Reactive Programming with RxJava for Efficient Data Access Ben Christensen | Software Engineer, Netflix Michael Nitschinger | Software Engineer, Couchbase

RxJava Reactive Extensions for Async Programming

Reactive Extensions for Async Programming RxJava http://github.com/ReactiveX/RxJava http://reactivex.io Single Multiple Sync T getData() Iterable getData() Async Future getData() Observable getData()

Single Multiple Sync T getData() Iterable getData() Async Future getData() Observable getData() Observable.create(subscriber -> { subscriber.onNext("Hello world!"); subscriber.onCompleted(); }).forEach(System.out::println); Synchronous single value

Single Multiple Sync T getData() Iterable getData() Async Future getData() Observable getData() Observable.create(subscriber -> { subscriber.onNext("Hello"); subscriber.onNext("world"); subscriber.onNext("!"); subscriber.onCompleted(); }).forEach(System.out::println); Synchronous multi-value

Single Multiple Sync T getData() Iterable getData() Async Future getData() Observable getData() Observable.create(subscriber -> { try { subscriber.onNext(doSomething()); subscriber.onCompleted(); } catch (Throwable e) { subscriber.onError(e); } }).subscribeOn(Schedulers.io()) .forEach(System.out::println); Asynchronous single value with error handling

Single Multiple Sync T getData() Iterable getData() Async Future getData() Observable getData() Observable.create(subscriber -> { int i = 0; while (!subscriber.isUnsubscribed()) { subscriber.onNext(i++); } }).take(10).forEach(System.out::println); Synchronous multi-value with unsubscribe

Single Multiple Sync T getData() Iterable getData() Async Future getData() Observable getData() Observable.create(subscriber -> { AtomicInteger i = new AtomicInteger(); AtomicLong requested = new AtomicLong(); subscriber.setProducer(r -> { if (requested.getAndAdd(r) == 0) { do { if (subscriber.isUnsubscribed()) { break; } subscriber.onNext(i.incrementAndGet()); } while (requested.decrementAndGet() > 0); } }); }).observeOn(Schedulers.newThread()) .take(10).forEach(System.out::println); Synchronous multi-valued source that thread-hops with “reactive pull” backpressure

Single Multiple Sync T getData() Iterable getData() Async Future getData() Observable getData() Observable.from(iterable) .observeOn(Schedulers.newThread()) .take(10).forEach(System.out::println); Synchronous multi-valued source that thread-hops with “reactive pull” backpressure

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Abstract Concurrency ©2014 Couchbase, Inc. — Proprietary and Confidential 13

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

 Observable  b  =  Observable.flatMap({  T  t  -­‐>            Observable  r  =  ...  transform  t  ...          return  r;    })   flatMap!

 Observable  b  =  Observable.flatMap({  T  t  -­‐>            Observable  r  =  ...  transform  t  ...          return  r;    })   flatMap!

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

       Observable.zip(a,  b,  {  a,  b,  -­‐>                ...  operate  on  values  from  both  a  &  b  ...              return  [a,  b];  //  i.e.  return  tuple          })  

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

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public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

class  VideoService  {        def  VideoList  getPersonalizedListOfMovies(userId);        def  VideoBookmark  getBookmark(userId,  videoId);        def  VideoRating  getRating(userId,  videoId);        def  VideoMetadata  getMetadata(videoId);   }   class  VideoService  {        def  Observable  getPersonalizedListOfMovies(userId);        def  Observable  getBookmark(userId,  videoId);        def  Observable  getRating(userId,  videoId);        def  Observable  getMetadata(videoId);   }   ... create an observable api: instead of a blocking api ...

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); } 1 2 3 4 5 6

public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); } 1 2 3 4 5 6

Non-Opinionated Concurrency ©2014 Couchbase, Inc. — Proprietary and Confidential 37

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public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); }

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public Observable handle(HttpServerRequest request, HttpServerResponse response) { // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }).flatMap(data -> { // output as SSE as we get back the data (no waiting until all is done) return response.writeAndFlush(new ServerSentEvent(SimpleJson.mapToJson(data))); }); } 1 2 3 4 6

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// first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }) Decouples Consumption from Production

// first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }) Decouples Consumption from Production

// first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }) Decouples Consumption from Production

