105 lines
3.3 KiB
Java
105 lines
3.3 KiB
Java
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Example XML client
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package project;
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import java.io.IOException;
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import java.net.URL;
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import org.w3c.dom.Element;
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import com.sun.xml.tree.XmlDocument;
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import com.sun.xml.parser.Resolver;
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/**
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* This class is a sample XML messaging client, supporting simple "echo" and
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* "uppercase" messages that accept pure text messages to show mechanics
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* of sending and receiving valid XML documents as messages over HTTP(S).
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*
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* <P> Normally, XML documents would be designed to reflect the workflow of
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* some process that's being automated. The vocabulary (element tags, their
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* attributes, and the allowed contents) would be defined to reflect the
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* requirements of that particular proces, and would be described in one or
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* more "Document Type Declaration" (DTD) files, as done in this example.
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* DTDs also have documentation defining the semantics of their elements;
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* for simple DTDs this can be embedded in comments, but DTDs supporting
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* more complex procedures require external documentation.
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*
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* <P> The definitions of such vocabulary definitions need to be agreed
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* on only by the organizations participating in the process. They might
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* be parts of one organization developing an Intranet application, some
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* companies working on a private Extranet system, or an industry group
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* working on vertical supply chain integration. Open Standards processes
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* apply to the development of larger systems, such as those involved in
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* Internet Business frameworks.
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*
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* @version 1.3
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*/
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public class ExampleClient
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{
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// can't instantiate
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private ExampleClient () { }
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private final static String exampleDtdFPI =
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"+//Example DTD//foo//EN";
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/**
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* Driver for client, needs three parameters: URL of server,
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* method name, text message.
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*/
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public static void main (String argv [])
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{
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XmlRpcClient client;
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XmlDocument doc;
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Element root;
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if (argv.length != 3) {
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System.err.println ("usage: project.ExampleClient "
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+ "URL (echo|uppercase) Message");
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System.exit (1);
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}
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try {
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// prepare to call ...
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client = createClient (new URL (argv [0]));
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// create document that _should_ be valid (server validates!)
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doc = new XmlDocument ();
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doc.setDoctype (exampleDtdFPI, "http://www.example.com/xml", null);
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root = doc.createElement (argv [1]);
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doc.appendChild (root);
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root.appendChild (doc.createTextNode (argv [2]));
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// make call, print result
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doc = client.call (doc);
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doc.write (System.out);
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} catch (Exception e) {
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e.printStackTrace (System.err);
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}
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}
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//
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// Create a simple proxy for the object on the server side, which
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// understands the DTD used to define this (trivial) workflow
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// protocol.
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//
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private static XmlRpcClient createClient (URL uri)
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{
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XmlRpcClient retval = new XmlRpcClient (uri);
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Resolver r = new Resolver ();
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// In this example, the client doesn't need to customize
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// request or response documents with specialized DOM elements
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r.registerCatalogEntry (exampleDtdFPI,
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"project/example.dtd",
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ExampleClient.class.getClassLoader ());
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retval.customizeResolver (r);
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return retval;
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}
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}
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