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1 Copyright © 2012, Oracle and/or its affiliates. All rights reserved. JAX-RS 2.0: RESTful Java on Steroids Arun Gupta, Java EE & GlassFish Guy http://blogs.oracle.com/arungupta , @arungupta

JAX-RS 2.0: RESTful Web Services

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Page 1: JAX-RS 2.0: RESTful Web Services

1 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

JAX-RS 2.0: RESTful Java on Steroids Arun Gupta, Java EE & GlassFish Guy http://blogs.oracle.com/arungupta, @arungupta

Page 2: JAX-RS 2.0: RESTful Web Services

2 Copyright © 2012, Oracle and/or its affiliates. All rights reserved. 2 Copyright © 2011, Oracle and/or its affiliates. All rights reserved.

The following is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.

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3 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Part I: How we got here ?

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4 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

How We Got Here? •  Shortest intro to JAX-RS 1.0 •  Requested features for JAX-RS 2.0 •  JSR 339: JAX-RS 2.0

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5 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

JAX-RS Origins

•  JAX-RS 1.0 is Java API for RESTful WS •  RESTFul Principles: –  Assign everything an ID –  Link things together –  Use common set of methods –  Allow multiple representations –  Stateless communications

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6 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

JAX-RS 1.0 Goals

•  POJO-Based API •  HTTP Centric •  Format Independence •  Container Independence •  Inclusion in Java EE

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7 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: JAX-RS API

@Path("/atm/{cardId}")public class AtmService { @GET @Path("/balance") @Produces("text/plain") public String balance(@PathParam("cardId") String card, @QueryParam("pin") String pin) { return Double.toString(getBalance(card, pin)); } …

Built-in Serialization

Resources

URI Parameter Injection

HTTP Method Binding

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Example: JAX-RS API (contd.) … @POST @Path("/withdrawal") @Consumes("text/plain") @Produces("application/json") public Money withdraw(@PathParam("card") String card, @QueryParam("pin") String pin, String amount){ return getMoney(card, pin, amount); }}

Custom Serialization

Param Binding

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9 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: JAX-RS API (contd.)

Param Binding

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10 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: JAX-RS API (contd.)

Param Binding

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11 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Requested Features

•  Client API •  Client-side and Server-side Asynchronous •  Filters and Interceptors •  Improved Connection Negotiation •  Validation •  Hypermedia •  Alignment with JSR 330 •  Model-View-Controller

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12 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

JSR 339 Expert Group

•  EG Formed in March 2011 •  Oracle Leads: Marek Potociar / Santiago Pericas-G. •  Expert Group: –  Jan Algermissen, Florent Benoit, Sergey Beryozkin (Talend),

Adam Bien, Bill Burke (RedHat), Clinton Combs, Bill De Hora, Markus Karg, Sastry Malladi (Ebay), Julian Reschke, Guilherme Silveira, Dionysios Synodinos

•  Early Draft 3 published on Jun 7, 2012!

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13 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Part II: Where We Are Going

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14 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

In-Scope Features

•  Client API •  Filters and Interceptors •  Client-side and Server-side Asynchronous •  Improved Connection Negotiation •  Validation •  Hypermedia •  Alignment with JSR 330 •  Model-View-Controller

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15 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

New in JAX-RS 2.0

•  Client API •  Filters and Interceptors •  Client-side and Server-side Asynchronous •  Improved Connection Negotiation •  Validation •  Hypermedia •  Alignment with JSR 330

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16 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Client API - Motivation

•  HTTP client libraries too low level •  Sharing features with JAX-RS server API •  E.g., MBRs and MBWs

•  Supported by some JAX-RS 1.0 implementations •  Need for a standard

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17 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Client API – Old and New

• Client-side API URL url = new URL("http://.../atm/balance"); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET"); conn.setDoInput(true); conn.setDoOutput(false);             BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream())); String line; while ((line = br.readLine()) != null) {     out.println(line); }#

Client client = ClientFactory.newClient();#String balance = client.target("http://.../atm/balance")# .request()# .get(String.class);#

Old

New

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18 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Client API

// Get instance of ClientClient client = ClientFactory.newClient();Can also inject @URI for the target ß// Get account balanceString bal = client.target("http://.../atm/balance") .pathParam("card", "111122223333") .queryParam("pin", "9876") .request().get(String.class);

Param Binding

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19 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Client API (contd.)

