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spray: REST on Akka

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The slides of my talk at @nescalas (the northeast scala symposium, nescala.org) on March 9th, 2012

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spray: REST on Akka

  1. REST on Akka⇗ northeast scala symposium March 9th, 2012
  2. What is spray?
  3. What is spray?Suite of libraries for building and consumingRESTful web services on top of Akka
  4. What is spray?Suite of libraries for building and consumingRESTful web services on top of Akka• First released about 1 year ago
  5. What is spray?Suite of libraries for building and consumingRESTful web services on top of Akka• First released about 1 year ago• Principles: lightweight, async, non-blocking, actor-based, modular, few deps, testable
  6. What is spray?Suite of libraries for building and consumingRESTful web services on top of Akka• First released about 1 year ago• Principles: lightweight, async, non-blocking, actor-based, modular, few deps, testable• Philosophy: library, not framework
  7. Components
  8. Components• Rich immutable HTTP model
  9. Components• Rich immutable HTTP model• spray-server: DSL for server-side API construction
  10. Components• Rich immutable HTTP model• spray-server: DSL for server-side API construction• spray-client: complementary HTTP client
  11. Components• Rich immutable HTTP model• spray-server: DSL for server-side API construction• spray-client: complementary HTTP client• spray-can: low-level HTTP server and client
  12. Components• Rich immutable HTTP model• spray-server: DSL for server-side API construction• spray-client: complementary HTTP client• spray-can: low-level HTTP server and client• spray-json: straight JSON in scala (no Akka)
  13. spray-server
  14. spray-server• Runs on servlet containers or spray-can
  15. spray-server• Runs on servlet containers or spray-can• Tool for building a “self-contained” API layer
  16. spray-server• Runs on servlet containers or spray-can• Tool for building a “self-contained” API layer• Central element: Routing DSL for defining web API behavior
  17. spray-server• Runs on servlet containers or spray-can• Tool for building a “self-contained” API layer• Central element: Routing DSL for defining web API behavior• Focus: RESTful web API, not web GUI
  18. Basic Architecture Application Business Logic
  19. Basic ArchitectureREST API layer Application Routing Logic Business Logic
  20. Basic Architecture REST API layer ApplicationHTTP Request Routing Logic Business Logic
  21. Basic Architecture REST API layer ApplicationHTTP Request Action Routing Logic Business Logic
  22. Basic Architecture REST API layer ApplicationHTTP Request Action domain Routing object ! Business Logic Logic
  23. Basic Architecture REST API layer ApplicationHTTP Request Action domain Routing object ! Business Logic Logic Reply
  24. Basic Architecture REST API layer ApplicationHTTP Request Action domain Routing object ! Business Logic Logic Reply
  25. Basic Architecture REST API layer ApplicationHTTP Request Action domain Routing object ! Business Logic LogicHTTP Response Reply
  26. API Layer Responsibilities
  27. API Layer Responsibilities• Request routing based on method, path, query parameters, entity
  28. API Layer Responsibilities• Request routing based on method, path, query parameters, entity• (Un)marshalling to / from domain objects
  29. API Layer Responsibilities• Request routing based on method, path, query parameters, entity• (Un)marshalling to / from domain objects• Encoding / decoding
  30. API Layer Responsibilities• Request routing based on method, path, query parameters, entity• (Un)marshalling to / from domain objects• Encoding / decoding• Authentication / authorization
  31. API Layer Responsibilities• Request routing based on method, path, query parameters, entity• (Un)marshalling to / from domain objects• Encoding / decoding• Authentication / authorization• Caching and serving static content
  32. API Layer Responsibilities• Request routing based on method, path, query parameters, entity• (Un)marshalling to / from domain objects• Encoding / decoding• Authentication / authorization• Caching and serving static content• RESTful error handling
  33. Route ExampleA simple spray route:val route: Route = path("order" / HexIntNumber) { id => get { completeWith { "Received GET request for order " + id } }~ put { completeWith { "Received PUT request for order " + id } } }
  34. Routing BasicsRoutes in spray: type Route = RequestContext => Unit
  35. Routing BasicsRoutes in spray: type Route = RequestContext => Unit Explicit continuation- passing style
  36. Routing BasicsRoutes in spray: type Route = RequestContext => Unit Explicit continuation- passing styleCentral object: case class RequestContext( request: HttpRequest, ...) {   def complete(...) { ... }   def reject(...) { ... }   ... }
