Monolithic applications are defined as single-tiered software in which the user interface and data access code is combined into a single application for a single platform. Monoliths can impact your ability to create APIs, deliver capability quickly, and even perform routine application maintenance. Refactoring is the antidote to monolithic software. It can result in improved team agility and autonomy, plus it paves the way for API creation. Learn how DevOps for the Enterprise software can help you refactor- from discovery of your z/OS assets and impact analysis, to the modularization task itself, including editing, compiling, testing, and debugging.

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Refactoring Monolithic Applications
Bill Alexander, Architect - IBM Developer for z Systems
Paul Pilotto, Solution Architect ADDI

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Disclaimer
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without notice and at IBM’s sole discretion.
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products remains at our sole discretion.
 Performance is based on measurements and projections using standard IBM benchmarks in a
controlled environment. The actual throughput or performance that any user will experience will vary
depending upon many factors, including considerations such as the amount of multiprogramming in
the user’s job stream, the I/O configuration, the storage configuration, and the workload processed.
Therefore, no assurance can be given that an individual user will achieve results similar to those
stated here

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Discussion Topics
 Definition of a Monolithic Application
 Why refactor
 Approaches to refactoring
 Detailed walkthrough of scenarios

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Business Drivers Motivating People to Refactor
 Business Agility – Speed of change is faster with a more modular
architecture – micro-services architecture is a popular approach
 Accelerate Digital Transformation – Provide more flexibility in what
capabilities to reuse.
 Facilitate onboarding of new people – Reduce learning curve by
providing a more understandable architecture
 Enable rewrite (e.g. java, node) – Incremental approaches centered on
smaller components radically reduces risk.

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Monolithic Applications
Monolithic Applications are self-contained applications in which functionally
distinguishable aspects (for example presentation logic, business logic, and data
access) are all interwoven components.
All code exists in a single tier (all combined) and deploys as a single unit.
Business Logic
Data Access LogicPresentation LogicData Access Logic

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What are the pain points of Monolithic Applications
 Lack of Understanding
– Makes simple changes cumbersome
– Next generation programmers have no insight
– Business Logic exponentially grows by copy/paste
• Fear of making mistakes  duplication of logic
• Inability to leverage business logic
 Lack of Agility
– Small code changes require test and package of the entire application
– Slow response to API Economy
– Difficult integration with new technology (Mobile, Cloud, Continuous DevOps)
– Monoliths were designed assuming infrequent deployment

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The Danger of the Monolithic App
https://devops.com/danger-monolithic-app/

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Complementary Approaches to Be Used to Refactor
API enable transactions and other resources
• Enables these resources to be easily reused inside and outside IBM Z
• Moves the needle towards a micro services architectures
Break big applications into smaller applications, incrementally
• Localizes change impact, enabling agile / DevOps styles of development
• Provides a more fine-granular opportunity for reuse and API enablement
Rewrite business logic into business rules managed in a decision management tool
• Enables rules to be updated by SMEs without programming
• Facilitates reuse by ensuring business rule is only captured once
All of these approaches needs to be complemented by
• Governance of the refactoring effort to ensure clear goals are set and managed to
• Regression testing to ensure function and performance are not compromised

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API enable transactions and other assets
Application Discovery and Delivery
Intelligence (ADDI)
Discover And Understand
Your z/OS Assets
Refactor
applications to
leverage APIs
and test as
needed
Application Delivery
Foundation for z
Systems (ADFz)
Manage and
control the
API’s
IBM z/OS
Connect EE
Create
business API’s
for what you
discovered
IBM API
Connect

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Break big applications into smaller applications
Application Discovery
and Delivery
Intelligence (ADDI)
Identify code that
appears to be
somewhat loosely
coupled.
Leverage
refactoring wizard
to refactor module
into independent
program. Unit test
the code.
Application Delivery
Foundation for z
Systems (ADFz)
IBM z/OS
Connect EE
If appropriate,
create a
REST-ful API
for the
recently
refactored
application.
Application Discovery
and Delivery
Intelligence (ADDI)
Optimize test effort
and determine
whether acceptable
code coverage of
change code has
been achieved.

