Migrating Applications to the Cloud: Rehost, Refactor, Revise, Rebuild, or Replace?

Archived Published: 03 December 2010 ID: G00207162


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The CIO issues a simple directive: "Move some applications to the cloud." To do this, architects face bewildering choices. In this Decision Point, Principal Research Analyst Richard Watson steers architects to a choice from among five alternatives: Rehost on HIaaS, refactor using SIaaS and PaaS, revise for HIaaS or PaaS, rebuild on PaaS, or replace with SaaS. The decision must consider an organization's requirements, evaluation criteria, and architecture principles. However, no alternative offers a silver bullet: All alternatives require architects to understand application migration from multiple perspectives and criteria, such as IT staff skills, existing investments, and application architecture.

Table of Contents

  • Decision Point
  • Decision Context
    • Business Scenario
    • Architectural Context
    • Related Decisions
  • Evaluation Criteria
    • Requirements and Constraints
      • Migration Goals and Priorities
      • Legacy Application Characteristics
      • Modernization Requirements
      • Application Platform and Architecture Principles
      • Development and Operations Skills Constraints
      • Migration Cost Considerations
    • Principles
  • Alternatives
    • Rehost
    • Refactor
    • Revise
    • Rebuild
    • Replace
    • Comparing Alternatives
    • Distinguishing Products from Services
  • Future Developments
    • Progress on Portability Standards
    • Evolution of Cloud Business Models
    • Incumbent Platform Players Will Wake Up
  • Decision Tool
    • Pre-Decision Assumptions
      • Assumption 1: Quality of Service Risks
      • Assumption 2: IT Portfolio Management Frameworks
    • Using the Decision Tools
      • Decision Filters
      • Migration Goals Assessment Tool
  • Decision Justification
    • Use Rehost
    • Use Refactor
    • Use Revise
    • Use Rebuild
    • Use Replace
  • Recommended Reading
  • Revision History
  • Notes
© 2010 Gartner, Inc. and/or its Affiliates. All Rights Reserved. Reproduction and distribution of this publication in any form without prior written permission is forbidden. The information contained herein has been obtained from sources believed to be reliable. Gartner disclaims all warranties as to the accuracy, completeness or adequacy of such information. Although Gartners research may discuss legal issues related to the information technology business, Gartner does not provide legal advice or services and its research should not be construed or used as such. Gartner shall have no liability for errors, omissions or inadequacies in the information contained herein or for interpretations thereof. The opinions expressed herein are subject to change without notice.

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