If you want to do some OAF Development in JDeveloper for the first time, you will need to do the following things.
1] Download JDeveloper Patch
Based on your instance release level, check out the version of JDeveloper to use using below link.
You can identify the OA Framework version in your instance by activating diagnostics and click the “About This Page” from any OAF page. Click the “Technology Components” tab. The OA Framework version in the top row of the table can then be matched to the JDeveloper Patch.
Download the JDeveloper Patch.
2] Extract the JDeveloper patch in a directory say D:DevSuiteHome_1jdev
The patch actually contains below three directories
  • jdevbin – Includes an extended version of the Oracle JDeveloper 10executable and OA Framework class libraries.
  • jdevhome – Includes the OA Framework Toolbox Tutorial source and developer working area.
  • jdevdoc – Contains documentation.
3] Define an environment variable
Define an environment variable JDEV_USER_HOME for your local machine. This has to be set to jdevhomejdev directory. In above example it has to be D:DevSuiteHome_1jdevjdevhomejdev.
My Computer  Properties  Advanced tab  Environment Variables  New
Value: D:DevSuiteHome_1jdevjdevhomejdev
4] Extract Tutorial.zip
Extract D:DevSuiteHome_1jdev jdevbinTutorial.zip into D:DevSuiteHome_1jdev jdevhome.
It will create following directories
D:DevSuiteHome_1jdev jdevhomejdevmyhtml
D:DevSuiteHome_1jdev jdevhomejdevmyprojects
5] Get the DBC file
Obtain the FND database connection (.dbc) file from the system administrator who installed the OA Framework database where you want to do your development.
For the instance to use, you can get the .dbc file from $FND_SECURE and put it in <JDEV_USER_HOME>dbc_filessecure i.e. D:DevSuiteHome_1jdevjdevhomejdev dbc_filessecure
6] Creating a Desktop Shortcut to JDeveloper
To facilitate launching JDeveloper, create a desktop shortcut to jdevbinjdevbinjdevw.exe.
7] Configuring the Environment Encoding of JDeveloper
Confirm the environment encoding of your JDeveloper if it is appropriately set.
Go to Tools – Preferences – Environment – Encoding
If Encoding is not set to “UTF-8″, set it to “UTF-8″.
The initial setup is now complete!….Now you are ready to develop your first OAF page. For more information you can refer OAF Developer’s Guide.

Although Discoverer provides many functions for calculation in reports, sometime we require to use custom PL/SQL functions to meet additional Discoverer end user requirements (for example, to provide a complicated calculation). For this we first need to create the functions in database through Toad or other PL/SQL editors.
To access custom PL/SQL functions using Discoverer, you must register the functions in the EUL. When you have registered a custom PL/SQL function, it appears in the list of database functions in the “Edit Calculation dialog” and can be used in the same way as the standard Oracle functions.
Note: To register a PL/SQL function you must have EXECUTE privilege on that function.
You can register custom PL/SQL functions in two ways:
  •  Import automatically, by importing the functions (recommended)
  •  Manually

How to register custom PL/SQL functions automatically:

To register PL/SQL functions automatically you must import them in the following way:
 1. Choose Tools | Register PL/SQL Functions to display the “PL/SQL Functions dialog: Functions tab”.
 2. Click Import to display the “Import PL/SQL Functions dialog”. This dialog enables you to select the PL/SQL functions that you want to import.

3. Select the functions that you want to import. You can select more than one function at a time by holding down the Ctrl key and clicking another function.
4. Click OK.
Discoverer imports the selected functions and displays the function details in the “PL/SQL Functions dialog: Functions tab”. Information about the selected functions is imported automatically. In other words, you do not have to manually enter information or validate the information.
5. Click OK.
The PL/SQL function is now registered for use in Discoverer.

How to register custom PL/SQL functions manually:

To manually register a PL/SQL function for use in Discoverer:
1. Choose Tools | Register PL/SQL Functions to display the “PL/SQL Functions dialog: Functions tab”.
2. Click New and specify the function attributes.
3. Click Validate to check the validity and accuracy of the information you have entered.
4. If the function is invalid, correct the attributes and click Validate again.
5. (Optional) if the function accepts arguments:
a. Display the “PL/SQL Functions dialog: Arguments tab”.
b. On the Arguments tab, click New and specify the argument attributes.
6. Click OK when you have finished defining the function.
The custom PL/SQL function is now registered for use in Discoverer.
It is always recommended to register PL/SQL functions by importing automatically (especially if you have many functions to register), because it is easy to make mistakes when manually entering information about functions. When you import functions, all of the information about each function (for example, names, database links, return types, lists of arguments) is imported.

We can create list of values (LOV) for any parameter in discoverer reports through Item Classes. Here suppose in Discoverer Report, we have a parameter called Period Name. It has a small LOV icon in the right side.
When clicked on the LOV icon, the below window with all the Period Names will appear where you can choose one or many period names.
Now the question is how to do this. You just need to do the below steps to accomplish this task.

1] Create a custom folder named ‘Time Periods’ in a business area with the below query.
select  distinct
decode(period_num,1, 'January',
2, 'February',
3, 'March',
4, 'April',
5, 'May',
6, 'June',
7, 'July',
8, 'August',
9, 'September',
10, 'October',
11, 'November',
12, 'December', null) month_name
from gl_periods;

2] Select the business area in which you want to create an item class. Choose Insert > Item Class.

3] Select the LOV Item class attribute.


4] Select the above created folder (Time Periods) and choose the Period Name column.


5] Here you can select the various items of other folders that can use this item class. You can skip this stage and later you can manually assign this item class to other items.


6] Choose the defaults and click next.


7] Give a suitable name to the Item Class


8] Now go to the Item of the folder on which you created the Parameter (Period Name) and then go to Item Properties. Here you assign the item class that you have created just now.


9] If you already created the parameter in your workbook and your discover plus or desktop is open then close it and reopen. Then you can view the LOV attached to the parameter.

10] If you haven’t already created the parameter, then create the parameter and run the report. You can view the LOV attached to the parameter.