programming-best practices( beginner) adf_fusionapps

Oracle ADF Programming Best Practices for Beginners

Frank Nimphius

Senior Principal Product Manager

Application Development Tools


Program Agenda

Simplify Your Development Choice

ADF Business Components

ADF Task Flow

ADF Binding

ADF Faces

JavaScript

Break Out Of Isolation


Simplify Your Development Choice


Simplify Your Technology Choice Choose a Development Approach

Java EE Oriented Database Oriented SOA Oriented

RDBMS

ADF BC

ADF Binding

ADF Task Flow

ADF Faces

Data Visualization

• EJB / JPA

• ADF Binding

• ADF Task Flow

• ADF Faces

• Data Visualization

• Services

• ADF Binding

• ADF Task Flow

• ADF Faces



Simplify Your Technology Choice Common Technologies

RDBMS

ADF BC

ADF Binding

ADF Task Flow

ADF Faces

Data Visualization

• EJB / JPA

• ADF Binding

• ADF Task Flow

• ADF Faces


• Services

• ADF Binding

• ADF Task Flow

• ADF Faces


Java EE Oriented Database Oriented SOA Oriented



Application

Module

View

Object

Entity

Object

1 *

Data Model XML

Definition

View Object

Base Class

XML

Definition

Entity Object

Base Class

References References

XML

Definition

AM

Base Class

References


ADF Business Components Architecture Best Practices


Use ADF Business Components Preferences



EntityImpl

YourOrgEntityImpl

YourAppEntityImpl


ADF Architecture Square

Development

– Oracle ADF Development

Essentials

– ADF Code Guidelines (v1.00)

– ADF Naming and Project Layout

Guidelines (v2.00)

http://bit.ly/adfarchsquare


ADF Business Components Implementation Best Practices


General Considerations

Always create and use custom base-classes for at least

– ApplicationModuleImpl

– EntiyImpl

– ViewRowImpl

– ViewObjectImpl

Note that creating custom super classes for <object>Def classes are

less common

Custom Framework Extension Classes


Entity & View Object

Generate Java Impl files when entity objects are accessed from Java

or Groovy

Ensure code that accesses entity objects directly uses type safe APIs

instead of the generic framework APIs

Do not generate Impl classes without a need

– Keep code base size reasonable.

– Impl classes for the *def classes are rarely needed

When to generate Java Impl files


View Criteria

Not necessary to create separate VO that only differ by their WHERE

clause

Apply view criteria declaratively when defining view accessor and AM

data model instances

– Use bind variables with View Criteria

– Be aware that "Ignore Null Values" options is of bad performance

Avoid direct user input in ADF BC queries to protect against SQL

injection attacks

Prefer One View Object with Many View Criteria


Performance Tuning And Optimization

Premature optimizations as the root of all evil

– Measure Performance, don't guess it.

– If performance measures as bad, look for optimizations

Make the general assumption that ADF will probably get it right

– Consider the greater cost of do-it-yourself (DIY)

Think AM Pools!

– Good rule of thumb: One AM instance serves 10 - 15 users comfortably

– Size for peak load based on this.

Developers always strive for "better"


Read. Understand. Tune.

http://docs.oracle.com/middleware/1212/adf/

adf-monitortune.htm


ADF Task Flow


Bounded Task Flow Flows, Sub-Flows, Regions

Bounded Task Flow

Return Value

Return Value

Input Parameter

Input Parameter

Input Parameter Managed

Beans


ADF Task Flow Architecture Best Practices


Task Flow Oriented Architecture (TOA)

Think task flow from design time on

– Inventory existing task flows

– Identify patterns and standardize on them

Ensure objectives and requirements reflect task flow benefits

– Reuse, loose-coupling

Think "unit-of-work" and factor task flow functionality into subflows

– Share Data Control frame with sub-flows

– Hide sub-flows from showing in ADF library


Use Task Flow as a "Common Language"

Use task flow diagrammer as "common language"

