create a JDBC CallableStatement using the transaction's Connection object createCallableStatement()
Create a JDBC Statement using the transaction's Connection object createStatement()
Add a warning to the transaction's warning list. addWarning()

Methods You Typically Override in Your Custom DBTransactionImpl2 Subclass

 

If you want to... Override this method in your custom DBTransactionImpl2 class
Perform custom code before or after the transaction commit operation commit()
Perform custom code before or after the transaction rollback operation rollback()

In order to have your custom DBTransactionImpl2 subclass get used at runtime, there are two steps you must follow:

  1. Create a custom subclass of DatabaseTransactionFactory that overrides the create method to return an instance of your custom DBTransactionImpl2 subclass like this:

    package com.yourcompany.adfextensions;
    import oracle.jbo.server.DBTransactionImpl2;
    import oracle.jbo.server.DatabaseTransactionFactory;
    import com.yourcompany.adfextensions.CustomDBTransactionImpl;
    public class CustomDatabaseTransactionFactory extends DatabaseTransactionFactory {
      /**
       * Return an instance of our custom CustomDBTransactionImpl class
       * instead of the default implementation.
       *
       * @return An instance of our custom DBTransactionImpl2 implementation.
       */
      public DBTransactionImpl2 create() {
        return new CustomDBTransactionImpl();
      }
    }
  2. Tell the framework to use your custom transaction factory class by setting the value of the TransactionFactory configuration property to the fully-qualified class name of your custom transaction factory. As with other configuration properties, if not supplied in the configuration XML file, it can be provided alternatively as a Java system parameter of the same name.

EntityImpl Class

The EntityImpl See Javadoc for EntityImpl class is the base class for entity objects, which encapsulate the data, validation rules, and business behavior for your business domain objects.

Methods You Typically Call on EntityImpl

 

If you want to... Call this method in your EntityImpl subclass
Get the value of an attribute get AttributeName()

Note:

Code-generated getter method calls getAttributeInternal() but provides compile-time type checking.

Set the value of an attribute set AttributeName()

Note:

Code-generated setter method calls setAttributeInternal() but provides compile-time type checking.

Get the value of an attribute by name getAttributeInternal()
Set the value of an attribute by name setAttributeInternal()
Eagerly perform entity object validation validate()
Refresh the entity from the database refresh()
Populate the value of an attribute without marking it as being changed, but sending notification of its being changed so UI's refresh the value on the screen/page. populateAttributeAsChanged()
Access the definition object for an entity getDefinitionObject()
Get the Key object for an entity getKey()
Determine the state of the entity instance, irrespective of whether it has already been posted in the current transaction (but not yet committed) getEntityState()

Note:

Will return one of the constants STATUS_UNMODIFIED, STATUS_INITIALIZED, STATUS_NEW, STATUS_MODIFIED, STATUS_DELETED, or STATUS_DEAD indicating the status of the entity instance in the current transaction.

Determine the state of the entity instance getPostState()

Note:

This method is typically only relevant if you are programmatically using the postChanges() method to post but not yet commit entity changes to the database and need to detect the state of an entity with regard to its posting state

Get the value originally read from the database for a given attribute getPostedAttribute()
Eagerly lock the database row for an entity instance lock()

Methods You Typically Write in Your Custom EntityImpl Subclass

 

If you want to... Write a method like this in your EntityImpl subclass
Perform attribute-specific validation public boolean validate Something( AttrType value)

Note:

Register the attribute validator method by adding a "MethodValidator" on correct attribute in the Validation panel of the Entity Object editor. When you register the method validation

Perform entity-level validation public boolean validate Something()

Note:

Register the entity-level validator method by adding a "MethodValidator" on the entity in the Validation panel of the Entity Object editor.

Calculate the value of a transient attribute Add your calculation code to the generated get AttributeName() method.

Methods You Typically Override on EntityImpl

 

If you want to... Override this method in your custom EntityImpl subclass...
Set calculated default attribute values, including programmatically populating the primary key attribute value of a new entity instance. create()

Note:

After calling super.create(), call the appropriate set AttrName() method(s) to set the default values for that(/those) attributes.