// Withdraw some moneyMoney mon = client.target("http://.../atm/withdraw") .pathParam("card", "111122223333") .queryParam("pin", "9876") .request("application/json") .post(text("50.0"), Money.class);

Param Binding

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20 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Generic Interface (Command pattern, Batch processing) Invocation inv1 = client.target("http://.../atm/balance")… .request().buildGet();Invocation inv2 = client.target("http://.../atm/withdraw")… .request() .buildPost(text("50.0"));

Param Binding

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21 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Generic Interface (contd.) Collection<Invocation> invs = Arrays.asList(inv1, inv2);Collection<Response> ress = Collections.transform(invs, new F<Invocation, Response>() { public Response apply(Invocation inv) { return inv.invoke(); } });

Param Binding

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22 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

New in JAX-RS 2.0

•  Client API •  Filters and Interceptors •  Client-side and Server-side Asynchronous •  Improved Connection Negotiation •  Validation •  Hypermedia •  Alignment with JSR 330

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23 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Filters & Interceptors – Motivation

•  Customize JAX-RS implementations via well-defined extension points

•  Use Cases: Logging, Compression, Security, Etc. •  Shared by client and server APIs •  Supported by most JAX-RS 1.0 implementations •  All using slightly different types or semantics

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24 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Filters

•  Non-wrapping extension points •  Pre: Interface RequestFilter•  Post: Interface ResponseFilter

•  Part of a filter chain •  Do not call the next filter directly •  Each filter decides to proceed or break chain •  By returning FilterAction.NEXT or FilterAction.STOP

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25 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Filter Example: LoggingFilter @Providerclass LoggingFilter implements RequestFilter, ResponseFilter { @Override public FilterAction preFilter(FilterContext ctx) throws IOException { logRequest(ctx.getRequest()); return FilterAction.NEXT; } …

Param Binding

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26 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Filter Example: LoggingFilter (contd.)

@Override public FilterAction postFilter(FilterContext ctx) throws IOException { logResponse(ctx.getResponse()); return FilterAction.NEXT; } }

Param Binding

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27 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Interceptors

•  Wrapping extension points •  ReadFrom: Interface ReaderInterceptor•  WriteTo: Interface WriterInterceptor

•  Part of an interceptor chain •  Call the next handler directly •  Each handler decides to proceed or break chain •  By calling ctx.proceed()

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28 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Handler Example: GzipInterceptor!@Providerclass GzipInterceptor implements ReaderInterceptor, WriterInterceptor { @Override public Object aroundReadFrom(ReadInterceptorContext ctx) throws IOException { if (gzipEncoded(ctx)) { InputStream old = ctx.getInputStream(); ctx.setInputStream(new GZIPInputStream(old)); } return ctx.proceed(); } … }

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29 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Client

Order of Execution

Request Filter

WriteTo Handler

ReadFrom Handler

Response Filter

Server

Request Filter

ReadFrom Handler

WriteTo Handler

Response Filter

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30 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Binding Example: LoggingFilter!@NameBinding // or @Qualifier ?@Target({ElementType.TYPE, ElementType.METHOD})@Retention(value = RetentionPolicy.RUNTIME)public @interface Logged {}@Provider@Loggedpublic class LoggingFilter implements RequestFilter, ResponseFilter { … }

Param Binding

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Binding Example: LoggingFilter!

@Path("/")public class MyResourceClass { @Logged @GET @Produces("text/plain") @Path("{name}") public String hello(@PathParam("name") String name) { return "Hello " + name; }}

Param Binding

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32 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

New in JAX-RS 2.0

•  Client API •  Filters and Interceptors •  Client-side and Server-side Asynchronous •  Improved Connection Negotiation •  Validation •  Hypermedia •  Alignment with JSR 330

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33 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Asynchronous – Motivation

•  Let “borrowed” threads run free! •  Container environment

•  Suspend and resume connections •  Suspend while waiting for an event •  Resume when event arrives

•  Leverage Servlet 3.X async support (if available) •  Client API support •  Future<RESPONSE>, InvocationCallback<RESPONSE>

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34 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Suspend and Resume @Path("/async/longRunning")public class MyResource { @Context private ExecutionContext ctx; @GET @Produces("text/plain") public void longRunningOp() { Executors.newSingleThreadExecutor().submit( new Runnable() { public void run() { Thread.sleep(10000); // Sleep 10 secs ctx.resume("Hello async world!"); } }); ctx.suspend(); // Suspend connection and return } … }

