rest in an async world

Copyright©2017,Oracleand/oritsaffiliates.Allrightsreserved.|

DavidDelabassee@delabasseeOracle

RESTinanAsyncWorldIsrael–July2017


SafeHarborStatementThefollowingisintendedtooutlineourgeneralproductdirecPon.ItisintendedforinformaPonpurposesonly,andmaynotbeincorporatedintoanycontract.Itisnotacommitmenttodeliveranymaterial,code,orfuncPonality,andshouldnotberelieduponinmakingpurchasingdecisions.Thedevelopment,release,andPmingofanyfeaturesorfuncPonalitydescribedforOracle’sproductsremainsatthesolediscrePonofOracle.

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Agenda

• REST&JAX-RS•  Synchronousvs.Asynchronous• Client-sidevs.Server-side

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Client-sideREST

ConfidenPal–OracleInternal/Restricted/HighlyRestricted 6


JAX-RS

•  JavaAPIforRESTfulWebServices– JAX-RS2.0–JSR339(*)– JAX-RS2.1–JSR370

•  StandardbasedRESTfulframework– Server-sideandclient-side– Jersey,JBossRESTEasy,Restlet,ApacheCXF,ApacheWink,IBMJAX-RS,…

•  JavaSEandJavaEE

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Clientclient=ClientBuilder.newClient();WebTargettarget=client.target("http://weath.er/api").queryParam("city","Paris”);Forecastforecast=target.request().get(Forecast.class);…client.close();

JAX-RSClientAPI


JAX-RSClientAPI

• Client– Clientsidecontainer– Customizable&tunable• E.g.executorService()(newinJAX-RS2.1!)

• WebTarget– TargetremoteURI– Buildfromaclient– path()+resolveTemplates(),queryParam(),matrixParam()

javax.ws.rs.client.Clientinterface

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JAX-RSClientAPI

• RequestinvocaPonbuilder– BuildfromaWebTarget– acceptXXX(),cookie(),header(),cacheControl()…– HTTPmethods


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JAX-RSClientAPI

•  FluentAPI– ClientBuilderèClientèWebTargetèRequestbuildingèResponse


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List<Forecast>forecast=ClientBuilder.newClient().target("http://weath.er/cities").request().accept("application/json").header("Foo","bar").get(newGenericType<List<Forecast>>(){});


JAX-RSClientAPI

•  Synchronousinvoker

• Asynchronousinvoker

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Stringcity=client.target("http://locati.on/api").queryParam("city","Paris").request().get(String.class);

Future<String>fCity=client.target("http://locati.on/api").queryParam("city","Paris").request().async().get(String.class);


JAX-RSClientAPIAsynchronousinvoca.on

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Future<String>fCity=client.target("http://locati.on/api")…

.request().async().get(String.class);Stringcity=future.get();



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Future<String>fCity=client.target("http://locati.on/api")…

.request().async().get(String.class);

try{

Stringcity=future.get(4,TimeUnit.SECONDS);

}catch(TimeoutExceptiontimeout){…}



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Future<String>future=client.target("http://locati.on/api")…

.request().async().get(String.class);

while(!future.isDone()){//responsehasn'tbeenreceivedyet…}

Stringcity=f.get();…

//SetClientProperties.CONNECT_TIMEOUT&READ_TIMEOUT


JAX-RSClientAPI

•  InvocaPonCallbackInterface– javax.ws.rs.client.InvocaPonCallback<RESPONSE>

• ContainerwillreceiveasynchronousprocessingeventsfromaninvocaPon– completed(RESPONSEresponse)– failed(Throwablethrowable)

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Asynchronousinvoca.on


JAX-RSClientAPI

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Invoca.onCallback…WebTargetmyResource=client.target("http://examp.le/api/read");Future<Customer>future=myResource.request(MediaType.TEXT_PLAIN).async().get(newInvocationCallback<Customer>(){

@Overridepublicvoidcompleted(Customercustomer){//dosomethingwiththegivencustomer}

@Overridepublicvoidfailed(Throwablethrowable){//Oops!}

});


TheTravelService


TheTravelService-Synchronous• Customerdetails:150ms• RecommendeddesPnaPons:250ms• PricecalculaPonforacustomeranddesPnaPon:170ms(each)• WeatherforecastforadesPnaPon:330ms(each)