– Use task flow templates as blue prints

– Use verbs and meaningful names in control flow case names

editOrder, createOrder, manageEmployee

Use the display and description properties of the contained

activities to explain the non-obvious


Task Flow Design

Build Composite Task Flows

– Larger task flows built out of several smaller task flows

– Only top level task flow exposed for reuse

– Encapsulates task flow dependencies

Good for distributing work among developers

Dependency management "by agreement" in smaller teams

Smaller memory foot print through load-on-demand and task flow

private memory scopes

Task Flow Sizing Considerations


ADF Task Flow Implementation Best Practices


Handling Input / Return Parameter Values

Save task flow input / return parameter values

in managed beans in pageFlowScope

– Easy to document

– Type safe API

– EL accessible

– Easy to discover and manipulate

input parameter values

– NPE protection


Managed Beans

Java classes configured in faces-config.xml, adfc-config.xml

or <task-flow-name>.xml

Managed by JSF or ADF Controller

– Java EE scopes

request, session, application

– Additional ADF scopes

backingBean, view, pageFlow

Hold code for UI related logic and data


Bounded Task Flow & Managed Beans

Always use the smallest possible scope for managed beans

– Helps Framework to "clean up" memory footprints

– Think "state"

Does the managed bean need to keep state?

If so, how long?

Don't reference managed beans in session or application scope

– Violates task flow isolation and reuse

Best Practice


Data Control Scope

Use shared data control scope as often as possible

– Less database connections

– Simplifies task flow inter-communication

– Automatic parent view collection to child task flow detail

collection synchronization


Task Flow Exception Handler

Define an exception handler activity in every bounded task flow

Leverage Task Flow Templates

– Use as Blueprint or Reference

– Define exception handlers for

all bounded task flows


What Could Happen Task Flow Exception Propagation

Memory Stack

Current Task Flow

Task Flow 4

Task Flow 3

Task Flow 2

Task Flow 1

Task Flow 2

Call

Task Flow 3

Call

Task Flow 4

Call

!

!

View1

View2

View3

View4

Task Flow 1

Task Flow 2

Task Flow 3

Task Flow 4

EH

EH

Method

Call

Current Task Flow

BANG!



Memory Stack

Current Task Flow

Task Flow 2

Task Flow 1

Task Flow 2

Call

Task Flow 3

Call

Task Flow 4

Call

Propagate

Exception

Propagate

Exception

!

!

View1

View2

View3

View4

Task Flow 1

Task Flow 2

Task Flow 3

Task Flow 4

EH

EH

Current Task Flow

Method

Call

BANG!



!

!

View1

View2

Task Flow 1

Task Flow 2

EH

EH

Memory Stack

Current Task Flow

Task Flow 2

Task Flow 1

Task Flow 2

Call


Visual Example Task Flow Exception Propagation

BANG!

!


Best Practices at a Glance

Avoid cluttering diagrams for common navigation rules

Use wild card navigation for common functionality

– Cancel

– Commit

Wildcard Navigation


ADF Binding


Understanding ADF Bindings How Oracle ADF binds into JSF

Business Service ADF Data Binding

Web Service

POJO

ADF BC

EJB

JMX

TopLink

BAM UI Renderer

Component

FacesCtrl Binding

Expression Language

JSF Page

Data Control

Data Binding

ADF Faces Component Tag (<af:name../>)

Server Side JSF Component

Component Model

JUCtrl Generic Binding


Programming Against the Binding Layer

Expression Language

– Current binding layer can be accessed from #{bindings} or ${bindings}

Use from JSF components

– Populate UI component value #{bindings.firstName.inputValue}

Use from PageDef file

– E.g. access field binding value - ${bindings.firstName.inputValue}

Java

– ADF binding layer is represented by Java objects at runtime

– BindingContext.getCurrent()is the generic entry point


Use Public APIs Only

ADF classes have an API package and an IMPL package

– Define logical framework abstractions

– Simplifies implementation of future product changes

APIs in IMPL package are internal-only

– Not to be used outside of framework

– Internal packages have "internal" in the naming (It’s a clue!)

