1. Migration of Legacy Software to Service Oriented Architecture Edward Stehle, Brian Pyles, Jonathon Max- Sohmer, Kevin Lynch

2. Drexel University, College of Engineering Overview Motivation Legacy Software Approaches –Redevelopment –Wrapping –Migration Conclusions

3. Drexel University, College of Engineering Motivation Computing has been a part of Business for Decades Many computing systems are decades old Drawbacks of age eventually out weight the value delivered by the systems

4. Drexel University, College of Engineering Legacy Software Legacy software is any software that uses out of date technology ‘Any user organization which has been using information technology for more than five years has a legacy software problem’ Sneed et al. Increase in the rate of advance of technology = software becomes legacy faster

5. Drexel University, College of Engineering Legacy Software Why still around? –‘Legacy information systems are typically the backbone of an organizations information flow and the main vehicle for consolidating business information’ Bisabal et al. –Large investment –Critical to Operations –Well tested –Risk of developing new system Why change? Difficult to maintain Performance issues Integration issues Dependance on old hardware, languages, platforms

6. Drexel University, College of Engineering Approaches Redevelopment Wrapping Migration

7. Drexel University, College of Engineering Redevelopment Advantages Ground up SOA development Easier to maintain and extend within SOA No performance loss due to Wrapping Drawbacks Doesn’t leverage legacy system Expensive, time consuming ‘In reality, the risk of failure is usually to great for orginizations to seriously contemplate a redevelopment approach.’ Bisabal et al.

8. Drexel University, College of Engineering Relevant Legacy Code Determination Find the code segment that performs a desired action or data manipulation. Use of automated reverse engineering tools. Clustering tools Creation of data flow charts Extraction Decoupling of the code from the system. Formation of new component from code segments. Component Wrapping Integration of the created component into SOA. Create a WSDL interface. Form an XML schema using the SOAP framework. Creation of a proxy to link into the SOA. Wrapping – “the gluing of useful legacy code with wrapper code to incorporate it into the SOA system”

9. Drexel University, College of Engineering Wrapping Process Zhang’s Wrapping Process

10. Drexel University, College of Engineering Wrapping: Good or Bad? Low risk Mostly automated process Quick and simple Slow-down of service Code be not be able to be decoupled Future maintenance issues

11. Drexel University, College of Engineering Migration Incorporation of redevelopment and wrapping at different levels with the goal of full, long-term migration. Both redevelopment and wrapping applied in a different process. Code Decoupling and Extraction Interface Recreation Service Wrapping Interfaces to the code are recreated to adhere to a SOA structure. Component code is then incorporated into the SOA system with minimal wrapping. Some pieces of the design may need to be wrap, but this prevents the entire component from being wrapped.

12. Drexel University, College of Engineering Migration Process Sneed’s Migration Process

13. Drexel University, College of Engineering Migration: Good or Bad? Accomplishes long-term migration Uses techniques in the previous methodologies Balances wrapping with redevelopment More complicated to design and implement May not be required for every system

14. Drexel University, College of Engineering Conclusion The need for transferring legacy systems is an important area to address. SOA systems are becoming popular and useful in a variety of applications. The migration process attempts to optimally balance time, design, and efficiency.

15. Drexel University, College of Engineering Questions?