Moving the Guidewire platform to OSGi - Paul D'Albora
- 1. © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Moving the Guidewire platform to OSGi A case study Paul D’Albora Guidewire Software pdalbora@guidewire.com March 2012
- 2. 2 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Agenda • Introduction to the Guidewire platform • Motivation for moving to OSGi • Challenges • Where we are and where we’re going • Q & (hopefully) A
- 3. 3 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. The Guidewire Platform – Basics • Supports core system software for the global property/casualty insurance industry • Core services: ORM layer, web UI framework, business rules, workflow, automated upgrade, I18N, customer plugins, messaging and web services integration • High degree of configurability • Supports multiple JEE containers
- 4. 4 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. The Guidewire Platform – Pressures • Constantly adding and improving features for applications • Must not break existing customers • Large code base developed over ten years • Large and growing development team • All of which can lead to …
- 5. 5 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission.
- 6. 6 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission.
- 7. 7 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Goals • Test components in isolation • Reduce learning curve • Contain maintenance costs • Release components independently
- 8. 8 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. OSGi • Module system • Versioning • Manageability • Mature, well-defined specifications • Robust community • Services!
- 9. 9 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Givens • Application must be delivered as a JEE application (EAR/WAR) • Code divided into coarse-grained “modules” forming a DAG of compile-time dependencies • Non-Eclipse IDE (no PDE) • Custom build system
- 10. 10 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Step 1
- 11. 11 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Plan • Run Equinox embedded in JEE container using servlet bridge • Define a bundle for each existing code “module” • Replace/Convert 3rd -party jars with OSGi equivalents • Get automated tests running in framework • DON’T try to modularize yet
- 12. 12 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Roadblocks
- 13. 13 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Problem: Split Packages • Same package exists in multiple modules • Framework binds to one of them, causing the other “parts” of the package to effectively disappear • Typical for platform and one or more applications to define classes in the same package • This is pervasive in our code
- 14. 14 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Solution: Fragments • Define an empty “root” bundle • Every bundle is a fragment of root - Fragment-Host: com.guidewire.root • Simulates one bundle • More closely represents original, non-modular, global classpath environment
- 15. 15 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Problem: 3rd -party libraries • Lots of them (~102 ) • Signed jars • Classpath assumptions
- 16. 16 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Solution: Varied • Public OSGi bundle repositories – Eclipse Orbit – SpringSource • BND – For signed jars, embed jar within jar and use Bundle- ClassPath – Can combine related jars to deal with split packages • TCCL to work around classpath assumptions • Newer jars being packaged as OSGi bundles
- 17. 17 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Problem: Servlets • No longer registered in web.xml (just the servlet bridge) • How to register platform and application servlets with HttpService • Ordering requirements (<load-on-startup>)
- 18. 18 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Solution: Components • Felix Http Whiteboard • Declarative Services with Bnd - @Component(provide=Servlet.class, properties="alias=/path") • For ordering-dependent servlets, register in order with HttpService - Component with @Reference to HttpService
- 19. 19 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Practical Tips • Learn and use BND • Learn the classloading flow chart (R4.2 Spec, Fig 3.19) – Turn off osgi.compatibility.bootdelegation, osgi.context.bootdelegation in Equinox – No Require-Bundle • Lean on automated tests • Use the framework itself
- 20. 20 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Current Status • Applications and integration tests running successfully in development • Initial performance testing reveals no significant difference in response times or memory usage • Rolled out to application teams with minimal disruption
- 21. 21 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Next Steps • Define candidate areas for modularization • Use services to de-couple components • Use services to replace ad hoc registries • Educate developers about service-oriented programming
- 22. 22 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Example: Static Service Registry • Map of interface Class to implementation instance • Initialized by bootstrap class • Accessed via static methods
- 23. 23 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Static Service Registry – Code Sample 1
- 24. 24 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Static Service Registry – Code Sample 2
- 25. 25 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Static Service Registry – Code Sample 3
- 26. 26 © Guidewire Software, Inc. All rights reserved. Do not distribute without permission. Static Service Registry – Replacement
- 28. Give Feedback on the Sessions 1 Sign In: www.eclipsecon.org 2 Select Session Evaluate 3 Vote
Editor's Notes
- #6: We’re all probably familiar with this metaphor. It’s a natural consequence of code evolution without proper boundaries. Tug on one strand and you affect something on the other side of the “plate.” And we all know where this leads…
- #7: Leads to frustration for new developers
- #8: Understanding the pressures we face on the platform team, and that those are only likely to increase, we defined some goals we’d like to have in order to survive. Testing in isolation: we invest a lot in automated testing. Over time, more and more of our tests have had to be written as integration / end-to-end tests. We attempted to use mocks for more “unit” style testing, but our components are not de-coupled enough for that to work. New developers face a daunting challenge. No clear APIs, sub-systems tightly coupled Fixing bugs often requires knowledge over a broad area of the platform Platform must be delivered as a monolith
- #9: We decided to go with OSGi Module system provides a way to define boundaries and enforce them Has momentum Manageability is a big advantage – modular architecture allows for wide array of introspection tools Service layer is a simple but extremely powerful way of de-coupling code. Combined with Declarative Services, it is the most exciting aspect for us.
- #10: How are we going to get there? Here’s what we’ve got to work with. Customers familiar with and have expertise with managing their own JEE application servers. From their point-of-view, it’s still just a WAR. PL, apps depend on PL For development, no access to PDE Custom, script-based build system
- #11: First step is get the platform and applications running in OSGi: replace the foundation
- #12: Just want to get the framework in place and prove that it can work.
- #14: Renaming packages is not an option at this point. Neither is co-locating the packages. This is not unusual when the package doesn’t mean much.
- #15: Last point is important in light of our goal: get platform running in OSGi framework without breaking existing code.
- #17: Learned about unresolved dependencies, duplicate packages/classes
- #18: Entry points to the applications
- #21: Not yet released to customers