Spring Boot & Spring Cloud for Legacy Application

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Spring Boot & Spring Cloud for Legacy Applications Marten Deinum

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Spring I/O 2016 Disclaimer This slide intentionally left blank

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• By Day • Software Developer / Architect / Consultant / … • By Night • Husband & Father • Lifeguard (Instructor) • Scuba Instructor • Author • Spring Contributor Who Am I

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Spring I/O 2016 Spring Boot and Spring Cloud for Legacy Applications

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Spring I/O 2016 Spring Boot and Spring Cloud for Legacy Applications

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–Wikipedia “In computing a legacy system is an old method, technology, computer system, or application program,"of, relating to, or being a previous or outdated computer system." Often a pejorative term, referencing a system as "legacy" often implies that the system is out of date or in need of replacement.”

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Bookstore from Pro Spring MVC • Spring Framework 3.2 • JPA with Hibernate 4.2 • Using Tiles and JSP • XStream • Jackson 1 • Configuration using XML and JavaConfig • Deployed as a WAR • No Monitoring/Metrics/Health etc. The Application

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Spring I/O 2016 Agenda • Why • How • Challenges & Solutions • Demo • Q&A

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Spring I/O 2016 Why • You want to use Spring Boot / Cloud • Migration of Monolith to Microservices • Strangler Application / Pattern • Migration Strategy

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Spring I/O 2016 How • Go full Spring Boot / Spring Cloud • Use selective parts of Spring Boot / Spring Cloud • Auto Configuration is still just Configuration!

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Spring I/O 2016 Challenges • Full Spring Boot / Spring Cloud • Probably requires library upgrades • Deprecated library support • Removed library support • Auto Configuration

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Spring I/O 2016 Challenges • Use selective parts of Spring Boot / Spring Cloud • No benefit of auto configuration “magic” • Manual configuration can be a PITA • Requires digging into auto configuration sources • Incompatible library versions

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Spring I/O 2016 Solutions • Library Upgrades (and incompatible libraries) • Spring is generally very backwards compatible • Others require code upgrades

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Spring I/O 2016 Solutions • Deprecated Library support • Update your code to supported versions • Deprecated isn’t removed!

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Spring I/O 2016 Solutions • Removed Library support • Rewrite your code to supported versions • Include the older support in your project

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Spring I/O 2016 Solutions • Auto Configuration • Is just configuration • You can do manual configuration • Might require some workarounds

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Spring I/O 2016 Solutions • General Advice • Take Small Steps • Write Tests