Publisher


1   package org.getahead.dwrdemo.gidemo;
2   
3   import java.util.Collection  ;
4   import java.util.Random  ;
5   
6   import javax.servlet.ServletContext  ;
7   
8   import org.directwebremoting.ServerContext;
9   import org.directwebremoting.ServerContextFactory;
10  import org.directwebremoting.WebContext;
11  import org.directwebremoting.WebContextFactory;
12  import org.directwebremoting.proxy.ScriptProxy;
13  import org.directwebremoting.util.Logger;
14  
15  /**
16   * A generator of random objects to push to GI
17   * @author Joe Walker [joe at getahead dot ltd dot uk]
18   */
19  public class Publisher implements Runnable  
20  {
21      /**
22       * Create a new publish thread and start it
23       */
24      public Publisher()
25      {
26          WebContext webContext = WebContextFactory.get();
27          ServletContext   servletContext = webContext.getServletContext();
28  
29          serverContext = ServerContextFactory.get(servletContext);
30  
31          // A bit nasty: the call to serverContext.getScriptSessionsByPage()
32          // below could fail because the system might need to read web.xml which
33          // means it needs a ServletContext, which is only available  using
34          // WebContext, which in turn requires a DWR thread. We can cache the
35          // results simply by calling this in a DWR thread, as we are now.
36          webContext.getScriptSessionsByPage("");
37  
38          synchronized (Publisher.class)
39          {
40              if (worker == null)
41              {
42                  worker = new Thread  (this, "Publisher");
43                  worker.start();
44              }
45          }
46      }
47  
48      /* (non-Javadoc)
49       * @see java.lang.Runnable#run()
50       */
51      public void run()
52      {
53          try
54          {
55              log.info("Starting Publisher thread");
56  
57              while (!Thread.currentThread().isInterrupted())
58              {
59                  Collection   sessions = serverContext.getScriptSessionsByPage("/dwr/gi/index.html");
60                  ScriptProxy proxy = new ScriptProxy(sessions);
61  
62                  Corporation corp = corporations.getNextChangedCorporation();
63                  proxy.addFunctionCall("OpenAjax.publish", "gidemo", "corporation", corp);
64  
65                  int timeToSleep = random.nextInt(2500);
66                  Thread.sleep(timeToSleep);
67              }
68          }
69          catch (InterruptedException   ex)
70          {
71              // Ignore, we expect this
72          }
73          finally
74          {
75              log.info("Stopping Publisher thread");
76          }
77      }
78  
79      /**
80       * The thread that does the work
81       */
82      protected static Thread   worker;
83  
84      /**
85       * The set of corporations that we manage
86       */
87      private Corporations corporations = new Corporations();
88  
89      /**
90       * We use DWRs ServerContext to find users of a given page
91       */
92      private ServerContext serverContext;
93  
94      /**
95       * Used to generate random data
96       */
97      private Random   random = new Random  ();
98  
99      /**
100      * The log stream
101      */
102     private static final Logger log = Logger.getLogger(Publisher.class);
103 }
104
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