API {span}

{toc}
h1. Maven Dependency
{code:xml}
<dependency>
  <groupId>org.apache.cxf</groupId>
  <artifactId>cxf-rt-rs-client</artifactId>
  <version>3.0.0-milestone1<15</version>
</dependency>
{code}

{code:xml}
<dependency>
  <groupId>org.apache.cxf</groupId>
  <artifactId>cxf-rt-transports-http-hc</artifactId>
  <!-- 2.7.8 or 3.0.0-milestone115 --> 
  <version>${cxf.version}</version>
</dependency>
{code}


h1. 

@Path("/bookstore")
public interface BookStore {
   @GET
   Books getAllBooks();
   
   @Path("{id}")
   BookResource getBookSubresource(@PathParam("id") long id) throws NoBookFoundException;
}

public class BookStoreImpl implements BookStore {
   public Books getAllBooks() {}
   
   public BookResource getBookSubresource(long id) throws NoBookFoundException {}
}

public interface BookResource {
   @GET
   Book getBook();
}

public class BookResourceImpl implements BookResource {
   Book getBook() {}
}

BookStore store = JAXRSClientFactory.create("http://bookstore.com", BookStore.class);
// (1) remote GET call to http://bookstore.com/bookstore
Books books = store.getAllBooks();
// (2) no remote call
BookResource subresource = store.getBookSubresource(1);
// {3} remote GET call to http://bookstore.com/bookstore/1
Book b = subresource.getBook();

|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/package-frame.html] provides a short overview of how JAX-RS 2.0 Client API works.

Typically, one starts from [ClientBuilder|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/ClientBuilder.html] in order to create a [Client|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/Client.html]. 
Next [WebTarget|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/WebTarget.html] is created and further customized as needed. 

Next, [Invocation.Builder|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/Invocation.Builder.html] is initialized and the request can be made immediately using one of the [SyncInvoker|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/SyncInvoker.html] methods, with the builder directly implementing SyncInvoker.

{code:java}
Client client = ClientBuilder.newBuilder().newClient();
WebTarget target = client.target("http://localhost:8080/rs");
target = target.path("service").queryParam("a", "avalue");

Invocation.Builder builder = target.request();
Response response = builder.get();
Book book = builder.get(Book.class);

{code}

The above sequence can be easily collapsed into a single code sequence if preferred.
Note that SyncInvoker (and AsyncInvoker) expects [Entity|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/Entity.html] to represent the request body.

Invocation.Builder has a shortcut to [Invocation|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/Invocation.html] via its build(...) methods to further customize the invocation.
  
Invocation.Builder.async() links to AsyncInvoker.

Client and WebTarget are all can be individually configured, the implement [Configurable|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/core/Configurable.html] interface which can accept the providers and properties and return [Configuration|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/core/Configuration.html]. Configuring the Client directly or indirectly via ClientBuilder.withConfig method affects all the WebClients spawned by a given Client. 

h2. JAX-RS 2.0 and CXF specific API

CXF proxy and WebClient client code has been retrofitted to support JAX-RS 2.0 client filters, reader and writer interceptors, new exception classes and Response API.

WebClient offers shortcuts to JAX-RS 2.0 [AsyncInvoker|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/AsyncInvoker.html] and [SyncInvoker|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/SyncInvoker.html] interfaces.

WebClient.getConfig(Object client) supports JAX-RS 2.0 [WebTarget|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/WebTarget.html] and [Invocation.Builder|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/Invocation.Builder.html] for 2.0 clients to be able to get to the lower-level CXF configuration and set up the properties such as 'receiveTimeout', etc.   

h1. Proxy-based API

With the proxy-based API, one can reuse on the client side the interfaces or even the resource classes which have already been designed for processing the HTTP requests on the server side (note that a [cglib|http://cglib.sourceforge.net/]-nodeps dependency will need to be available on the classpath for proxies created from concrete classes). When reused on the client side, they simply act as remote proxies.

[JAXRSClientFactory|http://svn.apache.org/repos/asf/cxf/trunk/rt/frontend/jaxrs/src/main/java/org/apache/cxf/jaxrs/client/JAXRSClientFactory.java] is a utility class which wraps [JAXRSClientFactoryBean|http://svn.apache.org/repos/asf/cxf/trunk/rt/frontend/jaxrs/src/main/java/org/apache/cxf/jaxrs/client/JAXRSClientFactoryBean.java]. JAXRSClientFactory offers a number of utility methods but JAXRSClientFactoryBean can also be used directly if desired.