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Rewrite business logic into business rules
Application Discovery
and Delivery
Intelligence (ADDI)
Capture business
information, including
business terms.
Identify Candidate
Business rules and
author them as
Business Rules
(FUTURE)
Refactor code to
replace the
candidate rules with
calls to Business
rules in a business
rules engine like
ODM for
management of
business logic
outside the
Application logic.
Application Delivery
Foundation for z
Systems (ADFz)
Business Rule
Engine
Invoke and
manage
business rules
Application Discovery
and Delivery
Intelligence (ADDI)
Optimize test effort
and determine
whether acceptable
code coverage of
changed code has
been achieved.

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Refactor to fit in a DevOps strategy
Smaller modules have a more agile impact on DevOps

13. How ADDI and ADFz
help you in this
Refactoring Process
“The GPS for your Mainframe
Developers”
13

14. Increase Agility by
Simplifying and
Standardizing Work
Item Estimation
• Use standardized Metrics (such as Maintainability
Index or Halstead Complexity) to make more
realistic estimations
• Callgraphs, Usage Reports and other Reports help
planning application modernization and make
application portfolio decisions
• Dead-Code Reports give indications about
possible dead-code to remove
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Accelerate
Transformation

15. Navigate easily inside
large and complex
programs
• Program Flow provides a quick overview about
the parts of a specific program
• Find code lines accessing specific resources or
interacting with other programs
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Accelerate
Transformation

16. Navigate easily inside
large and complex
programs
• Flow-Charts show an in-detail view of the inner
workings of programs
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Accelerate
Transformation

17. Accelerate Refactoring
• Reduce guesswork about side-effects while
changing applications
• Navigate the code more effectively
• Understand unknown code faster
• Adopt a more structured approach to changes
using ADDI as a guidance
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Accelerate
Transformation

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IBM Application Discovery and Delivery Intelligence V5.0.3
(Available Now)
• Graphical artifact interdependency
analysis
• Web based search
• Extensibility improvements
• Preprocessors
• Custom communication layers
• Additional coding rules
• Additional language translations
• Performance, Scalability and
Usability improvements
• Several customer RFEs

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A central link in an integrated and flexible DevOps toolchain
IBM Developer for z Systems V14.1 (Available Now)
Issue
Tracker
Source
Code
Repository
Delivery
Pipeline
Insights
and
Analysis
• Refactoring support for monolithic programs
• API Enablement
• Agility through modularization
• Improve Maintainability
• Integration with Application Discovery
• Integration with SonarQube
• Improved Software Analyzer reports
• Enhanced SCM integration
• Day 1 support for IBM Z compilers & z/OS
• Several customer RFEs
https://developer.ibm.com/mainframe/2017/09/08/whats-new-idz-v14-1/

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Leverage existing investments in new ways
 Create new reusable programs from existing logic
 Invoke the new program from the original source
 Creating opportunities for new APIs

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IBM z/OS Connect Enterprise Edition
 Create new business opportunities
 Map RESTful APIs to existing mainframe services and data
 Single endpoint for service access

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Improve testability
 Program functionality can be easily tested in isolation
Testing a Monolith Testing individual components

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Test automation for z/OS applications
 Automating regression tests becomes easy using tools
– z/OS Automated Unit Testing Framework (zUnit feature in IDz)
– Rational Test Workbench
– XaTester (Xact Consulting A/S)
– MF-Test (MOST Technologies)

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Optimize Test Case
Execution
 Detect which regression tests cases maps to
changed code to reduce test efforts in early
iterations by a magnitude or more
 Optimize test case execution by identifying which
test cases may be redundant, so low value tests can
be reduced
 Close test gaps before exiting test phase by
showing code coverage of changed and unchanged
code.
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Increase
Productivity

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Improve agility
 Multiple developers can work concurrently
 Only deploy what has been modified
 Underlying technologies can change over time
Parallel component development Linear development of a monolith

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Reduce program complexity
 Program logic is easier to understand by humans and tools

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Summary
 Refactoring monolithic
applications into smaller
components has many potential
benefits, including…
– Reuse
– APIs
– Continuous Testing
– Continuous Feedback
– Continuous Delivery
– Maintainability
 IBM has tools that can help,
including…
 Application Delivery
Foundation for z Systems
 Application Discovery and
Delivery Intelligence
 z/OS Connect Enterprise
Edition

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