src/site/xdoc/docs/rest-ws.xml - axis-axis2-java-core - Git at Google

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 <html>
 <head>
   <meta http-equiv="content-type" content=""/>
   <title>RESTful Web Services Support</title>
 </head>

 <body lang="en">
 <h1>RESTful Web Services Support</h1>

 <p>This document presents an introduction on REST and REST with HTTP POST and
 GET.</p>

 <h2>Content</h2>
 <ul>
   <li><a href="#intro">Introduction</a></li>
   <li><a href="#rest_with_post">Doing REST Web Services with HTTP POST</a>
     <ul>
       <li><a href="#sample">Sample REST - HTTP POST Client</a></li>
     </ul>
   </li>
   <li><a href="#rest_with_get">Access a REST Web Service via HTTP GET</a></li>
 </ul>
 <a name="intro"></a>

 <h2>Introduction</h2>

 <p>WSDL 2.0 HTTP Binding defines a way to implement REST (Representational
 State Transfer) with Web services. Axis2 implements the most defined HTTP
 binding specification. REST Web services are a reduced subset of the usual
 Web service stack.</p>

 <p>The Axis2 REST implementation assumes the following properties:</p>
 <ol>
   <li>REST Web services are Synchronous and Request Response in nature.</li>
   <li>When REST Web services are accessed via GET, the service and the
     operations are identified based on the URL. The parameters are assumed as
     parameters of the Web service. In this case, the GET based REST Web
     services support only simple types as arguments and it should adhere to
     the <a
     href="http://www.w3.org/TR/2006/CR-wsdl20-adjuncts-20060327/#_operation_iri_style">IRI
     style</a>.</li>
   <li>POST based Web services do not need a SOAP Envelope or a SOAP Body.
     REST Web Services do not have Headers and the payload is sent
   directly.</li>
 </ol>

 <p>Axis2 can be configured as a REST Container and can be used to send and
 receive RESTful Web service requests and responses. REST Web services can be
 accessed using HTTP GET and POST.</p>
 <a name="rest_with_post"></a>

 <h2>REST Web Services with HTTP POST</h2>

 <p>If REST is enabled, the Axis2 server will act as both a REST endpoint and
 a SOAP endpoint. When a message is received, if the content type is text/xml
 and if the SOAPAction Header is missing, then the message is treated as a
 RESTful Message, if not it is treated as a usual SOAP Message.</p>

 <p>On sending a message, whether the message is RESTful or not, can be
 decided from the client API.<br/>
 Set a property in the client API.<br/>
 </p>
 <pre>...
 Options options = new Options();
 options.setProperty(Constants.Configuration.ENABLE_REST, Constants.VALUE_TRUE);
 ...</pre>
 <a name="sample"></a>

 <h3>Sample REST - HTTP POST Client</h3>

 <p>There is an example named, userguide.clients.RESTClient.java found in
 AXIS2_HOME/samples/userguide/src/userguide/clients which demonstrates the
 usage of the above. It uses the "echo" operation of the
 <code>userguide.example1.MyService </code>of the
 AXIS2_HOME/samples/userguide/src/userguide/example1.</p>

 <p>The class source will be as follows:</p>
 <pre>public class RESTClient {

     private static String toEpr = "http://localhost:8080/axis2/services/MyService";

     public static void main(String[] args) throws AxisFault {

         Options options = new Options();
         options.setTo(new EndpointReference(toEpr));
         options.setTransportInProtocol(Constants.TRANSPORT_HTTP);

         options.setProperty(Constants.Configuration.ENABLE_REST, Constants.VALUE_TRUE);

         ServiceClient sender = new ServiceClient();
         sender.engageModule(Constants.MODULE_ADDRESSING);
         sender.setOptions(options);
         OMElement result = sender.sendReceive(getPayload());

         try {
             XMLStreamWriter writer = XMLOutputFactory.newInstance()
                     .createXMLStreamWriter(System.out);
             result.serialize(writer);
             writer.flush();
         } catch (XMLStreamException e) {
             e.printStackTrace();
         } catch (FactoryConfigurationError e) {
             e.printStackTrace();
         }
     }

     private static OMElement getPayload() {
         OMFactory fac = OMAbstractFactory.getOMFactory();
         OMNamespace omNs = fac.createOMNamespace(
                 "http://example1.org/example1", "example1");
         OMElement method = fac.createOMElement("echo", omNs);
         OMElement value = fac.createOMElement("Text", omNs);
         value.addChild(fac.createOMText(value, "Axis2 Echo String "));
         method.addChild(value);

