📄 index.xtp

📁 RESIN 3.2 最新源码
💻 XTP
字号:
<document>  <header>    <product>resin</product>    <title>Hessian Addition</title>    <description>      <p>The addition example creates a Hessian web serviceswith a servlet and uses that web service from aJSP client and a Python client.</p>    </description>    <type>tutorial</type>    <tutorial-startpage>demo.jsp</tutorial-startpage>  </header>  <body>    <summary/>    <s1><p>Hessian is a lightweight binary RPC protocol.  Transferring binary objectslike files, images, or mp3s can avoid the protocol overheadthat XML-based protocols require.  Since it's simple, its performanceshould be usable for almost all sites.  Hessian is designed to beself-describing, eliminating the requirement for external IDLs or WSDL files.Because it is as small as possible and language-independent,non-Java Hessian implementations are can easily develop comprehensivetest suites.</p><p>This tutorial only requires the open source Java implementation ofthe Hessian client and server.  It can be downloadedfrom <a href="http://caucho.com/hessian/">http://www.caucho.com/hessian/</a>for non-Resin clients and servers.</p><p>Because Resin's EJB implementation uses Hessian as its primaryremote procedure call protocol, EJB developers can easily exposeservices to clients from other languages.</p><p>Because EJB clients and servers are written without knowledge of theunderlying protocol, even if you intend to deploy with another protocol,like RMI/IIOP, you can develop using Resin's Hessian.</p><p>The <a href="doc|hessian-1.0-spec.xtp">Hessian 1.0 spec</a>and  <a href="doc|hessian-2.0-spec.xtp">Hessian 2.0 spec</a> describethe full Hessian protocol.</p></s1><s1 title="Files in this tutorial"><deftable><tr><td><viewfile-link file="WEB-INF/classes/example/MathService.java"/>    </td><td>Interface for the math service.</td></tr><tr><td><viewfile-link file="WEB-INF/classes/example/HessianMathService.java"/>    </td><td>The main service implementation.</td></tr><tr><td><viewfile-link file="WEB-INF/web.xml"/>    </td><td>Configures the environment</td></tr><tr><td><viewfile-link file="demo.jsp"/>    </td><td>Client JSP</td></tr></deftable></s1><s1 title="The Hessian Protocol"><p>A Hessian call is just an HTTP POST to a URL.  The arguments areserialized into the Hessian binary format and passed to the server.</p><p>Most applications will never need to look at the Hessianprotocol, but it's simple enough that a basic example can help showwhat's happening underneath the API.</p><example title="Hessian call">c x01 x00  m x00 x03 add  I x00 x00 x00 x02  I x00 x00 x00 x03z</example><example title="Hessian reply">r x01 x00  I x00 x00 x00 x05z</example><p>The call does not need to specify the service name because theservice is uniquely specified by the URL.</p><p>The following Addition example shows how to create a basicserver so you can test Hessian.</p></s1><s1 title="A Hessian Example"><p>Using Hessian generally uses three components:</p><ol><li>A remote interface</li><li>The server implementation</li><li>The client (JSP or servlet)</li></ol><p>The remote interface is used by the Hessian proxyfactory to create a proxy stub implementing the service's interface.</p></s1><s1 title="Service Implementation"><p>Resin's Hessian provides a simple way of creating a server.  Just extend<code>HessianServlet</code> with your remote methods.  The Hessian call will justbe a POST to that servlet.  HessianServlet will introspect theservice and expose the methods.</p><example title="HessianMathService.java">package example;import com.caucho.hessian.server.HessianServlet;public class HessianMathService extends HessianServlet {  public int add(int a, int b)  {    return a + b;  }}</example></s1><s1 title="Remote Interface"><p>The Java interface describes the remote API.  This example has anaddition method, <var>add()</var>.</p><p>Resin's proxy client implementation uses the remote interface toexpose the API to the proxy stub.  Strictly speaking, though,the Java remote interface is not required for Hessian.  A non-Java clientwill not use the Java interface, except possibly as documentation.</p><example title="MathService.java">package example;public interface MathService {  public int add(int a, int b);}</example></s1><s1 title="Java Client"><p>RPC clients follow the following steps in using a remote object:</p><ol><li>Determine the URL of the remote object.</li><li>Obtain a proxy stub from a proxy factory.</li><li>Call methods on the proxy stub.</li></ol><example title="client.jsp">&lt;%@ page import="com.caucho.hessian.client.HessianProxyFactory" %&gt;&lt;%@ page import="example.MathService" %&gt;&lt;%HessianProxyFactory factory = new HessianProxyFactory();// http://localhost:8080/resin-doc/protocols/tutorial/hessian-add/hessian/mathString url = ("http://" +              request.getServerName() + ":" + request.getServerPort() +              request.getContextPath() + "/hessian/math");MathService math = (MathService) factory.create(MathService.class, url);out.println("3 + 2 = " + math.add(3, 2));%&gt;</example><results>3 + 2 = 5</results></s1><s1 title="Python Client"><p>The <a href="http://www.caucho.com/hessian">Hessian site</a> hasa basic Python library for Hessian.</p><example title="client.py">from hessianlib import Hessiansite = "http://localhost:8080/resin-doc/protocols/tutorial/hessian-add"url = site + "/hessian/math"proxy = Hessian(url);print "3 + 2 =", proxy.add(2, 3)</example><results>3 + 2 = 5</results></s1>  </body></document>
⌨️ 快捷键说明

复制代码 Ctrl + C
搜索代码 Ctrl + F
全屏模式 F11
切换主题 Ctrl + Shift + D
显示快捷键 ?
增大字号 Ctrl + =
减小字号 Ctrl + -