This document discusses modernizing legacy application architecture. It describes moving from monolithic to microservice architectures by refactoring applications into self-contained systems (SCS) modules. This allows embracing new technologies while reusing existing code. Operational Decision Manager is also discussed as a way to externalize business rules from code for improved agility. The overall approach emphasizes APIs, DevOps practices, and leveraging tools like Application Discovery and Delivery Intelligence to transform legacy applications.

1. © 2018 IBM Corporation
New generation of application architecture
and
Business rules embedded in legacy code
Yann Kindelberger
Executive Architect
IBM Systems, Montpellier Client Center
yannkindelberger@fr.ibm.com
NRB Mainframe Day 2018, October 18th

2. © 2018 IBM Corporation
The legacy application characteristics
System
ApplicationApplication
System
all your code here
Presentation Logic
Business Logic
Integration Logic
Persistence
…
System
…
modulemodule
modulemodule
Persistence
Currently the legacy applications (ie Core Banking System…) use to be quite monolithic (siloed) with
tight coupling among modules (when modules exist)
Coupling among architecture layers (no separation of concerns)
… preventing agility, flexibility and time to market (whilst increases costs)

3. © 2018 IBM Corporation
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
– Monoliths were designed assuming infrequent deployment
– 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)

4. © 2018 IBM Corporation
Business Drivers Motivating People to Modernise
 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) or re-platforming – Incremental
approaches centered on smaller components radically reduces risk.

5. © 2018 IBM Corporation
Evolution toward a Microservice Architecture
What are microservices?
 The microservice architecture is an
architectural style that structures an
application as a collection of loosely
coupled services.
 The microservice architecture enables the
continuous delivery/deployment of
large, complex applications. It also
enables an organisation to evolve its
technology stack.
 Essentially, microservice architecture is a
method of developing software
applications as a suite of independently
deployable, small, modular services in
which each service runs a unique process
and communicates through a well-defined,
lightweight mechanism to serve a business
goal.
From: http://microservices.io/patterns/microservices.html

6. © 2018 IBM Corporation
The approach for Modularity: Something in the middle between Silos and Micros: Self-
Contained Systems (SCS) – split the monolith
Bring the microservices principle of decoupling to the SCS Module level and use internally
the architecture and technology approach that best fit the requirements: Monoliths (or
pseudo) with Cobol/CICS, JavaEE or Microservices or Commercial Package Components
The Data Domain nature and its requirements
and NFR (Consistency, Performance,
Transactionality, etc.) are the key decision factors.
SoR Modularity: “The” Design Principle

7. © 2018 IBM Corporation
Self-Contained Systems (SCS): The SCS general structure (regardless the
internal technology). A black box that offer clear interfaces (service and event)
Data belongs to the Module.
Internally consistency could
be strict or eventual. Among
modules always eventual to
prevent coupling
Self-Contained
Systems (SCS)
allows polyglot
systems facilitating
coexistence
Limiting the
Transactionality
s-SCS
Proceses Rules
Transactional Boundary
New Architectural Style with Traditional Technologies
SoR Architecture: “The” Design Principle

8. © 2018 IBM Corporation
An overall architecture based on open standards, APIs, microservices deployed in
the Cloud (public / private) with a DevOps approach
Systems of Insight
Modernised Mainframe
Systems of RecordSystem of
Integration &
Flexibility
Legacy Platform
Batch Processing
Domain
Domain
Domain
Domain
Domain
Domain
Domain
Domain
Domain
Domain Domain Domain
Online Processing
Domain
Domain
Domain
Domain
Domain
Domain
Domain
Domain
Domain
Domain Domain Domain
Systems of
Engagement
LegacyInterfaceSystems of Insight
s-SCS
NewInterface
s-SCS
s-SCS
s-SCS
s-SCS
s-SCS
s-SCS
s-SCS
Domain Domain DomainDomain Domain Domain
Cloud Private on premise
Existing application
New applications
Cobol /
PLI

9. © 2018 IBM Corporation
Discover Candidates for Modernisation / Refactoring
IBM Z
Input/
Output
Monolithic Application
Read
Customer
Info
If..then..
else
Rule
Update
AddressUpdate
AddressUpdate
Address

10. © 2018 IBM Corporation
API Enable the monolith application
REST
APIs
IBM Z
Get (…)
Put (….)
Post (…)
Delete (…)
Input/
Output
Monolithic Application
z/OS
Connect EE
New generation of
REST applications
(z/OS information
easy to consume)
Java
Node
Microservices based
new Mobile and Cloud
interactive apps

