ADF Lifecycle

The ADF Lifecycle provides support allowing a web page to interact with ADF Model data bindings. The lifecycle calls the correct binding container needed for a JSP or UIX page, updates values in the binding container's bindings if necessary, and
prepares the data to be rendered. The binding container stores this data locally before rendering the page.

Implementations of Lifecycle should be thread-safe and use the LifecycleContext object as the place to store any per-request state they may need.


ADF Lifecycle phases:

1. initialize
This phase initializes the values of the associated request, binding container and lifecycle. The method that is used from the Interface Lifecyle for this purpose is :

initializeMethodParameters(LifecycleContext lcContext, oracle.jbo.uicli.binding.JUCtrlActionBinding actionBinding)
This method is invoked before any ControlBinding or custom method is being executed.

2. prepareModel

This phase prepares and initializes the Model. Page parameters are set and methods in the executable section of the page definition of the ADF page are executed. The interface LifeCycle method used :

prepareModel(LifecycleContext lcContext)


3. applyInput
This phase handles the request parameters. These may come by adding the request parameters in the URL or as a result of HTML form post action. A list of events is build using these request parameters. These are actually mapped to the bindings in the pageDef. This phase resolves the list of request parameters bind to attributes in the page def. This results into a list of updatedValues which is used in Update Model phase.

The interface LifeCycle method used :

buildEventList(LifecycleContext lcContext)
Builds the list of events with their possible associated action binding from the request parameters.


4. validateInput

This phase validates the list of values built in the Apply input values field with model.

5. updateModel

This phase updates data model with the list of values created in apply input values phase.

The interface LifeCycle method used :
processUpdateModel(LifecycleContext lcContext)
Update the data model with values submitted in the request.



6. validateModelUpdates

This phase validates the Updates in the previous phase by calling the associated lifecycle's binding container .
The interface LifeCycle method used :

validateModelUpdates(LifecycleContext lcContext)
Forces model-level validation to occur.

7. Process Component Updates

This phase handles any events in the list built during the apply input values phase. Named events as well as all the events tied to the databindings created in the pagdef are handled in this phase.

The interface LifeCycle method used :
processComponentEvents(LifecycleContext lcContext)
Handle any events in the action binding list previously built in processUpdateModel using the buildEventList method.

8. Metadata Commit

This phase commits the runtime metadata changes to the model. This phase is always executed before prepare render phase.


9. Prepare Render

This is the final phase where page is sent for rendering. prepareRender event is sent to all the registered listeners. This notification signals bindings to prepare or process the data for rendering. Binding container is also refreshed. This helps
in updating any changes that happened during validation phases.



References :
- Lifecycle (Oracle Fusion Middleware Java API reference for Oracle ADF Lifecycle)

- Phases in ADF LifeCycle

What are ADF business components and which component provides transaction management?

A challenge every Java developer developing applications using data from a database faces is mapping Java objects to relational tables, managing transactions and locking, and ensuring adequate performance. There are many frameworks that help us handle this, without us needing to build everything from scratch. The open source community has produced a large number of more or less complete and robust frameworks for working with databases and Java objects. Oracle's solution is the Oracle Application Development Framework Business Components.

The main components of the ADF Model layer are:

1. The Entity objects or EO's
2. The View objects or VO's and
3. Entity Association's
4. View Object ViewLinks
5. The Application modules or AM's
6. The Business Component Tester or AM tester

The EO/VO is similar to Object relational mapping elements.
So, in essence, EO/VO provide a standard way of interacting with database tables and serve as the data model source.

The Entity Object

An EO represents a table in simple terms. It defines the table's attributes, the data types, validation on the data, the primary keys and the entire business logic that needs to be defined for pushing data into the target table.


The View Object

The view object can be based on EO's, which are similar to SQL queries used to extract data, or it can be programatically populated, or with a static list.

However VO's based on EO's are most used option. While a few validations can be done even at the VO level, it's better to have business logic on the EO's as this will help provide a central point for all VO's dependent on them.


Associations and Viewlinks

They define the join or the link among EO's and VO's. Associations defines link between EO's. They can be considered as PrimaryKey/ForeignKey relationships between tables. They define the Join conditions.

A viewlink defines the link between VO's and can be based on an association or on attributes.

The Application Module

The application module packages the VO's and serves as the data control.The AM creates and manages the database transaction for ADF Model layer. It is the Application Module that exposes the data needed by the client. So, for an end user, the interaction and transactional capabilities are provided by the application module.

The Business Component Tester

The most used component of the model layer is the tester. It can be run to check the data model that is implemented. This serves as the first line of defense to see if data is exposed as desired, without the need to create a UI.

If you hit oracle.security.jps.JpsRuntimeException: Cannot read from policy store.

