Legacy Modernization Assessment: [Portfolio, domain or programme name]

Assessment of a legacy application portfolio and the modernization plan that follows from it: inventory, assessment criteria (business value, technical health, risk), a disposition for each application using the 7 Rs (retire, retain, rehost, relocate, replatform, repurchase, refactor or re-architect), a strangler fig plan for incremental replacement, data migration, dependencies, a sequenced roadmap, costs and benefits, risks and governance. Based on the widely used 7 Rs migration strategies and the strangler fig pattern. Replace every [bracketed] value and every row marked Example; the examples follow an insurer modernizing its policy administration estate.

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Contents

1. Introduction
2. Application portfolio inventory
3. Assessment criteria and scoring
4. Disposition using the 7 Rs
5. Target state and strangler fig plan
6. Data migration
7. Dependencies
8. Sequencing roadmap
9. Costs and benefits
10. Risks
11. Governance
12. Appendices

1. Introduction

1.1 Purpose and drivers

[State the business and technical drivers.] Example: The policy administration estate runs on a mainframe whose support contract ends in 36 months. Product launches take nine months because rules are hard-coded in COBOL, and four of the six engineers who know the system will retire within five years. The board wants new products launched in under three months and run costs reduced by at least 25%.

1.2 Scope

In scope: [applications, environments, business units]. Example: 12 applications supporting motor and home insurance, including their batch jobs, interfaces and reporting extracts.

Out of scope: [list]. Example: the claims platform (modernized in 2024) and the corporate finance ledger.

1.3 Success measures

2. Application portfolio inventory

Data sources for the inventory: [CMDB export date, interviews, cost reports, licence records].

3. Assessment criteria and scoring

3.1 Criteria

3.2 Composite scores

Each dimension score is a weighted average of its criteria:

where $b_{ak}$ and $h_{ak}$ are the 1-5 scores of application $a$ and the weights in each dimension sum to 1.

Example for APP-01: strategic fit 5, criticality 5, change demand 4 gives $BV = 0.40(5) + 0.35(5) + 0.25(4) = 4.75$; supportability 1, maintainability 1, scalability 3, security 2 gives $TH = 0.30(1) + 0.30(1) + 0.20(3) + 0.20(2) = 1.60$.

The quadrant gives a starting point: high value with poor health points to replatform or refactor; low value with poor health points to retire or repurchase; high value with good health points to retain; low value with good health points to retain with minimal investment or consolidate.

4. Disposition using the 7 Rs

4.1 Definitions

The definitions below are written for this template.

4.2 Disposition per application

Disposition summary: [counts per R]. Example: 1 retire, 0 retain, 0 rehost, 0 relocate, 2 replatform, 2 repurchase, 2 refactor.

5. Target state and strangler fig plan

5.1 Target state summary

[Summarise the target architecture.] Example: Policy, rating and document capabilities exposed as services on the container platform, event-driven integration through the enterprise event broker, an operational data store per service, and the data platform as the single source for reporting.

5.2 Strangler fig approach

The strangler fig pattern replaces a legacy system gradually: a routing facade sits in front of the old system, new functionality is built alongside it, and routes are switched to the new implementation one capability at a time until the old system can be removed. The diagram shows the intermediate state where quoting has moved and policy changes have not.

6. Data migration

Principles: [list]. Example: source remains the system of record until reconciliation passes; every migration run is repeatable and logged; personal data is not copied to non-production without masking; retention rules are applied during migration, not afterwards.

7. Dependencies

The diagram shows the main runtime dependencies between applications in scope; arrows point from consumer to provider.

8. Sequencing roadmap

The roadmap below shows three waves and the platform foundation they depend on.

9. Costs and benefits

Measured benefits: [link to success measures in 1.3]. Example: annual run cost falls from USD 6.4 m to USD 4.8 m (saving 1.6 m, 25%), product launch time falls to 3 months, and seven unsupported platforms are removed. Simple payback on one-off and double running costs of USD 9.15 m is about 5.7 years at full savings; strategic benefits (time to market, key-person risk) are the main justification.

10. Risks

11. Governance

Phase gates: each wave passes a gate with evidence against its exit criteria (section 8), updated costs (section 9) and a refreshed risk view (section 10). The assessment scores in section 3 are refreshed yearly or when a major driver changes.

12. Appendices

12.1 Glossary

12.2 References

Standard and licence note

Based on common industry practice for application portfolio assessment, the 7 Rs migration strategies (an extension of Gartner's original "5 Rs" popularised by cloud providers) and the strangler fig pattern described by Martin Fowler. Definitions are written in original words for this collection; examples and figures are illustrative. Template licence: MIT.