ADF Interview Questions - Set 4

Question: Can you make View Link bidirectional?
Answer: Yes, you can make a view link bidirectional. It’s handled by view link query.
View Links created on Association are also bidirectional.

Question: How to create read only VO?
Answer: While creating View select option "Read-only access through SQL query". Also view is read-only if it does not have Primary Keys or if all its entity references are reference-only.

Question: Explain Data Control Palette hierarchy.
Answer: The Data Control Palette displays two types of actions/operations:
1. Actions that typically operate on all data collections in the current web page's binding context (such as Commit and Rollback) in the Operations folder at the root level of the hierarchy.
2. Operations on a specific data collection (for example, MyView1). Data collection-specific operations (such as Create and Delete) appear in the Operations folder as child nodes of the collection in the Data Control Palette.

Question: How many types of VOs we can create in Oracle ADF?
Answer: There are four types of VOs we can create as shown in below image, select radio button & create VO.
1. Updatable VO (Updatable access through entity objects) - Here EO need to be created for updatable VOs.
2. Read only VO (Read-only access through SQl query) - No need to create EO, VOs can be created using SQL queries, table, or views.
3. Rows populated programmatically, not based on query - This is also read-only view. Here add one or more attributes to use in program. In the Attribute Settings page, adjust any setting you may need to for the attributes you defined.
4. Static VO (Rows populated at design time- Static List): You use the Create View Object wizard to create static view objects. The wizard lets you define the desired attributes (columns) and enter as many rows of data as necessary. The wizard displays the static data table as you create it. Attributes can be added from a comma-separated value (CSV) file as well.

Question: Can we change DB connection for any particular AM?
Answer: Steps to change DB connection: 
1. Double click on AM.
2. Go to the configuration tab, click on configuration file bc4j.xml
3. Here we have attribute JDBCName under element AppModuleConfig, change the connection which is created for other DB.

Question: What is Managed Bean?
Answer: Managed bean is a java class, which is initialized by JSF framework. It is primarily used to hold view and controller logic. It is also used to execute java code to be executed on a user action like Button Click.
Managed bean describes how the bean is created and initialized. As you know, jsf uses the lazy initialization model. It means that the bean in the particular scope is created and initialized not at the moment when the scope is started, but on-demand, i.e. when the bean is first time required.

Question: What are Backing Bean?
Answer: Backing beans are those managed beans which have 1:1 mapping with a page. They defines a set of methods that perform functions for the component, such as getters and setters, validating the component’s data, handling events that the component fires and performing processing associated with navigation when the component activates.

Question: What is difference between managed and backing beans?
Answer: Backing bean has 1:1 relation with page whereas managed beans can be used in multiple pages.
Backing beans scope is limited to the page whereas managed beans can have other scopes too.

Question: How can you define custom component?
Answer: There is multiple way of creating the custom component
1. Declarative: Using this way you can create jspx page with adf components and provide property and methods which you want to expose to client.
2. Extending Component: You can extend your existing component to define custom component.

Question: Can Service Methods return type Void?
Answer: Yes, Service Methods can Return type Void

Question: What is the return type of Service Methods?
Answer: Service Methods can return Scalar or Primitive Data types.

Question: Can Service Methods return Complex Data types?
Answer: No, service methods can return only primitive/scalar data types.

Question: What is the Business Component Tester? 
Answer: The mostly used component of the model layer is the tester, which is used to run and check the data model that is implemented. This serves as the first line of defense to see if data is exposed as we need it and to test the data model without a need to create a UI.

Question: What is Association Accessor? 
Answer: It’s an operation by which an entity instance at one end of an association can access the related entity object instance at the other end of the association. An Accessor that travels from destination to source is called a source accessor and an accessor that travel from source to destination is called a destination accessor. It is described in the entity object definition xml files which can be used by view object and view link definition to specify cross entity relationship. Its return type will be the entity object class of associated entity object definition or ‘EntityImpl’ if the associated entity object definition has no entity object class.

Question: What are the various access scopes supported by ADF?
Answer: ADF Faces supports the following scopes:
1. Application Scope
2. Session Scope
3. PageFlow Scope
4. Request Scope
5. BackingBean Scope.

Question: What are the security application layers & how they handled in Oracle ADF?