Presentation from UKOUG Tech13 conference on Worst Practices for Developing an ADF Application. This is a collection of worst practices and lessons to be learned collected by Steven Davelaar and Wilfred van der Deijl

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Worst Practices for
Developing an ADF
Application
UKOUG ADF EMG Version 12.1.2.3.4.0.0b
Build WORST_PRACTICES_12.1.2.3.4.0.0b_UKOUG_2013 ADF EMG

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About us
Paco van der Linden
AMIS
www.adfplus.com
@pavadeli
Wilfred van der Deijl
The Future Group
www.redheap.com
@wilfreddeijl

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About us
Steven Davelaar
Oracle
ateam-oracle.com
@stevendavelaar
Wilfred van der Deijl
The Future Group
www.redheap.com
@wilfreddeijl

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Ideal project
● 1 developer
That’s you of course!

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Threats to a healthy ADF project
● Customer / Business / Functional designer
● Architect
● Project manager

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Threats to a healthy ADF project
● Customer / Business / Functional designer
● Architect
● Project manager
● Other developers
● Graphic designer

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Other Developers…
Are not a member of ADF EMG

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Other Developers…
Do not use ADF EMG Taskflow Tester

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ADF EMG Taskflow Tester - Wiki

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ADF EMG Taskflow Tester

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Other Developers…
Don’t add ADF Source code library
● How to get ADF Source
○
○
○
○
○
○
Go to support.oracle.com
Log Service Request for JDeveloper/ADF
“ADF Source Code Request” as problem type
Sign agreement and upload to SR
Get access to ZIP, typically within one day
New versions don’t need new agreement
● Allows debugging of ADF framework

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Other Developers…
Don’t add ADF Source code library

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Other Developers…
Don’t adhere to ADF Code Guidelines

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ADF Code Guidelines
● 38 pages of excellent content by ADF guru’s
● Topics include:
○
○
○
○
○
○
○
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General Code Guidelines
ADF Business Components
ADF Faces
ADF TaskFlows
ADF Binding Layer
Security
High Availability
… and more

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Other developers
● Don’t adhere to your project specific coding
guidelines
● Other developers need your help
○ Reserve time to review each other’s version control
commits
○ You might learn from their code as well!!
● Reserve time to perform QA checks
○ Against ADF coding guidelines and project specific
guidelines
○ ...or automate this
■ come back tomorrow 10:15 - Exchange 6
“Quality Assurance with JDev Auditing Framework”

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Threats to a healthy ADF project
● Customer / Business / Functional designer
● Architect
● Project manager
● Other developers
● Graphic designer

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Graphic designer - Pitfalls
● Website ≠ Application
● “HTML is for semantics, CSS is for layout…”
○ ADF Fragment ≠ HTML, ADF skin ≠ CSS
○ ADF Skin
→ primarily colours,
ADF Fragment → the rest
● Bad practice: CSS for layout management

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ADF Skinning Tips
● Use stand-alone Skin Editor
● Use ADF component selectors
○ don’t look at the generated HTML
○ use ADF Faces Skin Selectors Tag Reference
● Choice
○ UI Designer to learn ADF skinning (preferred choice)
○ ADF developer to learn CSS

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How to Write Code

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Logging
● Bad practice: System.err.println()
● Best practice: ADFLogger
○
○
○
○
Configure at Runtime without restart
Analyze Log for Performance
Time your own code
Better insight into ADF Framework internals

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ADFLogger - Runtime Configuration

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ADFLogger - Runtime Configuration

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ADFLogger - Log Analyzer
...or open log file from other (production) server

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Time custom code with
ADFLogger::begin and
ADFLogger::end
bit.ly/adflogger

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Understanding ADF Layers
● Bad: code ADF applications like open source
frameworks
● What do we mean by that?
○ All application state is kept in ViewController:
○ Lots of data queried from ADF BC and stored in JSF
managed beans or entries in JSF memory scope
maps
○ State passed back to ADF BC on subsequent
requests: AM methods with lots of arguments
● Good: leverage ADF BC Active Data Model
○ Easy access to previously entered data
○ Row Currency management

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Understanding ADF Layers
● Signs of ViewController doing ADF BC work
○ import oracle.jbo…
○ Iterating RowSets
○ Storing lots of data in memory scopes or managed
beans. Should only contain true UI state
○ Calling ApplicationModule methods with lots of
arguments even when using binding layer
● Project Audits often show 50-80% of
ViewController code is unnecessary
○ Either completely redundant
○ ...or should be moved to ADF BC layer

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ADF Faces
a.k.a. the ViewController project

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ADF Lifecycle - Immediate property
● Bad: I run into issues, let’s try immediate=true
● Big difference: immediate on input component
vs input on command component
● Almost always wrong in input components
● Make sure you understand both JSF lifecycle
and ADF Optimized Lifecycle
● Steven Davelaar’s 18 Lessons
○ also available as ADF Insider Video
bit.ly/jsf-lifecycle

