Author: buildbot
Date: Thu Feb 11 02:01:13 2021
New Revision: 1071128
Log:
Production update by buildbot for cxf
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websites/production/cxf/content/docs/developing-a-consumer.html
Modified: websites/production/cxf/content/cache/docs.pageCache
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--- websites/production/cxf/content/docs/developing-a-consumer.html (original)
+++ websites/production/cxf/content/docs/developing-a-consumer.html Thu Feb 11
02:01:13 2021
@@ -117,7 +117,7 @@ Apache CXF -- Developing a Consumer
<td height="100%">
<!-- Content -->
<div class="wiki-content">
-<div id="ConfluenceContent"><h1
id="DevelopingaConsumer-DevelopingaConsumerwithCXF">Developing a Consumer with
CXF</h1><h2 id="DevelopingaConsumer-GeneratingtheStubCode">Generating the Stub
Code</h2><p>The starting point for developing a service consumer (or client) in
CXF is a WSDL contract, complete with port type, binding, and service
definitions. You can then use the <a shape="rect"
href="wsdl-to-java.html">wsdl2java</a> utility to generate the Java stub code
from the WSDL contract. The stub code provides the supporting code that is
required to invoke operations on the remote service.<br clear="none"> For CXF
clients, the wsdl2java utility can generate the following kinds of
code:</p><ul><li>Stub code - supporting files for implementing a CXF
client.</li><li>Client starting point code - sample client code that connects
to the remote service and invokes every operation on the remote
service.</li><li>Ant build file - a <code>build.xml</code> file intended for
use with the ant buil
d utility. It has targets for building and for running the sample client
application.</li></ul><h4
id="DevelopingaConsumer-BasicHelloWorldWSDLcontract">Basic HelloWorld WSDL
contract</h4><p>The below shows the HelloWorld WSDL contract. This contract
defines a single port type, <code>Greeter</code>, with a SOAP binding,
<code>Greeter_SOAPBinding</code>, and a service, <code>SOAPService</code>,
which has a single port, <code>SoapPort</code>.</p><p><span
class="confluence-anchor-link"
id="DevelopingaConsumer-Example1"></span></p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeHeader panelHeader pdl"
style="border-bottom-width: 1px;"><b>HelloWorld WSDL Contract</b></div><div
class="codeContent panelContent pdl">
+<div id="ConfluenceContent"><h1
id="DevelopingaConsumer-DevelopingaConsumerwithCXF">Developing a Consumer with
CXF</h1><h2 id="DevelopingaConsumer-GeneratingtheStubCode">Generating the Stub
Code</h2><p>The starting point for developing a service consumer (or client) in
CXF is a WSDL contract, complete with port type, binding, and service
definitions. You can then use the <a shape="rect"
href="wsdl-to-java.html">wsdl2java</a> utility to generate the Java stub code
from the WSDL contract. The stub code provides the supporting code that is
required to invoke operations on the remote service.<br clear="none">For CXF
clients, the wsdl2java utility can generate the following kinds of
code:</p><ul><li>Stub code - supporting files for implementing a CXF
client.</li><li>Client starting point code - sample client code that connects
to the remote service and invokes every operation on the remote
service.</li><li>Ant build file - a <code>build.xml</code> file intended for
use with the ant build
utility. It has targets for building and for running the sample client
application.</li></ul><h4
id="DevelopingaConsumer-BasicHelloWorldWSDLcontract">Basic HelloWorld WSDL
contract</h4><p>The below shows the HelloWorld WSDL contract. This contract
defines a single port type, <code>Greeter</code>, with a SOAP binding,
<code>Greeter_SOAPBinding</code>, and a service, <code>SOAPService</code>,
which has a single port, <code>SoapPort</code>.</p><p><span
class="confluence-anchor-link"
id="DevelopingaConsumer-Example1"></span></p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeHeader panelHeader pdl"
