Re: Class Reloading in Weblogic 6.1 - Using Struts 1.1 b2

[David Graff]

Re: Class reloading error in Tomcat on Sun Solaris

[Demon]

>  I try to use Tomcat 4.0.2 with Struts 1.0.2 on Sun Solaris. After I
upload
> new Form class or Action class (without tomcat shutdowning) the errore
> occure: "javax.servlet.ServletException: Parsing error processing resource
> path /WEB-INF/struts-config.xml" or "javax.servlet.ServletException:
Cannot
> find ActionMappings or ActionFormBeans collection" or so on.
>   Reloading of application, Start/Stop of application, Removing/Deploing
of
> application affect no results.
>
>   This problem no appeare on Windows NT 4.0.

I had a similar thing which I fixed by reading the log files.  It turned out
that my Ant build.xml
file was no longer deploying some third party jars, although I had them in a
Tomcat common/lib
directory on the Windows NT machine (so that hid the problem).

Check the logs!

Guy.


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Re: Class reloading error in Tomcat on Sun Solaris

[keithBacon]

You can't complain then! If you are running multiple live web-apps on Tomcat
you are pushing your luck! Maybe you need a commercial server. The more you pay
the more flexible the operational environment (I would hope!!).

--- Struts Newsgroup <[EMAIL PROTECTED]> wrote:
> Subject: Re: Class reloading error in Tomcat on Sun Solaris
> From: "Denis A.Vishniakov" <[EMAIL PROTECTED]>
>  ===
> 
> > Are you saying restarting the server doesn't make it go away?
> 
>   Restart of Tomcat is the only way to restore work of the application.
>   After restarting application work until I upload a new Form or Action
> class...
>   But restaring is undesirable because it is too long and I have
> others application on Tomcat than must still work anytime.
> 
> > I get this sort of thing after recompiling & have to restart Tomcat (on
> Win98).
> > As I understand I shouldn't have to.
> 
>   Whether there is other way of the decision of a problem?
> 
>   Denis A.Vishniakov
> 
> 
> 
> 
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Re: Class reloading error in Tomcat on Sun Solaris

[@Basebeans.com]

Subject: Re: Class reloading error in Tomcat on Sun Solaris
From: "Denis A.Vishniakov" <[EMAIL PROTECTED]>
 ===

> Are you saying restarting the server doesn't make it go away?

  Restart of Tomcat is the only way to restore work of the application.
  After restarting application work until I upload a new Form or Action
class...
  But restaring is undesirable because it is too long and I have
others application on Tomcat than must still work anytime.

> I get this sort of thing after recompiling & have to restart Tomcat (on
Win98).
> As I understand I shouldn't have to.

  Whether there is other way of the decision of a problem?

  Denis A.Vishniakov




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Re: Class reloading error in Tomcat on Sun Solaris

[keithBacon]

Heavens - don't let Bill Gates find out about this. He'll start crowing. Win NT
beats Solaris - oh dear.
Are you saying restarting the server doesn't make it go away?
I get this sort of thing after recompiling & have to restart Tomcat (on Win98).
As I understand I shouldn't have to.


--- Struts Newsgroup <[EMAIL PROTECTED]> wrote:
> Subject: Class reloading error in Tomcat on Sun Solaris
> From: "Denis A.Vishniakov" <[EMAIL PROTECTED]>
>  ===
> 
>   Hello!
> 
>   I try to use Tomcat 4.0.2 with Struts 1.0.2 on Sun Solaris. After I upload
> new Form class or Action class (without tomcat shutdowning) the errore
> occure: "javax.servlet.ServletException: Parsing error processing resource
> path /WEB-INF/struts-config.xml" or "javax.servlet.ServletException: Cannot
> find ActionMappings or ActionFormBeans collection" or so on.
>   Reloading of application, Start/Stop of application, Removing/Deploing of
> application affect no results.
> 
>   This problem no appeare on Windows NT 4.0.
> 
>   Can You help me?
> 
>   WBR, Denis A.Vishniakov.
> 
> 
> 
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> To unsubscribe, e-mail:   
> For additional commands, e-mail: 
> 


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Re: Class reloading?

[Craig R. McClanahan]

Johan Compagner wrote:

> > Tomcat 3.1 and 3.2 seem to reliably detect cases where the servlet class
> > you are actually calling has been changed, but they do not always seem
> > to catch the fact that other classes have been changed.
> >
> > Tomcat 4.0 uses a different mechanism that reliably catches *all*
> > changes to classes found in WEB-INF/classes.
>
> But that is not needed.
> It is nice in a development environment but what happens if i update de war file
> Is that detected and is it automaticly being extracted ect ect?
>

For updating a production app, Tomcat 3.x includes an "admin" application and Tomcat
4.0 includes a "manager" application that can be used to shut down the previous
version of a web app, and bring up a new one, without restarting Tomcat.  Neither
version of Tomcat currently does this automatically (and there are some JDK problems
that make replacing an existing JAR file harder than it should be).