For example, given these class definitions:

{code:java}
@Path("/bookstore")
public interface BookStore {
   @GET
   Books getAllBooks();
   
   @Path("{id}")
   BookResource getBookSubresource(@PathParam("id") long id) throws NoBookFoundException;
}

public class BookStoreImpl implements BookStore {
   public Books getAllBooks() {}
   
   public Book getBookSubresource(long id) throws NoBookFoundException {}
}

public interface BookResource {
   @GET
   Book getBook();
}

public class BookResourceImpl implements BookResource {
   Book getBook() {}
}

{code}

the following client code retrieves a Book with id '1' and a collection of books: 

{code:java}
BookStore store = JAXRSClientFactory.create("http://bookstore.com", BookStore.class);
// (1) remote GET call to http://bookstore.com/bookstore
Books books = store.getAllBooks();
// (2) no remote call
BookResource subresource = store.getBookSubresource(1);
// {3} remote GET call to http://bookstore.com/bookstore/1
Book b = subresource.getBook();
{code}     

When proxies are created, initially or when subresource methods are invoked, the current URI is updated with corresponding \@Path, \@PathParam, \@QueryParam or @MatrixParam values, while \@HttpHeader and \@CookieParam values contribute to the current set of HTTP headers. Same happens before the remote invocation is done. 

It is important to understand that strictly speaking there is no direct relationship between a given method on the client side and the same one on the server side. The job of the proxy is to construct a correct URI according to given class and method specifications - it may or may not be the same method on the corresponding server class that will be invoked (provided of course that it is a JAX-RS annotated server resource class - but that may not be the case!) More often than not, you will see a method foo() invoked on a server resource class whenever the same method is invoked on the corresponding remote proxy - but in the presence of \@Path annotations with arbitrary regular expressions this is not guaranteed, however this doesn't matter, as the most important thing is that a proxy will produce a correct URI and it will be matched as *expected* by a server class.   

Client-side MessageBodyReaders and MessageBodyWriters are used to process request or response bodies just as they do on the server side. More specifically, method body writers are invoked whenever a remote method parameter is assumed to be a request body (that is, it has no JAX-RS annotations attached) or when a form submission is emulated with the help of either \@FormParams or the JAX-RS MultivaluedMap. 

You can make multiple remote invocations on the same proxy (initial or subresource), the current URI and headers will be updated properly for each call. 

If you would like to proxify concrete classes such as BookStoreImpl for example (say you can not extract interfaces), then drop the cglib-nodeps.jar on a classpath. Such classes must have a default constructor. All methods which have nothing to do with JAX-RS will simply be ignored on the client side and marked as unsupported.

h2. Customizing proxies 

Proxies end up implementing not only the interface requested at proxy creation time but also a [Client|http://svn.apache.org/repos/asf/cxf/trunk/rt/frontend/jaxrs/src/main/java/org/apache/cxf/jaxrs/client/Client.java] interface. In many cases one does not need to explicitly specify commonly used HTTP headers such as Content-Type or Accept as this information will likely be available from \@Consumes or \@Produces annotations. At the same time you may explicitly set either of these headers, or indeed some other header. You can use a simple [WebClient|http://svn.apache.org/repos/asf/cxf/trunk/rt/frontend/jaxrs/src/main/java/org/apache/cxf/jaxrs/client/WebClient.java] utility method for converting a proxy to a base client:

{code:java}
BookStore proxy = JAXRSClientFactory.create("http://books", BookStore.class);
WebClient.client(proxy).accept("text/xml");
// continue using the proxy    
{code}

{code:java}
BookStore proxy = JAXRSClientFactory.create("http://books", BookStore.class);
try {
    proxy.getBook();
} catch(WebApplicationException ex) {
  Response r = ex.getResponse();
  String message = ex.getMessage();
}
{code}

SpringBusFactory bf = new SpringBusFactory();
Bus bus = bf.createBus("org/apache/cxf/systest/jaxrs/security/jaxrs-https.xml");
BusFactory.setDefaultBus(bus);
// BookStore proxy will get the configuration from Spring
BookStore proxy = JAXRSClientFactory.create("http://books", BookStore.class);

<jaxrs:client id="restClient"
    address="http://localhost:${testutil.ports.BookServerRestSoap}/test/services/rest"
    serviceClass="org.apache.cxf.systest.jaxrs.BookStoreJaxrsJaxws"
    inheritHeaders="true">
    <jaxrs:headers>
        <entry key="Accept" value="text/xml"/>
    </jaxrs:headers>
</jaxrs:client>  

