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WHICH RESTFUL WEB SERVICES
FRAMEWORK IS BETTER?

JAX-RS OR SPRING FRAMEWORK

Hien Luu

Agenda
  REST Overview
  Spring Framework & JAX-RS (Jersey)

  Resource Identifier & Implementation

  Resource Representation Support

  Content Negotiation

  Caching Support

  Securing RESTful web services APIs

  RESTful Client Library

  Conclusion

REST Overview

GET /v1/cu
stomers/10
Accept: app 1 HTTP/1.1
lication/xm
Client 1 l

www.you.com
.1
/101 HTTP/1
rs
/v1/c ustome json
Get cation/
cept : appli
Ac
Client 2

Two different resource representations

RESTful Web Services Framework
  Spring Framework
  Supports REST in 3.0
  Extension to the MVC framework

  JAX-RS
  Java API for RESTful Web Services – JSR-311
  Implementations
  Jersey
  RESTEasy – jboss
  Restlet
  Apache CXF

Resource Identifier & Implementation

  Binding resource identifier to resource method
  Root resource, sub-resource

  Instantiation Model

  Request data

  Matrix parameter

  Response, status code

  Exception Handling


GET /customers/101 HTTP/1.1

JAX-RS Spring Framework

@Path @RequestMapping

@Path("/customers") @Controller
public class CustomerResource { @RequestMapping("/customers")
public class CustomerResource {
@GET
@Path("{id}”) @RequestMapping("{id}”,
public Customer getCustomer( method=RequestMethod.GET)
@PathParam("id") int id) {} public Customer getCustomer(
@PathVariable("id") int id) {}

} }


  JAX-RS: Binding URI Regular Expression
@Path("/customers")

@GET
@Path("{id: d+}”)
public Customer getCustomer(
@PathParam("id") int id) {}
}

  Spring Framework: Ant-style expression
@RequestMapping("/customers")

@RequestMapping(“/*/customer/{id}”)
public Customer getCustomer(@PathVariable int id) {
}
}

JAX-RS

@Path("/customers")

@POST
@Consumes("application/xml")
public Response createCustomer(Customer customer) {}

@GET
@Path("{id}")
@Produces("application/xml")
public Customer getCustomer(@PathParam("id") int id) {}

@PUT
@Path("{id}")
public Customer updateCustomer(@PathParam("id") int id,
Customer customer) {}
}

Spring
@Controller

@RequestMapping(method=Request.POST,
headers="Content-Type=application/xml")
public String createCustomer(Customer customer) {}

@RequestMapping(value=“/{id}”, method=Request.GET,
headers=“Accept=application/xml”)
public Customer getCustomer(@PathVariable int id) {}

@RequestMapping(value=“/{id}”, method=Request.PUT,
headers="Content-Type=application/xml")
public Customer updateCustomer(@PathParam("id") int id,
Customer customer) {}

}


  JAX-RS Sub Resource Locator
  Dynamically dispatch requests
  Absent of request method designator: GET, POST, etc.

  Return an object to handle HTTP request

@Path("widgets")
public class SubResourceLocatorResource {

@Path("{region}")
public SubResource dispatcher(@PathParam("region") String region) {
return new SubResource(region);
}
}

  Spring Framework - no sub resource locator


  Instantiation Model
  JAX-RS
  New resource instance per request (default)
  Singleton (up to implementation)

  Spring Framework
  Singleton (default)


Request Data

@QueryParam* @RequestParam*
@FormParam* @RequestParam*
@PathParam* @PathVariable*
@CookieParam* @CookieValue*
@HeaderParam* @RequestHeader*
@MatrixParam* Not supported
@Context
• Can specify default value • Can specify require or not
@DefaultValue • Can specify default value

JAX-RS allows above annotations on fields and setters with per-request scope resource

JAX-RS
@GET
@Path(“/foo/{id}”)
public Response bar(@PathParm(“id”) int id,
@QueryParam(“a”) @DefaultValue(“JavaOne”) String a,
@FormParam(”b”) int b,
@MatrixParam(“m”),
@CookieParam(“token”) String token,
@HeaderParam(“User-Agent”) String userAgent {}