style="border-bottom-width: 1px;"><b>HelloWorld WSDL Contract</b></div><div
class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default"><wsdl:definitions
name="HelloWorld" targetNamespace="http://apache.org/hello_world_soap_http";
xmlns="http://schemas.xmlsoap.org/wsdl/";
xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/";
@@ -285,11 +285,11 @@ Apache CXF -- Developing a Consumer
</pre>
</div></div><p>The <code>Greeter</code> port type defines the following WSDL
operations:</p><ul><li><code>sayHi</code> - has a single output parameter, of
<code>xsd:string</code>.</li><li><code>greetMe</code> - has an input parameter,
of <code>xsd:string</code>, and an output parameter, of
<code>xsd:string</code>.</li><li><code>greetMeOneWay</code> - has a single
input parameter, of <code>xsd:string</code>. Because this operation has no
output parameters, CXF can optimize this call to be a oneway invocation (that
is, the client does not wait for a response from the
server).</li><li><code>pingMe</code> - has no input parameters and no output
parameters, but it can raise a fault exception.</li></ul><p>This WSDL also
defines a binding, <code>Greeter_SOAPBinding</code>, for the SOAP protocol. In
practice, the binding is normally generated automatically - for example, by
running either of the CXF wsdl2soap or wsdl2xml utilities. Likewise, the
<code>SOAPService</code> service can be gener
ated automatically by running the CXF wsdl2service utility.</p><h4
id="DevelopingaConsumer-Generatingthestubcode">Generating the stub
code</h4><p>After defining the WSDL contract, you can generate client code
using the CXF wsdl2java utility. Enter the following command at a command-line
prompt:</p><div class="panel" style="border-width: 1px;"><div
class="panelContent">
<p><code>wsdl2java -ant -client -d <em>ClientDir</em>
hello_world.wsdl</code></p>
-</div></div><p>Where <em>ClientDir</em> is the location of a directory where
you would like to put the generated files and<code> hello_world.wsdl</code> is
a file containing the contract shown in the WSDL above. The <code>-ant</code>
option generates an ant <code>build.xml</code> file, for use with the ant build
utility. The <code>-client</code> option generates starting point code for a
client <code>main()</code> method.</p><p>The preceding wsdl2java command
generates the following Java
packages:</p><ul><li><code>org.apache.hello_world_soap_http</code> <br
clear="none"> This package name is generated from the <code>
+</div></div><p>Where <em>ClientDir</em> is the location of a directory where
you would like to put the generated files and<code> hello_world.wsdl</code> is
a file containing the contract shown in the WSDL above. The <code>-ant</code>
option generates an ant <code>build.xml</code> file, for use with the ant build
utility. The <code>-client</code> option generates starting point code for a
client <code>main()</code> method.</p><p>The preceding wsdl2java command
generates the following Java
packages:</p><ul><li><code>org.apache.hello_world_soap_http</code> <br
clear="none">This package name is generated from the <code>
<span class="nolink">http://apache.org/hello_world_soap_http</span>
- </code> target namespace. All of the WSDL entities defined in this target
namespace (for example, the Greeter port type and the SOAPService service) map
to Java classes in the corresponding Java
package.</li><li><code>org.apache.hello_world_soap_http.types</code> <br
clear="none"> This package name is generated from the <code>
+ </code> target namespace. All of the WSDL entities defined in this target
namespace (for example, the Greeter port type and the SOAPService service) map
to Java classes in the corresponding Java
package.</li><li><code>org.apache.hello_world_soap_http.types</code> <br
clear="none">This package name is generated from the <code>
