data not coming to web client

**rd2008** · February 3rd, 2009, 05:26 AM

INCOMING DATA for D~D --> {t=-1.0, h=-1.0, vo=-1, mi=-1.0, lst=null, P=-1.0, status=0, l=-1.0, c=0.0, sl=D, e=D, q=-1, lt=-1.0, dc=1, bq=-1, pg=0.0, ap=-1.0, bb=-1.0}
03-Feb-09 11:13:15,906 |DEBUG|LightstreamerLogger.subscriptions|Simple updates queue |Manager: com.lightstreamer.c.kb@149105b
03-Feb-09 11:13:15,906 |WARN |LightstreamerLogger.preprocessor |Simple updates queue |Unexpected snapshot event for MERGE item D~D
03-Feb-09 11:13:15,906 |TRACE|LightstreamerLogger.pump |PUMP POOLED THREAD 2 |Pumping event in session S425f52b86927c020T1220500: d(2,1,3,"","","","","","","-1","","","-1","-1.0","","","null");
03-Feb-09 11:13:15,906 |TRACE|LightstreamerLogger.push |PUMP POOLED THREAD 2 |RELEASING DATA --> <script>d(2,1,3,"","","","","","","-1","","","-1","-1.0","","","null");</script>

My web client does not receive any value in the onItemUpdate event. Can this be caused by my web client or my MetaAdapter. My Data Adapter implements DataProvider and I use update(itemName, currentValue, isSnapshot) is called in onEvent. In both snapshot requierd and not required settings this happens.

Thanks

**rd2008** · February 3rd, 2009, 08:59 AM

I'm trying to find where the actual error is. Is it my web client or my LS server.
According to LS log it seems that it releases correct data. But it is not available at webclient. onItemUpdate it returns null values when any subscribed field is called by getNewValue(). Who actually drops it? is it my client or my server. Can you please let me know the last place it should be available on my server side and the first place it is available on my webclient?

**rd2008** · February 3rd, 2009, 11:01 AM

//temp
document.getElementById("testnon").innerHTML = "STREAMING";

var ntable = new NonVisualTable("item1 item2", "bid_quantity", "MERGE");
ntable.setDataAdapter("QUOTE_ADAPTER");
ntable.setSnapshotRequired(true);
pushPage.addTable(ntable, "nstocks");
ntable.onItemUpdate = function(itemIndex,update,itemName){
//alert(update.getNewValue("bid_quantity"));
document.getElementById("testnon").innerHTML = update.getNewValue("bid_quantity");

}

It seems that I've messed some basics. I wonder why this is not working in Basic Stock-List Demo web client using demo adapter. [i'm using a trial vivace]

**DarioCrivelli** · February 4th, 2009, 08:43 AM

May you please report a longer log snippet, starting from the actual subscription?
Moreover, the client code shown is not consistent with the data flow reported in the log, because item names and field names don't match, unless your Metadata Adapter changes them. I mean that that Server log snippet cannot be originated by that client code.
Anyway, if your goal is to attach your demo Data Adapter with the Basic Stock-List Demo front-end, then you must ensure that the item names and field names requested by the front-end and the ones supplied by the Data Adapter match.

**rd2008** · February 5th, 2009, 12:11 PM

I'm going to go from the basics...

I created a simple web client that uses a nonvisual table.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html>

<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Lightstreamer :: Basic Stock-List Demo</title>
<link rel="stylesheet" type="text/css" href="css/table.css" />


<script src="ls/lscommons.js" type="text/javascript"></script>
<script src="ls/lspushpage.js" type="text/javascript"></script>
</head>

<body>
<table width="766" border="0">
<tr>
<td><a href="http://www.lightstreamer.com" target="_blank">
<img src="images/logo.gif" alt="LIGHTSTREAMER" hspace="0" border="0" /></a></td>
<td class="demoTitle">demo basic</td>
</tr>
</table>

<br />

<div id="test2">This is a test</div>
<div id="testnon">--</div>
<script type="text/javascript">

//////////////// Master Push-Page Configuration

var pushPage = new PushPage();
pushPage.context.setDebugAlertsOnClientError(true) ; // (set false in production)
pushPage.context.setDomain()// (set the domain when deploying on web server)

pushPage.onEngineCreation = function(lsEngine) {
lsEngine.context.setDebugAlertsOnClientError(true) ; // (set false in production)
lsEngine.connection.setLSHost(null); // (set the hostname when deploying on web server)
lsEngine.connection.setLSPort(null); // (set the port when deploying on web server)
lsEngine.connection.setAdapterName("MY_REAL_TIME") ;
//lsEngine.policy.setMaxBandwidth(40); // ignored in Moderato and Allegro editions
lsEngine.changeStatus("STREAMING");
};

pushPage.bind();
pushPage.createEngine("MyCommonEngine", "ls/", "SHARE_SESSION", true);
// both group and schema need to be defined by the backend
var nvTable = new NonVisualTable("a","b","MERGE");
nvTable.setSnapshotRequired(true);
nvTable.setRequestedMaxFrequency(1.0);
nvTable.setDataAdapter("DEMO");
pushPage.addTable(nvTable , "nlist");
nvTable.onItemUpdate = function(itemIndex,update,itemName) {
document.getElementById("testnon").innerHTML =update.getNewValue("last_price");

}
</script></body></html>

My Meta adapter needs to determine both group and schema.

package stocklist_demo.adapters;

import com.lightstreamer.interfaces.metadata.*;

/**
* Created by IntelliJ IDEA.
* User: admin
* Date: Feb 5, 2009
* Time: 5:25:10 PM
* To change this template use File | Settings | File Templates.
*/
public class MyMetaAdapter extends MetadataProviderAdapter {

public String[] getItems(String user, String session, String id) throws ItemsException {
//TODO return items depending on id
return new String[] {"item1","item2","item3"};
}

public String[] getSchema(String user, String session, String groupId, String schema) throws ItemsException, SchemaException {
//TODO return customized schema
return new String[] {"last_price", "ref_price", "open_price"};
}

public void notifyUser(String user, String password,java.util.Map httpHeaders) throws AccessException, CreditsException {
if (!authenticate(user, password)) {
throw new AccessException("Unauthorized user");
}

}

private boolean authenticate(String userName, String password){

//do authentication here
return true;
}

}

I use the StockListDemo_DataAdapter as it is.

My log looks like this.

**rd2008** · February 5th, 2009, 12:15 PM

i've attached the log file

Thanks

**rd2008** · February 6th, 2009, 05:47 AM

It works fine if I set the schema in the web client. But in my case I'm aiming to determine the schema in the meta adapter depending on the groupid and schema id.

**Mone** · February 6th, 2009, 09:10 AM

Hi,

the problem here is that your client doesn't know the names of your fields because you're creating your table with a schema name (string) instead of using a field list (array of strings)

this way you can't access the fields by name as the library doesn't know at all how the schema was expanded by your metadata adapter, but you should access them by index

let me know if you need further help.