Unable to find Engine

ap7256

Hello guys,

i have created a simple .NET adapter. Now I need to create a simple web page that would connect to LS server and get everything that the adapter sends out. LS is running locally on my developement machine. I created an HTML code like this:

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

var schema = "hdln smbl body tpcid cmnd";

var lsPage = new PushPage();
lsPage.context.setDomain(null);
lsPage.onEngineCreation = startEngine;
lsPage.onEngineReady = engineReady;
lsPage.bind();
lsPage.createEngine("SLEngine", "LS/lsengine.html");

function startEngine(eng) 
{
	eng.policy.setMaxBandwidth(30);
	eng.policy.setIdleTimeout(30000);
	eng.policy.setPollingInterval(1000);
	eng.connection.setLSHost("localhost");
	eng.connection.setLSPort("8080");
	eng.connection.setAdapterName("HEADLINESDEMO");
	eng.changeStatus("STREAMING");
}

function engineReady ()
{
    var newTable = new NonVisualTable("item",schema,"MERGE");
    newTable.onItemUpdate = updateItem; 
    lsPage.addTable(newTable, "1");
}

when I open this page I am getting an error message "ER Bind Unable to find Engine..check your.. bla bla".

Could you please point me out how do I create a client application?

Thanks

Mone

Hello,

Probably you have some experience with the old loadEngine/loadEngineMinimal methods.

there is an error on your createEngine call:
[syntax="JS"]lsPage.createEngine("SLEngine", "LS/lsengine.html");[/syntax]
The path for the createEngine method is not the path of the lsengine.html file but the path of the library.
So your call should be:
[syntax="JS"]lsPage.createEngine("SLEngine", "ls/");[/syntax]

ap7256

Mone,

thanks a lot for the reply. I changed the path to the library to "ls/" and now everytime I open my page I see a message "Streaming system is connecting..." at the bottom of the browser. And nothing happens next.. I have my LS server up and running and my adapter is connected to the LS server.

ap7256

Mone,

Do you have a simple step-by-step tutorial with a simple sample code of how to connect to a LS server from a web page and get simple updates from it?

I have implemented my client side according to those sample code you provided here but it sill does not work.

Thanks a lot

Mone

Hello,

you can find a tutorial here, and another one on the software distribution. Look for LS_HOME/DOCS-SDKs/sdk_client_web/doc/Web Client Tutorial.pdf . Read also LS_HOME/DOCS-SDKs/sdk_client_web/examples/StockListDemo/README.TXT .

Your configuration is ok if you access the page from Lightstreamer internal web server with an url like http://localhost:8080/MyApp/

Please note that the use of localhost is discouraged. Please use a complete machine name (e.g.: mypc.mydomain.com) even if you are just testing LS on your local environment.

ap7256

I put LSS on the same machine as the webserver and created a DNS record "test.domain.com". Here is the new client side code:

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

  var lsPage = new PushPage();
  lsPage.context.setDomain(null);
  lsPage.onEngineCreation = startEngine;
  lsPage.onEngineReady = engineReady;
  lsPage.bind();
  lsPage.createEngine("SLEngine", "ls/");

 function startEngine(eng) 
 {
   eng.policy.setMaxBandwidth(30);
   eng.policy.setIdleTimeout(30000);
   eng.policy.setPollingInterval(1000);
   eng.connection.setLSHost("test.domain.com");
   eng.connection.setLSPort(8080);
   eng.connection.setAdapterName("HEADLINESDEMO");
   eng.changeStatus("STREAMING");
}

function engineReady ()
{
    var newTable = new NonVisualTable(new Array("item"), new Array("id", "hdln","smbl","body","tpcid","cmnd"), "DISTINCT"); 
    newTable.onItemUpdate = updateItem; 
    lsPage.addTable(newTable, "1");
}

function updateItem(item, updateInfo, name) 
{
    trace (...);
}

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

I am still on the same page. When this page is opened in the browser I see "Streaming system is connecting..." message :Smile_Ac:

ap7256

Must any Adapter be started and hooked into LS server before clients start connecting to LS server?

Mone what did you mean saying "Your configuration is ok if you access the page from Lightstreamer internal web server with an url like http://localhost:8080/MyApp/"?

My testing HTML page is on my development machine, LS server is also on my development machine, a .NET adapter is also on my development machine. Is this some kind of confugration that would probably not work?

Thanks

Mone

@ap7256, Wrote: Mone what did you mean saying "Your configuration is ok if you access the page from Lightstreamer internal web server with an url like http://localhost:8080/MyApp/"?