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Know your ADF Memory Scopes
● Bad: Overuse of SessionScope &
PageFlowScope
● Can have significant impact on mem usage
● Good: The smaller, the better
● Do not cache shorter living objects
○ Should be cheap to request each time when needed
○ Can have disastrous consequences, for example
caching binding objects

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Extreme Disastrous Caching

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Extreme Disastrous Caching

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Memory Scopes Guidelines
● SessionScope
○ only use for user context
○ often (UTF) PageFlowScope is better
■ Two browser tabs share SessionScope but have
independent UTF PageFlowScope
● RequestScope
○ often BackingBeanScope is better
○ each ADF Region or Declarative Component has own
BackingBeanScope but share RequestScope
● Bad: Accessing SessionScope beans from BTF
○ BTF should be reusable and not rely on SessionScope
○ taskflow parameters are there for a reason

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tion
olu
“My ADF application is memoryhhungry”
es
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al
ave
th
We
igh
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(sm
a
of t
rt

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JSF Component Binding
JDeveloper Generated Code
<af:inputText binding=”#{pageFlowScope.MyBean.lastName}”/>

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JSF Component Binding
● First ask yourself if it is really needed
● binding=”#{pageFlowScope.MyBean.lastName}”
references UIComponent in PageFlow bean
● UIComponents should be released after each
request
● But Managed Bean might require
PageFlowScope for its functionality

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JSF Component Binding
ComponentReference
Enhancement Request logged

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“My JSF Component seems to travel around”

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Building Component Tree
binding
attribute
No
create
component
Not Null
use
component
Yes
call
getter
Null
create
component
call setter
bit.ly/compbind

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ADF Business
Components
a.k.a. the Model project

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ADF BC Data Model - Master Detail
Beware of excessive querying
Navigate row here...
Requery
(if
populated)

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ADF BC Data Model - Master Detail
Prevent excessive querying
● Use top level ViewObject instances with bind
variables
● or reset detail ViewObject on master row
navigation
bit.ly/masterdetail

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ADF BC Data Model - Master Detail
Prevent excessive querying

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“I encountered a dramatic ADF bug!!!
Sometimes users lose entered data when the
application is under heavy load.”

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Disable Application Module Pooling

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Don’t Simply passivate all!

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“ADF has huge performance problems!!!
When under heavy load requests can take
several minutes.”
“Besides, what is this PS_TXN table for? It is
eating up our tablespace.”

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Don’t Simply Passivate All
● Every ViewRow with transient atts is
persisted
● During activation all state is applied

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Simply passivate all?
No!
○ Every ViewRow with transient atts is
persisted
○ During activation all state is applied

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What is passivated?
○ Set logger:
oracle.jbo.server.Serializer
○ To:

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What is passivated?
○ Set logger:
oracle.jbo.server.Serializer
○ To:

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“My ADF application is hacked!!!
Sometimes users see data from other
sessions.”
“By the way, I did test the application with AM
pooling off.”

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Application Module Recycling
Not Losing, but Leaking state
● AM Instances Recycled for other users under
load
● Not detected by disabling AM pooling!

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Detecting State Leakage

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Default AM Pool Tuning

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Default ViewObject Tuning

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Eclipse Memory Analyzer Tool
bit.ly/eclipsemat

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Eclipse Memory Analyzer Tool (MAT)
● Make heap dump of running server
JDK_HOME/bin/jmap -dump:file=path
jvm_process_id
●
●
●
●
Download and run standalone Eclipse MAT
Inspect all objects in heap
Query Heap Objects
Predefined Reports and Tools
bit.ly/eclipsemat

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Java Mission Control
bit.ly/miscontrol

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Java Mission Control
●
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Any version of JRockit
Hotspot (aka Sun JVM) since 1.7.0_40
Record a period of time
Analyze
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CPU performance
Memory Usage
Garbage Collection
Thread Concurrency
etcetera

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Miscellaneous

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Password management
● Bad: Credentials in clear text (eg. web.xml)
● Worse: Override with deployment plans
bit.ly/secure-adf

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Reading Credential Store
bit.ly/secure-adf

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Load/Stress Testing
● 5 developers on a Friday afternoon:
“Ready…. Set…. Go”
● Every ADF project initially has performance
issues
● Consider
○ JMeter - Free open source, not optimized for ADF
○ Oracle Application Testing Suite - ADF aware
● Requires
○ Production like testing environment
○ Good knowledge of chosen test tool
○ 10 days setup (assuming test tool experience)

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Further Reading
● bit.ly/adflogger
○ ADFLogger Custom Timings
● bit.ly/secure-adf
○ FMW Credential Store
● bit.ly/eclipsemat
○ Memory Analyzer Tool
● bit.ly/miscontrol
○ Java Mission Control
● bit.ly/jsf-lifecycle
○ Steven Davelaar’s JSF Lifecycle Lessons
● bit.ly/compbind
○ JSF Component Bindings
● bit.ly/masterdetail
○ Lazy Master Detail Query

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That’s all folks!