If you are not sure …

– Use EL in Java: #{bindings.allDepartments.treeModel.makeCurrent}


Understanding ADF Programming Example: Accessing the Binding Layer

import oracle.adf.model.BindingContext;

import oracle.binding.BindingContainer;

…

BindingContext bctx = BindingContext.getCurrent();

BindingContainer bindings = null;

bindings = bctx.getCurrentBindingsEntry();


Understanding ADF Programming Example: Accessing Attribute Binding

AttributeBinding attributeBinding = null;

attributeBinding =

(attributeBinding)bindings.get("AttributeName");

/* set / get value */

attributeBinding.setInputValue(value);

attributeBinding.getInputValue();


Understanding ADF Programming Example: Method and Action Bindings

//get method or action binding

OperationBinding methodBinding =

(OperationBinding)bindings.get("methodOrActionName");

//optional: if method expects arguments

Map paramsMap = methodBinding.getParamsMap();

paramsMap.put("argumentName1",value);

Object result = methodBinding.execute();

//check for errors, e.g. exceptions

List errors = method.getErrors();

If(!errors.isEmpty()){ …}


Accessing Business Service Methods

Encapsulate all model manipulation code in custom AM and/or VO

methods & invoke them declaratively

– Makes your app easier to regression test

Only code that belongs in a JSF managed bean is…

– Complex, dynamic UI component manipulation

– Complex conditional navigation

Even if you require backing bean code, invoke custom AM or VO

methods using action binding

– Guarantees uniform error handling

Best Practice


Always Work Through the Binding Layer Best Practice – Accessing Business Service Methods

PageDef

method

binding

Managed

Bean

Button

attribute

binding

Text

Application

Module

Data Model

AM Impl public void invokePlSQL()

AM Client Interface public void invokePlSQL()

Business Service Business Layer View Layer


ADF Model Error Handler

The ADF model error handler deals with

– All ADF binding errors

– Business service errors that occur when accessing a service trough the

ADF binding layer

Formats and displays error message

Default error handler skips the top-level JboException because it

only is a bundled exception wrapper for other business exceptions


Build A Custom ADF Model Error Handler

Extend oracle.adf.model.binding.DCErrorHandlerImpl and configure your custom

error error handler in DataBindings.cpx

Override the following methods as needed

– reportException

Override this method to analyze exceptions for errors you want to handle

– getDisplayMessage

Override to change or suppress (null value) the displayed message

– getDetailedDisplayMessage

Override this method to provide HTML markup formatted detail information

– skipException(Exception ex)

Called by the framework to check if an exception should be ignored

Best Practice


Configuring A Custom Error Handler


ADF Faces


ADF Faces Rich Client Components

Ajax & HTML5 enabled JSF

components

Pluggable look and feel

Accessibility & internationalization

Touch gesture support

Built-in advanced functionality:

– Partial Page Refresh (PPR),

Partial Submit

– Drag and drop framework

– Dialog and pop-up framework

Based on Java Server Faces Standard


Backing Bean

"Special use" of a managed bean

– Contain UI Component references

<af:inputText label="…" binding="#{BackingBeanName.lastNameField}"/>

– Must be defined in request scope

JSF components are not serializable (!)

Best Practices

– Avoid backing beans and perform dynamic component lookup using

FacesContext.getCurrentInstance().getViewRoot().findComponent(…)

Relative search: component.findComponent()

org.apache.myfaces.trinidad.util.ComponentUtils.findRelativeComponent(…, …)


When Using Backing Beans …

Use separate beans for separate views

– Avoids "pinning" of UI components and their state

– If views are exactly identical, consider reuse


Avoid Expression Language Gotcha

EL accessing managed beans in Java EE scopes

– Request, session, application

– No scope prefix

– #{beanName}

EL accessing managed beans in ADF scopes

– backingBean, view, pageFlow

– Require scope prefix

– #{scope.beanName}, #{backingBeanScope.beanName}

Manage Bean Scope – Prefix or don't Prefix?