         return method;
     }
 }</pre>
 <a name="rest_with_get"></a>

 <h2>Access a REST Web Service via HTTP GET</h2>

 <p>Axis2 allows users to access Web services that have simple type parameters
 via HTTP GET. For example, the following URL requests the Version Service via
 HTTP GET. However, the Web service arriving via GET assumes REST. Other
 parameters are converted into XML and put into the SOAP body.</p>
 <pre>http://127.0.0.1:8080/axis2/services/Version/getVersion</pre>
 <p>The result can be shown in the browser as follows:</p>
 <img src="images/userguide/http-get-ws.jpg"/>

 <p>For example, the following request,</p>
 <pre>http://127.0.0.1:8080/axis2/services/Version/getVersion</pre>
 will be converted into the following SOAP message for processing by
 Axis2.
 <pre>
    &lt;soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"&gt;
       &lt;soapenv:Body&gt;
           &lt;axis2:getVersion xmlns:axis2="http://ws.apache.org/goGetWithREST" /&gt;
       &lt;/soapenv:Body&gt;
    &lt;/soapenv:Envelope&gt;
     </pre>

 <h2>Resources</h2>

 <p>How I Explained REST to My Wife, By Ryan Tomayko- <a
 href="http://naeblis.cx/articles/2004/12/12/rest-to-my-wife">http://naeblis.cx/articles/2004/12/12/rest-to-my-wife</a></p>

 <p>Building Web Services the REST Way, By Roger L. Costello- <a
 href="http://www.xfront.com/REST-Web-Services.html">
 http://www.xfront.com/REST-Web-Services.html</a></p>

 <p>Resource-oriented vs. activity-oriented Web services, By James Snell- <a
 href="http://www-128.ibm.com/developerworks/webservices/library/ws-restvsoap/">http://www-128.ibm.com/developerworks/webservices/library/ws-restvsoap/</a></p>
 </body>
 </html>
	<!--
	~ Licensed to the Apache Software Foundation (ASF) under one
	~ or more contributor license agreements. See the NOTICE file
	~ distributed with this work for additional information
	~ regarding copyright ownership. The ASF licenses this file
	~ to you under the Apache License, Version 2.0 (the
	~ "License"); you may not use this file except in compliance
	~ with the License. You may obtain a copy of the License at
	~
	~ http://www.apache.org/licenses/LICENSE-2.0
	~
	~ Unless required by applicable law or agreed to in writing,
	~ software distributed under the License is distributed on an
	~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	~ KIND, either express or implied. See the License for the
	~ specific language governing permissions and limitations
	~ under the License.
	-->

	<html>
	<head>
	<meta http-equiv="content-type" content=""/>
	<title>RESTful Web Services Support</title>
	</head>

	<body lang="en">
	<h1>RESTful Web Services Support</h1>

	<p>This document presents an introduction on REST and REST with HTTP POST and
	GET.</p>

	<h2>Content</h2>
	<ul>
	<li><a href="#intro">Introduction</a></li>
	<li><a href="#rest_with_post">Doing REST Web Services with HTTP POST</a>
	<ul>
	<li><a href="#sample">Sample REST - HTTP POST Client</a></li>
	</ul>
	</li>
	<li><a href="#rest_with_get">Access a REST Web Service via HTTP GET</a></li>
	</ul>
	<a name="intro"></a>

	<h2>Introduction</h2>

	<p>WSDL 2.0 HTTP Binding defines a way to implement REST (Representational
	State Transfer) with Web services. Axis2 implements the most defined HTTP
	binding specification. REST Web services are a reduced subset of the usual
	Web service stack.</p>

	<p>The Axis2 REST implementation assumes the following properties:</p>
	<ol>
	<li>REST Web services are Synchronous and Request Response in nature.</li>
	<li>When REST Web services are accessed via GET, the service and the
	operations are identified based on the URL. The parameters are assumed as
	parameters of the Web service. In this case, the GET based REST Web
	services support only simple types as arguments and it should adhere to
	the <a
	href="http://www.w3.org/TR/2006/CR-wsdl20-adjuncts-20060327/#_operation_iri_style">IRI
	style</a>.</li>
	<li>POST based Web services do not need a SOAP Envelope or a SOAP Body.
	REST Web Services do not have Headers and the payload is sent
	directly.</li>
	</ol>