Spring
@RequestMapping(value=“/foo/{id}”, method=Request.GET)
public void bar(@PathVariable int id,
@RequestParam(value=“a”, defaultValue=“JavaOne”) String a,
@RequestParam(”b”, required=false) int b,
@CookieValue(“token”) String token,
@RequestHeader(“User-Agent”) String userAgent {}

  Context information - @Context
  UriInfo – static and dynamic, per-request information
  Application – resources
  HttpHeaders – request header information
  Request - precondition evaluation, representation variant
  SecurityContext – security context of current request
  Providers – look up provider instances

@GET
@Path("/{info: .+}")
public Response getContextInfo(@Context Application app,
@Context UriInfo uriInfo,
@Context HttpHeaders headers,
@Context Request request,
@Context SecurityContext securityContext) {
return Response.ok().build();
}


  HttpServletRequest
  Header

  HttpServletResponse
  Response

  ApplicationContext

@RequestMapping(”/info")
public void getContextInfo(HttpServletRequest request,
HttpServletResponse response) {

//
}


Resource Method Response

void* void*
Response* Any Java type
GenericEntity* ResponseEntity<?>
Any Java type*

*null return status code 204 * Handle response itself


  JAX-RS
  ResponseBuilder, Response, UriBuilder
  Convenient for status code, setting headers

@GET
@Path(“/foo/{id}”)
public Response bar(@PathParm(“id”) int id) {
StringBuffer buf = new StringBuffer();

ResponseBuilder responseBuilder =
Response.ok(buf.toString(), MediaType.TEXT_HTML_TYPE).
location(URI.create("/foo”).
lastModified(new Date());

return responseBuilder.build();
}


  ResponseEntity<?>, HttpHeaders
@ReuestMapping(value=“{id}”, method=RequestMethod=GET)
public ResponseEntity<Customer> bar(@PathVariable int id) {

Customer customer = …;

HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.setLocation(URI.create("/customers/" + id));
responseHeaders.setContentType(MediaType.APPLICATION_XML);

return new ResponseEntity(customer,
responseHeaders, HttpStatus.OK);
}

Exception Handling - JAX-RS
  Resource method
  Canthrow checked or unchecked exception
  WebApplicationException
  Response – use directly if available
  Can specify response code

  Exception mapping interface
  Mapping of an exception to specific Response
@Provider   Total control the response
public class ExceptionMappingProvider implements ExceptionMapper<MyException>{
public Response toResponse(MyException exception) {
return Response.status(Response.Status.FORBIDDEN).
entity(exception.getMessage()).build();
}
}

Exception Handling - JAX-RS
@GET
@Path(“{id}”)
public Customer (@PathParm(“id”) int id) {
Customer customer = getCustomer(id);
if (customer == null) {
throw new WebApplicationException(Response.Status.NOT_FOUND);
} else {
return customer;
}
}

@GET
@Path("/uncheckedException")
public Response uncheckedException() {
throw new MyException("just for fun");
}
@Provider
public class ExMappingProvider implements
ExceptionMapper<MyException> {
public Response toResponse(MyException exc) {
…
}
}

Exception Handling – Spring
  Resource method
  Canthrow checked or unchecked exception
  @ResponseStatus – annotation on exception class
  to control status code
  Exception handler at resource class level (not global)
  Can control status code and returned message
  @ResponseBody
  @ResponseStatus
  Doesn’t support ResponseEntity

  Default is 500 status code

Exception Handling – Spring
@ResponseStatus(value=HttpStatus.FORBIDDEN)
public class ForbiddenException extends RuntimeException {
public ForbiddenException(String msg) {
super(msg);
}
}

@Controller
@RequestMapping("/exceptions")
public class ExceptionResource {

@ResponseStatus(value=HttpStatus.NOT_FOUND)
@ExceptionHandler(ResourceNotFoundException.class)
public @ResponseBody String exceptionHandler1(
ResourceNotFoundException ex1) {
return ex1.getMessage();
}
@RequestMapping("/resourceNotFoundException")
public void resourceNotFoundException() {
throw new ResourceNotFoundException("resource not found");
}
}

Score Card

Scores

Feature JAX-RS Spring
Resource URI 5.0 4.5
Sub resource 5.0 4.0
Request Data 5.0 4.8
Response, status code 5.0 4.5
Exception Handling 5.0 5.0

