I really like the thread-pooling API (in java.util.concurrent package), especially when you are hitting x number of API dealing with outside network to fetch information for a single request.
Example: A website dealing with some kind of ticket booking service and there are 4 different vendors (sources where you retrieve ticket status from).

Classes you need to import.

import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors
import java.util.concurrent.Callable
import java.util.concurrent.Executors
import java.util.concurrent.TimeUnit
import java.util.concurrent.Future

I am discussing it here in a very simple Groovish manner.

def myClosure = {num -> println "I Love Groovy ${num}"}
def threadPool = Executors.newFixedThreadPool(4)
 try {
  List<Future> futures = (1..10).collect{num->
    threadPool.submit({->
    myClosure num } as Callable);
  }
  // recommended to use following statement to ensure the execution of all tasks.
  futures.each{it.get()}
}finally {
  threadPool.shutdown()
}

In the above example, thread pool size is 4, that means concurrent 4 tasks would be executed in a single go. And task is the code in ‘myClosure’.

Let’s say you rely on output from tasks. Then you need to do something like following

 Collection results = futures.collect{it.get()}

Salil Kalia
salil [at] intelligrape [dot] com

It’s common requirement when we work on some portal – we need to provide support for various languages.
messages.properties/ResourceBundle is out of the scope of this post. Here I am just mentioning –

how to switch to a different language taking an advantage of GRAILS

On your view (gsp) page add following -

<%
String targetUri = (request.forwardURI - request.contextPath)
%>
 <g:link controller="lang" action="lang" params="[lang: 'en', targetUri: targetUri]">English</g:link>
 <g:link controller="lang" action="lang" params="[lang: 'fr', targetUri: targetUri]">French</g:link>
 <g:link controller="lang" action="lang" params="[lang: 'es', targetUri: targetUri]">Spanish</g:link>
.....
.....

I just wanted to give you a rough idea. But you can create a custom tag for this – depending upon your requirement.



Now the trick here is to send parameter with name “lang”. And GRAILS automatically recognizes it and set locale itself.
Following is the code at server side (controller/action).

//import org.springframework.context.i18n.LocaleContextHolder
//import org.springframework.web.servlet.support.RequestContextUtils as RCU;
 
class LangController {
def lang = {
       String targetUri = params.targetUri ? params.targetUri : "/"
       // String language = params.lang ? params.lang : 'en'
       // LocaleContextHolder.setLocale(new Locale(language))
       // RCU.getLocaleResolver(request).setLocale(request, response, new Locale(language))
       redirect(uri: targetUri)
}
}

If you notice above, I have commented out few lines (with the help of grails internal implementation, we need to do nothing explicitly to switch to a different language).

So in SINGLE LINE:

Base URL: http://example.com/cont/act/id  <!--Grails will use "messages.properties" now -->
Locale specific URL: http://example.com/cont/act/id?lang=fr <!--Grails will use "messages_fr.properties" now -->

Hope it helps!
Salil Kalia