I mean that if your LS server also serve the static pages you can access it via localhost and without setting the domain, in the other case (i.e.: pages from a web server, streaming from Lightstreamer) than you need to set the domain accordingly to the LS host setting. In your case (in the case you're not using Lightstreamer internal web server) you should change the setDomain call:
[syntax="JS"]lsPage.context.setDomain("domain.com");[/syntax]

If you're using Lightstreamer internal web server than the configuration seems correct. Please could you send Lightstreamer's log?

Peterhuang

Hi Mone,

Could you help me to confirm this quesiton? Thanks!

If I config Demo on server which has public IP address but no domain name,
how should I set domain and LSHost?
One important point: Someone will visit this Demo through internet.

I try to write web page like below, but it throw exception like "ER Bind Unable to find Engine..."

<script>
var lsPage = new PushPage();
lsPage.context.setDomain("55.55.55.55");
lsPage.onEngineCreation = function(engine) {
engine.connection.setLSHost("55.55.55.55");
engine.connection.setLSPort(8080);
engine.connection.setAdapterName("DEMO");
engine.changeStatus("STREAMING");
}
lsPage.bind();
</script>

Or

<script>
var lsPage = new PushPage();
lsPage.context.setDomain(null);
lsPage.onEngineCreation = function(engine) {
engine.connection.setLSHost("55.55.55.55");
engine.connection.setLSPort(8080);
engine.connection.setAdapterName("DEMO");
engine.changeStatus("STREAMING");
}
lsPage.bind();
</script>

Mone

Hi,

NOTE that this is advised against, but if it's only for some tests it is ok:

if the pages are on Lightstreamer internal web server just use null (for everything...):
[syntax="JS"]var lsPage = new PushPage();
lsPage.context.setDomain(null);
lsPage.onEngineCreation = function(engine) {
engine.connection.setLSHost(null);
engine.connection.setLSPort(null);
engine.connection.setAdapterName("DEMO");
engine.changeStatus("STREAMING");
}
lsPage.bind();
[/syntax]
and access you application via IP (works at least on FX and IE, not sure on other browsers)

in the other case you can't access the page via IP but you need a hostname (2 if LS and web server are on different machines)

HTH

Peterhuang

Hi Mone,

Thanks for your reply.

My environment is that the demo is running in external web server on same machine.

Under this environment, I can't use IP address directly for accessing from Internet, right?

Mone

Sorry, you can't.

If you can access the client machine's hosts file you can map there your IP to something like www.mysite.com.

Moreover note that use two server (web & LS) on the same machine is not compatible with Opera browser: http://www.lightstreamer.com/vb/showthread.php?t=28

Peterhuang

Yes, you're right.

Thanks for your answer.

bandanna2k

Please help! I have been following this and a few other threads concerning the binding of domain and host. And have been unsuccessful getting a test environment up and running.

I am successful when accessing Lightstreamer directly on port 8080, but my setup fails when I try with webpages on my webserver.

I have Windows XP
I have Lightstreamer running on port 8080.
I have IE as my client.
I have Netbeans with Tomcat as my webserver.

Lightstreamer config I have.

<http_server name="laptop">

My HOSTS file contains

192.168.1.88        mycompany.net

My computer is called 'laptop' with domain suffix 'mycompany.net'

My HTML code contains

    page.context.setDomain( "mycompany.net" ); // (set the domain when deploying on web server)

    page.onEngineCreation = function( engine )
	{
        engine.context.setDebugAlertsOnClientError(true); // (set false in production)
        engine.connection.setLSHost( "laptop.mycompany.net" ); // (set the hostname when deploying on web server)
        engine.connection.setLSPort( 8080 ); // (set the port when deploying on web server)

I look forward to someone pointing out my obvious mistake!
DN

Mone

hi,

it seems correct, how do you access tomcat (ie which address do you write in the address bar to access your web page)?

Which browser/s are you testing?

Mone

on a second thought I noticed something (my colleague Dario pointed me on it)

you say

the binding of domain and host.

but you're writing on the "Unable to find the Engine" thread. Which is exactly your problem? Do you see the "unable to find the engine...." message or you can't just connect?

you wrote in your hosts file

192.168.1.88 mycompany.net

and then set the LSHost as laptop.mycompany.net. Are you sure that with such setting you can access your local servers through the laptop.mycompany.net address?
Note that the name of the http_server element of the lightstreamer conf is just an helper used for logging purposes and has no effect on the system.

HTH