org.eclipse.scada.da.client.samples

Class Sample5

java.lang.Object

org.eclipse.scada.da.client.samples.SampleBase

org.eclipse.scada.da.client.samples.Sample5

All Implemented Interfaces:

java.util.Observer

public class Sample5
extends SampleBase
implements java.util.Observer

Sample showing how to subscribe for events using the DataItem class.

The example shows how to create a new connection, connect, and listen for events coming using the DataItem class which simplifies some parts of receiving events from Eclipse SCADA. The DataItem class performs all the merging and cache value handling for us. It extends the common Observable class and therefore simplifies that handling a little bit. You do not get the much more detailed event information since you only get the information object changed. On the other side you have an instance which always has the latest value merged up for you. So you can access it using DataItem.getSnapshotValue(), DataItem.getAttributes() and DataItem.getSubscriptionState() at any time.

We will listen to the time data item of the test server. The item is an input item and will provided the current unix timestamp every second.

Field Summary

Fields inherited from class org.eclipse.scada.da.client.samples.SampleBase

connection, uri

Constructor Summary

Constructors

Constructor and Description
Sample5(java.lang.String uri, java.lang.String className)

Method Summary

Methods

Modifier and Type	Method and Description
void	connect()
static void	main(java.lang.String[] args)
void	subscribe()
void	unsubscribe()
void	update(java.util.Observable o, java.lang.Object arg)

Methods inherited from class org.eclipse.scada.da.client.samples.SampleBase

dispose, sleep

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Sample5

public Sample5(java.lang.String uri,
       java.lang.String className)
        throws java.lang.Exception

Throws:

java.lang.Exception

Method Detail

connect

public void connect()
             throws java.lang.Exception

Overrides:

connect in class SampleBase

Throws:

java.lang.Exception

subscribe

public void subscribe()

unsubscribe

public void unsubscribe()

update

public void update(java.util.Observable o,
          java.lang.Object arg)

Specified by:

update in interface java.util.Observer

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

Throws:

java.lang.Exception