Download as PDF, PPTX
![Copyright
©
2015,
Oracle
and/or
its
affiliates.
All
rights
reserved.
The
Why
• Client
specific
API
– Different
needs
for
various
devices:
screen
size,
payment
methods,
...
• Single
Entry
Point
– No
need
to
communicate
with
mul%ple
services
• Thinner
client
– No
need
to
consume
different
formats
of
data
• Less
frequent
client
updates
– Doesn’t
ma]er
if
one
service
is
removed
in
favor
of
another
service
Building
an
Orchestra6on
Layer](https://image.slidesharecdn.com/reactivejerseyclient-150127032330-conversion-gate01/85/Reactive-Jersey-Client-6-320.jpg)
![Copyright
©
2015,
Oracle
and/or
its
affiliates.
All
rights
reserved.
Resources
• JAX-‐RS
Client
API
– h]ps://jax-‐rs-‐spec.java.net/nonav/2.0/apidocs/overview-‐summary.html
– h]ps://jersey.java.net/documenta%on/latest/client.html
• Jersey
Rx
Client
– h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client
– h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client-‐guava
– h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client-‐java8
– h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client-‐jsr166e
– h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client-‐rxjava
JAX-‐RS
and
Jersey](https://image.slidesharecdn.com/reactivejerseyclient-150127032330-conversion-gate01/85/Reactive-Jersey-Client-31-320.jpg)
![Copyright
©
2015,
Oracle
and/or
its
affiliates.
All
rights
reserved.
Resources
• 3rd
party
libraries
– h]ps://code.google.com/p/guava-‐libraries/
– h]ps://github.com/Reac%veX/RxJava
– h]p://docs.oracle.com/javase/8/docs/api/java/u%l/concurrent/package-‐
summary.html
– h]p://gee.cs.oswego.edu/dl/concurrency-‐interest/index.html
• Example
(JDK7)
– h]ps://github.com/jersey/jersey/tree/master/examples/rx-‐client-‐webapp
Example
and
Libraries](https://image.slidesharecdn.com/reactivejerseyclient-150127032330-conversion-gate01/85/Reactive-Jersey-Client-32-320.jpg)
Uploaded byMichal Gajdos
Reactive Jersey Client
The document discusses building an orchestration layer for a travel agency service using JAX-RS 2.0 and Jersey 2. It describes a naive synchronous approach that makes sequential requests slowing performance, and proposes an optimized asynchronous approach using asynchronous requests to improve performance by processing requests concurrently instead of sequentially. It provides examples of synchronous and asynchronous client code to call external services.
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Reactive Jersey Client
- 1. Reac%ve Jersey Client Michal Gajdos michal.gajdos@oracle.com January, 2015 Copyright © 2014, Oracle and/or its affiliates. All rights reserved.
- 2. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Safe Harbor Statement The following is intended to outline our general product direc%on. It is intended for informa%on purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or func%onality, and should not be relied upon in making purchasing decisions. The development, release, and %ming of any features or func%onality described for Oracle’s products remains at the sole discre%on of Oracle.
- 3. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. The Problem A Travel Agency
- 4. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. A Travel Agency Service Orchestra%ng Services Weather Customers Des%na%ons Quo%ng Travel Agency
- 5. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. The Why
- 6. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. The Why • Client specific API – Different needs for various devices: screen size, payment methods, ... • Single Entry Point – No need to communicate with mul%ple services • Thinner client – No need to consume different formats of data • Less frequent client updates – Doesn’t ma]er if one service is removed in favor of another service Building an Orchestra6on Layer
- 7. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. The How JAX-‐RS 2.0 and Jersey 2
- 8. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Demo Applica%on • “Remote” – applica%on/json, applica%on/xml – delays • “Agent” – applica%on/json – dependent calls Exposed resources
- 9. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. A Naïve Approach Implemen%ng the Service Get Customer Details Get a list of 10 Recommended Des6na6ons Get Quote for the Customer Get Weather Forecast for each Des6na6on for each Des6na6on
- 10. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Client client = ClientBuilder.newClient(); WebTarget rx = client.target("http://example.com/rx").register(JacksonFeature.class); WebTarget forecasts = rx.path("remote/forecast/{destination}"); Forecast forecast = forecasts.resolveTemplate("destination", dest.getDestination()) .request("application/xml") .get(Forecast.class); JAX-‐RS 2.0 Client – Synchronous
- 11. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. DEMO
- 12. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. A Naïve Approach Implemen%ng the Service Get Customer Details Get a list of 10 Recommended Des6na6ons Get Quote for the Customer Get Weather Forecast for each Des6na6on for each Des6na6on 150 ms 250 ms 1 700 ms 170 ms 3 300 ms 330 ms 5 400 ms
- 13. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Client – Synchronous Approach • Easy to read, understand and debug – Simple requests, Composed requests • Slow – Sequen%al processing even for independent requests • Was%ng resources – Wai%ng threads • Suitable for – Lower number of requests – Single request that depends on the result of previous opera%on
- 14. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Op6mized Approach Implemen%ng the Service 170 ms Get Customer Details Get a list of 10 Recommended Des6na6ons Async Get Quote for the Customer Async Get Weather Forecast for each Des6na6on for each Des6na6on 150 ms 250 ms 330 ms 330 ms 730 ms
- 15. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Future<Forecast> forecast = forecasts.resolveTemplate("destination", d.getDestination()) .request() .async() .get(new InvocationCallback<Forecast>() { @Override public void completed(Forecast forecast) { // Do Something. } @Override public void failed(Throwable throwable) { // Do Something else. } }); while (!forecast.isDone()) { // Do Something. } System.out.println(forecast.get()); JAX-‐RS 2.0 Client – Asynchronous
