RE: Tomcat + Apache lifecycle question
Hi, -Original Message- From: Daniel Drasin [mailto:[EMAIL PROTECTED]] Sent: Friday, February 08, 2002 3:37 PM To: Tomcat Users List Subject: Tomcat + Apache lifecycle question I've set up Tomcat 4.x to work with Apache 1.3.x using the Warp connector stuff. I followed the standard instructions for how to modify the httpd.conf file of apache, etc. (All pretty straightforward...) My problem is that i need to have a certain activity occur when Tomcat starts up. This activity is to initialize a certain set of java objects and make them available to servlets. Because of classpath issues (i.e. classloaders) i was unable to use the lifecycle hooks of the contexts and had to settle for the (hackish) method of making a dummy servlet that only exists to have its load-on-startup value set (excerpt from the web.xml is below). This servlet has an init() definition that initializes the objects in question (example definition below.) The issue is that i need to have this activity occur once and only once - so i add a static flag into the init method to see if it's already run. However, this doesn't work. When i start tomcat, the initialization code runs and when i start apache, it runs again - despite the flag. (Output included below). My guess is that the flag doesn't help because these init() calls are occuring in two different object spaces (class loaders) so the flag really is false both times. So my question is - what's going on here. Fundamentally, how can i achieve my goal outlined in paragraph 1. At a deeper level, my question is - why do i get two calls to startup? Well, AFAIK yes. But by default there are two Services. Standalone and Apache-Tomcat. So, you either have to choose one of them (since they're really different) or try to use JNDI for that purpose. Is tomcat starting a new context for apache? If so, why doesn't it use the one that it's already started? Is there a way to surpress the starting of one of the contexts? Any help is appreciated Dan Anton -- To unsubscribe: mailto:[EMAIL PROTECTED] For additional commands: mailto:[EMAIL PROTECTED] Troubles with the list: mailto:[EMAIL PROTECTED]
Re: Tomcat + Apache lifecycle question
Daniel Drasin a écrit :
I've set up Tomcat 4.x to work with Apache 1.3.x using the
Warp connector stuff. I followed the standard instructions for
how to modify the httpd.conf file of apache, etc. (All pretty
straightforward...) My problem is that i need to have a certain
activity occur when Tomcat starts up. This activity is to initialize
a certain set of java objects and make them available to servlets.
Because of classpath issues (i.e. classloaders) i was unable to use
the lifecycle hooks of the contexts and had to settle for the
(hackish) method of making a dummy servlet that only exists to
have its load-on-startup value set (excerpt from the web.xml is
below). This servlet has an init() definition that initializes the
objects in question (example definition below.)
The issue is that i need to have this activity occur once and only
once - so i add a static flag into the init method to see if it's
already run. However, this doesn't work. When i start tomcat,
the initialization code runs and when i start apache, it runs
again - despite the flag. (Output included below).
My guess is that the flag doesn't help because these init() calls
are occuring in two different object spaces (class loaders) so the
flag really is false both times.
So my question is - what's going on here. Fundamentally, how can
i achieve my goal outlined in paragraph 1. At a deeper level, my
question is - why do i get two calls to startup? Is tomcat starting
a new context for apache? If so, why doesn't it use the one that
it's already started? Is there a way to surpress the starting of
one of the contexts?
Any help is appreciated
Dan
-CODE AND OUTPUT---
...
servlet
servlet-name
ServletTest
/servlet-name
servlet-class
ServletTest
/servlet-class
load-on-startup0/load-on-startup
...
...
public class ServletTest extends HttpServlet {
static int i = 0;
static boolean flag = false;
static {
i++;
if(!flag) {
flag = true;
System.out.println(***GOT + i + **);
}
}
...
...
Starting service Tomcat-Standalon
Apache Tomcat/4.0.1
***GOT 1 **
delete this service ( everything in the right Service section ) from
server.xml
hope this helps
Starting service Tomcat-Apache
Apache Tomcat/4.0.1
***GOT 1 **
...
--
Daniel Drasin Applied Reasoning
[EMAIL PROTECTED] 8612 Long Meadow Ct.