<span class="nolink">http://apache.org/hello_world_soap_http/types</span>
- </code> target namespace. All of the XML types defined in this target
namespace (that is, everything defined in the <code>wsdl:types</code> element
of the HelloWorld contract) map to Java classes in the corresponding Java
package.</li></ul><p>The stub files generated by the wsdl2java command fall
into the following categories:</p><ul><li>Classes representing WSDL entities
(in the <code>org.apache.hello_world_soap_http</code> package) - the following
classes are generated to represent WSDL entities:<ul><li><code>Greeter</code>
is a Java interface that represents the Greeter WSDL port type. In JAX-WS
terminology, this Java interface is a service endpoint
interface.</li><li><code>SOAPService</code> is a Java class that represents the
SOAPService WSDL <code>service</code> element.</li><li><code>PingMeFault</code>
is a Java exception class (extending <code>java.lang.Exception</code>) that
represents the pingMeFault WSDL <code>fault</code>
element.</li></ul></li><li>Classes representi
ng XML types (in the <code>org.apache.hello_world_soap_http.types</code>
package) - in the HelloWorld example, the only generated types are the various
wrappers for the request and reply messages. Some of these data types are
useful for the asynchronous invocation model.</li></ul><h2
id="DevelopingaConsumer-ImplementingaCXFClient">Implementing a CXF
Client</h2><p>This section describes how to write the code for a simple Java
client, based on the WSDL contract <a shape="rect"
href="developing-a-consumer.html">above</a>. To implement the client, you need
to use the following stub classes:</p><ul><li>Service class (that is,
<code>SOAPService</code>).</li><li>Service endpoint interface (that is,
<code>Greeter</code>).</li></ul><h4
id="DevelopingaConsumer-Generatedserviceclass">Generated service
class</h4><p>The below shows the typical outline for a generated service class,
<code>ServiceName</code>, which extends the <code>javax.xml.ws.Service</code>
base class.</p><p><span class="conflu
ence-anchor-link" id="DevelopingaConsumer-Example2"></span></p><div
class="code panel pdl" style="border-width: 1px;"><div class="codeHeader
panelHeader pdl" style="border-bottom-width: 1px;"><b>Outline of a Generated
Service Class</b></div><div class="codeContent panelContent pdl">
+ </code> target namespace. All of the XML types defined in this target
namespace (that is, everything defined in the <code>wsdl:types</code> element
of the HelloWorld contract) map to Java classes in the corresponding Java
package.</li></ul><p>The stub files generated by the wsdl2java command fall
into the following categories:</p><ul><li>Classes representing WSDL entities
(in the <code>org.apache.hello_world_soap_http</code> package) - the following
classes are generated to represent WSDL entities:<ul><li><code>Greeter</code>
is a Java interface that represents the Greeter WSDL port type. In JAX-WS
terminology, this Java interface is a service endpoint
interface.</li><li><code>SOAPService</code> is a Java class that represents the
SOAPService WSDL <code>service</code> element.</li><li><code>PingMeFault</code>
is a Java exception class (extending <code>java.lang.Exception</code>) that
represents the pingMeFault WSDL <code>fault</code>
element.</li></ul></li><li>Classes representi
ng XML types (in the <code>org.apache.hello_world_soap_http.types</code>
package) - in the HelloWorld example, the only generated types are the various
wrappers for the request and reply messages. Some of these data types are
useful for the asynchronous invocation model.</li></ul><h2
id="DevelopingaConsumer-ImplementingaCXFClient">Implementing a CXF
Client</h2><p>This section describes how to write the code for a simple Java
client, based on the WSDL contract <a shape="rect"
href="https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=84803638";>above</a>.
