Re: Strange Error

[Randall R Schulz]

Rob,

If you don't want to use a better browser, you should at least reconfigure 
your IE to give you more complete and accurate error mesages. I'm sure the 
method varies from version to version of Windows and IE, but I'll tell you 
how it's done on Win2K Pro with IE 6:

Open your "Internet Properties" control panel. This can be done in the 
"Control Panel" folder in a Windows Explorer windo or via the "Control 
Panel" sub-menu in your system's "Start" menu.

Once you have the "Internet Properties" control panel open, switch to the 
"Advanced" tab (the right-most one). Look for the option "Show friendly 
HTTP error messages" and disable it. What's friendly to a real person is 
not necessarily friendly to a S/W developer...

If that doesn't disclose enough information to solve the problem, report 
back with more detailed error messages.

By the way, if you're developing software for general public release or for 
release to a user community not under some sort of single-browser dictate, 
you should test your software with a variety of browsers. I use Netscape 
4.7x, Mozilla and Opera and IE. That's a rather minimal set, actually. For 
Mac users, there's iCab, too and in general there's a larger set of 
browsers than many people realize. At least test on a few unless you know 
your user community is using a restricted set of browsers.

Good luck.

Randall Schulz


At 19:17 2002-09-05, Rob Grundel wrote:
>Hi,
>
>I am having a very strange error @ the moment where I can access a servlet
>on Tomcat (4.0.4 Standalone on WinNT) by directly typing the address of the
>servlet into a web browser however if I access the servlet as a form
>processor (action on a form) the browser tells me that "The page cannot be
>displayed." (standard IE error)
>
>I have checked everything in the web.xml file over and over again. Has
>anybody else had this problem. Is it to do with host names. Please get back
>to me quickly. It is kind of urgent.
>
>Cheers
>
>Rob Grundel
>Software Engineer
>Pitt & Sherry IT
>[EMAIL PROTECTED]
>ph: (03) 63231931
>mob ph: 0417762243
>
>
>
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Re: JAVA PROCESS

[Randall R Schulz]

Ángel,

I assume no other Java programs are running and that all 36 of the entries 
you're seeing in the "ps" output are from Catalina. This implies that 36 
threads have been created by Catalina. Under Linux, each thread shows up 
separately in the ps listing.

On my Windows system (Win 2K, Tomcat 4.0.4, J2 SDK 1.4.0_01) merely 
starting Tomcat causes 30 threads to be created, corresponding to the six 
configured connectors each with a "minProcessors=" attribute of 5. Check 
your ".../conf/server.xml" file for  elements and add up all the 
minProcessors= attributes. That should be your 36.

If the number grows and stays up even when there are no requests being 
processed, it might be a sign of a problem. If the number fluctuates but 
returns to 36 when Tomcat is again idle, then things are OK.

Randall Schulz
Mountain View, CA USA


At 17:28 2002-09-02, you wrote:
>Hi all:
>
>When I start catalina in Linux, I type:
>
>ps aux |grep java
>
>And The system has 36 java process but the java process grows...
>
>Can you help me, please?
>
>Is it normal?
>
>Thank you very much.
>
>
>Ángel


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Re: Tomcat 4.0.4 under Windows NT crashes: "memory cannot be read"

[Randall R Schulz]

Jocelyn,

I didn't read enough or carefully enough.


You really ought to get a more up-to-date version of the JRE or SDK. I 
recommend 1.4.0_01 or 1.3.1, but using 1.2 at this point is not a good idea.


By the way, how do you (or your colleague) you get Tomcat to run as a 
service? Via Apache?

Are you certain that it's the Tomcat process that's crashing? Your 
diagnostic didn't include the application name that is (I believe) in the 
window title of the alert whose contents you reported. Is it "java.exe" or 
something else?


