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Graceful Growth Consulting (India) Private Limited. Legacy Information Systems: Migration Challenges and Methodologies. IS apoplexy. L egacy ISs pose one of the most serious problems for large organizations
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Graceful Growth Consulting (India) Private Limited Legacy Information Systems: Migration Challenges and Methodologies
IS apoplexy Legacy ISs pose one of the most serious problems for large organizations Costs due to problems of a single legacy IS (e.g., failures, maintenance, inappropriate functionality, lack of documentation, poor performance) can often exceed hundreds of millions of dollars per year. They are not only inordinately expensive to maintain, but also inflexibleand brittle Perhaps worse is the widespread fear that legacy ISs will, one day, break beyond repair. Such fears combined with a lack of techniques or technology to fix legacy IS problems result in IS apoplexy. Insight . Innovation . Agility
Target model IS Compatibility Source model ? Semantic model Semantic level Semantic model ? Logical model Logical level Logical model ? Physical model Physical model Physical level 3 Insight . Innovation . Agility
Why do so many data migration projects fail? The reality is very different All legacy data Legacy data Transformations Migration is an easy sources are quality is will be simple project with limited scope identified acceptable Legacy data All required data Data integration ETL and/or SQL are formats are exists in the skills can easily effective tools for understood legacy system handle data data migration migration needs Many new legacy Transformations Legacy data Problems are found data sources are are extremely piecemeal, so migration quality is much discovered complex becomes a moving target worse than throughout the with huge, increasing scope expected project Legacy system Legacy data is Migration is an ETL and/or SQL are documentation is not adequate to order of magnitude too sluggish to out-of-date & operate the new more difficult than handle the huge assumptions are system integration volume of changes incorrect
Classification of Migration Issues The issues common to software engineering projects, such as testing and database model selection, have been widely researched; those related specifically to migration, such as populating the target system’s database, have received less attention. Insight . Innovation . Agility
Current Research on Legacy Migration Insight . Innovation . Agility • Although legacy information system migration is a major research issue, there are only a limited number of general migration methods available • The migration process as a whole is a very complex procedure encompassing many different fields of research • Following works in the area of Legacy Migration are discussed in this session • The Butterfly Methodology is being developed as part of the MILESTONE project, an ongoing collaborative project involving Trinity College Dublin, Broadcom EireannResearch, Telecom Eireann, and Ericsson which started in July 1996 • The DARWIN project from the University of California Berkeley introduced ―Chicken little as an approach to incrementally migrate legacy systems with the constraint of interoperability between legacy and target system. This project also introduced ‘Cold Turkey’ as alternative approach
Cold Turkey Cold Turkey involves rewriting a legacy IS from scratch to produce the target IS using modern software techniques and hardware of the target environment Insight . Innovation . Agility
Cold Turkey Challenges Insight . Innovation . Agility Business conditions are ever changing so is IS Specifications rarely exist Undocumented dependencies frequently exist Legacy ISs can be too big to cut-over Management of Large projects is hard and they tend to bloat Lateness is seldom tolerated A better system must be promised
Chicken Little strategy Chicken Little involves migrating the legacy IS, in place, by small incremental steps until the desired long term objective is reached. Each step requires a relatively small resource allocation (e.g., a few person years), a short time, and produces a specific, small result towards the desired goal Insight . Innovation . Agility
Chicken Little Methodology Michael Brodie and Michael Stonebraker proposed the Chicken Little strategy, which lets LIS and target systems interoperate during migration using a mediating module, generally known as a “gateway.” The Chicken Little strategy offers an 11- step plan for cutting over from the LIS to the target system. Each step is incremental Analyze the LIS. Decompose the LIS structure. Design the target interface. Design the target application. Design the target database. Install the target environment. Create and install necessary gateways. Migrate the legacy databases. Migrate the legacy applications. Migrate the legacy interfaces. Cut over to the target information system Insight . Innovation . Agility
The Butterfly Methodology Migration using this methodology can be divided into six major phases. Each phase consists of a number of individual, normally independent, migration activities: Phase 0: Prepare for Migration Phase 1: Understand the semantics of the legacy system and develop the target data schema(s) Phase 2: Build up a Sample Data store, based upon the Target Sample Data, in the target system Phase 3: Incrementally migrate all the components (except for data) of the legacy system to the target architecture Phase 4: Gradually migrate the legacy data into the target system and train users in target system Phase 5: Cut-over to the completed target system. Insight . Innovation . Agility
GISFI (CSeON) Work Proposal Insight . Innovation . Agility Investigate the different methods being used for the Legacy Information Migration Come up with the best practices for migration projects Come up with the check list that helps to find out if the information migration is complete both syntactically and semantically (Completeness and correctness) Tools suggestion
About Graceful Growth An organization with an objective to help organizations grow gracefully, with least pain as well as manage their operations with very high effectiveness and efficiency - by applying techniques/frameworks such as Theory of Constraints, First Time Right, Enterprise Architecture, Technology Adoption (Enterprise Mobility), etc. Insight . Innovation . Agility
Thank You Basavaraj.hooli@gracefulgrowth.com; Phone: +91 97644 49718 Insight . Innovation . Agility