BookStore proxy = JAXRSClientFactory.create("http://books", BookStore.class);

Book book = null;
final InvocationCallback<Book> callback = new InvocationCallback<Book>() {
  public void completed(Book response) {
     book = response;
  }
  public void failed(Throwable error) {
  }
};


WebClient.getConfig(proxy).getRequestContext().put(InvocationCallback.class.getName(), callback);
assertNull(proxy.getBook());
Thread.sleep(3);
assertNotNull(book);

BookStore proxy = JAXRSClientFactory.create("http://books", BookStore.class);

// Book
Book book = null;
final InvocationCallback<Book> bookCallback = new InvocationCallback<Book>() {
  public void completed(Book response) {
     book = response;
  }
  public void failed(Throwable error) {
  }
};
// Chapter
Chapter chapter = null;
final InvocationCallback<Chapter> chapterCallback = new InvocationCallback<Chapter>() {
  public void completed(Chapter response) {
     chapter = response;
  }
  public void failed(Throwable error) {
  }
};
 
WebClient.getConfig(proxy).getRequestContext().put(InvocationCallback.class.getName(), 
                            of the invocation will still be available
- the remote invocation has failed for whatever reasons on the client side, example, no MessageBodyWriter is available.

Note org.apache.cxf.jaxrs.client.ClientWebApplicationException is used to represent the client processing exceptions before CXF 2.7.0.

h2. Configuring proxies in Spring

When creating a proxy with JAXRSClientFactory, you can pass a Spring configuration location as one of the arguments. Or you can create a default bus using Spring configuration and all proxies will pick it up:

{code:java}
SpringBusFactory bf = new SpringBusFactory();
Bus bus = bf.createBus("org/apache/cxf/systest/jaxrs/security/jaxrs-https.xml");
BusFactory.setDefaultBus(bus);
// BookStore proxy will get the configuration from Spring
BookStore proxy = JAXRSClientFactory.create("http://books", BookStore.class);
{code} 

h2. Injecting proxies

For injecting proxies via a spring context, use the jaxrs:client element like:
{code:xml}
  <jaxrs:client id="restClient"
         address="http://localhost:${testutil.ports.BookServerRestSoap}/test/services/rest"
         serviceClass="org.apache.cxf.systest.jaxrs.BookStoreJaxrsJaxws"
         inheritHeaders="true">
         <jaxrs:headers>
             <entry key="Accept" value="text/xml"/>
         </jaxrs:headers>
  </jaxrs:client>  
{code}

See this [bean|http://svn.apache.org/repos/asf/cxf/trunk/systests/jaxrs/src/test/resources/jaxrs_soap_rest/WEB-INF/beans.xml] for a full example of how jaxrs:client can be used to inject a proxy 

h2. Limitations

Proxy sub-resource methods returning Objects can not be invoked. Prefer to have sub-resource methods returning typed classes: interfaces, abstract classes or concrete implementations. 

*The following applies to CXF 2.6.x-2.4.x only*:

When a proxy method returning a JAX-RS Response is invoked, the returned Response.getEntity() will return a response InputStream by default. Starting with CXF 2.3.2 one can register an org.apache.cxf.jaxrs.client.ResponseReader provider and cast the Response.getEntity() to more specific application classes:

{code:java}
ResponseReader reader = new ResponseReader();
reader.setEntityClass(Book.class);
        
BookStore bs = JAXRSClientFactory.create("http://localhost:8080/books", BookStore.class,
                        Arrays.asList(bookCallback, chapterCallback));
// Get Book
assertNull(proxy.getBook(123L));
Thread.sleep(3);
assertNotNull(book);
 
// Get             Collections.singletonList(readerBook Chapter
assertNull(proxy.getBookChapter(123L));
Response r1 = bs.getBook("123"Thread.sleep(3);
Book book = (Book)r1.getEntity();

reader.setEntityClass(Author.class);
Response r2 = bs.getBookAuthor("123");
Author book = (Author)r2.getEntity();
{code}

h2. Working with user models

Proxies can be created with the external user model being applied to a proxy class, forassertNotNull(chapter);

 example:

{code:java}
JAXRSClientFactory.createFromModel("http://books", BookNoAnnotations.class, "classpath:/resources/model.xml", null);
{code}