Randall Schulz
Mountain View, CA USA


At 23:59 2002-08-31, you wrote:
>
>
>My system: Tomcat 4.0.4 is running stand-alone on Windows NT 4 (service
>pack 3); starting it by invoking Tomcat's startup.bat from a DOS window.
>My Java is Sun's "Classic VM (build JDK-1.2-V, native threads)". Machine
>is a 64 MB Dell Latitude.
>
>My colleague's system is a new Sony Vaio running Windows XP, same version
>of Tomcat, also a Sun JVM but probably a slightly newer one. Tomcat
>running as a service...
>
>Jocelyn Paine


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Re: Tomcat 4.0.4 under Windows NT crashes: "memory cannot be read"

[Randall R Schulz]

Jocelyn,

That's not a Tomcat problem.

The diagnostic you're seeing is indicative of a problem in the JVM or a 
native library or of some flaw external to the whole Tomcat / JVM complex 
(hardware or driver, e.g.). Short of a bug in the bytecode interpreter, the 
JIT translator or other code running as native instructions within the 
JVM's address space, this cannot happen.

Thus the problem is by definition not Tomcat, since Tomcat is 100% Java. 
Even if only Tomcat triggers the symptom, it cannot be a problem in the 
Tomcat code. Such a bug would produce misbehavior (non-compliant with the 
pertinent specs) and / or an inappropriate or unhandled Java exception, 
possibly even abortive shutdown of Tomcat as a whole, but not a low-level 
fault such as you've reported.

You should consider driver bugs (network driver, e.g.) or bugs in the 
platform's native (JNI) libraries or corrupted files containing code that 
is activated when you run Tomcat.

You should also consider hardware problems. Run a RAM diagnostic at the 
very least (check out MemTest86--it's good and mature. Get the latest 
release, especially if you have a P4-based system).

Good luck.

Randall Schulz
Mountain View, CA USA


At 23:59 2002-08-31, Jocelyn Paine wrote:
>I'm using Tomcat for Java and JSP in a large server-side application under
>NT4. Most of it works fine, but in a few parts of the application, Tomcat
>crashes:
>   Application Error. The instruction at ""
>   referenced memory at "". The memory cannot be read.
>
>...
>
>Jocelyn Paine


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Re: Simple WAR files

[Randall R Schulz]

James,

At 08:49 2002-08-30, you wrote:
>-BEGIN PGP SIGNED MESSAGE-
>Hash: SHA1
>
>On Fri, Aug 30, 2002 at 11:41:19AM -0400, Wagoner, Mark wrote:
> > I would use an IDE like Netbeans or Forte to get started.  It will do most
> > of this for you, including packaging the entire app into a WAR file.
>
>no offense but i recommend /not/ doing this.  the ide's do a lot of
>stuff behind the scenes that you may not understand.  if you really
>want to understand the process, do it manually.  once you can do
>simple things manually, you can switch to an ide because you now know
>what the ide is doing under the covers.


I agree with Peter. Learn the ins and outs of Web App configuration first 
and later you can rely on automation to relieve you of the burden.

Besides, you  might be surprised with the simplicity of a web.xml file, 
especially if you have only JSP pages. Here's the web.xml file I'm 
currently using (for a project that's still quite young). It includes a 
custom tag library:

-==--==-


http://java.sun.com/dtd/web-app_2_3.dtd";>



 
 /tau-web-elements
 /WEB-INF/TWE.tld
 


-==--===-

No big deal, eh? If I didn't have the custom tags, it could have been 
omitted entirely.

Of course, once a proper controller enters the picture, I'll need at least 
one servlet declaration and probably some filters. The point is to start 
small and simple and then work your way up to more ambitious 
configurations. That way you'll know what's what and won't be in the dark 
when you need some variation that's not easily obtained from your IDE 
(assuming you use one).



> > Once you go through the process within the IDE it starts to make much more
> > sense.
>
>once you start creating large complicated applications, ide's make
>sense because they take some of the manual labor out of the process.
>
>- --
>Peter Abplanalp


Randall Schulz
Mountain View, CA USA


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Re: Processor Availability

[Randall R Schulz]

Rodrigo,

An addendum to my previous message:

>CTRL-D doesn't send a signal on any OS I've ever worked with, including 
>Windows.
>
>Use CTRL-BREAK. You'll get a nice, verbose thread dump. Make sure you've 
>configured your console window for at least a few hundred lines of 
>scroll-back, because the dump comes very fast. On my system with a newly 
>launched Tomcat 4.0.4-LE, there were almost 240 lines after the CTRL-BREAK.


