AtlasCamp 2012: Polyglot Plugin Programming

https://www.atlassian.com/company/about/events/atlascampeu/2012/day1/polyglot-plugin-programming

Transcript

2. How to write plugins in a language other than Java Stefan Saasen Confluence Team Lead, Atlassian Polyglot Plugin Development 2
3. Audience 3
4. • Written an Atlassian plugin in Java Audience 3
5. • Written an Atlassian plugin in Java • Interested in other programming languages Audience 3
6. • Written an Atlassian plugin in Java • Interested in other programming languages • Eager to see what is possible with Atlassian plugins Audience 3
7. Show of hands 4
8. • Who has actually written a Atlassian plugin? • In any other language than Java? Show of hands 4
10. 6 Rhino
12. 8 https://bitbucket.org/ssaasen/atlassian-jruby-example-plugin https://bitbucket.org/ssaasen/atlassian-scala-example-plugin
13. • Why? • How? • Example 1: Scala • Example 2: JRuby • Go and do it! Polyglot Plugins 9
14. Why not? 10
15. Why ? 11
16. 12 What to tell the boss?
17. • Leverage existing knowledge in the team 12 What to tell the boss?
18. • Leverage existing knowledge in the team • Libraries/applications already written in language X 12 What to tell the boss?
19. • Leverage existing knowledge in the team • Libraries/applications already written in language X • Time to market/devspeed 12 What to tell the boss?
20. • Leverage existing knowledge in the team • Libraries/applications already written in language X • Time to market/devspeed • Explore technologies in a sandboxed environment 12 What to tell the boss?
21. • Leverage existing knowledge in the team • Libraries/applications already written in language X • Time to market/devspeed • Explore technologies in a sandboxed environment • Grass looks always greener on the other side 12 What to tell the boss?
22. • Leverage existing knowledge in the team • Libraries/applications already written in language X • Time to market/devspeed • Explore technologies in a sandboxed environment • Grass looks always greener on the other side 13 What to tell the boss?
24. 15 “Succinctness” “No time to write in Java” “Less bugs”
26. • Why? • How? • Example 1: Scala • Example 2: JRuby • Go and do it! Polyglot Plugins 17
27. • Hybrid language: Object oriented & functional • Concise, statically typed (with type inference) • Higher order/first class functions, pattern matching • Powerful type system • Rich standard library 18
32. How? 23
33. 24 Overview Java JVM Java Standard Library Scala Runtime Library javac scalac Java Bytecode *.class Scala
36. • Start with Maven to get the AMPS goodness • Use the maven-scala- plugin • Add SBT if necessary Build process 27
37. • Compile time is a concern! • FSC • Useful Maven goals: mvn scala:cc mvn scala:console Build process f. 28
38. Bundle runtime 29
39. Size might be a problem :( 30
40. 31 Option Scope Package Size Bundle Bundle & Shrink w/ProGuard Install separately compile mvn package -Pbundle 8.5 MB Simple compile mvn package -Pproduction 680 KB Deploy externally provided mvn package 50 KB Deploy internally Deployment options
41. 31 Option Scope Package Size Bundle Bundle & Shrink w/ProGuard Install separately compile mvn package -Pbundle 8.5 MB Simple compile mvn package -Pproduction 680 KB Deploy externally provided mvn package 50 KB Deploy internally Deployment options
42. 31 Option Scope Package Size Bundle Bundle & Shrink w/ProGuard Install separately compile mvn package -Pbundle 8.5 MB Simple compile mvn package -Pproduction 680 KB Deploy externally provided mvn package 50 KB Deploy internally Deployment options
43. 31 Option Scope Package Size Bundle Bundle & Shrink w/ProGuard Install separately compile mvn package -Pbundle 8.5 MB Simple compile mvn package -Pproduction 680 KB Deploy externally provided mvn package 50 KB Deploy internally Deployment options
44. Simply install using the plugin manager! 32
45. • Dependencies: Scala libraries are jar files and often available from Maven repositories • Compile time: mvn scala:cc for continuous compilation • Workflow: scala:cc & atlas-cli pi or mvn package && atlas-install-plugin • Profit: mvn scala:console to get the Scala REPL 33 Development checklist
46. Scala: Working with Java APIs 34
47. • Collections • Method naming conventions • Annotations • Null vs. Option Scala gotchas (the 80%) 35
48. • Immutable vs Mutable, serial vs. parallel • Rich API: Prefer Scala collections • Convert between Java and Scala collections when calling Java methods • Solution: JavaConverters (explicit, preferred) vs. JavaConversions (implicit) • Watch out for serialization: Bandana/XStream Collections 36
52. • Libraries rely on bean style naming conventions e.g. XWork, Velocity • Scala: uniform access principle • Solution: Use @BeanProperty and @BooleanBeanProperty Method naming conventions 40
56. • How to use @JavaAnnotation on a getter method when defining fields? • Scala meta annotations @beanGetter, @beanGetter, @field, @getter, @setter (Meta)-Annotations 44
