Lean microservices using OSGi

Transcript

1. Lean microservices on OSGi By Christian Schneider Open Source Architect at Talend chris@die-schneider.net @schneider_chris
2. Participate in Demo Connect to irc network freenode Channel #jbcnconf
3. Microservices ...way of designing software applications as suites of independently deployable services.... organization around business capability, automated deployment, intelligence in the endpoints, and decentralized control of languages and data. - Martin Fowler • Create application out of independently deployable services • Verticals around business capabilities • Decentralized data • Automated deployment • 1 service per process • Lightweight communications between services (typically REST)
4. Spring boot • Framework for micro service development based on spring • Easy to start. Paste snippets of “starter” dependencies into pom • Convention over configuration • Good docker and cloud support
5. The Dark side of microservices
6. No, no, no. Quicker, easier, more seductive... Are microservices stronger than OSGi?
7. Dependencies between microservices
8. Operations Container vessel - Application Server
9. Microservices operation - Theory
10. Microservices operation - Practice
11. Microservices can not cure bad design
12. Microservices with spring-boot… What is wrong with it? • Lots of dependencies already at design time • Microservices always must communicate remotely • Proprietary Annotations / API • No flexibility in packaging 1 Microservice = 1 Deployment Unit = 1 Process
13. A small spring boot project • Pollutes the classpath • Difficult to establish rules which APIs to use 90 dependencies 20 MB jar file
14. Why is OSGi different? • Coding against APIs and specs • Self describing modules (bundles) • OSGi services to communicate between bundles • Semantic versioning • Remote Service Admin for Remote calls and REST • Flexible packaging
15. Semantic Versioning • MAJOR version - incompatible API changes, • MINOR version - added functionality in a backwards-compatible manner • BUGFIX version - backwards-compatible bug fixes Mind the difference between API and SPI.
16. Remote Service Admin • Exports and imports OSGi services • Service Properties to mark for export and configure transports, … • Highly customizable (Policies, Transports, Serialization, Discovery)
17. Rest services with RSA • Just JAX-RS annotations on interface REST Endpoint User bundle HTTP OSGi service CXF Transport for Aries RSA Creates Topology Manager Detects Selects transport
18. Lets see it in practice Small chat application • Modules talk to each other using an OSGi ChatListener interface described in API bundle • IRC connector using camel • Shell integration using gogo • Tinkerforge Display and Motion detector • Optional Remoting using Aries RSA
19. Chat API Chat shell integration Tinkerforge LCD display IRC Connector IRC All in one • 1 Process • 6MB runnable jar • No remote calls inside application • Still modular as bundles only coupled through API and OSGi service
20. Container vessel - OSGi deployment in one process
21. Chat API IRC Connector Aries RSA IRC Microservice Deployment Chat API Tinkerforge LCD and motion detect Aries RSA Chat API Chat shell integration Aries RSA Zookeeper
22. Microservice Deployment • Same bundles as before • As many deployment units as needed • Each deployment unit can scale • Runnable jars or docker containers • Cloud native if needed • Aries RSA overhead 300 KB + 800 KB zookeeper lib • Remote calls or local calls as needed • Many options for remotings (tcp, fastbin, SOAP, REST, JMS)
23. But beware of the same management issues as any other micro services
24. OSGi can scale from very small to very large But no simple cure for the operational problems of microservices
25. Unsure if you actually need a microservice architecture? • Develop your application using modular bundles • Stay on single process as long as possible • Decide about the packaging and deployment as late as possible • Deploy only as fine granular as needed
26. Further Reading • Achim Nierbeck - Microservices on OSGi • Milen Dyankow - Microservices and Modularity • OSGi Chat example code • Example for REST export using Aries RSA and CXF