org.cafesip.gwtcomp.client.ui.charting
Class LiveDataPanel

java.lang.Object
  com.google.gwt.user.client.ui.UIObject
      com.google.gwt.user.client.ui.Widget
          com.google.gwt.user.client.ui.Panel
              com.google.gwt.user.client.ui.ComplexPanel
                  com.google.gwt.user.client.ui.FlowPanel
                      org.cafesip.gwtcomp.client.ui.charting.LiveDataPanel

All Implemented Interfaces:

HasHandlers, EventListener, HasWidgets, IndexedPanel, InsertPanel, Iterable<Widget>

public class LiveDataPanel
extends FlowPanel

Enables GWT application to display live data in the form of charts and tables. The chart display dynamic data that is updated from the server side at a pre-defined intervals. Such panels are useful for displaying changing information such as stock values, temperature, etc. In order to display live charts, GWT applications have to instantiate an object of this type and add it to a panel of the GWT application you are developing. In addition, you need to provide a server-side class(es) that contain the logic to provide the chart configurations and the data needed to populate the charts periodically. Each class handles a single chart that is identified by a context (see below). The GWTCOMP server-side framework will instantiate these classes and invoke methods on them periodically to fetch the data. The fetched data is then transferred to the client-side which displays the data on the panels. Note that the communication between the client and the server components is transparent and your application will not have to deal with it. The data source classes must implement the LiveDataSource interface or extend a convenience class like SimpleLiveDataSource (more such classes will be added in future releases). A GWT application may contain multiple live data panels. Each data panel is identified by there parameters:

1. context - may be used to identify the type of chart, For example - "STOCKS". You application may have multiple contexts like "STOCKS", "BONDS", "FUTURES", etc. As explained above, you can provide a data source for every context.
2. instance - may be used to identify a specific instance. For example - "STOCKS-US".
3. param - an additional parameter to specify additional parameters. For example - "GOOG, MSFT"

When the data source is invoked by the GWTCOMP framework, these parameters are passed to the method being invoked. You application can use these parameters to locate the data from a database or other data sources.

In order for this to work, you will need to add the following elements to the web.xml file for your application:

  <servlet>
  <servlet-name>LiveDataService</servlet-name>
  <servlet-class>
  org.cafesip.gwtcomp.server.LiveDataServiceImpl
  </servlet-class>
  <init-param>
  <param-name>data-source-class-contextName</param-name>
  <param-value>org.cafesip.gwtcomp.examples.server.LiveDataSourceSample</param-value>
  </init-param>
  </servlet>
 
  <servlet-mapping>
  <servlet-name>LiveDataService</servlet-name>
  <url-pattern>/gwtcomp/liveDataService</url-pattern>
  </servlet-mapping>
 
 

Note the use of the parameter data-source-class-contextName. Replace the contextName with the name of the context. This is the context that you will specify in the constructor parameters. In addition, replace the value of the init-param, data-source-class with the fully qualified class name of your data source class. This class must be present in the server classpath. You can have multiple data-source-class-contextName init parameters, one for each context. In addition, you can add an init parameter data-source-class (no context) to specify the default data source class. When the GWTCOMP server side receives a request with an context that is not specified in the web.xml, it lets the default data source class handle the request.

The following jars must be present in your classpath in order to compile the client-side of the GWT application. These jars must be in the classpath regardless of whether you are using LiveDataPanel or not because of the way the GWT compiler works.

• gchart.jar

CSS Style Rules:

• .gwtcomp-LiveDataPanel { } - style for the LiveDataPanel

Screen-Shots:

Author:

Amit Chatterjee

Nested Class Summary

Nested classes/interfaces inherited from class com.google.gwt.user.client.ui.UIObject

UIObject.DebugIdImpl, UIObject.DebugIdImplEnabled

Field Summary

static double

GOLDEN_RATIO

Fields inherited from class com.google.gwt.user.client.ui.UIObject

DEBUG_ID_PREFIX

Constructor Summary

LiveDataPanel(String context, String instance, String param)
A constructor for this class.