  37. Routing BasicsThe simplest route: ctx => ctx.complete("Say hello to spray")
  38. Routing BasicsThe simplest route: ctx => ctx.complete("Say hello to spray")or: _.complete("Say hello to spray")
  39. Routing BasicsThe simplest route: ctx => ctx.complete("Say hello to spray")or: _.complete("Say hello to spray")or using a “directive”: completeWith("Say hello to spray")
  40. Routing BasicsThe simplest route: ctx => ctx.complete("Say hello to spray")or: _.complete("Say hello to spray")or using a “directive”: completeWith("Say hello to spray") def completeWith[T :Marshaller](value: => T): Route = _.complete(value)
  41. DirectivesRoute structure built with directives:val route: Route = path("order" / HexIntNumber) { id => get { completeWith { "Received GET request for order " + id } }~ put { completeWith { "Received PUT request for order " + id } } }
  42. Directives Route structure built with directives: val route: Route = path("order" / HexIntNumber) { id => get { completeWith { "Received GET request for order " + id }directive }~ name put { completeWith { "Received PUT request for order " + id } } }
  43. DirectivesRoute structure built with directives:val route: Route = path("order" / HexIntNumber) { id => get { completeWith { "Received GET request for order " + id } }~ args put { completeWith { "Received PUT request for order " + id } } }
  44. DirectivesRoute structure built with directives:val route: Route = path("order" / HexIntNumber) { id => get { extractions completeWith { "Received GET request for order " + id } }~ put { completeWith { "Received PUT request for order " + id } } }
  45. DirectivesRoute structure built with directives:val route: Route = path("order" / HexIntNumber) { id => get { completeWith { "Received GET request for order " + id } }~ put { completeWith { "Received PUT request for order " + id } } inner route }
  46. DirectivesRoute structure built with directives:val route: Route = path("order" / HexIntNumber) { id => get { completeWith { "Received GET request for order " + id }~ } route concatenation: put { recover from rejections completeWith { "Received PUT request for order " + id } } }
  47. DirectivesRoute structure built with directives:val route: Route = path("order" / HexIntNumber) { id => get { completeWith { "Received GET request for order " + id } }~ put { completeWith { "Received PUT request for order " + id } } }
  48. DirectivesRoute structure built with directives:val route: Route = path("order" / HexIntNumber) { id => get { completeWith { "Received GET request for order " + id } }~ put { completeWith { "Received PUT request for order " + id } } Route structure } forms a tree!
  49. DirectivesDRYing up with the `|` operator:val route = path("order" / HexIntNumber) { id => (get | put) { ctx => ctx.complete("Received " + ctx.request.method + " request for order " + id) } }
  50. DirectivesPulling out a custom directive:val getOrPut = get | putval route = path("order" / HexIntNumber) { id => getOrPut { ctx => ctx.complete("Received " + ctx.request.method + " request for order " + id) } }
  51. DirectivesThe `&` operator as alternative to nesting:val getOrPut = get | putval route = (path("order" / HexIntNumber) & getOrPut) { id => ctx => ctx.complete("Received " + ctx.request.method + " request for order " + id) }
  52. DirectivesPulling out once more:val orderGetOrPut = path("order" / HexIntNumber) & (get | put)val route = orderGetOrPut { id => ctx => ctx.complete("Received " + ctx.request.method + " request for order " + id) }
  53. DirectivesOperators are type-safe:val orderPath = path("order" / IntNumber)
  54. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)
  55. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)val dir = orderPath | get
  56. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)val dir = orderPath | get
  57. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)val dir = orderPath | getval dir = orderPath | path("[^/]+".r / DoubleNumber)
  58. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)val dir = orderPath | getval dir = orderPath | path("[^/]+".r / DoubleNumber)
  59. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)val dir = orderPath | getval dir = orderPath | path("[^/]+".r / DoubleNumber)val dir = orderPath | parameter(order.as[Int])
  60. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)val dir = orderPath | getval dir = orderPath | path("[^/]+".r / DoubleNumber)val dir = orderPath | parameter(order.as[Int])
  61. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)val dir = orderPath | getval dir = orderPath | path("[^/]+".r / DoubleNumber)val dir = orderPath | parameter(order.as[Int])val order = orderPath & parameters(oem, expired ?)
  62. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)val dir = orderPath | getval dir = orderPath | path("[^/]+".r / DoubleNumber)val dir = orderPath | parameter(order.as[Int])val order = orderPath & parameters(oem, expired ?)