	<p>Axis2 can be configured as a REST Container and can be used to send and
	receive RESTful Web service requests and responses. REST Web services can be
	accessed using HTTP GET and POST.</p>
	<a name="rest_with_post"></a>

	<h2>REST Web Services with HTTP POST</h2>

	<p>If REST is enabled, the Axis2 server will act as both a REST endpoint and
	a SOAP endpoint. When a message is received, if the content type is text/xml
	and if the SOAPAction Header is missing, then the message is treated as a
	RESTful Message, if not it is treated as a usual SOAP Message.</p>

	<p>On sending a message, whether the message is RESTful or not, can be
	decided from the client API.<br/>
	Set a property in the client API.<br/>
	</p>
	<pre>...
	Options options = new Options();
	options.setProperty(Constants.Configuration.ENABLE_REST, Constants.VALUE_TRUE);
	...</pre>
	<a name="sample"></a>

	<h3>Sample REST - HTTP POST Client</h3>

	<p>There is an example named, userguide.clients.RESTClient.java found in
	AXIS2_HOME/samples/userguide/src/userguide/clients which demonstrates the
	usage of the above. It uses the "echo" operation of the
	<code>userguide.example1.MyService </code>of the
	AXIS2_HOME/samples/userguide/src/userguide/example1.</p>

	<p>The class source will be as follows:</p>
	<pre>public class RESTClient {

	private static String toEpr = "http://localhost:8080/axis2/services/MyService";

	public static void main(String[] args) throws AxisFault {

	Options options = new Options();
	options.setTo(new EndpointReference(toEpr));
	options.setTransportInProtocol(Constants.TRANSPORT_HTTP);

	options.setProperty(Constants.Configuration.ENABLE_REST, Constants.VALUE_TRUE);

	ServiceClient sender = new ServiceClient();
	sender.engageModule(Constants.MODULE_ADDRESSING);
	sender.setOptions(options);
	OMElement result = sender.sendReceive(getPayload());

	try {
	XMLStreamWriter writer = XMLOutputFactory.newInstance()
	.createXMLStreamWriter(System.out);
	result.serialize(writer);
	writer.flush();
	} catch (XMLStreamException e) {
	e.printStackTrace();
	} catch (FactoryConfigurationError e) {
	e.printStackTrace();
	}
	}

	private static OMElement getPayload() {
	OMFactory fac = OMAbstractFactory.getOMFactory();
	OMNamespace omNs = fac.createOMNamespace(
	"http://example1.org/example1", "example1");
	OMElement method = fac.createOMElement("echo", omNs);
	OMElement value = fac.createOMElement("Text", omNs);
	value.addChild(fac.createOMText(value, "Axis2 Echo String "));
	method.addChild(value);

	return method;
	}
	}</pre>
	<a name="rest_with_get"></a>

	<h2>Access a REST Web Service via HTTP GET</h2>

	<p>Axis2 allows users to access Web services that have simple type parameters
	via HTTP GET. For example, the following URL requests the Version Service via
	HTTP GET. However, the Web service arriving via GET assumes REST. Other
	parameters are converted into XML and put into the SOAP body.</p>
	<pre>http://127.0.0.1:8080/axis2/services/Version/getVersion</pre>
	<p>The result can be shown in the browser as follows:</p>
	<img src="images/userguide/http-get-ws.jpg"/>

	<p>For example, the following request,</p>
	<pre>http://127.0.0.1:8080/axis2/services/Version/getVersion</pre>
	will be converted into the following SOAP message for processing by
	Axis2.
	<pre>
	<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
	<soapenv:Body>
	<axis2:getVersion xmlns:axis2="http://ws.apache.org/goGetWithREST" />
	</soapenv:Body>
	</soapenv:Envelope>
	</pre>

	<h2>Resources</h2>

	<p>How I Explained REST to My Wife, By Ryan Tomayko- <a
	href="http://naeblis.cx/articles/2004/12/12/rest-to-my-wife">http://naeblis.cx/articles/2004/12/12/rest-to-my-wife</a></p>

	<p>Building Web Services the REST Way, By Roger L. Costello- <a
	href="http://www.xfront.com/REST-Web-Services.html">
	http://www.xfront.com/REST-Web-Services.html</a></p>

	<p>Resource-oriented vs. activity-oriented Web services, By James Snell- <a
	href="http://www-128.ibm.com/developerworks/webservices/library/ws-restvsoap/">http://www-128.ibm.com/developerworks/webservices/library/ws-restvsoap/</a></p>
	</body>
	</html>