Resource Representation Support

JAX-RS Spring
erter
Message ageConv
XML BodyRea
der HttpMess XML

erter
Message
BodyWr HttpMessageConv
iter
Java
POJO
der
eB odyRea HttpMe
ssageC
Messag onverte
r
iter HttpMe
JSON
sageB odyWr ssageCo
nverter
JSON
Mes

Out-of-the-box Support

byte[] (*/*) byte[]
String (*/*) String
InputStream (*/*) MultiValueMap
Reader (*/*) Source
File (*/*) Class<T>
Source (*/xml)
JAXBElement (*/xml) Registered by default
MultivalueMap (application/x-www-
form-urlencoded)
StreamingOutput (*/*)
Class<T>

Content Negotiation

GET http://<host>:<port>/customers/1
Accept: application/xml;q=0.8, application/json;q=0.6

HTTP/1.1 200 OK
Content-type: application/xml
<customer id=“1”>….</customer>

HTTP/1.1 200 OK
Content-type: application/json
{“customer” : { “id” : 1 …}}

HTTP/1.1 406 Not Acceptable

JAX-RS
Content-Type: application/xml @PUT
@Path(”id}")
@Consumes(“application/xml”)
@Produces("application/xml”)
public Customer updateCustomer(..) {
..
Accept: application/xml }

Spring

@RequestMapping(value=“{id}”, method=RequetMethod.PUT,
headers="Content-Type=application/xml”)
public ResponseEntity<Customer> updateCustomer(..) {
..
}

JAX-RS
@GET
@Path("{id}")
@Produces({"application/xml", "application/json"})
public Customer getCustomer(@PathParam("id") int id) {
Customer customer = lookUpCustomer(id);
return customer;
}

Spring

@RequestMapping(value = "/{id}", method = RequestMethod.GET,
headers=“Accept=application/xml,application/json”)
public ResponseEntity<Customer> getCustomer(@PathVariable int id) {
return ResponseEntiry<Customer>(customer, HttpStatus.OK);
}

JAX-RS

public interface MessageBodyReader<T> { public interface MessageBodyWriter<T> {
boolean isReadable(Class<?> type, ….);
boolean isWriteable(Class<?> type, …);
T readFrom(Class<?>, …); long getSize(T t, Class<?> type,…);
} void writeTo(T t, Class<?> type,…)
}

@Provider @Provider
public class MyMBR implements public class MyMBW implements
MessageBodyReader<MyCustomerClass> { MessageBodyWriter<MyCustomerClass>
{
… …
} }

Spring

public interface HttpMessageConverter<T> {
boolean canRead(Class<?> clazz, MediaType mediaType);
boolean canWrite(Class<?> clazz, MediaType mediaType);
List<MediaType> getSupportedMediaTypes();
T read(Class<? extends T> clazz, HttpInputMessage inputMessage)
void write(T t, MediaType contentType, HttpOutputMessage outputMessage)
}

public class MyHttpMessageConverter<MyCustomerClass> implements
MessageBodyReader<MyCustomerClass> {

…
}

Spring - Content Negotiation Through URI Pattern

GET http://<host>:<port>/customers/1.xml Request
Resource

GET http://<host>:<port>/customers/1.json

ContentNegotiatingViewResolver

application/json
MappingJacksonJsonView
JSON JSON - application/json
XML - application/xml
application/xml
MarshallingView
XML

Advanced Content Negotiation

GET http://<host>:<port>/customers/1

Accept: application/xml;q=0.8, application/json;q=0.6
Accept-Language: fr;q=1.0, en;p=0.5
Accept-Encoding: gzip, deflate

public class Variant {
public Variant(MediaType mediaType, Locale locale,
String encoding) {
}
}
JAX-RS
public interface Request {
public Variant selectVariant(List<Variant> variants);
……
}

Advanced Content Negotiation
@GET
@Path("{id}”)
public Response getCustomer(@PathParam("id") int id, @Context Request request){