  63. Directives Compiles?Operators are type-safe:val orderPath = path("order" / IntNumber)val dir = orderPath | getval dir = orderPath | path("[^/]+".r / DoubleNumber)val dir = orderPath | parameter(order.as[Int])val order = orderPath & parameters(oem, expired ?)val route = order { (orderId, oem, expired) => ... // inner route}
  64. Directivesspray 0.9.0 comes with 69 predefined directives:alwaysPass, authenticate, authorize, autoChunk, cache, cacheResults, clientIP,completeWith, content, cookie, decodeRequest, delete, deleteCookie, detach,dynamic, encodeResponse, filter, filter1, filter2, filter3, filter4, filter5, filter6,filter7, filter8, filter9, formField, formFields, get, getFromDirectory, getFromFile,getFromFileName, getFromResource, getFromResourceDirectory, handleWith,hardFail, head, headerValue, headerValuePF, host, jsonpWithParameter, method,optionalCookie, options, parameter, parameters, path, pathPrefix, post,produce, provide, put, redirect, reject, respondWithContentType,respondWithHeader, respondWithHeaders, respondWithMediaType,respondWithStatus, setCookie, trace, transformChunkedResponse,transformRejections, transformRequest, transformRequestContext,transformResponse, transformRoute, transformUnchunkedResponse, validate
  65. Real World Examplelazy val route = { encodeResponse(Gzip) { path("") { get { redirect("/doc") } }~ pathPrefix("api") { jsonpWithParameter("callback") { path("top-articles") { get { parameter(max.as[Int]) { max => validate(max >= 0, "query parameter max must be >= 0") { completeWith { (topArticlesService ? max).mapTo[Seq[Article]] } } } } }~ tokenAuthenticate { user => path("ranking") { get { countAndTime(user, "ranking") { parameters(fixed ? 0, mobile ? 0, sms ? 0, mms ? 0,
  66. } } }~ } } Real World Example tokenAuthenticate { user => path("ranking") { get { countAndTime(user, "ranking") { parameters(fixed ? 0, mobile ? 0, sms ? 0, mms ? 0, data ? 0).as(RankingDescriptor) { descr => (rankingService ? Ranking(descr)).mapTo[RankingResult] } } } }~ path("accounts") { post { authorize(user.isAdmin) { content(as[AccountDetails]) { details => (accountService ? NewAccount(details)).mapTo[OpResult] } } } }~ path("account" / IntNumber) { accountId => get { ... } ~ put { ... } ~ delete { ... } } }}~pathPrefix("v1") {
  67. } }~ Real World Example path("account" / IntNumber) { accountId => get { ... } ~ put { ... } ~ delete { ... } } } }~ pathPrefix("v1") { proxyToDjango } }~ pathPrefix("doc") { respondWithHeader(`Cache-Control`(`max-age`(3600))) { transformResponse(_.withContentTransformed(markdown2Html)) { getFromResourceDirectory("doc/root", pathRewriter = appendFileExt) } } }~ }~ cacheIfEnabled { encodeResponse(Gzip) { getFromResourceDirectory("public") } }}
  68. Best Practices
  69. Best Practices• Keep route structure clean and readable, pull out all logic into custom directives
  70. Best Practices• Keep route structure clean and readable, pull out all logic into custom directives• Don’t let API layer leak into application
  71. Best Practices• Keep route structure clean and readable, pull out all logic into custom directives• Don’t let API layer leak into application• Use (Un)marshalling infrastructure
  72. Best Practices• Keep route structure clean and readable, pull out all logic into custom directives• Don’t let API layer leak into application• Use (Un)marshalling infrastructure• Wrap blocking code with `detach`
  73. Best Practices• Keep route structure clean and readable, pull out all logic into custom directives• Don’t let API layer leak into application• Use (Un)marshalling infrastructure• Wrap blocking code with `detach`• Use sbt-revolver + JRebel for fast dev turn- around
  74. There is more ...
  75. There is more ...• SprayJsonSupport, LiftJsonSupport, TwirlSupport, ScalateSupport
  76. There is more ...• SprayJsonSupport, LiftJsonSupport, TwirlSupport, ScalateSupport• Asynchronous response push streaming
  77. There is more ...• SprayJsonSupport, LiftJsonSupport, TwirlSupport, ScalateSupport• Asynchronous response push streaming• Testing spray routes
  78. There is more ...• SprayJsonSupport, LiftJsonSupport, TwirlSupport, ScalateSupport• Asynchronous response push streaming• Testing spray routes• RESTful errors
  79. There is more ...• SprayJsonSupport, LiftJsonSupport, TwirlSupport, ScalateSupport• Asynchronous response push streaming• Testing spray routes• RESTful errors• spray-client
  80. Current State
  81. Current State• spray 0.9.0 just released (last release for Akka 1.x)
  82. Current State• spray 0.9.0 just released (last release for Akka 1.x)• Current focus: Release first Akka 2.0 compatible milestone of spray 1.0
  83. Current State• spray 0.9.0 just released (last release for Akka 1.x)• Current focus: Release first Akka 2.0 compatible milestone of spray 1.0• Coming features: new documentation site, deeper REST support, monitoring, request throttling, and more ...
  84. A few current sprayers ...
  85. Getting started• Main site & documentation: https://github.com/spray/spray/wiki• Mailing list: http://groups.google.com/group/spray-user• Twitter: @spraycc
  86. Thank you!
  87. More
  88. Proxying with sprayCombining with spray-client to build a proxy:val conduit = new HttpConduit("target.example.com", 8080)lazy val proxyToTarget: Route = { ctx => ctx.complete { conduit.sendReceive { ctx.request.withHeadersTransformed { _.filter(_.name != "Host") } }.map { _.withHeadersTransformed { _.filter(_.name != "Date") } } }

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