(Quick Reference)

7 Browsing Messages In A Queue

Version: 2.0.0.RC2

7 Browsing Messages In A Queue

If you are looking on ways to obtain the contents of a given javax.jms.Queue without changing its state the JmsService offers a set of methods designed for this task.

The browse(destination, jmsTemplateName, browserCallback) method.

Will retrieve all messages inside the given queue at that time without changing its state i.e messages will not be consumed. This method will convert the javax.jms.Message using the JmsTemplate . If you need the javax.jms.Message you should use the browseNoConvert() method and its variants as described further on.

destination

An instance of javax.jms.Queue , a String or a Map . Needs to be a queue .

A String destination argument will be interpreted as the name of a destination queue .

A Map destination argument can be used in the following ways:

// browse literal queue
List messages = jmsService.browse(queue: "aQueue", "standard", null)// browse the queue '«appname».person'
List messages = jmsService.browse(service: "person", "standard", null)
// browse the queue '«appname».person.doIt'
List messages = jmsService.browse(service: "person", method: "doIt", "standard", null)
// browse the queue 'remote.person.doIt'
List messages = jmsService.browse(app: "remote", service: "person", method: "doIt", "standard", null)

jmsTemplateName

The name of the template that should be used to send the message. If this value is null , the standard template will be used (called "standard").

browserCallback

An optional closure that can be used to "process" the message before being added to the returning message list. The value returned by this callback will be the one added to the returning list if such value is not null.

browse() method variants

There are variations of the browse() method for convenience...

List messages = jmsService.browse(queue)List messages = jmsService.browse(queue, browserCallback)
List messages = jmsService.browse(queue, jmsTemplateBeanName)

The browseNoConvert(destination, jmsTemplateName, browserCallback) method.

This method will not convert the javax.jms.Message . In other words the browserCallback:Closure will receive a javax.jms.Message or if no callback is defined a list containing javax.jms.Message instances will be returned. You can't update the returned javax.jms.Message objects, they are read-only instances.

List messages = jmsService.browseNoConvert(queue)//You can do the following to filter messages or use a selector through the browseSelected* methods
List messages = jmsService.browseNoConvert(queue){ javax.jms.Message msg ->
    ( msg.getStringProperty('aproperty') ? msg : null )
}
List messages = jmsService.browseNoConvert(queue, jmsTemplateBeanName)
messages.each {
    assert it instanceof javax.jms.Message
}

The browseSelected(destination, selector, jmsTemplateName, browserCallback) method.

Will retrieve messages that match the selector inside the given queue at the time of the call without changing its state i.e messages will not be consumed. This method will convert the javax.jms.Message using the JmsTemplate . If you need the javax.jms.Message you should use the browseSelectedNotConvert() method and its variants as described further on.

selector

This is the message selector as described by the JMS Specification. In a nutshell a message selector lets a client specify a statement, which is similar to an SQL92 statement, that will be used to filter messages through the values of their message headers and message properties. "Only messages whose header and property values match the selector are delivered". As described in the JMS Specification what it means for a message not to be delivered depends on the MessageConsumer being used. It is important to mention that the selectors can only access header or properties but will not be able to access any message body values.

List messages = jmsService.browseSelected(queue, " anIntProperty > 0 AND anotherProperty='a Value'")//filtering through body content.
List messages = jmsService.browseSelected(queue, " anIntProperty > 0 AND anotherProperty='a Value'"){
    ( msg == 'avalue' ?: null )
}
List messages = jmsService.browseSelected(queue, " anIntProperty > 0 AND anotherProperty='a Value'", jmsTemplateBeanName)

The browseSelectedNotConvert(destination, selector, jmsTemplateName, browserCallback) method.

Will retrieve messages that match the selector inside the given queue at the time of the call without changing its state i.e messages will not be consumed. As the browseNoConvert this method will not convert the javax.jms.Message .

List messages = jmsService.browseSelectedNotConvert(queue, " anIntProperty > 0 AND anotherProperty='a Value'")List messages = jmsService.browseSelectedNotConvert(queue, " anIntProperty > 0 AND anotherProperty='a Value'"){ javax.jms.Message msg ->
    return msg.JMSCorrelationID
}
List messages = jmsService.browseSelectedNotConvert(queue, " anIntProperty > 0 AND anotherProperty='a Value'", jmsTemplateBeanName)
messages.each {
    assert it instanceof javax.jms.Message
}

<< 6Receiving Messages With Selectors

8Message Conversion >>