Variant.VariantBuilder vb = Variant.VariantBuilder.newInstance();
vb.mediaTypes(MediaType.APPLICATION_ATOM_XML_TYPE,
MediaType.APPLICATION_XML_TYPE, MediaType.APPLICATION_JSON_TYPE);
vb.languages(Locale.CHINESE, Locale.FRANCE, Locale.ENGLISH);
vb.encodings("deflate", "gzip");
List<Variant> variants = vb.add().build();

Variant matchedVariant = request.selectVariant(variants);
ResponseBuilder responseBuilder = Response.ok(customer);
responseBuilder.type(matchedVariant.getMediaType())
.language(matchedVariant.getLanguage())
.header("Content-Encoding", matchedVariant.getEncoding());

return responseBuilder.build();
}


Scores

Request mapping 5.0 4.9
Resource representation 5.0 5.0
Custom data serialization 5.0 5.0
Content negotiation 5.0 5.0

Caching & Concurrency

Caching & Concurrency Control HTTP Headers

Cache Request Header Response Header
Validation Cache-Control

If-Modified-Since Last-Modified
If-None-Match ETag

If-Unmodified-Since Last-Modified
If-Match Etag
Concurrency
Control

Caching With Date

GET /customers/1
Accept: application/xml
HTTP/1.1 200 OK
Cache-Control: private, no-store, max-age=600
Last-Modified: Sun, 22 August 2010 05:21 GMT

GET /customers/1
If-Modified-Since: Sun, 22 August 2010 05:21 EST

HTTP/1.1 304 Not Modified

Caching With ETag

GET /customers/1
HTTP/1.1 200 OK
Etag: “123456789”

GET /customers/1
If-None-Match: “123456789”

HTTP/1.1 304 Not Modified

Conditional Updates

GET /customers/1
HTTP/1.1 200 OK
Etag: “123456789”

PUT /customers/1
If-None-Match: “123456788”

HTTP/1.1 412 Precondition Failed

JAX-RS

  CacheControl
  Abstraction for Cache-Control header
  EntityTag
  Abstraction for entity tag
  Request
  evaluatePreconditions(EntityTagtag)
  evaluatePreconditions(Date date)

  Return non-null builder

Spring

  Servlet Filter
  ShallowEtagHeaderFilter

  Generate MD5 hash of the response
  Automatically add Etag header

  Detect If-None-Match and take action

  Not flexible


Scores

Caching 5.0 4.5
Concurrency Control 5.0 4.5

Securing RESTful web services APIs
  Authentication
  Basicauthentication – password is in Base64
  Digest authentication – secure MD5 hashes

  Authorization
  Assign roles to users
  API interact with servlet & J2EE
  Setup in web.xml


JAX-RS Annotation Security
@Path("/customers")
@RolesAllowed(“ADMIN”, “CUSTOMER_REP”})

@RolesAllowed(“ADMIN”)
@POST
public Response createCustomer(InputStream is) {}

@PermitALL
@GET
@Path("{id}")
@Produces("application/xml")
public StreamingOutput getCustomer(@PathParam("id") int id) {}

}


JAX-RS Programmatic Security
@Path("/customers")

@POST
public Response createCustomer(Customer customer,
@Context SecurityContext sc) {

System.out.println(“User: “ + sc.getUserPrincipal().getName());
if (!sc.isUserInRole(“ADMIN”)) {
// return 401
}
}
}

Thin wrapper on HTTPServletRequest Security


Spring Programmatic Security

@RequestMapping(method = RequestMethod.POST,
headers="Content-Type=application/xml”)
public ResponseEntity<Customer> createCustomer(Customer customer,
HttpServletRequest request) {

if (!request.isUserInRole(“ADMIN”)) {
// return 401
}
}
}


Scores

Security 5.0 5.0

RESTful Client Library
  Goals
  Make it easy to work with Restful web services
  Work at Java object level

  Jersey Client
  Notpart of JAX-RS
  HTTPURLConnection, HTTPClient
  Work with MessageBodyReader and MessageBodyWriter

  Part of SpringFramework – RestTemplate
  HTTPURLConnection,HTTPClient
  Work with HttpMessageConverter

RESTful Client Library

Scores

RESTful Client Library 0 5.0

Each JAX-RS implementation provides their own
client library

Summary

JAX-RS ~
= Spring

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