Email RIS file
Bookmark
Report an Issue

Working with Legacy Systems : a Practical Guide to Looking after and Maintaining the Systems We Inherit

Author
Annett, Robert
Published
Birmingham : Packt Publishing, Limited, 2019.
Physical Description
1 online resource (152 pages)
Access Online

Availability

I Want It
I Want It

Finding items...

Contents
Cover; FM; Table of Contents; Preface; Chapter 1: Definition, Issues, and Strategy; What is Legacy?; An IT-Centric View of the World; Systems Development in Context; Systems Development Scaled with Time; Examples of Real Legacy Systems; Common Issues; No Documentation; Lost Knowledge; Hidden Knowledge; Unused Functionality; No Coherent Design/Inconsistent Implementation; Fragility (versus Stability); Tight Coupling; Loose Coupling; Zombie Technologies; Licensing; Regulation; Politics; Organization Constraints and Change are Reflected in the System, External Processes Have Evolved to Fit around the SystemExternal Systems Have Evolved to Fit around the System; Decaying Data; Now What?; Reasons to be Cheerful; A Legacy System is a Successful System; You Have Real Users You Can Talk To; You Can Learn a Lot about the Business; You Can Have a Large Impact Quickly; It's Important, But Not Trendy, So You'll Get Paid Well!; Strategies; Ignore It; What is it?; Investigation; Maintenance; Upgrade; Migration; Incremental Improvements; Replacement; A Special Note on Decommissioning; Conclusion; Chapter 2: Investigation and System Review, Architectural Description and ReviewStakeholders; Locate the stakeholders; End Users; Support Staff; System's Infrastructure Staff; Audit and Compliance; Budget Holders; Third-Party Suppliers; Developers/Software Engineers/Database Analysts; Document the Stakeholders; Architectural Sketches; Why Sketch?; Context Diagram; Container Diagram; Component Diagram; C4 -- Classes; Further Analysis; What Else Can Be Done?; Further Static Analysis; Further Dynamic Analysis; Security Considerations; Passwords; Account Maintenance and Life cycle; Cryptographic Keys; Certificates, Third-Party Passwords and KeysLack of Patching; Moving from Closed to Open Networks; Modernizing Data Formats; New Development and Copied Data; Server and Infrastructure Consolidation; Improved Backup Processes; Checklist of Questions and Actions; Chapter 3: Making Changes; Safely Making Changes; Virtualization Is Your Friend; 50,000-Foot View of the Virtualization Process; Actions to Make a System Safe to Change; Preparation Issues; External Dependencies Required for Testing; Duplicate Test System Data Becomes Stale Quickly; Internal Coupling Stops You Swapping Components, and Changes Cause Unexpected ErrorsLicensing and Regulation Issues Running Multiple Copies; Structural Changes for Disaster Recovery/High Availability; Stabilization; Why Stability?; What Have We Achieved Already?; Bad Data; Removing Unwanted Data; Data Cleansing; Removing Unneeded Components; Removing Unneeded Tasks; Process Cleansing; Removing Unused User Options; Don't Underestimate a Resource Boost; Re-Examine your Application Settings; Optimize the Users' Actions; Leaving a Good Legacy; Why Bother Leaving a Good Legacy?; Documentation; Tests; Design Considerations; Appendix A: Example Legacy Scenario.
Summary
The IT industry is obsessed with new technologies. Courses, books, and magazines mostly focus on what is new. Starting with what a legacy system looks like to applying various techniques for maintaining and securing these systems, this book gives you all the knowledge you need to maintain a legacy system.
Subject(s)
ISBN
1838988572
9781838988579 (electronic bk.)
View MARC record | catkey: 43148972