Param Binding

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35 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: @Suspend Annotation @Path("/async/longRunning")public class MyResource { @Context private ExecutionContext ctx; @GET @Produces("text/plain") @Suspend public void longRunning() { Executors.newSingleThreadExecutor().submit( new Runnable() { public void run() { Thread.sleep(10000); // Sleep 10 secs ctx.resume("Hello async world!"); } }); // ctx.suspend(); Suspend connection and return } … }

Param Binding

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36 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Client API Async Support // Build target URITarget target = client.target("http://.../atm/balance")… // Start async call and register callbackFuture<?> handle = target.request().async().get( new InvocationCallback<String>() { public void complete(String balance) { … } public void failed(InvocationException e) { … } }); // After waiting for a while …If (!handle.isDone()) handle.cancel(true);

Param Binding

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37 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

New in JAX-RS 2.0

•  Client API •  Filters and Interceptors •  Client-side and Server-side Asynchronous •  Improved Connection Negotiation •  Validation •  Hypermedia •  Alignment with JSR 330

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38 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Improved Connection Negotiation

GET http://.../widgets2Accept: text/*; q=1…Path("widgets2")public class WidgetsResource2 { @GET @Produces("text/plain", "text/html") public Widgets getWidget() {...}}

Param Binding

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39 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Improved Conneg (contd.)

GET http://.../widgets2Accept: text/*; q=1…Path("widgets2")public class WidgetsResource2 { @GET @Produces("text/plain;qs=0.5", "text/html;qs=0.75") public Widgets getWidget() {...}}

Param Binding

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40 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

New in JAX-RS 2.0

•  Client API •  Filters and Interceptors •  Client-side and Server-side Asynchronous •  Improved Connection Negotiation •  Validation •  Hypermedia •  Alignment with JSR 330

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41 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Validation – Motivation

•  Services must validate data •  Bean Validation already provides the mechanism •  Integration into JAX-RS

•  Support for constraint annotations in: •  Fields and properties •  Parameters (including request entity) •  Methods (response entities) •  Resource classes

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42 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Constraint Annotations

@Path("/")class MyResourceClass { @POST @Consumes(MediaType.APPLICATION_FORM_URLENCODED) public void registerUser( @NotNull @FormParam("firstName") String fn, @NotNull @FormParam("lastName") String ln, @Email @FormParam("email") String em) { ... } }

Param Binding

Custom

Built-in

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Example: User defined Constraints @Target({ METHOD, FIELD, PARAMETER })@Retention(RUNTIME)@Constraint(validatedBy = EmailValidator.class)public @interface Email { ... }class EmailValidator implements ConstraintValidator<Email, String> { public void initialize(Email email) { … } public boolean isValid(String value, ConstraintValidatorContext context) { // Check 'value' is e-mail address … } }

Param Binding

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44 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Request Entity Validation @CheckUser1class User { ... }@Path("/")class MyResourceClass { @POST @Consumes("application/xml") public void registerUser1(@Valid User u) { … } @POST @Consumes("application/json") public void registerUser12(@CheckUser2 @Valid User u) { … } }

Param Binding

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45 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

New in JAX-RS 2.0

•  Client API •  Filters and Interceptors •  Client-side and Server-side Asynchronous •  Improved Connection Negotiation •  Validation •  Hypermedia •  Alignment with JSR 330

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46 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Motivation

•  REST principles •  Identifiers and Links •  HATEOAS (Hypermedia As The Engine Of App State)

•  Link types: •  Structural Links •  Transitional Links

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47 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Structural vs. Transitional Links

Link: <http://.../orders/1/ship>; rel=ship, <http://.../orders/1/cancel>; rel=cancel...<order id="1"> <customer>http://.../customers/11</customer> <address>http://.../customers/11/address/1</customer> <items> <item> <product>http://.../products/111</products> <quantity>2</quantity> </item> ... </order>

Param Binding

Transitional

Structural

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48 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Example: Using Transitional Links // Server APIResponse res = Response.ok(order) .link("http://.../orders/1/ship", "ship") .build(); // Client APIResponse order = client.target(…) .request("application/xml").get();if (order.getLink(“ship”) != null) { Response shippedOrder = client .target(order.getLink("ship")) .request("application/xml").post(null); … }

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49 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

Other Topics Under Consideration •  Better integration with JSR 330 •  Support @Inject and qualifiers

•  High-level client API?

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50 Copyright © 2012, Oracle and/or its affiliates. All rights reserved.

More Information

•  JSR: http://jcp.org/en/jsr/detail?id=339 •  Java.net: http://jax-rs-spec.java.net •  User Alias: [email protected] •  All EG discussions forwarded to this list

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Q&A