I have a simple webservice created with Netbeans 6.5 and deployed into 2 glassfish servers V2.1 and V3. The ws has a basic method GetInstanceID that I call 3 times from a client.
@WebService()
public class FirstWS {
private long m_instanceID = 0; //instance id
//Log
private void WriteLog(String cadena){
String msg = "";
DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss:SSS");
Date fecha = new Date();
msg = dateFormat.format(fecha) + " ***** " + this.getClass().getName() + " (m_instanceID=" + m_instanceID + "): " + cadena +
" " + "ThreadID=" + Thread.currentThread().getId() + " ThreadName=" + Thread.currentThread().getName();
Logger.getLogger(this.getClass().getName()).log(Level.INFO,msg);
}
//Constructor
public FirstWS() {
Random rnd = new Random();
m_instanceID = rnd.nextLong();
WriteLog("Executing Constructor");
}
//PostConstruct
@PostConstruct
public void ThisIsThePostConstruct() {
WriteLog("Executing PostConstruct");
}
//PreDestroy
@PreDestroy
public void ThisIsThePreDestroy() {
WriteLog("Executing PreDestroy");
}
//Method
@WebMethod(operationName = "GetInstanceID")
@WebResult(name="InstanceID")
public long GetInstanceID() {
//TODO write your implementation code here:
WriteLog("Executing GetInstanceID");
return m_instanceID;
}
}
I always though that web services were singleton by default.
On the glassfish V2.1 server the ws is working as expected, with a singleton lifecycle:
- Only one instance is created.
- Only one execution of constructor method.
- Only one execution if postconstructor method.
- Only one execution of predestroy method when ws is undeployed.
Client log
InstanceID = -4747957096764272596
InstanceID = -4747957096764272596
InstanceID = -4747957096764272596
Server log
26/08/2010 13:08:15:146 ***** first.test.FirstWS (m_instanceID=-4747957096764272596): Executing Constructor ThreadID=68 ThreadName=httpSSLWorkerThread-8080-0
26/08/2010 13:08:15:161 ***** first.test.FirstWS (m_instanceID=-4747957096764272596): Executing PostConstruct ThreadID=68 ThreadName=httpSSLWorkerThread-8080-0
26/08/2010 13:08:15:364 ***** first.test.FirstWS (m_instanceID=-4747957096764272596): Executing GetInstanceID ThreadID=69 ThreadName=httpSSLWorkerThread-8080-1
26/08/2010 13:08:15:380 ***** first.test.FirstWS (m_instanceID=-4747957096764272596): Executing GetInstanceID ThreadID=69 ThreadName=httpSSLWorkerThread-8080-1
26/08/2010 13:08:15:396 ***** first.test.FirstWS (m_instanceID=-4747957096764272596): Executing GetInstanceID ThreadID=69 ThreadName=httpSSLWorkerThread-8080-1
26/08/2010 13:08:38:849 ***** first.test.FirstWS (m_instanceID=-4747957096764272596): Executing PreDestroy ThreadID=626 ThreadName=Thread-540
But on the glassfish V3 server the ws isn’t working as expected, because a new instance of the ws is created for EVERY call to the GetInstanceID:
- One instance is created for every call.
- One execution of constructor method for every call.
- Two (!?!?!) executions of postconstructor method for every call.
- The predestroy method isn’t called when ws is undeployed.
Client log
InstanceId = 7754248300017958713
InstanceId = -1714184485890589231
InstanceId = -4156829683887899017
Server log
INFO: 26/08/2010 15:16:11:429 ***** first.test.FirstWS (m_instanceID=7754248300017958713): Executing Constructor ThreadID=103 ThreadName=http-thread-pool-8080-(2)
INFO: 26/08/2010 15:16:11:429 ***** first.test.FirstWS (m_instanceID=7754248300017958713): Executing PostConstruct ThreadID=103 ThreadName=http-thread-pool-8080-(2)
INFO: 26/08/2010 15:16:11:429 ***** first.test.FirstWS (m_instanceID=7754248300017958713): Executing PostConstruct ThreadID=103 ThreadName=http-thread-pool-8080-(2)
INFO: 26/08/2010 15:16:12:429 ***** first.test.FirstWS (m_instanceID=7754248300017958713): Executing GetInstanceID ThreadID=103 ThreadName=http-thread-pool-8080-(2)
INFO: 26/08/2010 15:16:12:460 ***** first.test.FirstWS (m_instanceID=-1714184485890589231): Executing Constructor ThreadID=102 ThreadName=http-thread-pool-8080-(1)
INFO: 26/08/2010 15:16:13:429 ***** first.test.FirstWS (m_instanceID=-1714184485890589231): Executing PostConstruct ThreadID=102 ThreadName=http-thread-pool-8080-(1)
INFO: 26/08/2010 15:16:13:429 ***** first.test.FirstWS (m_instanceID=-1714184485890589231): Executing PostConstruct ThreadID=102 ThreadName=http-thread-pool-8080-(1)
INFO: 26/08/2010 15:16:14:429 ***** first.test.FirstWS (m_instanceID=-1714184485890589231): Executing GetInstanceID ThreadID=102 ThreadName=http-thread-pool-8080-(1)
INFO: 26/08/2010 15:16:14:445 ***** first.test.FirstWS (m_instanceID=-4156829683887899017): Executing Constructor ThreadID=103 ThreadName=http-thread-pool-8080-(2)
INFO: 26/08/2010 15:16:15:429 ***** first.test.FirstWS (m_instanceID=-4156829683887899017): Executing PostConstruct ThreadID=103 ThreadName=http-thread-pool-8080-(2)
INFO: 26/08/2010 15:16:15:429 ***** first.test.FirstWS (m_instanceID=-4156829683887899017): Executing PostConstruct ThreadID=103 ThreadName=http-thread-pool-8080-(2)
INFO: 26/08/2010 15:16:15:429 ***** first.test.FirstWS (m_instanceID=-4156829683887899017): Executing GetInstanceID ThreadID=103 ThreadName=http-thread-pool-8080-(2)
INFO: Closing Metro monitoring root: amx:pp=/mon/server-mon[server],type=WSEndpoint,name=/FirstWebApplication-FirstWSService-FirstWSPort
So, why this behaviour on glassfish V3? How could I have a singleton web service on glassfish V3?
Finally I found the problem: the type of the project. In NetBeans I created the web service in a “Web Aplication” project so it was deployed into a servlet container in Glassfish and @Stateless and @Singleton annotations don’t work. You must create the ws in a “EJB Moule” project and it will be deployed into a EJB container so @Stateless and @Singleton annotations work correctly.
As Java EE 6 says “Singleton session beans offer similar functionality to stateless session beans but differ from them in that there is only one singleton session bean per application, as opposed to a pool of stateless session beans, any of which may respond to a client request. Like stateless session beans, singleton session beans can implement web service endpoints.”