Slides from Oracle's ADF Architecture TV series covering the Design phase of ADF projects, investigation the task data control scope options. Like to know more? Check out: - Subscribe to the YouTube channel - http://bit.ly/adftvsub - Design Playlist - http://www.youtube.com/playlist?list=PLJz3HAsCPVaSemIjFk4lfokNynzp5Euet - Read the episode index on the ADF Architecture Square - http://bit.ly/adfarchsquare

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Task Flow Data Control Scope Options
ORACLE
PRODUCT
LOGO
Real World ADF Design & Architecture Principles
15th Feb 2013 v1.0

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Learning Objectives
• At the end of this module you should be able to:
– Understand how the traditional concept of transactions
aligns to that of ADF
– Identify different data controls and their transaction capabilities
– Explain the influence of the task flow data control scope option
and how it relates to data controls
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Program Agenda
• Transactions Revisited
• ADF Data Controls
• Task Flow “Data Control Scope"

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In terms of database systems what is a
transaction? Why are they needed?
In ADF where are the transactional
capabilities defined?
Exercise
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Transactions Revisited
• The common definition
– A collection of work with a start and end
– Commit or rollback acts on the entire collection of work
– If an errors occur we don’t get stuck half way
– Other users are isolated from the transactions
– Only future transactions see the results

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Transactions – What You Forgot
• Remember transactions aren’t just about commit and rollback
– They allow one user to chain operations together
– Not just separate atomic actions
– Each operation sees the previous changes within the transaction
– Not visible to other users, but are visible to the current user
– As such transactions are also a form of state management

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Where in ADF are the
transactional capabilities
exposed (defined) to the UI
layer again?
Exercise
Image: imagerymajestic/ FreeDigitalPhotos.net

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Transactions & Data Controls
• Data controls provide the transactional APIs in ADF
– Remember this isn’t just commit and rollback
– But also state management
• Typically one instance is given to each user session
– This separates users’ transactions
• Dependent on design
– A user can be given multiple instances to perform multiple
transactions

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Program Agenda
• Transactions Recap
• ADF Data Controls
• Task Flow “Data Control Scope"

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ADF Data Controls Types
• ADF BC
• EJB/JPA
• POJO
• RESTful/URL
• SOAP/Web service
• Custom data controls
All designed
to carry state
EJB/JPA out-of-the-box
uses an implicit commit
model
Only ADF BC supports
explicit commit &
rollbacks

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ADF Data Controls Challenges
• If transactions are logically mapped to navigating groups of web pages
– Q: How do we map the data control transaction to these boundaries?
• If we need to support separate transactions per session
– Q: How do we configure this with just one data control?
• If ADF libraries may split data control definitions
– Q: How to combine @ runtime with one instance and they can share state?
• If our application uses multiple different data control types
– Q: How to commit/rollback as a group?

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ADF Data Controls Challenges & Solutions
• If transactions are logically mapped to navigating groups of web pages
– Q: How do we map the data control transaction to these boundaries?
– A: Task flows allow you to define groups of pages/fragments and task flows
• If we need to support separate transactions per session
– Q: How do we configure this with just one data control?
– A: Task flows can create a new data control or share an existing one
• If ADF libraries may split data control definitions
– Q: How to combine @ runtime with one instance and they can share state?
– A: Intelligence is built in to combine data controls at runtime
• If our application uses multiple different data control types
– Q: How to commit/rollback as a group?
– A: Task flows track the data controls attached as a group

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ADF Data Controls Challenges & Solutions
• If transactions are logically mapped to navigating groups of web pages
– Q: How do we map the data control transaction to these boundaries?
– A: Task flows allow you to define groups of pages/fragments and task flows
• If we need to support separate transactions per session
– Q: How do we configure this with just one data control?
– A: Task flows can create a new data control or share an existing one
• If ADF libraries may split data control definitions
– Q: How to combine @ runtime with one instance and they can share state?
– A: Intelligence is built in to combine data controls at runtime
• If our application uses multiple different data controls
– Q: How to commit/rollback as a group?
– A: Task flows track the data controls attached as a group
Answered in the previous presentations

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ADF Data Controls Challenges & Solutions
• If transactions are logically mapped to navigating groups of web pages
– Q: How do we map the data control transaction to these boundaries?
– A: Task flows allow you to define groups of pages/fragments and task flows
• If we need to support separate transactions per session
– Q: How do we configure this with just one data control?
– A: Task flows can create a new data control or share an existing one
• If ADF libraries may split data control definitions
– Q: How to combine @ runtime with one instance and they can share state?
– A: Intelligence is built in to combine data controls at runtime
• If our application uses multiple different data controls
– Q: How to commit/rollback as a group?
– A: Task flows track the data controls attached as a group
Answered in the this presentation

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ADF Data Controls Challenges & Solutions
• If transactions are logically mapped to navigating groups of web pages
– Q: How do we map the data control transaction to these boundaries?
– A: Task flows allow you to define groups of pages/fragments and task flows
• If we need to support separate transactions per session
– Q: How do we configure this with just one data control?
– A: Task flows can create a new data control or share an existing one
• If ADF libraries may split data control definitions
– Q: How to combine @ runtime with one instance and they can share state?
– A: Intelligence is built in to combine data controls at runtime
• If our application uses multiple different data controls
– Q: How to commit/rollback as a group?
– A: Task flows track the data controls attached as a group
Answered in the next presentation

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Task Flow Transaction and Data Control Scope Options
<?xml version="1.0" encoding="ISO-8859-1" ?>
<adfc-config xmlns="http://xmlns.oracle.com/adf/controller"
version="1.2">
<task-flow-definition id="task-flow-definition">
<transaction>
<new-transaction/>
</transaction>
<data-control-scope>
<isolated/>
</data-control-scope>
<use-page-fragments/>
</task-flow-definition>
</adfc-config>

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Shared Data Control Scope
• “Share data controls with calling task flow”
• Shared
– Between calling & called task flows
– If data controls are of the same
name and type
– Only one instance of the data
control will be created & shared
– And view objects sharing:
• Current row indicators
• Edit the same records
• One database connection

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Isolated Data Control Scope
• Don’t’ “Share data controls with calling task flow”
• Isolated
– Regardless two instances of the
data control
– Allows disparate data control
transactions
– Separate view objects
• No record coordination
• Isolated record editing
• Separate connections

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Our system provides the user access to two
isolated instances of the same data control
simultaneously, and we're now infrequently
hitting row lock errors.
Why and what’s the solution?
Exercise
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Shared Data Control Scope: To
2
1
3
4

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Shared Data Control Scope: Returning
1
3
4
2

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Isolated Data Control Scope: To
1
2
43

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Isolated Data Control Scope: Returning

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Isolated Data Control Scope: Returning
1
2
4
5
3
6

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Every isolated task flow means
separate data control instances,
more memory consumed, and if
using ADF BC more database
connections consumed.

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Rules for Sharing Data Controls
• Data control must be in same data control frame
• Same data control type – eg. ADF BC, EJB, WebService
• Across ADF Libraries
– At design time if same data
control comes from two
different ADF libraries, if they
have the same name they can
also share

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Conclusion
• The data control scope allows task flows to share
or create separate instances of data controls
• If shared they will share a transaction and state
• If isolated they will have their own transaction and state
• Isolated makes sense when parts of the application state must
be kept separate and independent
– But does have an overhead of extra memory and (for ADF BC) database
connections
– And you lose sharing state (such as current iterator positions) across
separate instances of the same view object

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Further Reading
Essential to view the next slides on
Task Flow Transaction Options

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