When trying to start your integrated weblogic server, if you come across the following error :-

oracle.security.jps.JpsRuntimeException: Cannot read from policy store.
  at oracle.security.jps.internal.policystore.xml.XmlPolicyStore.buildFromFile(XmlPolicyStore.java:425)
 at oracle.security.jps.internal.policystore.xml.XmlPolicyStore.(XmlPolicyStore.java:224)
        ...
Caused by: oracle.security.jps.JpsRuntimeException: javax.xml.stream.XMLStreamException: End Document reached prematurely.
  at oracle.security.jps.internal.core.datastore.xml.XmlDataStoreParser.getDataStoreEntryStax
 (XmlDataStoreParser.java:166)
   ...
   ... 28 more
   ...
weblogic.security.SecurityInitializationException: The loading of OPSS java security policy provider failed due to exception, see the exception stack trace or the server log file for root cause. If still see no obvious cause, enable the debug flag -Djava.security.debug=jpspolicy to get more information. Error message: 

  oracle.security.jps.JpsException: [PolicyUtil] Exception while getting default policy Provider
       at weblogic.security.service.CommonSecurityServiceManagerDelegateImpl.loadOPSSPolicy
    (CommonSecurityServiceManagerDelegateImpl.java:1398)
        ...
Caused By: oracle.security.jps.JpsRuntimeException: oracle.security.jps.JpsException: [PolicyUtil] Exception while getting default policy Provider
           at oracle.security.jps.internal.policystore.PolicyDelegationController.(PolicyDelegationController.java:291)
...       
Caused By: java.security.PrivilegedActionException: oracle.security.jps.JpsException: [PolicyUtil] Unable to obtain default JPS Context!
     at java.security.AccessController.doPrivileged(Native Method)
...
Caused By: oracle.security.jps.JpsRuntimeException: Cannot read from policy store.
    at oracle.security.jps.internal.policystore.xml.XmlPolicyStore.buildFromFile(XmlPolicyStore.java:42

Solution:-

This issue mostly occurs due to a corruption in the jazn-data.xml file. You could delete the jazn-data.xml file under the DefaultDomain directory or delete the 'DefaultDomain' directory under the system directory inside your view. This will create the domain afresh the next time you start your WLS.

oracle.jbo.attributeloadexception: JBO-27022

Problem scenario :

I was in the process of replacing a particular table in the database with a new table (table name and attribute names changed). Correspondingly this involved creating new Entity Object, View Object, Entity Associations and View Object links. This meant replacing the old associations that are present in any of the VOs with the new ones.

As part of this, all required attributes from the EO need to be shuttled properly to be present as part of the VO. The catch here is, if the EO has any transient or calculated attributes, then these should not be shuttled into the VO. If you happen to do this, you are bound to hit the above exception when testing the VO:-

(oracle.jbo.AttributeLoadException) JBO-27022: Failed to load value at index 19 with java object of type java.lang.Long due to java.sql.SQLException.

Solution :
Remove the extra transient attributes (in the VO) that were added from the EO.
The VO test should now pass fine. The number of attributes in the Select clause of the VO object query and the number of attributes in the VO should potentially be the same!

The below link provides some more useful information on the same front :-
http://oracle-hack.blogspot.com/2009_05_01_archive.html

Removing hard coded set-attribute in EOImpl

I was faced with the below issue and posted it on several forums :-

Some EO's in my application have hard-coded setAttribute in order to get around an ADF issue where we have these transient attributes for EO assocations, but they don't show up on newly created rows.


For example:

protected void create(AttributeList attributeList) {
super.create(attributeList);
this.setAttribute("TransientAttribute1","SOME_LITERAL_VALUE1");
this.setAttribute("TransientAttribute2","SOME_LITERAL_VALUE2");
this.setAttribute("TransientAttribute3","SOME_LITERAL_VALUE3");
}

Our requirement is to get away with this method and instead achieve the above using either groovy expression or derived from sql expression. Using this, the values of the Transient attributes show up as null currently. We need to have the literal values show up on creating a new row.

Finally, what worked for me was :-

I had the setAttribute in the EOImpl file removed.
Instead I had the literal values set in the 'Literal' window and the 'Derived from SQL expression' window.
The test cases for most entities passed fine.
I added tests in entity unit tests to test the default values for common association attributes in case of new row creation as well as fetch row from DB. They worked perfectly fine in both cases

Recursively copying files along with directory structure in linux

Although this is something relatively simple, sometimes doesnt work correctly especially if you're trying it after a long time. You could be faced with errors like :

cp: cannot create symbolic link , etc.

If you wanna copy say, multiple files along with directory structure from
/ab/cd/ef/gh/ij/kl/mn/op/qr/st/uv/*

to

/aba/cdc/efe/ghg/iji/klk/mnm/opo/qrq/sts/uvu/*

then typically

cp -R /ab/cd/ef/gh/ij/kl/mn/op/qr/st/uv/ /aba/cdc/efe/ghg/iji/klk/mnm/opo/qrq/sts/uvu/

should work good for you.

The entire list of files along with the directory structure, gets copied at the destination location. It is important here to give the complete paths for source as well as destination instead of trying to use relative paths!

Installing and using ScrumWorks on Linux

ScrumWorks is an agile management software by CollabNet meant for an enterprise and comes in 2 flavors : ScrumWorks Pro and ScrumWorks Basic.

To run Scrumworks on your linux box, you need to install the server.
a. Download the ScrumWorks Basic Linux distribution file from the download site.
b. Extract the file in the directory you want to install ScrumWorks Basic to.
c. Change to the directory that was created during extraction.
d. Run ./setup.sh to configure your server and get instructions for starting it.

A pre-requisite to do the above installation is to have JDK already installed on your machine. However, right now, apparently, Scrumworks Basic only supports JDK2. Higher versions are not supported yet. So, you need to have version 2 necessarily installed for sure!!