Turn on Render on Demand"

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With ZK EE, you can enable <b>Render on Demand</b> for Grid, Listbox, or Tree to boost performance when showing a huge amount of data. Grid and Listbox will load only the necessary data chunk from associated ListModel, render required Row(s)/Listitem(s) on the server,  then create only the required corresponding widgets and render the DOM elements really needed in the browser. It improves the performance and saves memory significantly on both the server and browser sides.
 
With ZK EE, you can enable <b>Render on Demand</b> for Grid, Listbox, or Tree to boost performance when showing a huge amount of data. Grid and Listbox will load only the necessary data chunk from associated ListModel, render required Row(s)/Listitem(s) on the server,  then create only the required corresponding widgets and render the DOM elements really needed in the browser. It improves the performance and saves memory significantly on both the server and browser sides.
  
−
Note: ROD actually brings a performance boost on both the client-side and server-side. However, if you use <tt>forEach</tt> to populate Rows or Listitems, the components will be all in memory, which does not give you any performance benefits on the server-side. (The client-side still enjoys a boost.) If you want to fully leverage the power of ROD, using a ZK model object like <tt>ListModel</tt> is necessary.
+
Note: ROD actually brings a performance boost on both the client-side and server-side. However, if you use <code>forEach</code> to populate Rows or Listitems, the components will be all in memory, which does not give you any performance benefits on the server-side. (The client-side still enjoys a boost.) If you want to fully leverage the power of ROD, using a ZK model object like <code>ListModel</code> is necessary.
  
 
Notice that you can [[ZK_Configuration_Reference/zk.xml/The_Library_Properties| enable this feature in different scopes]].
 
Notice that you can [[ZK_Configuration_Reference/zk.xml/The_Library_Properties| enable this feature in different scopes]].
  
 
= Grid =
 
= Grid =
−
If you want to enable Grid ROD for the whole application, you can specify a library property called <javadoc>org.zkoss.zul.Grid</javadoc> rod with <tt>true</tt>. For example, specify the following in zk.xml:
+
If you want to enable Grid ROD for the whole application, you can specify a library property called <javadoc>org.zkoss.zul.Grid</javadoc> rod with <code>true</code>. For example, specify the following in zk.xml:
  
 
<syntaxhighlight line lang="xml">
 
<syntaxhighlight line lang="xml">
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</syntaxhighlight>
 
</syntaxhighlight>
  
−
Or, if you prefer to enable it for a particular page, then specify <tt>true</tt> to a page's attribute called <javadoc>org.zkoss.zul.Grid</javadoc> rod, such as
+
Or, if you prefer to enable it for a particular page, then specify <code>true</code> to a page's attribute called <javadoc>org.zkoss.zul.Grid</javadoc> rod, such as
  
 
<syntaxhighlight line lang="xml">
 
<syntaxhighlight line lang="xml">
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</syntaxhighlight>
 
</syntaxhighlight>
  
−
Or, if you prefer to enable it for all descendant grids of a particular component, then specify <tt>true</tt> to the component's attribute. You can enable it for a subset of the descendant grids. For example,
+
Or, if you prefer to enable it for all descendant grids of a particular component, then specify <code>true</code> to the component's attribute. You can enable it for a subset of the descendant grids. For example,
  
 
<syntaxhighlight line lang="xml">
 
<syntaxhighlight line lang="xml">
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Note that Grid ROD will not work unless the Grid is configured with a limited <b>view port</b>, so the user can see only a portion of rows; i.e. you have to set one of the following attributes:
 
Note that Grid ROD will not work unless the Grid is configured with a limited <b>view port</b>, so the user can see only a portion of rows; i.e. you have to set one of the following attributes:
  
−
* <tt>height</tt>
+
* <code>height</code>
−
* <tt>vflex</tt>
+
* <code>vflex</code>
−
* <tt>mold="paging"</tt>
+
* <code>mold="paging"</code>
  
 
== Specifies the number of rows rendered  ==
 
== Specifies the number of rows rendered  ==
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= Listbox =
 
= Listbox =
−
If you want to enable Listbox ROD for the whole application, you can specify a library property called <javadoc>org.zkoss.zul.Listbox</javadoc> rod with <tt>true</tt>. For example, specify the following in zk.xml:
+
If you want to enable Listbox ROD for the whole application, you can specify a library property called <javadoc>org.zkoss.zul.Listbox</javadoc> rod with <code>true</code>. For example, specify the following in zk.xml:
  
 
<syntaxhighlight line lang="xml">
 
<syntaxhighlight line lang="xml">
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</syntaxhighlight>
 
</syntaxhighlight>
  
−
Or, if you prefer to enable it for a particular page, then specify <tt>true</tt> to a page's attribute called <javadoc>org.zkoss.zul.Listbox</javadoc> rod, such as
+
Or, if you prefer to enable it for a particular page, then specify <code>true</code> to a page's attribute called <javadoc>org.zkoss.zul.Listbox</javadoc> rod, such as
  
 
<syntaxhighlight line lang="xml">
 
<syntaxhighlight line lang="xml">
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</syntaxhighlight>
 
</syntaxhighlight>
  
−
Or, if you prefer to enable it for all descendant listboxs of a particular component, then specify <tt>true</tt> to the component's attribute. And, you can enable it for a subset of the descendant listboxs. For example,
+
Or, if you prefer to enable it for all descendant listboxs of a particular component, then specify <code>true</code> to the component's attribute. And, you can enable it for a subset of the descendant listboxs. For example,
  
