The resequencer pattern, shown in Figure A.5, enables you to resequence messages according to the sequence number stored in an NMR property. The ServiceMix EIP resequencer pattern maps to the Fuse Mediation Router resequencer configured with the stream resequencing algorithm.
The sequence of messages emitted from the resequencer is determined by the value of the
sequence number property: messages with a low sequence number are emitted first and messages
with a higher number are emitted later. By default, the sequence number is read from the
org.apache.servicemix.eip.sequence.number property in ServiceMix, but you can
customize the name of this property using the eip:default-comparator element in
ServiceMix.
The equivalent concept in Fuse Mediation Router is a sequencing expression,
which can be any message-dependent expression. When migrating from ServiceMix EIP, you
normally define an expression that extracts the sequence number from a header (a Fuse Mediation Router
header is equivalent to an NMR message property). For example, to extract a sequence number
from a seqnum header, you can use the simple expression,
header.seqnum.
Example A.13 shows how to define a resequencer using the ServiceMix EIP component.
Example A.13. ServiceMix EIP Resequncer
<eip:resequencer
service="sample:Resequencer"
endpoint="ResequencerEndpoint"
comparator="#comparator"
capacity="100"
timeout="2000">
<eip:target>
<eip:exchange-target service="sample:SampleTarget" />
</eip:target>
</eip:resequencer>
<!-- Configure default comparator with custom sequence number property -->
<eip:default-comparator xml:id="comparator"
sequenceNumberKey="seqnum"/>Example A.14 shows how to define an equivalent route using Fuse Mediation Router XML configuration.
Example A.14. Fuse Mediation Router Resequencer Using XML
<route>
<from uri="jbi:endpoint:sample:Resequencer:ResequencerEndpoint"/>
<resequencer>
<simple>header.seqnum</simple>
<to uri="jbi:service:sample:SampleTarget" />
<stream-config capacity="100" timeout="2000"/>
</resequencer>
</route>Example A.15 shows how to define an equivalent route using the Fuse Mediation Router Java DSL.
Example A.15. Fuse Mediation Router Resequencer Using Java DSL
from("jbi:endpoint:sample:Resequencer:ResequencerEndpoint").
resequencer(header("seqnum")).
stream(new StreamResequencerConfig(100, 2000L)).
to("jbi:service:sample:SampleTarget"); |  |  |
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