6 Receiving Messages With Selectors
Version: 2.0.0.RC2
Table of Contents
6 Receiving Messages With Selectors
As mentioned in chapter 4 this plugin adds a service called jmsService to your application. In addition to the
methods already described in other chapters the jmsService has the following methods that can be used to receive a
selected message as a single operation without a Service Listener.The receiveSelected(destination, selector, timeout, jmsTemplateBeanName)
destinationAn instance of javax.jms.Destination , javax.jms.Topic , a String or a Map .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:// Expect/Receive a message with a *selector* on a literal queue waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. jmsService.receiveSelected(queue: "aQueue", selector, timeout, "standard") // Expect/Receive a message with a *selector* on a literal topic waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. jmsService.receiveSelected(topic: "aTopic", selector, timeout, "standard") // Expect/Receive a message with a *selector* on the queue '«appname».person' waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. jmsService.receiveSelected(service: "person", selector, timeout, "standard")// Expect/Receive a message with a *selector* on the queue '«appname».person.doIt' waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. jmsService.receiveSelected(service: "person", method: "doIt", selector, timeout, "standard") // Expect/Receive a message with a *selector* on the queue 'remote.person.doIt' waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. jmsService.receiveSelected(app: "remote", service: "person", method: "doIt", selector, timeout, "standard")
References
JavaEE 1.3 javax.jms.MessageActiveMq SelectorsIBM Guide on Selectors timeoutA long value that specifies the amount of milliseconds that this call should wait until desisting and returning null .
jmsTemplateNameThe 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").There are variations of the receiveSelected() method for convenience...receiveSelected() method variants
jmsService.receiveSelected(destination, selector) // use the default timeout and standard template
jmsService.receiveSelected(destination, selector, timeout) // use the standard templateSpecifying a timeout through configuration or the template.
If no timeout is specified the JmsService uses a 500 millisecond timeout. You can also specify a timeout through the Config.groovy file.
//Specifying a 100 milliseconds timeout jms.receiveTimeout=100l
JmsTemplate through its receiveTimeout attribute.Note: Both timeouts will be ignored if set to zero, the only way of setting a zero timeout would be by passing such timeout as an argument to the call.The receiveSelectedAsync(destination, selector, timeout, jmsTemplateBeanName)
This methods provides a variant to the receiveSelected method, the difference is that this method will execute the request asynchronously by wrapping a call to the
receiveSelected within an Executor Service (see java.util.concurrent.ExecutorService in your JDK API 1.5+ ).Some examples..
// Expect/Receive a message with a *selector* on a literal queue waiting up to the given *timeout*. // Will return a java.util.concurrent.Future that holds the result of the asynchronous execution. java.util.concurrent.Future afuture = jmsService.receiveSelectedAsync(queue: "aQueue", selector, timeout, "standard")// Expect/Receive a message with a *selector* on a literal topic waiting up to the given *timeout*. // Will return a java.util.concurrent.Future that holds the result of the asynchronous execution. java.util.concurrent.Future afuture = jmsService.receiveSelectedAsync(topic: "aTopic", selector, timeout, "standard")
6.1 Receiving Methods Added To Controllers And Services
The methods described below are not supported in the current 2.0.0 milestone but will be added soon.The plugin will inject the following methods to
Conrollers and Services .Synchronous calls.
// Expect/Receive a message with a *selector* on a literal queue waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. def msg =receiveSelectedJMSMessage(queue: "aQueue", selector, timeout, "standard") // Expect/Receive a message with a *selector* on a literal topic waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. def msg =receiveSelectedJMSMessage(topic: "aTopic", selector, timeout, "standard") // Expect/Receive a message with a *selector* on the queue '«appname».person' waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. def msg =receiveSelectedJMSMessage(service: "person", selector, timeout, "standard")// Expect/Receive a message with a *selector* on the queue '«appname».person.doIt' waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. def msg =receiveSelectedJMSMessage(service: "person", method: "doIt", selector, timeout, "standard") // Expect/Receive a message with a *selector* on the queue 'remote.person.doIt' waiting up to the given *timeout*. // Will return the converted message or null if the message was not available. def msg = receiveSelectedJMSMessage(app: "remote", service: "person", method: "doIt", selector, timeout, "standard")
Asynchronous calls.
// Expect/Receive a message with a *selector* on a literal queue waiting up to the given *timeout*. // Will return a java.util.concurrent.Future wrapping the result the task. def afuture = receiveSelectedAsyncJMSMessage(queue: "aQueue", selector, timeout, "standard") // Expect/Receive a message with a *selector* on a literal topic waiting up to the given *timeout*. // Will return a java.util.concurrent.Future wrapping the result the task. def afuture = receiveSelectedAsyncJMSMessage(topic: "aTopic", selector, timeout, "standard") // Expect/Receive a message with a *selector* on the queue '«appname».person' waiting up to the given *timeout*. // Will return a java.util.concurrent.Future wrapping the result the task. def afuture = receiveSelectedAsyncJMSMessage(service: "person", selector, timeout, "standard")// Expect/Receive a message with a *selector* on the queue '«appname».person.doIt' waiting up to the given *timeout*. // Will return a java.util.concurrent.Future wrapping the result the task. def afuture = receiveSelectedAsyncJMSMessage(service: "person", method: "doIt", selector, timeout, "standard") // Expect/Receive a message with a *selector* on the queue 'remote.person.doIt' waiting up to the given *timeout*. // Will return a java.util.concurrent.Future wrapping the result the task. def afuture = receiveSelectedAsyncJMSMessage(app: "remote", service: "person", method: "doIt", selector, timeout, "standard")
Specifying your own Executor for Async. Receivers using Spring IoC.
beans = {
jmsAsyncReceiverExecutor( java.util.concurrent.Executors ) { executors ->
executors.factoryMethod = "newFixedThreadPool"
executors.constructorArgs = [ 5 ]
}
}