BookNoAnnotations is either an interface or concrete class with no ;

h1. CXF WebClient API

HTTP centric clients are [WebClient|http://svn.apache.org/repos/asf/cxf/trunk/rt/frontend/jaxrs/src/main/java/org/apache/cxf/jaxrs/client/WebClient.java] instances which also implement the [Client|http://svn.apache.org/repos/asf/cxf/trunk/rt/frontend/jaxrs/src/main/java/org/apache/cxf/jaxrs/client/Client.java] interface. In addition to setting various Client request properties, you can also make an explicit HTTP invocation with an HTTP verb being the name of a given operation :

{code:java}
WebClient client = WebClient.create("http://books");
Book book = client.path("bookstore/books").accept("text/xml").get(Book.class);
{code}

{code:java}
WebClient client = WebClient.create("http://books");
client.path("bookstore/books");
client.type("text/xml").accept("text/xml")
Response r = client.post(new Book());
Book b = r.readEntity(Book.class);
{code}

{code:java}
WebClient client = WebClient.create("http://books");
List<Book> books = getBooks(client, 1L, 2L, 3L)

private List<Book> getBooks(WebClient client, Long ...ids) {
   List<Book> books = new ArrayList<Book>(); 
   for (Long id : ids) {
       books.add(client.path(id).get(Book.class));
       client.back(); 
   } 
   return books;
}
{code}

{code:java}
Book book = WebClient.create("http://books").path("{year}/{id}", 2010, 123).get(Book.class);
// as opposed to
// WebClient.create("http://books").path(2010).path(123).get(Book.class);
{code}


When reusing the same WebClient instance for multiple invocations, one may want to reset its state with the help of the reset() method, for example, when the Accept header value needs to be changed and the current URI needs to be reset to the baseURI (as an alternative to a back(true) call). The resetQuery() method may be used to reset the query values only. Both options are available for proxies too.

{anchor:asynchronousinvocations}
h2. Asynchronous invocations

WebClient has several methods accepting JAX-RS 2.0 [InvocationCallback|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/InvocationCallback.html] and returning Future. Alternatively, users can also use WebClient.async() shortcut to work with a standard [AsyncInvoker|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/client/AsyncInvoker.html].

h2. Working with explicit collections

WebClient supports [GenericEntity|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/core/GenericEntity.html] and JAX-RS 2.0 [GenericType|https://jax-rs-spec.java.net/nonav/2.0/apidocs/javax/ws/rs/core/GenericType.html] directly and via JAX-RS 2.0 SyncInvoker and AsyncInvoker to make it easier to work with the explicit collections.

WebClient also has few collection-aware methods, example:

{code:java}

Collection<? extends Book> books = WebClient.getCollection(Book.class);
Collection<? extends Book> books = WebClient.postAndGetCollection(new ArrayList<Book>(), Book.class);

{code}

h2. Handling exceptions


You can handle remote exceptions by either explicitly getting a Response object as shown above and handling error statuses as needed or you can catch either 

 done with proxies. 

h2. Configuring HTTP clients in Spring

Like proxies, HTTP clients can be created using a number of WebClient static utility methods: you can pass a location to a Spring configuration bean if needed or you can set up a default bus as shown above. For example:
{code:xml}
<bean id="myJsonProvider" 
class="org.apache.cxf.jaxrs.provider.JSONProvider" > 
        <property name="supportUnwrapped" value="true" /> 
        <property name="wrapperName" value="nodeName" /> 
    </bean> 

<util:list id="webClientProviders"> 
    <ref bean="myJsonProvider"/> 
</util:list> 

<bean id="myWebClient" class="org.apache.cxf.jaxrs.client.WebClient" 
factory-method="create"> 
        <constructor-arg type="java.lang.String" 
value="http://some.base.url.that.responds/" /> 
        <constructor-arg ref="webClientProviders" /> 
</bean> 
{code} 

{code:xml}
<jaxrs:client id="webClient"
         address="https://localhost:${port}/services/rest"
         serviceClass="org.apache.cxf.jaxrs.client.WebClient">
         <jaxrs:headers>
             <entry key="Accept" value="text/xml"/>
         </jaxrs:headers>
  </jaxrs:client>
{code}

 headers is thread-safe. The only limitation in this case applies to proxies, in that they can not get "out of band" headers without synchronizing, ex :
{code:java}
// get some response headers passed to us 'out of band', which is not thread-safe for a plain proxy: 
String bookHeader = WebClient.toClientclient(injectedBookStoreProxy).getHeaders().getFirst("BookHeader"); 
{code}  