Put use of HTML on a "By Exception" List

HTML and JavaServer Faces are different technologies

– Markup oriented vs. component oriented

– Compile – Render, vs. multi stop request lifecycle

Facelets in JSF 2.x support mixing of HTML and JavaServer Faces

components

– Prior to Facelets and JSF 2.x, mixing HTML and JSF is a no-go

– Still with JSF 2.0 problems may occur because ADF Faces components come with

their own sizing behavior (geometry management)

Recommendation: Build pages and views with ADF Faces components

Avoid Mixing HTML and JSF components


Avoid ui:include and jsp:include Tags

ADF PageDef file is not aware of ui:include or jsp:include references

in a page or view

– Included fragments fail at runtime if they use ADF bound components

– You can copy ADF bindings used by the included content into the view's

PageDef file.

Prevents reuse of the fragments

Recommendation

– Use ui:include and jps:include for layouts only (if at all)

– Use ADF regions to add ADF bound content to a page at runtime


Use inlineStyle and contentStyle By Exception

inlineStyle property allows developers to add CSS to a component

rendering

– CSS is applied to top-level DOM component

– CSS is directly added to the page output

– Best Practice: Use ADF Faces skinning and reduce the use of CSS to the

absolute minimum (e.g. conditional color coding)

contentStyle property allows developers to add CSS to the value content

area of an ADF Faces component

– Styles component content area better than inlineStyle but has same issue as

mentioned above

Learn to Love Skinning


JavaScript


ADF Faces Client JavaScript Architecture

Label1

Label2

Label3

DOM

Peer Objects

Document

UI Components

Servlet

JSF Lifecycle

Component Tree

View Root

Form

Renderer

OK

Form

Form

UI Components

Server Side Client Side


ADF Faces Client JavaScript Architecture

JavaScript component API

af:clientListener

– Listens to DOM and ADF Faces component events

af:serverListener

– XMLHttp JavaScript call to server

– Queued as custom event on client

– Answered by managed bean

ExtendedRenderKitService

– Trinidad class to invoke JavaScript from Java

Features


Using JavaScript in ADF Faces

Use JavaScript by Exception

Don't overuse JavaScript and first try and find a solution in ADF Faces

Put JavaScript code in external *.js files

– Include using af:resource

Code against ADF Faces component model, not the browser DOM

– Component oriented vs. markup oriented

– "document.getElementById" is a serious programming mistake

Don't use JS classes in internal packages

– See JavaScript docs

Best Practice


Break Out Of Isolation.


Join A Community

OTN forum

– Best Practice

Articulate your question well

– Take the same time for asking a question that you want

forum members to spend on answering it

– Keep questions short but comprehensive

– Include your JDeveloper version

Use Google prior to asking to save time

Contribute

EMG

– Architecture, integration, concepts and infrastructure topics

– https://groups.google.com/forum/#!forum/adf-methodology


Schau Dich Schlau Make yourself a smart cookie by watching ADF Architecture TV

http://bit.ly/adftvsub


Best Practices Summary Dress For Success

Don't fight the

framework

Always work

through the binding layer

Think Task Flow


Best Practices Summary Dress For Even More Success

Use Case Matters

Join a Community

& Participate

Schau Dich Schlau!


Join the Oracle ADF Community http://oracle.com/ADF

@jdeveloper

/jdeveloper ADF Insider

ADF Architecture

JDeveloper


Learn More at Oracle OpenWorld

Title Time Location

Oracle ADF and Oracle ADF Mobile: Lessons Learned

in Real-World Implementations

Wed

11:45

Marriot – Golden Gate C3

Hands-on Lab: Developing Mobile Applications with

Oracle ADF Mobile

Wed

10:15

Marriot – Salon 12

One Size Doesn’t Fit All: Oracle ADF Architecture

Fundamentals

Thu

11:00

Marriot – Golden Gate A

Related sessions and labs

Oracle ADF booth at the Oracle Demo Ground – Moscone South


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