Modify attribute values before changes are posted to the database prepareForDML()
Augment/change the standard INSERT, UPDATE, or DELETE DML operation that the framework will perform on your entity object's behalf to the database doDML()

Note:

Check the value of the operation flag to the constants DML_INSERT, DML_UPDATE, or DML_DELETE to test what DML operation is being performed.

Perform complex, SQL-based validation after all entity instances have been posted to the database but before those changes are committed. beforeCommit()
Insure that a related, newly-created, parent entity gets posted to the database before the current child entity on which it depends postChanges()

Note:

If the parent entity is related to this child entity via a composition association, then the framework already handles this automatically. If they are only associated (but not composed) then you need to override postChanges() method to force a newly-created parent entity to post before the current, dependent child entity. See this OTN article for the code you typically write in your overridden postChanges() method to accomplish this.


NOTE:

It is possible to write attribute-level validation code directly inside the appropriate set AttributeName method of your EntityImpl class, however adopting the MethodValidator approach suggested above results in having a single place on the Validation tab of the Entity Object editor to look in order to understand all of the validations in effect for your entity object, so it can result in easier to understand components.


It is also possible to override the validateEntity() method to write entity-level validation code, however if you want to maintain the benefits of the ADF bundled exception mode — where the framework collects and reports a maximal set of validation errors back to the client user interface — it is recommended to adopt the MethodValidator approach suggested in the table above. This allows the framework to automatically collect all of your exceptions that your validation methods throw without your having to understand the bundled exception implementation mechanism. Overriding the validateEntity() method directly shifts the responsibility on your own code to correctly catch and bundle the exceptions like the ADF framework would have done by default, which is non-trivial and a chore to remember and hand-code each time.

EntityDefImpl Class

The EntityDefImpl See Javadoc for EntityDefImpl class is a singleton, shared metadata object for all entity objects of a given type in a single Java VM. It defines the structure of the entity instances and provides methods to create new entity instances and find existing instances by their primary key.

Methods You Typically Call on EntityDefImpl

 

If you want to... Call the EntityDefImpl method
Find an entity object of a this type by its primary key findByPrimaryKey()

Note:

See this tip for getting findByPrimaryKey() to find entity instances of subtype entities as well.

Access the current DBTransaction object getDBTransaction()
Find any EntityDefImpl object by its fully-qualified name findDefObject() (static method)
Retrieve the value of an entity object's custom property getProperty(), getProperties()
Set the value of an entity object's custom property setProperty()
Create a new instance of an entity object createInstance()

Note:

This method has protected access, so you'll need visit the Java tab of the Entity Object editor to indicate you want a custom EntityDefImpl subclass for your entity object in question. Then, from code you write inside this custom subclass, you can invoke this method.

Alternatively, you can expose custom create XXX() methods with your own expected signatures in that same custom EntityDefImpl subclass. See the next section for details.

Iterate over the entity instances in the cache of this entity type. getAllEntityInstancesIterator()
Access ArrayList of entity definition objects for entities that extend the current one. getExtendedDefObjects()

Methods You Typically Write on EntityDefImpl

 

If you want to... Write a method like this in your custom EntityDefImpl class
Allow other classes to create an entity instance with an initial type-safe set of attribute values or setup information. create XXXX( Type1 arg1, ..., TypeN argN)

Note:

Internally, this would create and populate an instance of a NameValuePairs object (which implements AttributeList) and call the protected method createInstance(), passing that NameValuePairs object. Make sure the method is public if other classes need to be able to call it.

Methods You Typically Override on EntityDefImpl

 

If you want to... Call the EntityDefImpl method
Perform custom metadata initialization when this singleton metaobject is loaded. createDef()
Avoid using the RETURNING INTO clause to support refresh-on-insert or refresh-on-update attributes isUseReturningClause()

Note:

Return false to disable the use of RETURNING INTO, necessary sometimes when your entity object is based on a view with INSTEAD OF triggers that doesn't support RETURNING INTO at the database level.