LiveDataPanel(String context, String instance, String param, int width)
A constructor for this class.

LiveDataPanel(String context, String instance, String param, int width, int height)
A constructor for this class.

Method Summary

TimeSeriesChartPanel	getChartPanel()
String	getContext()
String	getParam()
protected void	onAttach()
protected void	onDetach()
void	setChartPanel(TimeSeriesChartPanel chartPanel)
void	setContext(String context)
void	setParam(String param)
void	startRefresh() Start (restart) screen refresh.
void	stopRefresh() Stop refreshing the screen with new data.

Methods inherited from class com.google.gwt.user.client.ui.FlowPanel

add, clear, insert

Methods inherited from class com.google.gwt.user.client.ui.ComplexPanel

add, adjustIndex, checkIndexBoundsForAccess, checkIndexBoundsForInsertion, getChildren, getWidget, getWidgetCount, getWidgetIndex, insert, insert, iterator, remove, remove

Methods inherited from class com.google.gwt.user.client.ui.Panel

adopt, adopt, disown, doAttachChildren, doDetachChildren, onLoad, onUnload, orphan

Methods inherited from class com.google.gwt.user.client.ui.Widget

addDomHandler, addHandler, delegateEvent, fireEvent, getHandlerCount, getLayoutData, getParent, isAttached, isOrWasAttached, onBrowserEvent, removeFromParent, setLayoutData, sinkEvents

Methods inherited from class com.google.gwt.user.client.ui.UIObject

addStyleDependentName, addStyleName, ensureDebugId, ensureDebugId, ensureDebugId, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleElement, getStyleName, getStyleName, getStylePrimaryName, getStylePrimaryName, getTitle, isVisible, isVisible, onEnsureDebugId, removeStyleDependentName, removeStyleName, setElement, setElement, setHeight, setPixelSize, setSize, setStyleName, setStyleName, setStyleName, setStylePrimaryName, setStylePrimaryName, setTitle, setVisible, setVisible, setWidth, toString, unsinkEvents

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.google.gwt.user.client.ui.IndexedPanel

getWidget, getWidgetCount, getWidgetIndex, remove

Field Detail

GOLDEN_RATIO

public static final double GOLDEN_RATIO

See Also:

Constant Field Values

Constructor Detail

LiveDataPanel

public LiveDataPanel(String context,
                     String instance,
                     String param)

A constructor for this class.

Parameters:

context - see above

instance - see above

param - see above

LiveDataPanel

public LiveDataPanel(String context,
                     String instance,
                     String param,
                     int width,
                     int height)

A constructor for this class.

Parameters:

context - see above

instance - see above

param - see above

width - width of the panel

height - height of the panel

LiveDataPanel

public LiveDataPanel(String context,
                     String instance,
                     String param,
                     int width)

A constructor for this class.

Parameters:

context - see above

instance - see above

param - see above

width - the width of the panel. The height is calculated using the GOLDEN_RATIO.

Method Detail

getContext

public String getContext()

Returns:

Returns the context.

setContext

public void setContext(String context)

Parameters:

context - The context to set.

getParam

public String getParam()

Returns:

Returns the param.

setParam

public void setParam(String param)

Parameters:

param - The param to set.

stopRefresh

public void stopRefresh()

Stop refreshing the screen with new data.

startRefresh

public void startRefresh()

Start (restart) screen refresh.

onDetach

protected void onDetach()

Overrides:

onDetach in class Widget

onAttach

protected void onAttach()

Overrides:

onAttach in class Widget

getChartPanel

public TimeSeriesChartPanel getChartPanel()

Returns:

Returns the chartPanel.

setChartPanel

public void setChartPanel(TimeSeriesChartPanel chartPanel)

Parameters:

chartPanel - The chartPanel to set.