Modernizing Legacy Systems: Software Technologies, Engineering Processes, and Business Practices (Paperback)

Table of Contents

Preface.
1. The Legacy Crisis.

Modernization Challenges.

Complexity.
Software Technology and Engineering Processes.
Risk.
Commercial Components.
Business Objectives.

How Did We Get Here?
The Legacy Crisis.
Evolving Legacy Systems.

Maintenance.
Modernization.
Replacement.

Software Reengineering.

Retargeting.
Revamping.
Commercial Components.
Source Code Translation.
Code Reduction.
Functional Transformation.

Incremental Development and Deployment.
Summary.
For Further Reading.

2. The Beast.

The Retail Supply System.

Database.
User Interface.
Transactions.

Recent History.

Web Enablement.
Reports.

Summary.

3. Risk-Managed Modernization.

Risk Management.

Portfolio Analysis.
Identify Stakeholders.
Understand Requirements.
Create the Business Case.
Understand the Legacy System.
Understand Existing Software Technologies.
Evaluate Technology.
Define Target Architecture.
Define Modernization Strategy.
Reconcile Modernization Strategy with Stakeholders.
Estimate Resources for Modernization Strategy.

Summary.

4. Developing the Business Case.

Where Are We?
Identify Stakeholders.
Understand Requirements.

Requirements.
Constraints.

RSS Requirements.

New Functionality.
Architecture Compliance.
Incremental Development and Deployment.
Modernization Goals.

Create a Business Case.

General Structure and Contents.
Incremental Modernization.

The RSS Business Case.

Problem Statement.
Solution.
Risks.
Benefits.

Summary.
For Further Reading.

5. Understanding the Legacy System.

Where Are We?
The Context for Program Understanding: The Horseshoe Model.

Code Transformations.
Functional Transformations.
Architectural Transformations.

Reconstruction.

Code-Structure Representation.
Function-Level Representation.
Architecture-Level Representation.

Architecture Reconstruction.
Issues.

Tool Support versus Manual Effort.
Decompilation/Disassembly.

Summary.
For Further Reading.

6. Architecture Representation.

Where Are We?
Purpose of Architecture Representation.
Architecture Representation Requirements.

Views of the System.
Levels of Granularity.

Architectural Views.

Module Views.
Component-and-Connector Views.
Deployment View.

Additional Considerations.

System Context.
Hybrid Views.

Summary.
For Further Reading.

7. Languages and Data Management.

Where Are We?
COBOL.

History.
General Structure.
Arithmetic.
Variables.
Calling and Parameter Passing.
Composing Source Files.
Obsolete Language Features.
Standards.
Products.

Java.

History.
General Structure.
The Java Platform.
Characteristics of the Java Language.
Types of Java Programs.
Java Application Programming Interfaces (APIs).
Products.

Data Repositories.

Database Management Systems.
Data Warehouses.
Standards.
Products.

Data Representations for Information Exchange.

EDI.
XML.
Standards.
Products.

Summary.

8. Transaction Technology.

Where Are We?
Distributed Communication.
Transactions.

Flat Transactions.
Flat Transactions with Save Points.
Chained Transactions.
Closed Nested Transactions.
Open Nested Transactions.
Multilevel Transactions.
Distributed-Access Transactions.

Distributed Transactional Operations.

Distributed-Transaction Model.
Resource Manager Component.
Communication Resource Manager Component.
Transaction Manager Component.
Application Components.
Queued-Transaction Model.

Comparison of Transactional Models.
Standards.
Products.
Summary.

9. Software Infrastructure.

Where Are We?
Enterprise JavaBeans.

Enterprise JavaBean Types.
Persistence for Entity Beans.
Support for Transactions.
Security.
Products.

Message-Oriented Middleware.

Messages.
Queues.
Queue Manager.
Triggers.
Message Queue Interface.
Transaction Support.
Products.

Java 2 Enterprise Edition.

J2EE Services.
Deployment.

XML Messaging.

XML Messaging Components.
BizTalk.
Electronic Business XML.
Open Applications Group Integration Specification.
RosettaNet.
How These Standards Relate.
Other Standards Related to XML Messaging.

Summary.

10. Maintaining Transactional Context.

Where Are We?
Model Problem: Retail Supply System.
Contingency Planning.

MQSeries.
Object Transaction Service.
Oracle Pro*Cobol.
Net Express.

Definition of the Model Problem.
Solution of the Model Problem.

Design of the Model Solution.
Building the Test Adapter.

Evaluation.
Summary.

11. Business Object Integration.

Where Are We?
A Tale of Two Architectures.

J2EE Architecture.
B2B Architecture.

Quality Attributes.

Performance.
Security.
Availability.
Data Integrity.
Modifiability.
Portability.
Reusability.
Integrability.

Summary.

12. Target Architecture.

Where Are We?
Forces Affecting the Architecture.

Data Requirements.
Organizational Requirements.
Technology Requirements.

Overview of the Architecture.

Application Components.
Business Objects.
Service Components.
Data Components.
Wrapper Components.
BSR Interface.

Architectural Patterns.

Data Access Involving One Business Object.
Data Access Involving More Than One Business Object.
Report.
Ad Hoc Query.
Roll-Ups.
Batch Roll-Up.
Continuously Updated Roll-Up.
Transactions.
Data Warehouses.

Summary.

13. Architecture Transformation.

Where Are We?
Data Adapters.

Data Replication.
Data-Access Layer.
Database Gateway.
Hybrids.
Comparison.

Logic Adapters.

Object-Oriented Wrapping.
Component Wrapping.
Comparison.

Architecture Transformation Strategy.

Code Migration.
Data Migration.
Deployment Strategy.

Componentization Trail Maps.
Use of Adapters in RSS.
Summary.

14. System Preparation.

Where Are We?
Analysis of Alternatives.

Plan 1: DMS on OS 2200.
Plan 2: RDMS on OS 2200.
Plan 3: Oracle on the Solaris Platform.
Plan 4: Everything on the Solaris Platform.
Plan 5: Everything on Solaris+.
Evaluation of Alternatives.

Summary.

15. Code and Data Migration.

Where Are We?
Structural Analysis.

Initial Plan.
Revised Plan.

Code Migration Plan.
Data Migration Plan.
Summary.

16. Integrated Plan.

Where Are We?
Reconciliation Objectives.
Reconciliation Plan.
Stakeholder Priorities.

User Representatives.
Architecture Team.
Legacy System Maintainers.
Management.
Observations.

Stakeholder Ideal Profiles.

User Representatives.
Architecture Team.
Legacy System Maintainers.
Management.

Stakeholder Consensus Meetings.
Code-Migration Prioritization Results.
Summary.

17. Resource Estimation.

Where Are We?
Cost Estimation Overview.

Function-Based Estimation.
Task-Based Estimation.

Costing an Increment.

Legacy System Size.
Adapters.
Maintenance Costs.
Growth Factor.

Estimation of Cost and Duration.

Productivity Ratio Approach.
Cost Estimation Models.

Costing the Preparation Work.
Costing the Final Database Migration.
Data Collection.
Summary.
For Further Reading.

18. Recommendations.

Find a Better Way.
Use Commercial Components.
Manage Complexity.
Develop and Deploy Incrementally.
Software Engineering Skills.
Component-Centric Approach.
Architecture-Centric Approach.
High Levels of Concurrent Development.
Continuous Integration.
Risk-Managed Development.
Final Word.