How to create Data Adapter?

**Mone** · January 28th, 2008, 01:47 PM

Hi,

this is a very simple dataadapter. You can subscribe any item name. Each item has 2 fields, timestamp and count.

package com.lightstreamer.adapters.simplest; 
 
import java.io.File; 
import java.util.Date; 
import java.util.HashMap; 
import java.util.Map; 
 
import com.lightstreamer.interfaces.data.DataProvider; 
import com.lightstreamer.interfaces.data.DataProviderExce ption; 
import com.lightstreamer.interfaces.data.FailureException ; 
import com.lightstreamer.interfaces.data.ItemEventListene r; 
import com.lightstreamer.interfaces.data.SubscriptionExce ption; 
 
public class Simplest implements DataProvider { 
 
 private ItemEventListener listener; 
 private Map<String, ItemThread> threads = new HashMap<String, ItemThread>(); 
 
 public void init(Map params, File configDir) throws DataProviderException { 
 } 
 
 
 public boolean isSnapshotAvailable(String itemName) 
 throws SubscriptionException { 
 return false; 
 } 
 
 
 public void setListener(ItemEventListener listener) { 
 this.listener = listener; 
 } 
 
 
 
 public synchronized void subscribe(String itemName, boolean needsIterator) 
 throws SubscriptionException, FailureException { 
 
 ItemThread it = threads.get(itemName); 
 if (it == null) { 
 it = new ItemThread(itemName); 
 it.start(); 
 threads.put(itemName, it); 
 } 
 
 } 
 
 
 public synchronized void unsubscribe(String itemName) throws SubscriptionException, 
 FailureException { 
 
 ItemThread it = threads.get(itemName); 
 if (it != null) { 
 it.close(); 
 threads.remove(itemName); 
 } 
 } 
 
 
 class ItemThread extends Thread { 
 
 private final String item; 
 private volatile boolean go = true; 
 
 public ItemThread(String item) { 
 this.item = item; 
 } 
 
 public void run() { 
 int c = 0; 
 while(go) { 
 Map<String, String> data = new HashMap<String, String>(); 
 data.put("timestamp", (new Date()).toString()); 
 data.put("count", String.valueOf(c)); 
 listener.update(item, data, false); 
 c++; 
 try { 
 Thread.sleep(1000); 
 } catch (InterruptedException e) { 
 } 
 } 
 } 
 
 public void close() { 
 go = false; 
 } 
 } 
 
 
}

this is the relative adapters.xml

and an example client (my libraries are located under /LS4/):

<html> 
 
<head> 
 <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> 
<script language="JavaScript" src="/LS4/lscommons.js"></script> 
 <script language="JavaScript" src="/LS4/lspushpage.js"></script> 
</head> 
 
<body> 
 <h1>Simplest</h1> 
 
 <div> 
 Item1 
 Loading... 
 Loading... 
 </div> 
 
 <div> 
 MyItem 
 Loading... 
 Loading... 
 </div> 
 
<script> 
 
 
 
/////////////////PushPage Configuration 
 
 
 var lsPage = new PushPage(); 
 var debugAlerts = false; 
 var remoteAlerts = false; 
 var pushHost = null; 
 var pushPort = null; 
 var useDomain = null; 
 
 lsPage.context.setDomain(useDomain); 
 lsPage.context.setDebugAlertsOnClientError(debugAl erts); 
 lsPage.context.setRemoteAlertsOnClientError(remote Alerts); 
 
 lsPage.onEngineCreation = function(lsEngine) { 
 lsEngine.context.setDebugAlertsOnClientError(debug Alerts); 
 lsEngine.context.setRemoteAlertsOnClientError(remo teAlerts); 
 
 lsEngine.connection.setLSHost(pushHost); 
 lsEngine.connection.setLSPort(pushPort); 
 lsEngine.connection.setAdapterName("SIMPLEST"); 
 
 lsEngine.changeStatus("STREAMING"); 
 } 
 
 lsPage.bind(); 
 lsPage.createEngine("SimplestEngine","/LS4/","SHARE_SESSION"); 
 
///////////////////////Table configuration 
 
 var schema = ["timestamp","count"]; 
 
 var table1 = new OverwriteTable("Item1", schema, "MERGE"); 
 table1.setClearOnDisconnected(true); 
 table1.setClearOnRemove(true); 
 lsPage.addTable(table1, "table1"); 
 
 var table2 = new OverwriteTable("MyItem", schema, "MERGE"); 
 table2.setClearOnDisconnected(true); 
 table2.setClearOnRemove(true); 
 lsPage.addTable(table2, "table2"); 
 
</script> 
</body> 
 
</html>