GridJexlNodeFilter (GridGain 2.1.0 API)

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GridGain™ 2.1.0
Java API Specification

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org.gridgain.grid
Class GridJexlNodeFilter

java.lang.Object
  org.gridgain.grid.GridJexlNodeFilter

All Implemented Interfaces:: GridNodeFilter

public class GridJexlNodeFilter
extends Object
implements GridNodeFilter
extends Object
implements GridNodeFilter

Implementation of GridNodeFilter based on Apache JEXL expression language. The expression will be compiled only once, at the creation time, and all invocation will simply plugin the passed-in node into the compiled expression.

Example below shows how JEXL node filter can be used to get grid nodes.

 ...
 GridJexlNodeFilter filter = new GridJexlNodeFilter(
     "node.metrics.availableProcessors > 1 && " +
     "node.metrics.averageCpuLoad < 0.5 && " +
     "node.attributes['os.name'] == 'Windows XP'"
 );

 Collection<GridNode> nodes = grid.getNodes(filter);
 ...

Together with GridNodeFilterTopologySpi GridJexlNodeFilter allows for a fairly simple way to provide complex SLA-based task topology specifications. For example, expression below shows how the SPI can be configured with GridJexlNodeFilter to include all Windows XP nodes with more than one processor or core and that are not loaded over 50%

 <bean id="grid.custom.cfg" class="org.gridgain.grid.GridConfigurationAdapter" singleton="true">
       ...
       <property name="topologySpi">
           <bean class="org.gridgain.grid.spi.topology.nodefilter.GridNodeFilterTopologySpi">
               <property name="filter">
                    <bean class="org.gridgain.grid.GridJexlNodeFilter">
                        <property name="expression">
                            <value>
                                <![CDATA[node.metrics.availableProcessors > 1 &&
                                node.metrics.averageCpuLoad < 0.5 &&
                                node.attributes['os.name'] == 'Windows XP']]>
                            </value>
                        </property>
                    </bean>
                </property>
           </bean>
       </property>
       ...
 </bean>

Constructor Summary
`GridJexlNodeFilter()` Creates filter.
`GridJexlNodeFilter(String expr)` Creates filter.

Method Summary
`boolean`	`accept(GridNode node)` Tests if a specified grid node should be accepted.
`String`	`getExpression()` Gets expression.
`void`	`setExpression(String expr)` Sets expression.
`String`	`toString()`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`