To implement the client, you need to use the following stub
classes:</p><ul><li>Service class (that is,
<code>SOAPService</code>).</li><li>Service endpoint interface (that is,
<code>Greeter</code>).</li></ul><h4
id="DevelopingaConsumer-Generatedserviceclass">Generated service
class</h4><p>The below shows the typical outline for a generated service class,
<code>ServiceName</code>, which extends the <code>javax.xml.ws.Servi
ce</code> base class.</p><p><span class="confluence-anchor-link"
id="DevelopingaConsumer-Example2"></span></p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeHeader panelHeader pdl"
style="border-bottom-width: 1px;"><b>Outline of a Generated Service
Class</b></div><div class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default">public class
ServiceName extends javax.xml.ws.Service {
...
public ServiceName(URL wsdlLocation, QName serviceName) { }
@@ -304,7 +304,7 @@ Apache CXF -- Developing a Consumer
</pre>
</div></div><p>The <code>ServiceName</code> class defines the following
methods:</p><ul><li>Constructor methods - the following forms of constructor
are defined:<ul><li><code>
<em>ServiceName</em>(URL <em>wsdlLocation</em>, QName
<em>serviceName</em>)</code> constructs a service object based on the data in
the <em>serviceName</em> service in the WSDL contract that is obtainable from
<em>wsdlLocation</em>.</li><li><code>
- <em>ServiceName</em>()</code> is the default constructor, which
constructs a service object based on the service name and WSDL contract that
were provided at the time the stub code was generated (for example, when
running the CXF wsdl2java command). Using this constructor presupposes that the
WSDL contract remains available at its original
location.</li></ul></li><li><code>get_PortName_()</code> methods - for every
<em>PortName</em> port defined on the <em>ServiceName</em> service, CXF
generates a corresponding <code>get_PortName_()</code> method in Java.
Therefore, a <code>wsdl:service</code> element that defines multiple ports will
generate a service class with multiple <code>get_PortName_()</code>
methods.</li></ul><h4 id="DevelopingaConsumer-Serviceendpointinterface">Service
endpoint interface</h4><p>For every port type defined in the original WSDL
contract, you can generate a corresponding service endpoint interface in Java.
A service endpoint interface is the Java ma
pping of a WSDL port type. Each operation defined in the original WSDL port
type maps to a corresponding method in the service endpoint interface. The
operation's parameters are mapped as follows:</p><ol><li>The input parameters
are mapped to method arguments.</li><li>The first output parameter is mapped to
a return value.</li><li>If there is more than one output parameter, the second
and subsequent output parameters map to method arguments (moreover, the values
of these arguments must be passed using Holder types).</li></ol><p>For example,
the below shows the Greeter service endpoint interface, which is generated from
the Greeter port type defined in <a shape="rect"
href="developing-a-consumer.html">#Example1</a>. For simplicity, <a
shape="rect" href="developing-a-consumer.html">#Example3</a> omits the standard
JAXB and JAX-WS annotations.</p><p><span class="confluence-anchor-link"
id="DevelopingaConsumer-Example3"></span></p><div class="code panel pdl"
style="border-width: 1px;"><
div class="codeHeader panelHeader pdl" style="border-bottom-width:
1px;"><b>The Greeter Service Endpoint Interface</b></div><div
class="codeContent panelContent pdl">
+ <em>ServiceName</em>()</code> is the default constructor, which
constructs a service object based on the service name and WSDL contract that
were provided at the time the stub code was generated (for example, when
running the CXF wsdl2java command). Using this constructor presupposes that the
WSDL contract remains available at its original
location.</li></ul></li><li><code>get_PortName_()</code> methods - for every
<em>PortName</em> port defined on the <em>ServiceName</em> service, CXF
generates a corresponding <code>get_PortName_()</code> method in Java.
Therefore, a <code>wsdl:service</code> element that defines multiple ports will
generate a service class with multiple <code>get_PortName_()</code>
methods.</li></ul><h4 id="DevelopingaConsumer-Serviceendpointinterface">Service
endpoint interface</h4><p>For every port type defined in the original WSDL
contract, you can generate a corresponding service endpoint interface in Java.