60. • In Scala Option represents an optional value. • Don’t let the billion-dollar mistake leak into your Scala code! • Solution: wrap nullable method calls in an Option Option vs. null 48
65. Show me the code! 53
73. • Servlet & XWork action • Confluence macro • REST via Jersey/Jackson • Build setup • Use as a starting point Example Scala plugin 61 https://bitbucket.org/ssaasen/atlassian-scala-example-plugin
74. Let’s recap 62
75. • Replace Java entirely with Scala or mix and match Let’s recap 62
76. • Replace Java entirely with Scala or mix and match • Runtime library: 3 deployment options Let’s recap 62
77. • Replace Java entirely with Scala or mix and match • Runtime library: 3 deployment options • Fits into the AMPS development workflow Let’s recap 62
78. • Replace Java entirely with Scala or mix and match • Runtime library: 3 deployment options • Fits into the AMPS development workflow • Scala Gotchas: watch out for common problems Let’s recap 62
79. • Replace Java entirely with Scala or mix and match • Runtime library: 3 deployment options • Fits into the AMPS development workflow • Scala Gotchas: watch out for common problems • “Scala is a great fit to write Atlassian plugins in” Let’s recap 62
80. • Why? • How? • Example 1: Scala • Example 2: JRuby • Go and do it! Agenda 63
81. • Dynamic, object-oriented language • Everything is an object (no “primitives”) • Meta-programming and open, executable classes allow for easy creation of DSLs • JRuby: Ruby runtime written in Java (J)Ruby 64
83. How? 66
84. 67 Overview Java JVM Java Standard Library Ruby Runtime Ruby Standard Library RubyGems Your Ruby Code javac jrubyc Ruby files *.rb Java Bytecode *.class
89. 71 Plugins can’t be written in Ruby
90. 72 But we can still use Ruby in a plugin!
91. 73 Recipe for using JRuby
92. • Embed the Ruby Runtime 73 Recipe for using JRuby
93. • Embed the Ruby Runtime • Use Java to execute Ruby scripts and classes 73 Recipe for using JRuby
94. • Embed the Ruby Runtime • Use Java to execute Ruby scripts and classes • Make components of the host application available 73 Recipe for using JRuby
95. • Embed the Ruby Runtime • Use Java to execute Ruby scripts and classes • Make components of the host application available • Use the script execution result in Java 73 Recipe for using JRuby
96. 74 Embedding Strategies
97. • javax.scripting - JSR 223 74 Embedding Strategies
98. • javax.scripting - JSR 223 • Apache Bean Scripting Framework (BSF) 74 Embedding Strategies
99. • javax.scripting - JSR 223 • Apache Bean Scripting Framework (BSF) • JRuby Embed - lower level JRuby API 74 Embedding Strategies
100. • javax.scripting - JSR 223 Only configurable via system properties :( • Apache Bean scripting framework (BSF) No point in adding a separate API • JRuby Embed - lower level JRuby API 75 Embedding Strategies
102. 77 Building the plugin
103. • Package Ruby files 77 Building the plugin
104. • Package Ruby files • Download and package Ruby gems 77 Building the plugin
105. • Package Ruby files • Download and package Ruby gems • Make Ruby gems available on the Ruby LOAD_PATH 77 Building the plugin
106. • Package Ruby files • Download and package Ruby gems • Make Ruby gems available on the Ruby LOAD_PATH • Bundle everything into a plugin jar file 77 Building the plugin
107. • Package Ruby files • Download and package Ruby gems • Make Ruby gems available on the Ruby LOAD_PATH • Bundle everything into a plugin jar file • A lot of Maven XML :) 77 Building the plugin
108. • Package Ruby files • Download and package Ruby gems • Make Ruby gems available on the Ruby LOAD_PATH • Bundle everything into a plugin jar file • A lot of Maven XML :) • Caveat: JRuby runtime is even larger! 77 Building the plugin
109. Show me the code! 78
112. 81 1 minute
121. • How to use Rubygem based libraries in a plugin • How to access host components in Ruby • How to use the execution result • Sinatra in Confluence ;-) Example JRuby plugin 90 https://bitbucket.org/ssaasen/atlassian-jruby-example-plugin
122. • The plugin can’t be written in Ruby! • Use the Ruby runtime • Development workflow bonus: dynamic reloading! • The overhead of adding the runtime and providing Java glue code makes this only feasible for high value use cases :( 91 Let’s recap
123. • Scala is a great alternative when developing an Atlassian plugin • JRuby is powerful, makes developing in a dynamic language possible but requires more work and custom Java adapter code • Java interoperability needs to be well understood in both cases 92 Conclusion
124. #atlascamp TAKE-AWAYS The power of the Atlassian plugin framework allows you to build your plugins the way you want and Java doesn’t have to be the limit. “ ” 93
125. Thank you! 94
126. 95 • “Happy Foods” by swanksalot http://www.flickr.com/photos/swanksalot/5021262869/ • “Construction” by Daniel Morris http://www.flickr.com/photos/danielmorris/275438405/ • “70 80 90” by roujo http://www.flickr.com/photos/tekmagika/437989361