>
> That is what's needed if you use tomcat for deployment also (in combo with apache)
>
> johan

Craig

Re: Class reloading?

[Johan Compagner]

> Tomcat 3.1 and 3.2 seem to reliably detect cases where the servlet class
> you are actually calling has been changed, but they do not always seem
> to catch the fact that other classes have been changed.
> 
> Tomcat 4.0 uses a different mechanism that reliably catches *all*
> changes to classes found in WEB-INF/classes.

But that is not needed. 
It is nice in a development environment but what happens if i update de war file
Is that detected and is it automaticly being extracted ect ect?

That is what's needed if you use tomcat for deployment also (in combo with apache)

johan

Re: Class reloading?

[Craig R. McClanahan]

David Winterfeldt wrote:

> Do all version of Tomcat do this?
>

In theory.

Tomcat 3.1 and 3.2 seem to reliably detect cases where the servlet class
you are actually calling has been changed, but they do not always seem
to catch the fact that other classes have been changed.

Tomcat 4.0 uses a different mechanism that reliably catches *all*
changes to classes found in WEB-INF/classes.

In all versions, the application reload only occurs if the changed class
had in fact been used by the application already.  If it hasn't been
loaded yet, there is no reason to restart the app, because no old
version of the class needs to be thrown away.

>
> David
>

Craig


>
> --- "Craig R. McClanahan"
> <[EMAIL PROTECTED]> wrote:
> > Ned Seagoon wrote:
> >
> > > Hi guys,
> > >
> > > Just wondering about the situation that arises
> > when an Action class is
> > > changed in a running struts environment.
> > >
> > > I was under the impression that a single instance
> > of an action class is
> > > created and run inside multiple threads, yet if I
> > recompile the class and
> > > re-run the action then those changes are
> > reflected.
> > >
> > > Is this peculiar to VisualAge for Java (which I am
> > running under) or does
> > > this happen in every environment?
> > >
> > > Actually, this applies to all classes in a project
> > - can I just change them
> > > at will or do I need to do something more?
> > >
> > > Doesn't Tomcat use a special class loader to
> > reload changed servlet classes?
> > >
> > >
> >
> > Tomcat uses a special class loader, but it is global
> > to the entire web
> > app
> > rather than local to a particular class.  When
> > Tomcat recognizes that
> > you have
> > changed a class, it reloads the entire app
> > (destroying the old servlets,
> > initializing the new ones) and even saves your
> > sessions and session
> > attributes
> > if they implement Serializable.
> >
> > This capability is a feature of Tomcat that is
> > commonly implemented, but
> > it's
> > not in the servlet spec.
> >
> > > Regards
> > > Ned
> > >
> >
> > Craig
>
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Re: Class reloading?

[David Winterfeldt]

Do all version of Tomcat do this?

David

--- "Craig R. McClanahan"
<[EMAIL PROTECTED]> wrote:
> Ned Seagoon wrote:
> 
> > Hi guys,
> >
> > Just wondering about the situation that arises
> when an Action class is
> > changed in a running struts environment.
> >
> > I was under the impression that a single instance
> of an action class is
> > created and run inside multiple threads, yet if I
> recompile the class and
> > re-run the action then those changes are
> reflected.
> >
> > Is this peculiar to VisualAge for Java (which I am
> running under) or does
> > this happen in every environment?
> >
> > Actually, this applies to all classes in a project
> - can I just change them
> > at will or do I need to do something more?
> >
> > Doesn't Tomcat use a special class loader to
> reload changed servlet classes?
> >
> >
> 
> Tomcat uses a special class loader, but it is global
> to the entire web
> app
> rather than local to a particular class.  When
> Tomcat recognizes that
> you have
> changed a class, it reloads the entire app
> (destroying the old servlets,
> initializing the new ones) and even saves your
> sessions and session
> attributes
> if they implement Serializable.
> 
> This capability is a feature of Tomcat that is
> commonly implemented, but
> it's
> not in the servlet spec.
> 
> > Regards
> > Ned
> >
> 
> Craig


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Re: Class reloading?

[Craig R. McClanahan]

Ned Seagoon wrote:

> Hi guys,
>
> Just wondering about the situation that arises when an Action class is
> changed in a running struts environment.
>
> I was under the impression that a single instance of an action class is
> created and run inside multiple threads, yet if I recompile the class and
> re-run the action then those changes are reflected.
>
> Is this peculiar to VisualAge for Java (which I am running under) or does
> this happen in every environment?
>
> Actually, this applies to all classes in a project - can I just change them
> at will or do I need to do something more?
>
> Doesn't Tomcat use a special class loader to reload changed servlet classes?
>
>

Tomcat uses a special class loader, but it is global to the entire web
app
rather than local to a particular class.  When Tomcat recognizes that
you have
changed a class, it reloads the entire app (destroying the old servlets,
initializing the new ones) and even saves your sessions and session
attributes
if they implement Serializable.

This capability is a feature of Tomcat that is commonly implemented, but
it's
not in the servlet spec.

> Regards
> Ned
>

Craig