A service endpoint interface is the Java ma
pping of a WSDL port type. Each operation defined in the original WSDL port
type maps to a corresponding method in the service endpoint interface. The
operation's parameters are mapped as follows:</p><ol><li>The input parameters
are mapped to method arguments.</li><li>The first output parameter is mapped to
a return value.</li><li>If there is more than one output parameter, the second
and subsequent output parameters map to method arguments (moreover, the values
of these arguments must be passed using Holder types).</li></ol><p>For example,
the below shows the Greeter service endpoint interface, which is generated from
the Greeter port type defined in <a shape="rect"
href="https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=84803638";>#Example1</a>.
For simplicity, <a shape="rect"
href="https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=84803638";>#Example3</a>
omits the standard JAXB and JAX-WS annotations.</p><p><span
class="confluence-anchor-link" id="Dev
elopingaConsumer-Example3"></span></p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeHeader panelHeader pdl"
style="border-bottom-width: 1px;"><b>The Greeter Service Endpoint
Interface</b></div><div class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default">/* Generated by
WSDLToJava Compiler. */
package org.objectweb.hello_world_soap_http;
@@ -403,7 +403,7 @@ java.util.Map<String, Object> resp
((javax.xml.ws.BindingProvider)port).getResponseContext();
PropertyType propValue = (PropertyType)
responseContext.get(ContextPropertyName);
</pre>
-</div></div><p>The response context is of type, <code>java.util.Map<String,
Object></code>, which is a hash map that has keys of type
<code>String</code> and values of an arbitrary type. Use
<code>java.util.Map.get()</code> to access an entry in the hash map of response
context properties.</p><h4 id="DevelopingaConsumer-Supportedcontexts">Supported
contexts</h4><p>CXF supports the following context properties:</p><div
class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1"
rowspan="1" class="confluenceTh"><p>Context Property Name</p></th><th
colspan="1" rowspan="1" class="confluenceTh"><p>Context Property
Type</p></th></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>org.apache.cxf.ws.addressing.JAXWSAConstants.CLIENT_ADDRESSING_PROPERTIES</code></p></td><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>org.apache.cxf.ws.addressing.AddressingProperties</code></p></td></tr></tbody></table></div><h2
id="DevelopingaConsumer-Asynchrono
usInvocationModel">Asynchronous Invocation Model</h2><p>In addition to the
usual synchronous mode of invocation, CXF also supports two forms of
asynchronous invocation, as follows:</p><ul><li><strong>Polling
approach</strong> - in this case, to invoke the remote operation, you call a
special method that has no output parameters, but returns a
<code>javax.xml.ws.Response</code> instance. The <code>Response</code> object
(which inherits from the <code>javax.util.concurrency.Future</code> interface)
can be polled to check whether or not a response message has
arrived.</li><li><strong>Callback approach</strong> - in this case, to invoke
the remote operation, you call another special method that takes a reference to
a callback object (of <code>javax.xml.ws.AsyncHandler</code> type) as one of
its parameters. Whenever the response message arrives at the client, the CXF
runtime calls back on the <code>AsyncHandler</code> object to give it the
contents of the response message.</li></ul><p>Bo
th of these asynchronous invocation approaches are described here and
illustrated by code examples.</p><h4
id="DevelopingaConsumer-Contractforasynchronousexample">Contract for
asynchronous example</h4><p>The following example shows the WSDL contract that
is used for the asynchronous example. The contract defines a single port type,
<code>GreeterAsync</code>, which contains a single operation,
<code>greetMeSometime</code>.</p><p><span class="confluence-anchor-link"
id="DevelopingaConsumer-Example6"></span></p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeHeader panelHeader pdl"
style="border-bottom-width: 1px;"><b>HelloWorld WSDL Contract for Asynchronous
Example</b></div><div class="codeContent panelContent pdl">
+</div></div><p>The response context is of type, <code>java.util.Map<String,
