Better Taste, Less Filling: JS in your JVM with Hegemon

Video at: http://www.youtube.com/watch?v=YwnOst7Fplc

Abstract:

JVM developers need not be held hostage by the Java language. JavaScript for the JVM is available, but making it a first class member of your application can be tricky.

This talk will focus on libraries, tools, and techniques that the team at Cue (cueup.com) uses to make JavaScript in Java fun, easy, and efficient.

You’ll learn how to use JS 1.8 in your runtime, update applications without recompiling, run JUnit backed JS tests with just a browser reload, and provide an interactive console in your application.

Transcript

1. Better Taste, Less Filling: JS in your JVM with Hegemon github.com/Cue/hegemon Monday, January 14, 13
2. Kevin Clark github.com/kevinclark Monday, January 14, 13
3. cueup.com github.com/Cue/hegemon Monday, January 14, 13
4. Monday, January 14, 13
5. The old model: processes Monday, January 14, 13
6. The service Monday, January 14, 13
7. The service Monday, January 14, 13
8. Problem Y Problem X Monday, January 14, 13
9. Frontend Backend Monday, January 14, 13
10. Partitioning the problem lets us specialize tools Monday, January 14, 13
11. This happens at different levels of scale Monday, January 14, 13
12. Frontend Backend Monday, January 14, 13
13. Backend Frontend Monday, January 14, 13
14. Perf Constrained Chillin Monday, January 14, 13
15. Cue is built on Monday, January 14, 13
16. It’s the right tool for search. Monday, January 14, 13
17. {“bars”: [“bar”, “bar”]} Monday, January 14, 13
18. public class FooResponse { final List<String> bars; @JsonCreator FooCommand(@JsonProperty("bars") List<String> bars) { this.bars = bars; } public List<String> getBars() { return this.bars; } } Monday, January 14, 13
19. http://brokershandsontheirfacesblog.tumblr.com/image/ 10558726620 Monday, January 14, 13
20. The “right tool” becomes leaky Monday, January 14, 13
21. Java when you need it, and nowhere else. Monday, January 14, 13
22. What is Hegemon? Monday, January 14, 13
23. Tools for using the latest Rhino on the JVM Monday, January 14, 13
24. Rhino https://developer.mozilla.org/en-US/docs/Rhino Monday, January 14, 13
25. Rhino JavaScript Java Monday, January 14, 13
26. Basics hegemon-core Monday, January 14, 13
27. Running JavaScript Script script = new Script("function foo() { return 3 + 4; }", LoadPath.defaultPath()); script.run("foo"); // returns 7 Monday, January 14, 13
28. Running JavaScript Script script = new Script("function foo() { return 3 + 4; }", LoadPath.defaultPath()); script.run("foo"); // returns 7 Monday, January 14, 13
29. Running JavaScript Script script = new Script("function foo() { return 3 + 4; }", LoadPath.defaultPath()); script.run("foo"); Monday, January 14, 13
30. Loading Files new Script("function foo() { return definedInUtil(); }", LoadPath.defaultPath(), "util"); new Script(" load('util'); function foo() { return definedInUtil(); }", LoadPath.defaultPath(), 'hegemon/core'); Monday, January 14, 13
31. Loading Files new Script("function foo() { return definedInUtil(); }", LoadPath.defaultPath(), "util"); new Script(" load('util'); function foo() { return definedInUtil(); }", LoadPath.defaultPath(), 'hegemon/core'); Monday, January 14, 13
32. Loading Files new Script("function foo() { return definedInUtil(); }", LoadPath.defaultPath(), "util"); new Script(" load('util'); function foo() { return definedInUtil(); }", LoadPath.defaultPath(), 'hegemon/core'); Monday, January 14, 13
33. Loading Files new Script("function foo() { return definedInUtil(); }", LoadPath.defaultPath(), "util"); new Script(" load('util'); function foo() { return definedInUtil(); }", LoadPath.defaultPath(), 'hegemon/core'); Monday, January 14, 13
34. LoadPath.defaultPath() Loads from resources/javascript Monday, January 14, 13
35. Monday, January 14, 13
36. Caching Loads ScriptCache cache = new ScriptCache(LoadPath.defaultPath()); Script script = cache.get("myScript"); script.run("foo"); Monday, January 14, 13
37. Caching Loads ScriptCache cache = new ScriptCache(LoadPath.defaultPath()); Script script = cache.get("myScript", true); script.run("foo"); Monday, January 14, 13
