Maintain, Modernize or Migrate- (1)
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Transcript of Maintain, Modernize or Migrate- (1)
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Maintain, Modernize or Migrate?
An Iterative Model for Migrating Legacy Systems
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Overview
● Context of Software Maintenance● Case Study System● Iterative Model● Application of the Model● Open Discussion
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Software failure rate over time
Pressman, R. (1994), Software Engineering, a Practitioner's Approach (European Edition) ,McGraw Hill , New York .
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Maintenance DevelopmentEnhancing or correcting an existing software system to meet the current requirements.
The first attempt to capture the requirements as a software product.
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Comella-Dorda, S.; Wallnau, K. C.; Seacord, R. C. & Robert, J. E. (2000),A Survey of Black-Box Modernization Approaches for Information Systems., in 'ICSM' , IEEE Computer Society, , pp. 173-183 .
Maintenance effort over time
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● When the Chief architect retires...
● UCSB homegrown system● Developed on a commercial
framework
● Growing user community● Actively maintained and
modernized● Successfully adapted to
environmental changes● Oversight committee
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Legacy Legacy(Noun)
A thing handed down by a predecessor
(Adjective)
Denoting software or hardware that has been superseded but is difficult to replace because of its wide use.
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“Any systems that cannot be modified to adapt to constantly changing business requirements and their failure can have a serious impact on business”
~Brodie & Stonebraker
Brodie, M. L. & Stonebraker, M. (1995), Migrating Legacy Systems. Gateways, Interfaces, and the Incremental Approach , Morgan Kaufmann .
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"If you don't know where you are, a map won't help."
~Watts Humphrey
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Simplified view of possible legacy situations9
Users Software Engineers
Happy Happy Best situation, everyone is happy.
Happy Sad Most precarious, we must keep the users happy whilst enhancing a maintainable system
Sad Happy The worst situation. Avoid at all cost
Sad Sad 2nd best. Anything is better than the current software.
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Prepare for change
If new levels of upper management have a desire to retire the current system and migrate to a new one...
I had better learn what legacy system migration is all about!
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Khadka, R.; Saeidi, A.; Jansen, S. & Hage, J. (2013), A structured legacy to SOA migration process and its evaluation in practice., in Anca Daniela Ionita; Grace A. Lewis & Marin Litoiu, ed., 'MESOCA' , IEEE, , pp. 2-11 .
A structured legacy to SOA migration process and its
evaluation in practice
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M. Galinium and N. Shahbaz, “Success factors model: Case studies in the migration of legacy systems to service oriented architecture,” in Computer Science and Software Engineering (JCSSE), 2012 International Joint Conference on, pp. 236 – 241, IEEE, 2012.
Success Factors model for migrating
legacy systems
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Extended Iterative Maintenance Lifecycle
Using eXtreme Programming
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Choudhari, J. & Suman, U. (2014), 'Extended iterative maintenance life cycle using eXtreme programming.', ACM SIGSOFT Software Engineering Notes 39 (1), 1-12.nce and Software Engineering (JCSSE), 2012 International Joint Conference on, pp. 236 – 241, IEEE, 2012.
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Maintenance includes Migration
14International Standards Organisation (ISO) (2006), Standard 14764 on Software Engineering - Software Maintenance , ISO/IEC .
ISO 14764-2006 and other IEEE standards (like ISO/IEC 12207) place migration as a departure from the maintenance cycle…
But in my experience, it should be part of the maintenance cycle.
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The Iterative Model
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For Migrating Legacy Systems
(in three views)
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Maintenance as RC stories
Looking at the iterative model closely: request for change stories are:● Prioritized● Effort-estimated● Completed in a time-boxed
sprint16
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Migration as a Structured Process
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The iterative model looks like a way to categorize maintenance activities into phases of migration.
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Migration as Maintenance
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Looking at the big picture, we see the incorporation of migration planning into the cycling of maintenance process
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3 Key features of the iterative migration model
1. Melding migration into the maintenance cycle
2. Plan for success by incorporating success factors at every phase
3. Scrum practice for maintenance
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Applying the Iterative Model
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Applying the Iterative Model
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Legacy System Understanding
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Applying the Iterative Model
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Target System Understanding
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Applying the Iterative Model
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Migration Feasibility Determination
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Applying the Iterative Model
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Component System Integration
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The end.
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Thank you.