Welcome to My Oracle World

7/23/2014 Welcome to My Oracle World

https://blogs.oracle.com/prajkumar/tags/oracle_d2k_to_oa_transformation 1/4

What is the difference between Oracle D2K form and OA Framework?

It is a very innocent but important question for someone that desires to make transition fromD2K to OA Framework. I hope you have already read and implemented OA FrameworkGetting Started.

I will re-visit my own experience of implementing HelloWorld program in "OAFramework". When I implemented HelloWorld a year ago, I had no clue as to what I wasdoing & why I was doing those steps. I merely copied the steps from Oracle Tutorialwithout understanding them.

Hence in this blog, I will try to explain in simple manner the meaning of OA FrameworkHelloWorld Program and compare the steps to D2K form [where possible]. To keep thingssimple, only basics will be discussed.

Following key Steps were needed for HelloWorld

Step 1

Create a new Workspace and a new Project as dictated by Oracle's tutorial. When definingproject, you will specify a default package, which in this case was oracle.apps.ak.hello

This means the following: -

ak is the short name of the Application in Oracle

[means fnd_applications.short_name]

hello is the name of your project

Step 2

Next, you will create a OA Page within hello project

Think OA Page as the fmx file itself in D2K. I am saying so because this page gets attachedto the form function.

This page will be created within hello project, hence the package

nameoracle.apps.ak.hello.webuiNote the webui, it is a convention to have page in webui, means this page represents

the Web User Interface

You will assign the default AM [OAApplicationModule]. Think of AM "Connection

Manager" and "Transaction State Manager" for your page

I can't co-relate this to anything in D2k, as there is no concept of Connection Poolingand that D2k is not stateless. Reason being that as soon as you kick off a D2K Form, itconnects to a single session of Oracle and sticks to that single Oracle database session. So isnot the case in OAF, hence AM is needed.

Step 3

You create Region within the Page.

Region is what will store your fields. Text input fields will be of type messageTextInput.Think of Canvas in D2K. You can have nested regions. Stacked Canvas in D2K comes theclosest to this component of OA Framework

Step 4



Add a button to one of the nested regions

The itemStyle should be submitButton, in case you want the page to be submitted

when this button is clicked

There is no WHEN-BUTTON-PRESSED trigger in OAF. In Framework, you will add a

controller java code to handle events like Form Submit button clicks. JDeveloper

generates the default code for you. Primarily two functions [should I call methods] willbe created processRequest [for UI Rendering Handling] and processFormRequest

Think of processRequest as WHEN-NEW-FORM-INSTANCE, though processRequest

is very restrictive.

Note

What is the difference between processRequest and processFormRequest?

These two methods are available in the Default Controller class that gets created.

processFormRequest

This method is commonly used to react/respond to the event that has taken place, forexample click of a button.

Some examples are

if(oapagecontext.getParameter("Cancel") != null) (Do your processing for Cancellation/Rollback)

if(oapagecontext.getParameter("Submit") != null) (Do your validations and commit here)

if(oapagecontext.getParameter("Update") != null) (Do your validations and commit here)

In the above three examples, you could be calling oapagecontext.forwardImmediately to re-direct the page navigation to some other page if needed.

processRequest

In this method, usually page rendering related code is written. Effectively, each GUIcomponent is a bean that gets initialised during processRequest. Those who are familiar

with D2K forms, something like pre-query may be written in this method.

Step 5

In the controller to access the value in field "HelloName" the command is

String userContent = pageContext.getParameter("HelloName");

In D2k, we used :block.field.

In OAFramework, at submission of page, all the field values get passed into toOAPageContext object.

Use getParameter to access the field valueTo set the value of the field, use

OAMessageTextInputBean field

HelloName = (OAMessageTextInputBean)webBean.findChildRecursive("HelloName"); fieldHelloName.setText(pageContext,"Setting the default value" );



Note when setting field value in controller:

Note 1. Do not set the value in processFormRequest Note 2. If the field comes from View Object, then do not use setText in controller Note 3. For control fields [that are not based on View Objects], you can use setText to assignvalues in processRequest method

Lets take some notes to expand beyond the HelloWorld Project

Note 1

In D2K-forms we sort of created a Window, attached to Canvas, and then fields within thatCanvas.

However in OA Framework, think of Page being fmx/Window, think of Region being aCanvas, and fields being within Regions. This is not a formal/accurate understanding of analogy between D2k and Framework, but isclose to being logical.

Note 2

In D2k, your Forms fmb file was compiled to fmx. It was fmx file that was deployed on mid-tier. In case of OAF, your OA Page is nothing but a XML file. We call this MDS [meta data].

Whatever name you give to "Page" in OAF, an XML file of the same name gets created. Thisxml file must then be loaded into database by using XML Importer command.

Note 3

Apart from MDS XML file, almost everything else is merely deployed to your mid-tier.Usually this is underneath $JAVA_TOP/oracle/apps/../.. All java files will go underneath java top/oracle/apps/../.. etc.

Note 4

When building tutorial, ignore the steps for setting "Attribute Sets". These are notmandatory. Oracle might just have developed their tutorials without including these. Thinkof these like Visual Attributes of D2K forms

Note 5

Controller is where you will write any java code in OA Framework. You can create aController per Page or have a different Controller for each of the Regions with the samePage.

Note 6

In the method processFormRequest of the Controller, you can access the values of the pageby using notation pageContext.getParameter("<fieldname here>").

This method processFormRequest is executed when the OAF Screen/Page is submitted byclick of a button.

Note 7

Inside the controller, all the Database Related interactions for example interaction with ViewObjects happen via Application Module.

But why so? Because Application Module Manages the transaction state of the Application.



OAApplicationModuleImpl oaapplicationmoduleimpl =

OAApplicationModuleImpl)oapagecontext.getApplicationModule(oawebbean);

OADBTransaction oadbtransaction =

OADBTransaction)oaapplicationmoduleimpl.getDBTransaction();

Note 8

In D2K, we have control block or a block based on database view. Similarly, in OAFramework, if the field does not have view Object attached, then it is like a control field.Hence in HelloWorld example, field HelloName is a control field [in D2K terminology]. Aview Object can either be based on a view/table, synonym or on a SQL statement.

Note 9

I wish to access the fields in multi record block that is based on view Object. Can I do this inController? Sure you can. To traverse through those records, do the below

Get the reference to the View Object using(OAViewObject)oapagecontext.getApplicationModule(oawebbean).findViewObject("VOName Here")

Loop through the records in View Objects using count returned fromoaviewobject.getFetchedRowCount()

For each record, fetch the value of the fields within the loop as

oracle.jbo.Row row = oaviewobject.getRowAtRangeIndex(loop index here);

(String)row.getAttribute("Column name of VO here ");

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