- 16. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. DEMO
- 17. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Client – Asynchronous Approach • Returns immediately afer submigng a request – Future • Harder to understand, debug – Especially when dealing with mul%ple futures • Fast – Each request can run on a separate thread – Need to ac%vely check for comple%on event (future.isDone()) or block (slow) Futures
- 18. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Client – Asynchronous Approach • “Don’t call us, we’ll call you” • Harder to read, understand and debug – Especially for composed calls (dependent) • Need to find out when all Async requests finished – Relevant only for 2 or more requests (CountDownLatch) • Fast – Each request can run on a separate thread • Suitable for – Many independent calls The Callback Hell
- 19. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Beyond The Callback Hell Reac6ve (Jersey) Client
- 20. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Client – Reac%ve Approach • Data-‐Flows – Execu%on model propagates changes through the flow • Asynchronous – Preferably, Speed • Event-‐based – No%fy user code or another item in flow about con%nua%on, error, comple%on • Composable – Compose/Transform mul%ple flows into the resul%ng one
- 21. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Reac%ve Java Libraries • RxJava – Observable – Analogy to Iterable – Currently most advanced reac%ve API in Java – Contributed by Nemlix – hardened & tested in produc%on • Java SE 8 – CompletionStage and CompletableFuture – Na%ve part of JDK – Fits the new Java Stream API programming model – JSR166e – Support for CompletableFuture on Java SE 6 and Java SE 7 • Guava – ListenableFuture and Futures – Similar to Java SE 8
- 22. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Observable • Observable (push) – retrieve data – onNext(T) – discover error – onError(Exception) – complete – onCompleted() • Iterable (pull) – retrieve data – T next() – discover error – throws Exception – complete – !hasNext()
- 23. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Observable<Response> response = … ; List<String> visited = new ArrayList<>(10); // Read a list of destinations from JAX-‐RS response response.map(resp -‐> resp.readEntity(new GenericType<List<Destination>>() {})) // If an exception is thrown, continue with an empty list .onErrorReturn(throwable -‐> Collections.emptyList()) // Emit list of destinations as a new Observable .flatMap(Observable::from) // Take the first 10 destinations .take(10) // Obtain a string representation of a destination .map(Destination::getDestination) // Observe the destination events on a separate thread .observeOn(Schedulers.io()) // Subscribe to callbacks – OnNext, OnError, OnComplete .subscribe(visited::add, async::resume, () -‐> async.resume(visited)); An Observable<Response> Example
- 24. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Reac%ve Jersey Client • Remember #request() and #request().async() ? – request() returns Invoca6on.Builder; SyncInvoker – sync HTTP methods – request().async() returns AsyncInvoker – async HTTP methods • #rx() and #rx(ExecutorService) – Return an extension of RxInvoker Extension of JAX-‐RS Client
- 25. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. public interface SyncInvoker { Response get(); <T> T get(Class<T> responseType); <T> T get(GenericType<T> responseType); // ... } public interface AsyncInvoker { Future<Response> get(); <T> Future<T> get(Class<T> responseType); <T> Future<T> get(GenericType<T> responseType); // ... } SyncInvoker and AsyncInvoker
- 26. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. public interface RxInvoker<T> { T get(); <R> T get(Class<R> responseType); <R> T get(GenericType<R> responseType); // ... } public interface RxObservableInvoker extends RxInvoker<Observable> { Observable<Response> get(); <T> Observable<T> get(Class<T> responseType); <T> Observable<T> get(GenericType<T> responseType); // ... } RxInvoker and an extension Example
- 27. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Reac%ve Jersey Client – contd • Affected JAX-‐RS interfaces – RxInvoca%onBuilder<RX extends RxInvoker> extends Invoca%on.Builder – RxWebTarget<RX extends RxInvoker> extends WebTarget – RxClient<RX extends RxInvoker> extends Client • Rx class – RxObservable – RxComple%onStage – RxListenableFuture – RxCompletableFuture (JSR 166e) Extension of JAX-‐RS Client
- 28. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Client client = ClientBuilder.newClient(); WebTarget target = client.target("..."); // Rx RxClient<RxObservableInvoker> rxClient = Rx.newClient(RxObservableInvoker.class); RxClient<RxObservableInvoker> rxClient = Rx.client(client, RxObservableInvoker.class); RxWebTarget<RxObservableInvoker> rxTarget = Rx.target(target, RxObservableInvoker.class); // RxObservable RxClient<RxObservableInvoker> rxClient = RxObservable.newClient(); RxClient<RxObservableInvoker> rxClient = RxObservable.client(client); RxWebTarget<RxObservableInvoker> rxTarget = RxObservable.target(target); Reac%ve Client – Crea%on
- 29. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. DEMO
- 30. Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Q&A
- 31. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Resources • JAX-‐RS Client API – h]ps://jax-‐rs-‐spec.java.net/nonav/2.0/apidocs/overview-‐summary.html – h]ps://jersey.java.net/documenta%on/latest/client.html • Jersey Rx Client – h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client – h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client-‐guava – h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client-‐java8 – h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client-‐jsr166e – h]ps://github.com/jersey/jersey/tree/master/incubator/rx/rx-‐client-‐rxjava JAX-‐RS and Jersey
- 32. Copyright © 2015, Oracle and/or its affiliates. All rights reserved. Resources • 3rd party libraries – h]ps://code.google.com/p/guava-‐libraries/ – h]ps://github.com/Reac%veX/RxJava – h]p://docs.oracle.com/javase/8/docs/api/java/u%l/concurrent/package-‐ summary.html – h]p://gee.cs.oswego.edu/dl/concurrency-‐interest/index.html • Example (JDK7) – h]ps://github.com/jersey/jersey/tree/master/examples/rx-‐client-‐webapp Example and Libraries