com.levigo.jadice.server.nodes

Class RouterNode

java.lang.Object

com.levigo.jadice.server.internal.NodeInternal

com.levigo.jadice.server.Node

com.levigo.jadice.server.nodes.RouterNode

public class RouterNode
extends Node

This node can be used as simple but powerful way of dynamically routing or filtering Streams on server side to the different successor Nodes depending on the streams' meta data. The decision which way a stream goes is based on rules in the Spring Expression Language (SpEL) syntax. These outgoing streams and their stream descriptors are multiplexed (if necessary) but not modified in any other way.

The base of this rules can be the StreamDescriptor or what number of stream it is. These rules must be a Boolean expression. Due to the SpEL it is not necessary to write those expression as java code, it also supports property access using standard 'dot' notation.
Examples:

#streamDescriptor.getMimeType().equals("application/pdf") or in 'dot' notation #streamDescriptor.mimeType == 'application/pdf'

Evaluates to true for every stream with MIME type "application/pdf"

#streamNumber == 1

Evaluates to true only for the 2^nd stream (counting starts at zero!)

true

Always evaluates to true for any stream. Useful as a fallback rule for the last node in the evaluation chain if no previous rule matched.

The variables to access the StreamDescriptor or the stream number are also provided as constants STREAM_DESCRIPTOR_PATTERN and STREAM_NUMBER_PATTERN.

Rules and successor nodes stick together in the following way. If the n^th rule evaluates to true:

1. the incoming stream will be forwarded to the n^th successor node.
2. the rules n+1…N will only be evaluated if the routing policy is set to RouterNode.RoutingPolicy.EVERY_MATCH.

Default value of the routing policy is RouterNode.RoutingPolicy.FIRST_MATCH so that the incoming stream will only be forwarded to the first node of which the corresponding rule evaluates to true.

Since:

jadice server 4.3.1.0

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RouterNode.RoutingPolicy Routing policy if several rules evaluate to true for a given stream.

Nested classes/interfaces inherited from class com.levigo.jadice.server.Node

Node.Cardinality

Field Summary

Fields

Modifier and Type	Field and Description
static String	STREAM_DESCRIPTOR_PATTERN Pattern to access the StreamDescriptor in the routing rules.
static String	STREAM_NUMBER_PATTERN Pattern to access the stream number in the routing rules. Caveat: Counting is zero-based!

Fields inherited from class com.levigo.jadice.server.internal.NodeInternal

limits, subsidiaryNodes

Constructor Summary

Constructors

Constructor and Description
RouterNode()

Method Summary

Methods

Modifier and Type	Method and Description
Node.Cardinality	getOutputCardinality() Return the output cardinality of this node, i.e.
RouterNode.RoutingPolicy	getRoutingPolicy()
List<String>	getRoutingRules()
String	getWorkerClassName() Return the node's associated NodeWorker full qualified class's name.
void	setRoutingPolicy(RouterNode.RoutingPolicy routingPolicy) Set the routing policy if several rules evaluate to true.
void	setRoutingRules(List<String> routingRules) Set the routing rules in the syntax of the Spring Expression Language.
protected void	validateConfiguration()

Methods inherited from class com.levigo.jadice.server.Node

addTransportReceiver, appendSuccessor, apply, equals, getInputCardinality, getJob, getPredecessors, getSubsidiaryNodes, getSuccessors, getTransportSender, getUUID, hashCode, initialize, prependPredecessor, remove

Methods inherited from class com.levigo.jadice.server.internal.NodeInternal

addSubsidiaryNodes, getJobInternal, getLimit, getLimits, getNodeLimits, setNodeLimits

Methods inherited from class java.lang.Object

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

Field Detail

STREAM_DESCRIPTOR_PATTERN

public static final String STREAM_DESCRIPTOR_PATTERN

Pattern to access the StreamDescriptor in the routing rules.

See Also:

Constant Field Values

STREAM_NUMBER_PATTERN

public static final String STREAM_NUMBER_PATTERN

Pattern to access the stream number in the routing rules.
Caveat: Counting is zero-based!

See Also:

Constant Field Values

Constructor Detail

RouterNode

public RouterNode()

Method Detail

setRoutingPolicy

public void setRoutingPolicy(RouterNode.RoutingPolicy routingPolicy)

Set the routing policy if several rules evaluate to true.

Parameters:

routingPolicy - only the first match is considered iff value is set to RouterNode.RoutingPolicy.EVERY_MATCH (default value)

getRoutingPolicy

public RouterNode.RoutingPolicy getRoutingPolicy()

setRoutingRules

public void setRoutingRules(List<String> routingRules)

Set the routing rules in the syntax of the Spring Expression Language.

Caveat: The number of rules must correspond to the number of successor nodes.

Parameters:

routingRules - The rules that are parsed and evaluated on server side

See Also:

Node.appendSuccessor(Node)

getRoutingRules

public List<String> getRoutingRules()

getOutputCardinality

public Node.Cardinality getOutputCardinality()

Description copied from class: Node

Return the output cardinality of this node, i.e. how many bundles (not streams!) it expects to produce. By default, nodes are "pipe-style", i.e. one input, one output.

Overrides:

getOutputCardinality in class Node

Returns:

output cardinality

validateConfiguration

protected void validateConfiguration()
                              throws ConfigurationException

Overrides:

validateConfiguration in class Node

Throws:

ConfigurationException

getWorkerClassName

public String getWorkerClassName()

Description copied from class: Node

Return the node's associated NodeWorker full qualified class's name. By default, the worker class name is

• The same as the node name with the trailing "Node" replaced by "Worker" if the node name ends in "Node"
• The node class name with an appended "Worker" otherwise.

The package name of the worker class is the name of the Node's package with an appended ".worker".

This behavior can be overridden in concrete subclasses.

Overrides:

getWorkerClassName in class Node

Returns:

the full qualified class name of the worker of this node.