Object></code>, which is a hash map that has keys of type
<code>String</code> and values of an arbitrary type. Use
<code>java.util.Map.get()</code> to access an entry in the hash map of response
context properties.</p><h4 id="DevelopingaConsumer-Supportedcontexts">Supported
contexts</h4><p>CXF supports the following context properties:</p><div
class="table-wrap"><table class="wrapped confluenceTable"><tbody><tr><th
colspan="1" rowspan="1" class="confluenceTh"><p>Context Property
Name</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Context
Property Type</p></th></tr><tr><td colspan="1" rowspan="1"
class="confluenceTd"><p><code>org.apache.cxf.ws.addressing.JAXWSAConstants.CLIENT_ADDRESSING_PROPERTIES</code></p></td><td
colspan="1" rowspan="1"
class="confluenceTd"><p><code>org.apache.cxf.ws.addressing.AddressingProperties</code></p></td></tr></tbody></table></div><h2
id="DevelopingaConsumer-As
ynchronousInvocationModel">Asynchronous Invocation Model</h2><p>In addition to
the usual synchronous mode of invocation, CXF also supports two forms of
asynchronous invocation, as follows:</p><ul><li><strong>Polling
approach</strong> - in this case, to invoke the remote operation, you call a
special method that has no output parameters, but returns a
<code>javax.xml.ws.Response</code> instance. The <code>Response</code> object
(which inherits from the <code>javax.util.concurrency.Future</code> interface)
can be polled to check whether or not a response message has
arrived.</li><li><strong>Callback approach</strong> - in this case, to invoke
the remote operation, you call another special method that takes a reference to
a callback object (of <code>javax.xml.ws.AsyncHandler</code> type) as one of
its parameters. Whenever the response message arrives at the client, the CXF
runtime calls back on the <code>AsyncHandler</code> object to give it the
contents of the response message.</li></
ul><p>Both of these asynchronous invocation approaches are described here and
illustrated by code examples.</p><h4
id="DevelopingaConsumer-Contractforasynchronousexample">Contract for
asynchronous example</h4><p>The following example shows the WSDL contract that
is used for the asynchronous example. The contract defines a single port type,
<code>GreeterAsync</code>, which contains a single operation,
<code>greetMeSometime</code>.</p><p><span class="confluence-anchor-link"
id="DevelopingaConsumer-Example6"></span></p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeHeader panelHeader pdl"
style="border-bottom-width: 1px;"><b>HelloWorld WSDL Contract for Asynchronous
Example</b></div><div class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default"><wsdl:definitions
xmlns="http://schemas.xmlsoap.org/wsdl/";
xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/";
xmlns:tns="http://apache.org/hello_world_async_soap_http";
@@ -537,7 +537,7 @@ public final class Client {
}
}
</pre>
-</div></div><p>The <code>greetMeSometimeAsync()</code> method invokes the
<code>greetMeSometimes</code> operation, transmitting the input parameters to
the remote service and returning a reference to a
<code>javax.xml.ws.Response<GreetMeSometimeResponse></code> object. The
<code>Response</code> class is defined by extending the standard
<code>java.util.concurrency.Future<T></code> interface, which is
specifically designed for polling the outcome of work performed by a concurrent
thread. There are essentially two basic approaches to polling using the
<code>Response</code> object:</p><ul><li><p><strong>Non-blocking
polling</strong> - before attempting to get the result, check whether the
response has arrived by calling the non-blocking<br clear="none">
<code>Response<T>.isDone()</code> method. For example:</p><div
class="code panel pdl" style="border-width: 1px;"><div class="codeContent
panelContent pdl">
+</div></div><p>The <code>greetMeSometimeAsync()</code> method invokes the
<code>greetMeSometimes</code> operation, transmitting the input parameters to
the remote service and returning a reference to a
<code>javax.xml.ws.Response<GreetMeSometimeResponse></code> object. The
<code>Response</code> class is defined by extending the standard
<code>java.util.concurrency.Future<T></code> interface, which is
specifically designed for polling the outcome of work performed by a concurrent