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5400ms


TheTravelService-Asynchronous

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730ms


TheTravelService


TheTravelServicedestination.path("recommended").request().header("Rx-User","Async").async().get(newInvocationCallback<List<Destination>>(){@Overridepublicvoidcompleted(finalList<Destination>recommended){finalCountDownLatchinnerLatch=newCountDownLatch(recommended.size());finalMap<String,Forecast>forecasts=Collections.synchronizedMap(newHashMap<>());for(finalDestinationdest:recommended){forecast.resolveTemplate("dest",dest.getDestination()).request().async().get(newInvocationCallback<Forecast>(){@Overridepublicvoidcompleted(finalForecastforecast){forecasts.put(dest.getDestination(),forecast);innerLatch.countDown();}


JAX-RS2.0

@Overridepublicvoidfailed(finalThrowablethrowable){innerLatch.countDown();}});}

try{if(!innerLatch.await(10,TimeUnit.SECONDS)){//timeout}}catch(finalInterruptedExceptione){//Ooops,interrupted!}

//Continuewithprocessing…}

@Overridepublicvoidfailed(finalThrowablethrowable){//Recommendationerror}});


JAX-RS2.1

//JAX-RS2.1CompletionStage<Response>csResponse=ClientBuilder.newClient().target("http://example.com/api").request().rx().get();

Future<Response>fResponse=ClientBuilder.newClient().target("http://example.com/api").request().async().get();

Responseresponse=ClientBuilder.newClient().target("http://example.com/api").request().get();


ComplePonStageinterface

•  “AstageofapossiblyasynchronouscomputaPon,thatperformsanac.onorcomputesavalue”•  “Ontermina.onastagemayinturntriggerotherdependentstages.”•  StageexecuPontriggeredbycomplePonof– “then”-asinglestage– “combine”-bothoftwostages– “either”-eitheroftwostages

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ComplePonStageinterface

• ComputaPontakesanargumentandreturnsaresult?– “apply”–Func.ontakeresultofthepreviousstageasargument,returnaresult– “accept”–Consumeronlytakeanargument– “run”–Runnablenoargumentanddoesn’treturnaresult

• HowtheexecuPonofthecomputaPonisarranged?– Doesn'tendwith“async”–executeusingthestage’sdefaultexecuPonfacility– Endwith“async”-usethestage’sdefaultasynchronousexecuPonfacility

• …

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hsps://docs.oracle.com/javase/8/docs/api/java/uPl/concurrent/ComplePonStage.html


JAX-RS2.1

CompletionStage<Number>csPrice=client.target("price/{destination}").resolveTemplate("destination","Paris").request().rx().get(Number.class);CompletionStage<String>csForecast=client.target("forecast/{destination}").resolveTemplate("destination","Paris").request().rx().get(String.class);csPrice.thenCombine(csForecast,(price,forecast)->book(price,forecast));


DemoTheTravelService

hsps://github.com/jersey/jersey/tree/master/examples/rx-client-webapp


JAX-RSClientAPI

• RESTClientSidecontainer•  Synchronousinvoker– Defaultinvoker-javax.ws.rs.client.SyncInvoker

• Asynchronousinvokers– async()invoker-javax.ws.rs.client.AsyncInvoker• Mightblock->InvocaPonCallback

– ReacPverx()invoker-javax.ws.rs.client.RxInvoker•  NewinJAX-RS2.1!•  ComplePonStageAPI+otherReacPvelibrary(opt.)

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Summary


Server-sideREST



Server-side@Path("/Item")publicclassItemResource{@Path("{id}")@Produces(MediaType.APPLICATION_XML)publicItemResourcegetItemResource(@PathParam("id")Stringid){returnItemResource.getInstance(id);}@POST@Consumes(MediaType.APPLICATION_XML)@Produces(MediaType.APPLICATION_XML)publicResponsecreateItem(@QueryParam("name")Stringname){//...returnResponse.status(Status.OK).entity(…).build();}}


Server-sideAsync@Path("/Async")publicclassItemResource{

@GETpublicvoidheavyResource(@SuspendedAsyncResponsear){

mes.execute(newRunnable(){@Overridepublicvoidrun(){try{//longrunningcomputation...ar.resume(Response.ok(...).build());}catch(InterruptedExceptionex){//Ooops!}}});...


Server-sideAsync

• Providesmeansforasynchronousserversideresponseprocessing– Injectablevia@SuspendedOR– ResourcemethodcanreturnaComplePonStage<T>instance(newinJAX-RS2.1!)

