JMS Selector for messages having an underscore in one header with Camel and Blueprint

Question

I need to cleanup some messages in a JMS queue (ActiveMQ) where some of the message header contains an underscore.

Some example

Message 1: 
    header MyObject=urn:sap:order:ID1234
    body = <some xml>


Message 2: 
    header MyObject=urn:sap:order:ID9834_ABC
    body = <some xml>

My goal is to move the only messages looking like Message 2 (and all similar containing an underscore) and not messages without underscores (like Message 1) from the original queue MY_ORDERS.

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:ext="http://aries.apache.org/blueprint/xmlns/blueprint-ext/v1.0.0"
    xmlns:cm="http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.1.0"
    xsi:schemaLocation="
       http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
       http://camel.apache.org/schema/blueprint http://camel.apache.org/schema/blueprint/camel-blueprint.xsd
       http://aries.apache.org/blueprint/xmlns/blueprint-cm/v1.1.0 http://aries.apache.org/schemas/blueprint-cm/blueprint-cm-1.1.0.xsd">

    <cm:property-placeholder persistent-id="com.mycompany.order-temp" update-strategy="reload">
        <cm:default-properties>
            <cm:property name="amq.url" value="tcp://localhost:61616" />
            <cm:property name="queue.to.dump" value="activemq:queue:MY_ORDERS?selector=MyObject+LIKE+'urn:order:%&#95;%'" />
        </cm:default-properties>
    </cm:property-placeholder>
    <camelContext xmlns="http://camel.apache.org/schema/blueprint">
        <onException useOriginalMessage="true">
            <exception>java.lang.Exception</exception>
            <handled>
                <constant>true</constant>
            </handled>
            <to uri="activemq:queue:MY_ORDERS_DLQ?preserveMessageQos=true" />
        </onException>
        <route id="route-orders-to-temp">
            <from uri="{{queue.to.dump}}" />
            <to uri="activemq:queue:MY_ORDERS_TEMP" />
        </route>
    </camelContext>
    <bean id="activemq" class="org.apache.activemq.camel.component.ActiveMQComponent">
        <property name="brokerURL" value="${amq.url}" />
    </bean>
</blueprint>

By using the following posts and because the official ActiveMQ Documentation about selectors says it uses SQL 92 syntax:

I tried all the following combinations:

selector=MyObject+LIKE+'urn:sap:order:%&#95;%'
selector=MyObject+LIKE+'urn:sap:order:%_%'
selector=MyObject+LIKE+'urn:sap:order:%\_%'
selector=MyObject+LIKE+'urn:sap:order:%[_]%'
selector=MyObject+LIKE+'urn:sap:order:[a-Z0-9]*_[a-Z0-9]*'

But none of them seems to work. Any thoughts?

score 0 · Accepted Answer · answered Mar 13 '17 at 19:14

Finally I found the solution of my problem: there is a special syntax to define the escaping character which does not seems to be set by default.

By looking on Internet I finally found the following post which clearly shows the underscore must be escaped by e.g. \ then defining the escape character with ESCAPE '\'

If I apply to my cases the following lines:

selector=MyObject+LIKE+'urn:sap:order:%&#95;%' ESCAPE '\'
selector=MyObject+LIKE+'urn:sap:order:%\_%' ESCAPE '\'

will just work fine with the additional ESCAPE '\' at the end of the selector.

JMS Selector for messages having an underscore in one header with Camel and Blueprint

1 Answers1