DataAdapter with XML

**DarioCrivelli** · April 26th, 2010, 01:36 PM

As your XML file has a simple tabular structure, you can easily fit your data into the items/fields concepts used in Lightstreamer.
What you can associate to the concept of "item" depends on what your front-end page is aimed at representing.
Does your page explicitly mention each single match, so that you only need to decorate the match data with the current result?
Or does the page contain a table which just lists the current matches, so that new matches could even enter the table dynamically as they start?
The behavior of the page and the identification of what is a data "item" is a precondition for designing the Data Adapter.

**Irwin** · April 26th, 2010, 03:07 PM

Here is what I have for my front-end.

<html>
<head>
<title></title>
<link rel="stylesheet" type="text/css" href="style.css" />
<script language="JavaScript" src="LS/lscommons.js"></script>
<script language="JavaScript" src="LS/lspushpage.js"></script>

</head>

<body>
<div source="lightstreamer" table="hellotable" item="greetings" field="away">loading...</div>
<div source="lightstreamer" table="hellotable" item="greetings" field="home">loading...</div>
<div source="lightstreamer" table="hellotable" item="greetings" field="score">loading...</div>
<div source="lightstreamer" table="hellotable" item="greetings" field="inning">loading...</div>
<div source="lightstreamer" table="hellotable" item="greetings" field="timestamp">loading...</div>

<script type="text/javascript">
var page = new PushPage();
page.onEngineCreation = function(engine) {
engine.connection.setAdapterName("HELLOWORLD");
engine.changeStatus("STREAMING");
}
page.bind();
page.createEngine("HelloWorldApp", "LS", "SHARE_SESSION");

var pushtable = new OverwriteTable(null, null, "MERGE");
page.addTable(pushtable, "hellotable");
</script>
</body>
</html>

I'm just learning Java and Lightstreamer and that is why I'm having this basic problem.

**DarioCrivelli** · April 27th, 2010, 09:57 AM

You have a page that only has the place for displaying one match result.
However, your source XML file is supposed to contain a list of match results.

What, in your intentions, should the page show?
One of the results included in the XML file?
All the results included in the XML file in round, so that each result is displayed for a few seconds?

Or is your real intention that of showing a table which reports all the results (so that you would need to extend your page)?

**Irwin** · April 27th, 2010, 06:17 PM

I want my page to show all of my matches. I was looking at another example and they used an array. I figure that is what I should use. I'm just not sure on how to code it?

**DarioCrivelli** · April 28th, 2010, 09:09 AM

You have usually two options for displaying a set of matches
and again it all depends on your data.
1) you are managing a fixed set of matches, say 10 matches, and your page already includes static contents regarding those 10 matches.
2) you want to list whatever matches are currently available and your page, in its static part, has no knowledge of the available matches.

**Irwin** · April 28th, 2010, 03:11 PM

Yes I want to list whatever matches are currently available, in its static part, has no knowledge of the available matches.

**Mone** · April 29th, 2010, 09:08 AM

hi,

so what you need is to implement something similar to our PortfolioDemo.

Such demo is based on the MultiMetapush logic. There is a main item that in our case gives a list of stocks but in yours will give a list of matches and then each match will be related to its own item that supplies the updates related to such match.

We used two different data adapters to differentiate the kind of data sent. The main item is supplied by the PortfolioAdapter while the sub-items are supplied by the StockListDemo adapter.
Note that our main item is governed by client requests while yours will read its data from your XML. To receive orders from clients we needed to implement a custom metadata adapter, you'll probably can use the same metadata adapter of the hello world demo (LiteralBasedProvider)

You can find the sources and explanation of both data adapters in our distribution under DOCS-SDKs/sdk_adapter_java/examples/Portfolio_Adapters and DOCS-SDKs/sdk_adapter_java/examples/StockListDemo_DataAdapter

HTH