You might also want to make the Tomcat console window at least 120 
characters wide to avoid line-wrapping. That will also cut down a bit on 
the number of scroll-back lines required, and if you want to copy the 
window's contents to put it in an editor where you can search and such, you 
won't have to re-join any lines.

Randall Schulz
Mountain View, CA USA


At 05:20 2002-08-30, you wrote:
>Sending a QUIT signal works in Unix (Linux and Solaris), but Ctrl-D doesn't
>do anything in Windows 2000. Anybody knows something about it?
>
>Jeff, what kind of processing are you doing in your JSP/servlets? You could
>be experiencing deadlock problems. It's just an idea :-)
>
>Best regards,
>Rodrigo Ruiz


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Re: Processor Availability

[Randall R Schulz]

Rodrigo,

CTRL-D doesn't send a signal on any OS I've ever worked with, including 
Windows.

Use CTRL-BREAK. You'll get a nice, verbose thread dump. Make sure you've 
configured your console window for at least a few hundred lines of 
scroll-back, because the dump comes very fast. On my system with a newly 
launched Tomcat 4.0.4-LE, there were almost 240 lines after the CTRL-BREAK.

Randall Schulz
Mountain View, CA USA


At 05:20 2002-08-30, you wrote:
>Sending a QUIT signal works in Unix (Linux and Solaris), but Ctrl-D doesn't
>do anything in Windows 2000. Anybody knows something about it?
>
>Jeff, what kind of processing are you doing in your JSP/servlets? You could
>be experiencing deadlock problems. It's just an idea :-)
>
>Best regards,
>Rodrigo Ruiz


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Re: javax directory

[Randall R Schulz]

Tom,

The "javax" _package_ is for so-called "standard extensions" to the Java 
libraries.

The package javax.servlet are the servlet classes (duh!). 
Javax.servlet.http contains the HTTP servlet classes. 
Javax.servlet.http.HttpServlet is the abstract for all Servlet classes 
accessed via the HTTP protocol.

In the docs you'll find this package and class structure mimicked by HTML 
API documents generated by JavaDoc. Are those the HTML files to which 
you're referring?

If you're getting errors, it may be because you don't have the J2EE JAR 
files, which is where these particular "standard extensions" are defined. 
Either that, or you have the necessary JAR files, but they're not in your 
class-path (CLASSPATH environment or -classpath option) when you compile.

Randall Schulz
Mountain View, CA USA


At 09:19 2002-08-27, Reis, Tom wrote:
>What is the javax directory. I know there is one in the Tomcat-docs but I
>thought there class files and not just html files. The reason I am asking
>this question is I have a java program that has the following code:
>
>import javax.servlet.*;
>import javax.servlet.http.HttpServlet;
>
>I receive errors when trying to compile this program


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Re: Tomcat Installation on linux

[Randall R Schulz]

Hi,

At 08:48 2002-08-26, Peter T. Abplanalp wrote:

>On Mon, Aug 26, 2002 at 11:23:16AM -0400, khozaima shakir wrote:
> > Hi Randall,
> > Sorry, guess the way i typed was misleading, i typed just
> > "shutdown.sh" at command prompt.
> > The directory that I was in when I type in startup.sh or shutdown.sh is
> > user/userName/jakarta-tomcat-4.0.4/bin>
> > The output i get on shutdown is --  Segmentation fault
>
>Please execute the following in user/userName/jakarta-tomcat-4.0.4/bin
>and post it to the list:
>
>   sh -x ./shutdown.sh > shutdown.txt


Better make that:

sh -x shutdown.sh > shutdown.txt 2>&1

(the "./" is unnecessary here, since the PATH is not used to find 
"shutdown.sh" -- PATH would be consulted if you included the "-c" option, 
however)

The real point is to include the standard error in the output captured in 
"shutdown.txt"

And really, a ".txt" suffix? Yuck!