Decouples Consumption from Production

Decouples Consumption from Production // first request User object return new UserCommand(request.getQueryParameters().get("userId")).observe().flatMap(user -> { // then fetch personal catalog Observable> catalog = new PersonalizedCatalogCommand(user).observe() .flatMap(catalogList -> { return catalogList.videos().> flatMap(video -> { Observable bookmark = new BookmarkCommand(video).observe(); Observable rating = new RatingsCommand(video).observe(); Observable metadata = new VideoMetadataCommand(video).observe(); return Observable.zip(bookmark, rating, metadata, (b, r, m) -> { return combineVideoData(video, b, r, m); }); }); }); // and fetch social data in parallel Observable> social = new SocialCommand(user).observe().map(s -> { return s.getDataAsMap(); }); // merge the results return Observable.merge(catalog, social); }) 1 2 3 4 5

class  VideoService  {        def  Observable  getPersonalizedListOfMovies(userId);        def  Observable  getBookmark(userId,  videoId);        def  Observable  getRating(userId,  videoId);        def  Observable  getMetadata(videoId);   }   Clear API Communicates Potential Cost

Implementation Can Differ class  VideoService  {        def  Observable  getPersonalizedListOfMovies(userId);        def  Observable  getBookmark(userId,  videoId);        def  Observable  getRating(userId,  videoId);        def  Observable  getMetadata(videoId);   }   BIO Network Call Local Cache Collapsed Network Call

class  VideoService  {        def  Observable  getPersonalizedListOfMovies(userId);        def  Observable  getBookmark(userId,  videoId);        def  Observable  getRating(userId,  videoId);        def  Observable  getMetadata(videoId);   }   Collapsed Network Call Collapsed Network Call BIO NIO Network Call Local Cache Implementation Can Differ and Change

Retrieval, Transformation, Combination all done in same declarative manner

Couchbase Java Client 2.0 Reactive from top to bottom

Java SDK 2.0 ©2014 Couchbase, Inc. — Proprietary and Confidential 56 It is a complete rewrite compared to 1.* and provides asynchronous & synchronous document oriented APIs.

Couchbase Core IO ©2014 Couchbase, Inc. — Proprietary and Confidential 57 §  Common infrastructure & feature set for all language bindings §  Message oriented §  Asynchronous only §  Low overhead and performance focused §  Supports Java 6+ (including 8!) §  Disruptor RingBuffer for implicit batching and backpressure §  Netty for high performance IO

The Big Picture ©2014 Couchbase, Inc. — Proprietary and Confidential 58

Connecting ©2014 Couchbase, Inc. — Proprietary and Confidential 59

From Sync to Async ©2014 Couchbase, Inc. — Proprietary and Confidential 60

Connecting Async ©2014 Couchbase, Inc. — Proprietary and Confidential 61

Storing a Document ©2014 Couchbase, Inc. — Proprietary and Confidential 62

Loading a Document ©2014 Couchbase, Inc. — Proprietary and Confidential 63

Querying ©2014 Couchbase, Inc. — Proprietary and Confidential 64

Querying ©2014 Couchbase, Inc. — Proprietary and Confidential 65

Stability Patterns

Reacting to Failure ©2014 Couchbase, Inc. — Proprietary and Confidential 67 §  Resiliency is key §  Things will go wrong, so better plan for it §  Do not aim for QA, aim for production §  Do not trust integration points §  Treat the Database (SDK) as an integration point The more you sweat in peace, the less you bleed in war.

Useful Reading ©2014 Couchbase, Inc. — Proprietary and Confidential 68 §  Release It! by Michael T. Nygard §  Stability Patterns & Antipatterns §  Capacity planning §  Operations

Timeouts ©2014 Couchbase, Inc. — Proprietary and Confidential 69 §  The network is unreliable §  Servers fail §  The SDK contains bugs §  Always specify timeouts and deal with them! §  The synchronous wrapper defines them for you all the time.

Timeouts: Simple ©2014 Couchbase, Inc. — Proprietary and Confidential 70

Timeouts: Synchronous API ©2014 Couchbase, Inc. — Proprietary and Confidential 71

Timeouts: Complex Example ©2014 Couchbase, Inc. — Proprietary and Confidential 72

Coordinated Retry ©2014 Couchbase, Inc. — Proprietary and Confidential 73 Fail fast §  Don’t let your system get stuck §  Fail and backpressure Retry §  immediately won’t help §  either linear or exponential backoff necessary §  have a strategy if retry also doesn’t work (Fallbacks!)

Coordinated Retry: Fallback ©2014 Couchbase, Inc. — Proprietary and Confidential 74

Coordinated Retry with Delay ©2014 Couchbase, Inc. — Proprietary and Confidential 75

More Patterns ©2014 Couchbase, Inc. — Proprietary and Confidential 76 Circuit Breaker §  Closed if everything okay §  Opens once the integration point breaks §  Fail fast if open §  Rechecking with half-open Bulkheads §  Isolate failure where possible §  Don’t let your ship sink!

QA Thanks!