11. © 2018 IBM Corporation
REST
APIs
Shift to MicroServices / SCS for Monolithic Apps
REST
APIs
IBM Z
Get (…)
Put (….)
Post (…)
Delete (…)
Input/
Output
Monolithic Application
z/OS
Connect EE
New generation of
REST applications
(z/OS information
easy to consume)
Java
Node
Microservices based
new Mobile and Cloud
interactive apps
Java
Node
Business
Rules
Get (…)
Put (….)
Post (…)
Delete (…)

12. © 2018 IBM Corporation
Approach for Legacy Application Modernisation
12
Monolithic application Refactor into module
Component Reengineering
API Economy
DevOps and Agility
Application Discovery and
Delivery Intelligence (ADDI)
Application Delivery
Foundation for z Systems
(ADFz)
Operational Decision Manager
(ODM)
z/OS Connect & API Connect
ABO
Java
Node.js
…
Continuous Integration /
Continuous Delivery

13. © 2018 IBM Corporation
13
API Economy
Component Reengineering
DevOps and Agility
Refactor into moduleMonolithic application
Application Discovery and
Delivery Intelligence (ADDI)
Application Delivery
Foundation for z Systems
(ADFz)
Operational Decision Manager
(ODM)
z/OS Connect & API Connect
Approach for Legacy Application Modernisation
ABO
Java
Node.js
…
Continuous Integration /
Continuous Delivery

14. © 2018 IBM Corporation
Modern Development Environment
14
Application Discovery
and Delivery
Intelligence (ADDI)
Discover And Understand
Your z/OS Assets, carry
out impact analysis
Make changes and test
effectively using
operational feedback
IBM Developer for Z
Systems EE
Problem Determination
Tools • Reduce development and testing
efforts 10-30%
• Increase code quality by 50%
• Plan and manage automation activities
in 50% the time

15. © 2018 IBM Corporation
Approach for Legacy Application Modernisation
15
API Economy
Component Reengineering
DevOps and Agility
Refactor into moduleMonolithic application
Application Discovery and
Delivery Intelligence (ADDI)
Application Delivery
Foundation for z Systems
(ADFz)
Operational Decision Manager
(ODM)
z/OS Connect & API Connect
ABO
Java
Node.js
…
Continuous Integration /
Continuous Delivery

16. © 2018 IBM Corporation
Codify business policies, practices, and regulations
Operational
Decisions
ApplicationApplication
Decision logic
 Externalised decisions are easy to change
 Centralised decisions enable reuse and
consistency
 Hard coded decisions are difficult to change
 Rules intertwined within applications cannot
be reused by other systems
Without ODM With ODM
Manage decision logic independently from applications

17. © 2018 IBM Corporation
Redefined Application Change Cycle
Functional
Requirements
Functional
Enhancements /
Platform Upgrades
Business
policies
Business policy
and rule
changes
Business policy
and rule
changes
Business policy
and rule
changes
In-Production
Business Rule Application
Synchronisation
Business Rule
Management
Application
Development
Business policy
and rule
changes
Application
Developer
Business & IT
Functions / Tasks / Flow
changes in Weeks / Months
Decisions / Policies
Changes in Days / Weeks

18. © 2018 IBM Corporation
What’s the business problem & benefits of ODM?
Challenges for most System
z clients
1. Consolidation, isolation,
extension or extinction of
COBOL & PL/I application
portfolios
2. Be able to react to increasing
pace, variety and volume of
change requests
3. Sharing business rules across
platforms & channels
4. Ensuring seamless business
experience in migration/
application evolution
Benefits of the ODM Approach
 Cost savings
– Shorter change cycle, without increased business risk
– Rule engine processing is zAAP eligible
 Improved agility
– Improved Time to Market
– Manage business decisions in natural language
– Decouple development and business decision change lifecycles
 Single version of the Truth
– Consolidated and shared expression of business policy
– Maintainable with a Center of Competency model
 Incremental Adoption
– Deploy decision methodology one decision at a time
– Focus on decisions that need to change often & quickly
– Expand adoption of “market validated” decisions

19. © 2018 IBM Corporation
IBM Operational Decision Manager
Enterprise
Application
Application design
and environment
configuration
Decision
Center
Manage
Rules
Service
management
and monitoring
Design Monitor
Decision Server
MobilePOS BPM CRM
Business Users Environment for
Intuitive policy updates,
point and click decision validation
& social media style collaboration
Govern
Rules
Decision Server Insights
Available in ODM Advanced
Decision Server Rules
Policy Manager
Policy centralsation,
rules versioning and
decision sharing
Synchronisation
&
Deployment
Execute decisions
and expose services
Developer /
Architect
System
Administrator
Rule Administrator