 
<syntaxhighlight line lang="xml">
 
<syntaxhighlight line lang="xml">
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Note that Listbox ROD is not working unless the Listbox is configured with a limited <b>viewport</b>, so the user can see only a portion of listitems; i.e. you have to set  one of the following attributes:
 
Note that Listbox ROD is not working unless the Listbox is configured with a limited <b>viewport</b>, so the user can see only a portion of listitems; i.e. you have to set  one of the following attributes:
  
−
* <tt>height</tt>
+
* <code>height</code>
−
* <tt>vflex</tt>
+
* <code>vflex</code>
−
* <tt>rows</tt>
+
* <code>rows</code>
−
* <tt>mold="paging"</tt>
+
* <code>mold="paging"</code>
  
 
== Specifies the number of items rendered  ==
 
== Specifies the number of items rendered  ==

Revision as of 14:14, 12 January 2022


DocumentationZK Developer's ReferencePerformance TipsListbox, Grid and Tree for Huge DataTurn on Render on Demand
Turn on Render on Demand


  • Available for ZK:
  • http://www.zkoss.org/product/zkhttp://www.zkoss.org/whyzk/zkeeVersion ee.png

Since 5.0.0

Overview

With ZK EE, you can enable Render on Demand for Grid, Listbox, or Tree to boost performance when showing a huge amount of data. Grid and Listbox will load only the necessary data chunk from associated ListModel, render required Row(s)/Listitem(s) on the server, then create only the required corresponding widgets and render the DOM elements really needed in the browser. It improves the performance and saves memory significantly on both the server and browser sides.

Note: ROD actually brings a performance boost on both the client-side and server-side. However, if you use forEach to populate Rows or Listitems, the components will be all in memory, which does not give you any performance benefits on the server-side. (The client-side still enjoys a boost.) If you want to fully leverage the power of ROD, using a ZK model object like ListModel is necessary.

Notice that you can enable this feature in different scopes.

Grid

If you want to enable Grid ROD for the whole application, you can specify a library property called Grid rod with true. For example, specify the following in zk.xml: 

1 <library-property>
2 	<name>org.zkoss.zul.grid.rod</name>
3 	<value>true</value>
4 </library-property>

Or, if you prefer to enable it for a particular page, then specify true to a page's attribute called Grid rod, such as 

1 <custom-attributes org.zkoss.zul.grid.rod="true" scope="page"/>

Or, if you prefer to enable it for all descendant grids of a particular component, then specify true to the component's attribute. You can enable it for a subset of the descendant grids. For example, 

 1 <window>
 2   <custom-attributes org.zkoss.zul.grid.rod="true"/> <!-- enable it for descendant grids of window -->
 3   <grid ...>
 4     ..
 5   </grid>
 6   <div>
 7     <custom-attributes org.zkoss.zul.grid.rod="false"/> <!-- disable it for descendant grids of div -->
 8       <grid ...>
 9         ..
10       </grid>
11       ..
12   </div>
13 </window>

Fixed Viewport is Required

Note that Grid ROD will not work unless the Grid is configured with a limited view port, so the user can see only a portion of rows; i.e. you have to set one of the following attributes:

  • height
  • vflex
  • mold="paging"

Specifies the number of rows rendered

[default: 100]
[inherit: true]

Since 5.0.8

Specifies the minimum number of rows rendered on the client. It is only considered if Grid is using live data (Grid.setModel(ListModel)) and not using paging mold (Grid.getPagingChild()). 

1 <custom-attributes org.zkoss.zul.grid.initRodSize="30"/>

Listbox

If you want to enable Listbox ROD for the whole application, you can specify a library property called Listbox rod with true. For example, specify the following in zk.xml: 

1 <library-property>
2 	<name>org.zkoss.zul.listbox.rod</name>
3 	<value>true</value>
4 </library-property>

Or, if you prefer to enable it for a particular page, then specify true to a page's attribute called Listbox rod, such as 

1 <custom-attributes org.zkoss.zul.listbox.rod="true" scope="page"/>

Or, if you prefer to enable it for all descendant listboxs of a particular component, then specify true to the component's attribute. And, you can enable it for a subset of the descendant listboxs. For example, 

 1 <window>
 2   <custom-attributes org.zkoss.zul.listbox.rod="true"/> <!-- enable it for descendant listboxs of window -->
 3   <listbox ...>
 4     ..
 5   </listbox>
 6   <div>
 7     <custom-attributes org.zkoss.zul.listbox.rod="false"/> <!-- disable it for descendant listboxs of div -->
 8       <listbox ...>
 9         ..
10       </listbox>
11       ..
12   </div>
13 </window>

Fixed Viewport is Required

Note that Listbox ROD is not working unless the Listbox is configured with a limited viewport, so the user can see only a portion of listitems; i.e. you have to set one of the following attributes:

  • height
  • vflex
  • rows
  • mold="paging"

Specifies the number of items rendered

[default: 100]
[inherit: true]

Since 5.0.8

Specifies the number of items rendered when the Listbox first render. It is used only if live data (Listbox.setModel(ListModel)) and not paging (Listbox.getPagingChild()). 

1 <custom-attributes org.zkoss.zul.listbox.initRodSize="30"/>

Tree

To turn off ROD for a tree, you need to specify org.zkoss.zul.tree.initRodSize with -1: 

<custom-attributes org.zkoss.zul.tree.initRodSize="-1"/>

Version History

Last Update : 2022/01/12


Version Date Content
     



Last Update : 2022/01/12

Copyright © Potix Corporation. This article is licensed under GNU Free Documentation License.


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