Final option is to use a 

{code:java}
try { 
   webClient.path("bar") 
   webClient.header("bar", baz); 
   webClient.invoke(...); 
} finally { 
   // if using a proxy: WebClient.client(proxy).reset(); 
   webClient.reset(); 
} 
{code}

Book proxy = JAXRSClientFactory.create("http://books", Book.class);
ClientConfiguration config = WebClient.getConfig(proxy);
HTTPConduit conduit1 = (HTTPConduit)config.getConduit();

WebClient webclient = WebClient accessed like this :

{code:java}
Book proxy = JAXRSClientFactory.create("http://books", Book.class);
ClientConfigurationHTTPConduit config = WebClient.getConfig(proxy);
HTTPConduit conduit1 = (HTTPConduit)config.getConduit();

WebClient webclient = WebClient.create("http://books");
HTTPConduit conduit2 = (HTTPConduit)WebClient.getConfig(webclient).getConduit();
{code}


h1. Creating clients programmatically with no Spring dependencies

Example :

{code:java}
conduit2 = (HTTPConduit)WebClient.getConfig(webclient).getConduit();

//http.connection.timeout
//http.receive.timeout
//http.proxy.server.uri
//http.proxy.server.port
Client client = ClientBuilder.newClient();
client.property("http.receive.timeout", 1000000); 

JAXRSClientFactoryBean sf = new JAXRSClientFactoryBean();
sf.setResourceClass(CustomerService.class);
sf.setAddress("http://localhost:9000/");
BindingFactoryManager manager = sf.getBus().getExtension(BindingFactoryManager.class);
JAXRSBindingFactory factory = new JAXRSBindingFactory();
factory.setBus(sf.getBus());
manager.registerBindingFactory(JAXRSBindingFactory.JAXRS_BINDING_ID, factory);
CustomerService service = sf.create(CustomerService.class);
WebClient wc = sf.createWebClient();
{code} 


h1. Configuring an HTTP Conduit from Spring

{code:xml}
<http:conduit name="http://books:9095/bookstore.*"/> 
{code}

{code:xml}
<http:conduit name="*.http-conduit"/> 
{code}

{code:xml}
<http:conduit name="{http://foo.bar}BookService.http-conduit"/> 
{code}

{code:xml}
<http:conduit name="{http://localhost:8080}WebClient.http-conduit"/> 
{code}

In this example, 'http://localhost:8080' is the base service URI.

Please see [jaxrs-https-client1.xml|http://svn.apache.org/repos/asf/cxf/trunk/systests/jaxrs/src/test/java/org/apache/cxf/systest/jaxrs/security/jaxrs-https-client1.xml] and [jaxrs-https-client2.xml|http://svn.apache.org/repos/asf/cxf/trunk/systests/jaxrs/src/test/java/org/apache/cxf/systest/jaxrs/security/jaxrs-https-client2.xml] configuration files for more examples.

Also see [this wiki page|Client HTTP Transport (including SSL support)] on how to configure HTTPConduits.

h1. Clients and Authentication

Proxies and HTTP-centric clients can have the HTTP Authorization header set up explicitly:

{code:java}

// Replace 'user' and 'password' by the actual values
String authorizationHeader = "Basic " 
    + org.apache.cxf.common.util.Base64Utility.encode("user:password".getBytes());

// proxies
WebClient.client(proxy).header("Authorization", authorizationHeader);

// web clients
webClient.header("Authorization", authorizationHeader);

{code}

or by providing a username and password pair at client creation time, for example:
{code:java}
BookStore proxy = JAXRSClientFactory.create("http://books", BookStore.class, "username", "password", "classpath:/config/https.xml");

WebClient client = WebClient.create("http://books", "username", "password", "classpath:/config/https.xml");
{code}

When injecting clients from Spring, one can add 'username' and 'password' values as attributes to jaxrs:client elements or add them to WebClient factory create methods.http-conduit"/> 

// Replace 'user' and 'password' by the actual values
String authorizationHeader = "Basic " 
    + org.apache.cxf.common.util.Base64Utility.encode("user:password".getBytes());

// proxies
WebClient.client(proxy).header("Authorization", authorizationHeader);

// web clients
webClient.header("Authorization", authorizationHeader);

BookStore proxy = JAXRSClientFactory.create("http://books", BookStore.class, "username", "password", "classpath:/config/https.xml");

WebClient client = WebClient.create("http://books", "username", "password", "classpath:/config/https.xml");