38. Over HTTP Monday, January 14, 13
39. function GET(params) { return {"method": "GET", "params": params} } example.js Monday, January 14, 13
40. GET /script/example?foo=bar Monday, January 14, 13
41. GET /script/example?foo=bar { "method": "GET", "params": { "foo": "bar" } } Monday, January 14, 13
42. @Path("/script/{name}") @Produces(MediaType.APPLICATION_JSON) public class ScriptResource { private static ScriptCache scriptCache = new ScriptCache(LoadPath.defaultPath()); @GET public Object post(@PathParam("name") String name, @Context UriInfo uriInfo) throws IOException, LoadError, ScriptException { Map<String, List<String>> params = uriInfo.getQueryParameters(); final Script script = scriptCache.get("script/" + name + ".js"); script.load("common"); Object paramsObject = script.run("getParamsAsObject", params); return script.run("GET", paramsObject); } } Monday, January 14, 13
43. @Path("/script/{name}") @Produces(MediaType.APPLICATION_JSON) Monday, January 14, 13
44. private static ScriptCache scriptCache = new ScriptCache(LoadPath.defaultPath()); Monday, January 14, 13
45. @GET public Object get(@PathParam("name") String name, @Context UriInfo uriInfo) throws ... { Map<String, List<String>> params = uriInfo.getQueryParameters(); Monday, January 14, 13
46. final Script script = scriptCache.get("script/" + name + ".js"); script.load("common"); Object paramsObject = script.run("getParamsAsObject", params); return script.run("GET", paramsObject); Monday, January 14, 13
47. Demo Monday, January 14, 13
48. Debug Endpoint Monday, January 14, 13
49. @Path("/eval") @Produces(MediaType.APPLICATION_JSON) public class EvalResource { @POST public Object post(String postBody) throws IOException, LoadError { final Script compiled = new Script("function run() { " + postBody + " }", LoadPath.defaultPath(), "hegemon/core"); return compiled.run("run"); } } Monday, January 14, 13
50. Demo Monday, January 14, 13
51. Firewall it! Monday, January 14, 13
52. How do we test it? Monday, January 14, 13
53. function GET(params) { return {"method": "GET", "params": params} } example.js Monday, January 14, 13
54. load('script/example'); function testThatGETShouldReturnParams() { let params = {'foo': 'bar'}; let result = GET(params); Assert.assertEquals("GET", result.method); Assert.assertEquals(params, result.params); } Monday, January 14, 13
55. Link with JUnit @RunWith(HegemonRunner.class) @HegemonRunner.TestScript(filename = "exampleTest") public class ExampleTest { } Monday, January 14, 13
56. Run with JUnit Runners Monday, January 14, 13
57. http://xkcd.com/303/ Monday, January 14, 13
58. Run tests faster hegemon-testserver Monday, January 14, 13
59. public class ExampleJsTestServer extends HegemonTestServer { private static List<ScriptLocator> locatorsFromDirs(String ... sourceDirs) { List<ScriptLocator> dirs = Lists.newLinkedList(); for (String dir : sourceDirs) { dirs.add(new ExternalFromResourceScriptLocator(ExampleJsTestServer.class, dir)); } return dirs; } ExampleJsTestServer(String ... sourceDirs) { super(LoadPath.customPath(locatorsFromDirs(sourceDirs), Collections.<ScriptLocator>emptyList())); } public static void main(String[] args) throws Exception { HegemonTestServer.run( new ExampleJsTestServer( "../../src/main/resources/javascript", "../../src/test/resources/javascript"), 7070); } } Monday, January 14, 13
60. public static void main(String[] args) throws Exception { HegemonTestServer.run( new ExampleJsTestServer( "../../src/main/resources/javascript", "../../src/test/resources/javascript"), 7070); } Monday, January 14, 13
61. Demo Monday, January 14, 13
62. Future Work Monday, January 14, 13
63. hegemon-stdlib Monday, January 14, 13
64. modules / namespacing? Monday, January 14, 13
65. Other crazy ideas Monday, January 14, 13
66. Updates without compiles or restarts Monday, January 14, 13
67. hegemon.py Monday, January 14, 13
68. Stuff we haven’t tried (yet) Monday, January 14, 13
69. CLI Library Wrapper Monday, January 14, 13
70. JavaScript to test Java Monday, January 14, 13
71. Make it easy to be flexible on tooling Monday, January 14, 13
72. hegemon 0.0.1 github.com/Cue/hegemon kevin@cueup.com Monday, January 14, 13