20. © 2018 IBM Corporation
IBM Decision Server
Leverage a wide range of platforms to meet the varying needs of
enterprise architectures
IBM Decision Center
(Windows, AIX, Linux, Linux on System z, z/OS)
Multiple
z/OS
deployment
options
Cloud Distributed z/Linux z/OS
Runtime support
Repository
IBM Operational Decision Manager

21. © 2018 IBM Corporation
• Decisions can be invoked from existing CICS, batch and IMS applications
• Runtime support for COBOL and PL/I data types
• Flexible runtime deployment to fit any System z environment:
 Deployed on WebSphere Application Server for z/OS
Decision Server Runtime Options
Decision Server
z/OS
WebSphere
Application Server
for z/OS*
zEvents Execution
Rule Execution
Server
CICS TS v4.2+ * limited use
entitlement
included with
Decision Server
zRule Execution
Server
(on CICS)
zRule Execution
Server
(Standalone)
 Deployed standalone to z/OS
 Deployed in CICS TS 4.2 and above JVMServer environment

22. © 2018 IBM Corporation
Decision Management: Comprehensive Flexibility
z/OS
COBOL & PL/I
Applications
Distributed
WAS
WOLA
COBOL & PL/I
Applications
COBOL & PL/I
Applications
Java
Applications
CICS
z/OS Batch
IMS
zRES
RES
RES
Java
Applications
WAS for z/OS
RES
zRES
zRES
CrossMemory
Distributed or z/OS
Workstation
Rule Designer
Decision Center
Architect,
Application
Developer
Business
Analyst,
Business
Manager
Decision Center
Repository
Decision Server access on z/OS
optimised for COBOL & PL/I
Decision services delivering
consistent business behavior
enterprise wide
Deploy
Deploy

23. © 2018 IBM Corporation
Approach for Legacy Application Modernisation
23
API Economy
Component Reengineering
DevOps and Agility
Refactor into moduleMonolithic application
Application Discovery and
Delivery Intelligence (ADDI)
Application Delivery
Foundation for z Systems
(ADFz)
Operational Decision Manager
(ODM)
z/OS Connect & API Connect
ABO
Java
Node.js
…
Continuous Integration /
Continuous Delivery

24. © 2018 IBM Corporation
Building the solution

25. © 2018 IBM Corporation
Approach for Legacy Application Modernisation
25
API Economy
Component Reengineering
DevOps and Agility
Refactor into moduleMonolithic application
Application Discovery and
Delivery Intelligence (ADDI)
Application Delivery
Foundation for z Systems
(ADFz)
Operational Decision Manager
(ODM)
z/OS Connect & API Connect
ABO
Java
Node.js
…
Continuous Integration /
Continuous Delivery

26. © 2018 IBM Corporation
Approach for Legacy Application Modernisation
26
API Economy
Component Reengineering
DevOps and Agility
Refactor into moduleMonolithic application
Application Discovery and
Delivery Intelligence (ADDI)
Application Delivery
Foundation for z Systems
(ADFz)
Operational Decision Manager
(ODM)
z/OS Connect & API Connect
ABO
Java
Node.js
…
Continuous Integration /
Continuous Delivery

27. © 2018 IBM Corporation
Rapid iterations
Develop Build Test Deploy Production
API
Catalog
Develop Build Test Deploy
Slower iterations
Production
System of Engagement
System of Record
Digital Applications
Enterprise
Applications
In-sync iterations
Digital + Enterprise in sync: delivering apps at the speed the business requires…
from mobile to mainframe.

28. © 2018 IBM Corporation
End to End Pipe Line – Integrated with Open Source
IBM Z / © 2018 IBM Corporation
Development
Build Artifact
Repository
SCM
IBM Dependency Based Build
Deploy & Test
Automated Unit Tests Urbancode Deploy
Artifactory/Nexus
Urbancode Deploy
Rational Test Workbench
Other Testing Tools
Environments
Z Systems Development & Test
Environment
IBM Z
IBM Developer for Z Systems EE
IBM ADDI
Rational Team Concert
Code Review
IBM Cloud Private

29. © 2018 IBM Corporation
Conclusion
29
Monolithic application Refactor into module
Component Reengineering
API Economy
DevOps and Agility
Application Discovery and
Delivery Intelligence (ADDI)
Application Delivery
Foundation for z Systems
(ADFz)
Operational Decision Manager
(ODM)
z/OS Connect & API Connect
ABO
Java
Node.js
…
Continuous Integration /
Continuous Delivery

30. © 2018 IBM Corporation© 2017 IBM Corporation
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