Oracle ADF Architecture TV - Design - Advanced ADF Task Flow Concepts

Real World ADF Design & Architecture Principles
Advanced ADF Task Flow Concepts
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15th Feb 2013 v1.0

Learning Objectives
•  At the end of this module you should be able to:
–  Understand the difference between copied and inherited
task flow templates, their limitations and use cases
–  Understand loose coupling and when it is okay to create
dependencies between task flows
–  Know about task flow design considerations in terms of
granularity and size of individual task flows
–  Use bounded task flows as a common language between
developers as well as developers and domain experts
Image: imagerymajestic/ FreeDigitalPhotos.net

Program Agenda
•  Task Flow Templates
•  Good Task Flow Design Practices
•  Highly Reusable Task Flows

Task Flow Templates
•  Communication
–  Use templates to discuss business processes with non-technical domain
experts
•  Reuse
–  Use to implement pattern for reoccuring processes
• CRUD
• Lookup
–  Use to enforce development standards and good practices
Reuse and Communication

Task Flow Templates
•  Define common functionality to be inherited by or copied into flows
subsequently created bounded task flows
•  Use cases
–  Property Settings
–  Managed bean definitions
–  Exception handling flows
–  Logging
–  Auditing
–  Transaction behavior
•  Templates are either copied into new bounded task flow or referenced
Overview

Task Flow Templates
•  Template is a "blue print" for a family of related processes
–  Bounded task flows built from a template usually need to modify the flow
–  Later changes to the template should not be visible in bounded task flow
•  Beware!
–  Ensure unique ID in the bounded task flow metadata when copying from
a template to not break MDS functionality
When to Copy from Templates

Task Flow Templates
•  Template contains common functionality
–  Exception handling
–  Managed beans
–  Task flow entry / exit logging
•  Changes to the template should be immediately reflected in
bounded task flows
•  Be aware!
–  Before JDeveloper 12c: Activities in the referenced template don't show in visual
editor when designing bounded task flows
–  Properties inherited from a referenced template cannot be changed for a task flow
When to Reference Templates

Example: Jobs Task Flow

Tf-fragment-template

Task Flow Templates
•  Avoid name collisions with consuming task flows
•  Collisions will override functionality
•  Standardize on template naming schemes for:
–  Activities
–  Parameter
–  Managed beans
Avoid Pitfalls

Program Agenda

13 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.13 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.
How granular should our task
flows be?
Exercise

Task Flow Design
•  Small task flows:
–  Require a lot of calling and maintenance management overhead
–  Reasonable sizes for distributed team development
–  Provide ultimate flexibility in architecture
•  Large task flows:
–  Require less calls and maintenance management overhead
–  Less flexible as you can't call discrete functionality within the flow
–  Memory footprint likely bigger than small task flows
Task Flow Sizing Considerations

Task Flow Design
•  Meet in the Middle
–  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

Task Flow Design
•  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
–  If you cannot fully explain and describe a task flow in 60 seconds it
probably is too big
•  If you save a lot of data in pageFlowScope, keep the task flow small
and exit at earliest opportunity
•  Keep task flows that run in their own transaction as small as
possible and exit them at earliest opportunity
Sizing Guidelines

17 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.17 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.
How much should I care for
loose coupling?
Exercise

Loose Coupling
Where Would You Care The Most?
Bounded Task Flow
Task Flow
Call Activity
Bounded Task Flow
Task Flow
Call Activity
Bounded Task Flow
Task Flow
Call Activity
Bounded Task Flow
Task Flow
Call Activity
Bounded Task Flow
Task Flow
Call Activity
Bounded Task Flow
Task Flow
Call Activity
ADF Library
Library
internal
Library
internal
Library
internal
Library
internal

Program Agenda

Maximize Reuse
•  Define and configure:
–  A set of input parameters that allows you to configure various use cases
–  A router activity as the default activity to enable conditional flows
–  Dynamic iterator bindings to use a task flow both as a master region or
detail region
–  Configure display properties of UI components based on task flow input
parameters

Example 1: Dynamic Task Flow Entry

Example 2: Dynamic Iterator Binding
•  Solution
–  Dynamically reference view object instance name from iterator binding
property
–  Dynamically generate new View Object instance in ADF Business
Components model
•  Use method call activity to invoke View Object instance creation before rendering view
•  Use View Criteria to shape query result displayed by View Object
•  What does this help with?
–  Allows multiple regions to be added based on the same task flow with
shared data controls configuration
–  Each region shows different row data
Use case: Multiple Instances of Task Flow with Shared DC

Multiple Instances of Task Flow with Shared DC
Task Flow
af:region
Parent View
Managed Bean
Page Flow Scope
View
<file>.jsff
<file>PageDef.xml
allEmployeesIterator
allEmployees
View Object
Instance Name
Input Parameter
reads from
has "Binds"
property set to
Input Parameter
Query argument
(e.g. 60 for querying
department 60)

Multiple Instances of Task Flow with Shared DC
ADF BC Implementation (AM Impl)
public void createUniqueEmployeesVOInstance(Integer departmentId, String instanceName) {
ViewObject existingVO = findViewObject(instanceName);
if (existingVO == null) {
//create a new view object based on the existing Employees View Object
ViewObject newVO = this.createViewObject(instanceName,
this.getallEmployees().getDefFullName());
ViewCriteria vc = newVO.createViewCriteria();
ViewCriteriaRow vcRow = vc.createViewCriteriaRow();
//ensure View Object instance returns data specified by the
//task flow input parameters
vcRow.setAttribute("DepartmentId", "= "+departmentId);
vc.addElement(vcRow);
newVO.applyViewCriteria(vc);
} else {
//instance will be reused
}
}

Conclusion
•  Task Flow templates are blueprints that provide a
visual and common language between IT
professionals and business domain experts
•  Document task flows using diagram annotations
•  Keep task flows "just big enough" but as small as
possible so that task flows that open a separate
transaction or task flows that keep large objects in
memory are exited early.

Task Flows at the Heart of Oracle ADF
There is nothing more important than understanding task
flow-oriented design and architecture when developing
Oracle ADF applications

Further Reading
•  ADF Insider
–  Task Flow Overview Part 1
•  http://download.oracle.com/otn_hosted_doc/jdeveloper/11gdemos/taskflow-overview-p1/taskflow-overview-p1.html
–  Task Flow Overview Part 2
•  http://download.oracle.com/otn_hosted_doc/jdeveloper/11gdemos/taskflow-overview-p2/taskflow-overview-p2.html

Oracle ADF Architecture TV - Design - Advanced ADF Task Flow Concepts

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Oracle ADF Architecture TV - Design - Advanced ADF Task Flow Concepts