Control whether the UPDATE statements issued for this entity update only changed columns, or all columns isUpdateChangedColumns()

Note:

Defaults to true.

Find any EntityDefImpl object by its fully-qualified name findDefObject()

Note:

Static method.

Set the value of an entity object's custom property setProperty()
Allow other classes to create a new instance an entity object without doing so implicitly via a view object. createInstance()

Note:

If you don't write a custom create method as noted in the previous section, you'll need to override this method and widen the visibility from protected to public to allow other classes to construct an entity instance.

ViewObjectImpl Class

The ViewObjectImpl See Javadoc for ViewObjectImpl class the base class for view objects.

Methods You Typically Call on ViewObjectImpl

 

If you want to... Call this ViewObjectImpl method
Perform any of the common view object, rowset, or rowset iterator operations from inside your class, which can also be done from the client See the ViewObject Interface, RowSet Interface, and RowSetIterator Interface sections above.
Set an additional runtime WHERE clause on the default rowset setWhereClause()
Set bind variable values on the default rowset setWhereClauseParam()
Retrieved a subset of rows in a view object's row set based on evaluating an in-memory filter expression. getFilteredRows()
Retrieved a subset of rows in the current range of a view object's row set based on evaluating an in-memory filter expression. getFilteredRowsInRange()
Set the number of rows that will be fetched from the database per round-trip for this view object. setFetchSize()

Note:

The default fetch size is a single row at a time. This is definitely not optimal if your view object intends to retrieve many rows, so you should either set the fetch size higher at design time on the Tuning tab of the View Object editor, or set it at runtime using this API.

Methods You Typically Write in Your Custom ViewObjectImpl Subclass

 

If you want to... Write a method like this in your ViewObjectImpl subclass
Provide clients with type-safe methods to set bind variable values without exposing positional details of the bind variables themselves someMethodName( Type1 arg1, ..., TypeN argN)

Note:

Internally, this method would call the setWhereClauseParam() API to set the correct bind variables with the values provided in the type-safe method arguments.

JDeveloper 10g can generate you a custom YourViewObjectName interface containing view object custom methods that you've chosen to expose to the client. You can accomplish this by visiting the Client Interface tab of the View Object editor, and shuttling the methods you'd like to appear in your client interface into the Selected list.

Methods You Typically Override in Your Custom ViewObjectImpl Subclass

 

If you want to... Override this ViewObjectImpl method
Initialize custom view object class members (not row attributes!) when the view object instance is created for the first time. create()

Note:

This method is useful to perform setup logic that is applicable to every instance of a view object that will ever get created, in the context of any application module.

If instead of generic view object setup logic, you need to perform logic specific to a given view object instance in an application module, then override the prepareSession() method of your application module's ApplicationModuleImpl subclass and perform the logic there after calling findViewObject() to find the view object instance whose properties you want to set.

Write custom view object instance state to the state management XML snapshot passivateState()
Read and restore custom view object instance state from the state management XML snapshot activateState()
Customize the behavior of view object query execution, independent of whether the query was executed explicitly by calling executeQuery() or implicitly, for example, by navigating to the first() row when the query hadn't yet been executed. executeQueryForCollection()
Change/augment the way that the ViewCriteria collection of ViewCriteriaRows is converted into a query-by-example WHERE clause. getViewCriteriaClause()

ViewRowImpl Class

The ViewRowImpl See Javadoc for ViewRowImpl class the base class for view row objects.

Methods You Typically Call on ViewRowImpl

If you want to... Write a method like this in your custom ViewRowImpl class
Perform any of the common view row operations from inside your class, which can also be done from the client See the Row Interface section above.
Get the value of an attribute get AttrName()
Set the value of an attribute set AttrName()
Access the underlying entity instance to which this view row is delegating attribute storage. get EntityUsageAliasName()

Note:

You can change the name of the entity usage alias name on the Entity Objects tab of the View Object Editor

Methods You Typically Write on ViewRowImpl

 

If you want to... Write a method like this in your custom ViewRowImpl class
Calculate the value of a view object level transient attribute get AttrName()

Note:

JDeveloper generates the skeleton of the method for you, but you need to write the custom calculation logic inside the method body.