thread. There are essentially two basic approaches to polling using the
<code>Response</code> object:</p><ul><li><p><strong>Non-blocking
polling</strong> - before attempting to get the result, check whether the
response has arrived by calling the non-blocking<br
clear="none"><code>Response<T>.isDone()</code> method. For
example:</p><div class="code panel pdl" style="border-width: 1px;"><div
class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme:
Default">Response<GreetMeSometimeResponse> greetMeSomeTimeResp = ...;
if (greetMeSomeTimeResp.isDone()) {
@@ -584,7 +584,7 @@ public class TestAsyncHandler implements
}
}
</pre>
-</div></div><p>The implementation of <code>handleResponse()</code> shown in <a
shape="rect" href="developing-a-consumer.html">#Example11</a> simply gets the
response data and stores it in a member variable, <code>reply</code>. The extra
<code>getResponse()</code> method is just a convenience method that extracts
the sole output parameter (that is, <code>responseType</code>) from the
response.</p><p><a shape="rect"
href="developing-a-consumer.html">#Example12</a> illustrates the callback
approach to making an asynchronous operation call. Using this approach, the
client invokes the operation by calling the special Java method,
<code>_OperationName_Async()</code>, that returns a
<code>java.util.concurrency.Future<?></code> object and takes an extra
parameter of <code>AsyncHandler<T></code>.</p><p><span
class="confluence-anchor-link"
id="DevelopingaConsumer-Example12"></span></p><div class="code panel pdl"
style="border-width: 1px;"><div class="codeHeader panelHeader pdl" st
yle="border-bottom-width: 1px;"><b>Callback Approach for an Asynchronous
Operation Call</b></div><div class="codeContent panelContent pdl">
+</div></div><p>The implementation of <code>handleResponse()</code> shown in <a
shape="rect"
href="https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=84803638";>#Example11</a>
simply gets the response data and stores it in a member variable,
<code>reply</code>. The extra <code>getResponse()</code> method is just a
convenience method that extracts the sole output parameter (that is,
<code>responseType</code>) from the response.</p><p><a shape="rect"
href="https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=84803638";>#Example12</a>
illustrates the callback approach to making an asynchronous operation call.
Using this approach, the client invokes the operation by calling the special
Java method, <code>_OperationName_Async()</code>, that returns a
<code>java.util.concurrency.Future<?></code> object and takes an extra
parameter of <code>AsyncHandler<T></code>.</p><p><span
class="confluence-anchor-link" id="DevelopingaConsumer-Example12"></span></p><di
v class="code panel pdl" style="border-width: 1px;"><div class="codeHeader
panelHeader pdl" style="border-bottom-width: 1px;"><b>Callback Approach for an
Asynchronous Operation Call</b></div><div class="codeContent panelContent pdl">
<pre class="brush: java; gutter: false; theme: Default">package demo.hw.client;
import java.io.File;
@@ -618,7 +618,7 @@ public final class Client {
}
}
</pre>
-</div></div><p>The <code>Future<?></code> object returned by
<code>greetMeSometimeAsync()</code> can be used only to test whether or not a
response has arrived yet - for example, by calling
<code>response.isDone()</code>. The value of the response is only made
available to the callback object, <code>testAsyncHandler</code>.</p></div>
+</div></div><p>The <code>Future<?></code> object returned by
<code>greetMeSometimeAsync()</code> can be used only to test whether or not a
response has arrived yet - for example, by calling
<code>response.isDone()</code>. The value of the response is only made
available to the callback object, <code>testAsyncHandler</code>.</p><div
class="confluence-information-macro confluence-information-macro-warning"><span
class="aui-icon aui-icon-small aui-iconfont-error
confluence-information-macro-icon"></span><div
class="confluence-information-macro-body"><p>Please be careful when using
asynchronous consumers along with reactive / non-blocking libraries. There is
certain amount of intialization code (usually, on the first asynchronous
invocation) which may cause unnecessary blocking.</p></div></div></div>
</div>
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