• Boundtotherequest– Suspend– Resume– Configure– Cancel

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AsyncResponseinterface


Server-sideAsync

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Client Server

@Suspended

AsyncResponse.resume(…)

LongrunningoperaPon…

Request

Response


LongrunningRESToperaPons

è POST...longrunningoperaPon...ç ‘201Created’+LocaPon

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è POSTç ‘202Accepted’+TempLocaPon

è GETTempLocaPonç ‘200OK’(+ETA)…è GETTempLocaPonç ‘303SeeOther’+FinalLocaPon


Server-sentEvents

• Persistent,one-waycommunicaPonchannel•  Textprotocol,specialmediatype"text/event-stream"•  ServercansendmulPplemessages(events)toaclient• Cancontainid,name,commentretryinterval•  Supportedinallmodernbrowsers

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JAX-RS2.1

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SSE

•  SseEvent– ID,Name,Comment,…

• OutboundSseEvent– Server-siderepresentaPonofaServer-sentevent– OutboundSseEvent.Builder()

•  InboundSseEvent– Client-siderepresentaPonofaServer-sentevent


JAX-RS2.1

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SSE–Serverside

•  SseEventSink– OutboundServer-SentEventsstream– SseBroadcaster

@GET@Path("sse")@Produces(MediaType.SERVER_SENT_EVENTS)publicvoideventStream(@ContextSseEventSinkeventSink,@ContextSSEsse){...eventSink.send(sse.newEvent("anevent"));eventSink.send(sse.newEvent("anotherevent"));...eventSink.close();}


JAX-RS2.1

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SSE–Clientside

•  SseEventSource– ClientforprocessingincomingServer-SentEvents

SseEventSourcees=SseEventSource.target(SSE_target).reconnectingEvery(5,SECONDS).build();es.register(System.out::println);//InboundSseEventconsumeres.register(...);//Throwableconsumeres.open();...es.close();


Wrap-up



JAX-RS

•  JavaAPIforRESTfulWebServices– JAX-RS2.0–JSR339(*)– JAX-RS2.1–JSR370

•  StandardbasedRESTfulframework– Server-sideandclient-side– JavaSEandJavaEE– Jersey,JBossRESTEasy,Restlet,ApacheCXF,ApacheWink,IBMJAX-RS,…

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JAX-RS–Client-side

• RESTClientSidecontainer•  Invokers– Synchronous•  javax.ws.rs.client.SyncInvoker•  Default

– Asynchronous•  javax.ws.rs.client.AsyncInvoker

– ReacPve•  NewinJAX-RS2.1!•  javax.ws.rs.client.AsyncInvoker

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JAX-RS–Client-side

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Sync Async RXPerformanceandscalability ✗✗ ✔ ✔Easytodevelopandmaintain ✔ ✗ ✔

…complexworkflow ✗ ✗ ✔…errorhandling ✗ ✗ ✔

LeveragenewJavaSEfeature ✗ ✗ ✔


JAX-RS–ReacPveClientAPI•  JavaSE8ComplePonStage– Asmandatedbythespec.

•  Jersey– RxJava-rx.Observable– RxJava2-io.reacPvex.Flowable– Guava-ListenableFuture

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JAX-RS–Server-side

• AsyncResponse– ResumeexecuPononadifferentthread– @Suspended– ResourcemethodreturningaComplePonStage<T>instance

•  LongrunningoperaPonpasern•  Server-sentEvents

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JavaEE8

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BeanValida.on

CDI2.0

JSON-B1.0

Security1.0

BeanValida.on2.0

JSF2.3

Servlet4.0

JSON-P1.1

JAX-RS2.1 ReacPveclientAPI,Server-sentevents,…

HTTP/2,serverpush,…

Java<->JSONbinding

UpdatestoJSONstandards,JSONCollectors,…

Asyncevent,eventpriority,SEsupport,…

EmbraceJavaSE8,newconstraints

ImprovedCDI,WebSocket,SE8integraPon,…

StandardizedIdenPtyStore,AuthenPcaPon,SecurityContext


JavaEE8• Workinprogress– FinalRelease-Summer2017(plan)

• OpenSourceReferenceImplementaPons– hsps://github.com/jersey

– hsps://github.com/javaee

•  Staytuned…– hsps://blogs.oracle.com/theaquarium/

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תודה רבה.



Resources

•  JAX-RSspecificaPon– hsps://github.com/jax-rs/api

•  Jersey–AsynchronousServicesandClients– hsps://jersey.java.net/documentaPon/latest/async.html#d0e8611– hsps://github.com/jersey/jersey/tree/master/examples/rx-client-webapp

• ComplePonStage– hsps://docs.oracle.com/javase/8/docs/api/java/uPl/concurrent/ComplePonStage.html

•  JavaEETutorial– hsps://docs.oracle.com/javaee/7/tutorial/

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rest in an async world

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