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Subject: RE: Service Class as Singleton Class
Date: Mon, 30 Jun 2003 22:17:08 -0700
Message-ID: 
 <07EC20A3290A504EA73D914B4C08A48602720C69@usmail14.informatica.com>
Thread-Topic: Service Class as Singleton Class
Thread-Index: AcMkCXoykWbbCZL4TtmFLJp1kl6EkwbhtVUQ
From: "Agarwal, Naresh" <nagarwal@informatica.com>
To: <axis-dev@ws.apache.org>

Hi Aaron/Niket,

I believe you can tackle this problem by having your service class =
deployed in
"application" scope in AXIS.=20

Internally AXIS will make sure that only once instance of this service =
class would
serve all the request during the life time of Tomcat (or the servlet =
container used).

regards,
Naresh Agarwal

-----Original Message-----
From: Aaron Knauf [mailto:aknauf@xtra.co.nz]
Sent: Tuesday, May 27, 2003 10:06 AM
To: axis-dev@ws.apache.org
Subject: Re: Service Class as Singleton Class


The problem is that Axis instantiates and new service class instance=20
each time the service is invoked, using reflection to find the public=20
constructor.  It would be difficult to get Axis to cater for singletons, =

as the getInstance method could be called anything.

I found the instantiation of a new service class for each invocation to=20
be a problem, so I worked around it by implementing my service class as=20
a proxy to a singleton implementation class.  The wrapper gets=20
instantiated every time, but the class that implements all the logic is=20
only instantiated once.  This was to avoid expensive initialization code =

(such as starting up a pool of connections to a CORBA server) from being =

executed repeatedly, but it had the handy side effect of allowing me to=20
read in my config from the WSDD file in this wrapper, too, therby hiding =

the fact that the thing was running as a web service from the impl =
class.

Hope this helps.

Cheers

ADK

Niket Anand wrote:

> =20
>
>
>     Hello All,
>     I am newbie to Axis. I am facing problem as
>     java.lang.InstantiationException
>     =
<file:///C:/jdk1.3.1/docs/api/java/lang/InstantiationException.html>
>     exception when my service class is Singleton class and having
>     private constructor and getInstance() to get instance of this
>     class. When axis client ask for a method from the service class
>     then it throw this exception. If I remove the Singleton ability
>     and provide public constructor then it works fine. But I want it
>     to be remain Singleton . Please help me How to work with Service
>     class as Singleton and what modification needs to be done in wsdd.
>     =20
>     waiting for reply...
>     thanks,
>     Niket
>