Perform custom processing of the setting of a view row attribute set AttrName()

Note:

JDeveloper generates the skeleton of the method for you, but you need to write the custom logic inside the method body if required.

Determine the updateability of an attribute in a conditional way. isAttributeUpdateable()
Custom methods that expose logical operations on the current row, optionally callable by clients doSomething()

Note:

Often these view-row level custom methods simply turn around and delegate to a method call on the underlying entity object related to the current row.

JDeveloper 10g can generate you a custom YourViewObjectNameRow interface containing view row custom methods that you've chosen to expose to the client. You can accomplish this by visiting the Client Row Interface tab of the View Object editor, and shuttling the methods you'd like to appear in your client interface into the Selected list.

Methods You Typically Override in Your Custom ViewRowImpl Subclass

 

If you want to... Write a method like this in your custom ViewRowImpl class
Determine the updateability of an attribute in a conditional way. isAttributeUpdateable()

Setting Up Your Own Layer of Framework Base Classes

Before you begin to develop application specific business components, we recommend creating yourself a layer of classes that extend all of the ADF Business Components framework base implementation classes described in this paper. An example of a customized framework base class for application module components might look like this:

package com.yourcompany.adfextensions;
import oracle.jbo.server.ApplicationModuleImpl;
public class CustomApplicationModuleImpl extends ApplicationModuleImpl {
  /*
   * We might not yet have any custom code to put here yet, but
   * the first time we need to add a generic feature that all of
   * our company's application modules need, we will be very happy
   * that we thought ahead to leave ourselves a convenient place
   * in our class hierarchy to add it so that all of the application
   * modules we have created will instantly benefit by that new feature,
   * behavior change, or even perhaps, bug workaround.
   */
}

A common set of customized framework base classes in a package name of your own choosing like com.yourcompany.adfextensions , each importing the oracle.jbo.server.* package, would consist of the following classes.

  • public class CustomEntityImpl extends EntityImpl
  • public class CustomEntityDefImpl extends EntityDefImpl
  • public class CustomViewObjectImpl extends ViewObjectImpl
  • public class CustomViewRowImpl extends ViewRowImpl
  • public class CustomApplicationModuleImpl extends ApplicationModuleImpl
  • public class CustomDBTransactionImpl extends DBTransactionImpl2
  • public class CustomDatabaseTransactionFactory extends DatabaseTransactionFactory

For completeness, you may also want to create customized framework classes for the following classes as well, but overriding anything in these classes would be a fairly rare requirement.

  • public class CustomViewDefImpl extends ViewDefImpl
  • public class CustomEntityCache extends EntityCache
  • public class CustomApplicationModuleDefImpl extends ApplicationModuleDefImpl

Conclusion

Hopefully this short list of methods will assist you in getting started with Oracle ADF Business Components to focus your attention on these most frequently used methods instead of feeling bewildered about the many other methods that could be overridden but which aren't often done in practice.

If you have already been using ADF Business Components for some time and notice some methods you use frequently that didn't make my list, please send me an email to let me know what I should add to the list. Include in your email a brief description of how you're using the method, or what functionality you often providing in the overridden version of the method. Thanks!

Revision History

Date Comments
18-Nov-2004 Created
19-Nov-2004 Updated diagram to include StructureDef, AttributeDef, and AttributeHints, and added some text on the generated client proxy classes.
20-Nov-2004 Added a comment about passing null to the createRowSetIterator method
30-Nov-2004 Added getPostedAttribute() and getEntityState()
1-Dec-2004 Clarified getPostState() and getEntityState()
1-Jan-2005 Added some use case information for prepareSession()
14-Mar-2005 Clarified when to use VOImpl.create() vs AMImpl.prepareSession()
15-Mar-2005 Clarified when to prepareForDML() vs postChanges()
14-Jun-2005 Clarified that EntityImpl.create() is used for programmatically populating primary key attributes as well
19-Jan-2006 Updated javadoc links
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