(410)-461-6168 Columbia, MD, 21045
http://www.appliedreasoning.com
--
To unsubscribe: mailto:[EMAIL PROTECTED]
For additional commands: mailto:[EMAIL PROTECTED]
Troubles with the list: mailto:[EMAIL PROTECTED]
--
Julien OIX
Service Informatique de Gestion
Tél: 02 40 99 83 65
mail: [EMAIL PROTECTED]
--
To unsubscribe: mailto:[EMAIL PROTECTED]
For additional commands: mailto:[EMAIL PROTECTED]
Troubles with the list: mailto:[EMAIL PROTECTED]
RE: Tomcat + Apache lifecycle question
To achieve what you're trying to do, use the Singleton Pattern. I have used
it successfully. In the init method, have a class with a private constructor
and a public static synchronized method that creates an instance of the
class and creates and stores the objects in the context. But remember that
before creating the objects, first check to make sure that they do not exist
in the context. If they do, just return from the method.
I have not encountered situations where init is called more than once.
Tomcat 4.x complies to both the Servlet 2.3 and JSP 1.2 specifications.
Those specifications stipulate that init should be called only once. Since
Tomcat is Sun's (Microsystems) reference implementation for the Servlet and
JSP specs, it duly conforms.
Hope this is helpful.
Charles
-Original Message-
From: Julien OIX [mailto:[EMAIL PROTECTED]]
Sent: Friday, February 08, 2002 9:13 AM
To: Tomcat Users List
Subject: Re: Tomcat + Apache lifecycle question
Daniel Drasin a écrit :
I've set up Tomcat 4.x to work with Apache 1.3.x using the
Warp connector stuff. I followed the standard instructions for
how to modify the httpd.conf file of apache, etc. (All pretty
straightforward...) My problem is that i need to have a certain
activity occur when Tomcat starts up. This activity is to initialize
a certain set of java objects and make them available to servlets.
Because of classpath issues (i.e. classloaders) i was unable to use
the lifecycle hooks of the contexts and had to settle for the
(hackish) method of making a dummy servlet that only exists to
have its load-on-startup value set (excerpt from the web.xml is
below). This servlet has an init() definition that initializes the
objects in question (example definition below.)
The issue is that i need to have this activity occur once and only
once - so i add a static flag into the init method to see if it's
already run. However, this doesn't work. When i start tomcat,
the initialization code runs and when i start apache, it runs
again - despite the flag. (Output included below).
My guess is that the flag doesn't help because these init() calls
are occuring in two different object spaces (class loaders) so the
flag really is false both times.
So my question is - what's going on here. Fundamentally, how can
i achieve my goal outlined in paragraph 1. At a deeper level, my
question is - why do i get two calls to startup? Is tomcat starting
a new context for apache? If so, why doesn't it use the one that
it's already started? Is there a way to surpress the starting of
one of the contexts?
Any help is appreciated
Dan
-CODE AND OUTPUT---
...
servlet
servlet-name
ServletTest
/servlet-name
servlet-class
ServletTest
/servlet-class
load-on-startup0/load-on-startup
...
...
public class ServletTest extends HttpServlet {
static int i = 0;
static boolean flag = false;
static {
i++;
if(!flag) {
flag = true;
System.out.println(***GOT + i + **);
}
}
...
...
Starting service Tomcat-Standalon
Apache Tomcat/4.0.1
***GOT 1 **
delete this service ( everything in the right Service section ) from
server.xml
hope this helps
Starting service Tomcat-Apache
Apache Tomcat/4.0.1
***GOT 1 **
...
--
Daniel Drasin Applied Reasoning
[EMAIL PROTECTED] 8612 Long Meadow Ct.
(410)-461-6168 Columbia, MD, 21045
http://www.appliedreasoning.com
--
To unsubscribe: mailto:[EMAIL PROTECTED]
For additional commands: mailto:[EMAIL PROTECTED]
Troubles with the list: mailto:[EMAIL PROTECTED]
--
Julien OIX
Service Informatique de Gestion
Tél: 02 40 99 83 65
mail: [EMAIL PROTECTED]
--
To unsubscribe: mailto:[EMAIL PROTECTED]
For additional commands: mailto:[EMAIL PROTECTED]
Troubles with the list: mailto:[EMAIL PROTECTED]
--
To unsubscribe: mailto:[EMAIL PROTECTED]
For additional commands: mailto:[EMAIL PROTECTED]
Troubles with the list: mailto:[EMAIL PROTECTED]