Randall "when in Rome ..." Schulz
Mountain View, CA USA


>The command will create a file shutdown.txt which you can post.  This
>will give us an idea of where the seg fault is happening.
>
>- --
>Peter Abplanalp


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Re: Tomcat Installation on linux

[Randall R Schulz]

Shakir,

Sorry for the misunderstanding.

That's pretty odd. It's typical nowadays on Unix systems to omit "." from 
the PATH, so unless you've added "." (or an empty PATH element, which is to 
say a leading colon or two colons in a row), you need to enter "./shutdown" 
or a full path name ".../jakarta-tomcat-4.0.4/bin/shutdown.sh" (where "..." 
is the directory in which the Tomcat installation was performed) in order 
to invoke the proper script.

The Segmentation fault certainly should not occur. If it was the JVM that 
crashed like that, it's a sure indication of a bug in the JVM or in a 
native (as in JNI) library used by your platform's Java system. Make sure 
you have the latest stable release of Java installed on your system.

Randall Schulz
Mountain View, CA USA


At 08:23 2002-08-26, khozaima shakir wrote:
>Hi Randall,
>Sorry, guess the way i typed was misleading, i typed just
>"shutdown.sh" at command prompt.
>The directory that I was in when I type in startup.sh or shutdown.sh is 
>user/userName/jakarta-tomcat-4.0.4/bin>
>The output i get on shutdown is --  Segmentation fault
>Shakir
>
>
>>From: Randall R Schulz <[EMAIL PROTECTED]>
>>Reply-To: "Tomcat Users List" <[EMAIL PROTECTED]>
>>To: [EMAIL PROTECTED]
>>Subject: Re: Tomcat Installation on linux
>>Date: Mon, 26 Aug 2002 07:18:58 -0700
>>
>>Shakir,
>>
>>Where did you get that command from?
>>
>>Here's what you did: You truncated your "shutdown.sh" script. The ":" is 
>>the no-op command that is used when one wants to use side-effects (such 
>>as I/O redirection) without running a command. The ">" is similar to that 
>>of the DOS/CMD.exe/Command.com in Windows, it redirects output to the 
>>file whose name follows. So you ran the null command (which produces no 
>>output) and redirected it to the "shutdown.sh" script, thus truncating 
>>it. Had you used the append output redirection, ">>", all would be OK, 
>>since adding 0 bytes to the end of "shutdown.sh" would not do any damage 
>>(it would only alter the last modification time of that file, which you 
>>could see with "ls -l shutdown.sh").
>>
>>So you'll have to retrieve the "shutdown.sh" script from your Tomcat 
>>distribution.
>>
>>Then to use it, just invoke it. Since it usually does not run 
>>indefinitely and does not produce a lot of output or usually any 
>>particularly interesting output, there's no need to redirect its output.
>>
>>
>>I recommend that people recently switching from Windows to Linux or 
>>another Unix-like system get some tutorial materials on these basics. 
>>There are some vague similarities with Windows, but a lot is different 
>>and groping around in the dark is not really advisable.
>>
>>Good luck.
>>
>>Randall Schulz
>>Mountain View, CA USA
>>
>>
>>At 04:21 2002-08-26, khozaima shakir wrote:
>>>Hi Jhair,
>>>yes, I am running tomcat from shell.
>>>About shoutdown, I shutdown tomcat by : > shutdown.sh
>>>Thanks
>>>Shakir


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Re: Tomcat log in linux

[Randall R Schulz]

Neal,

On Unix (-like) systems, I'll usually start a separate terminal window (I 
assume you've got an X Window System display connected to the Unix system 
you're using) and start Tomcat there so I can monitor the standard output. 
This achieves the same results as the window created by Windows when you 
launch Tomcat there.

You should familiarize yourself with the "tail" command, particularly it's 
"-f" option. (Use the "man" command: "man tail"). This allows you to 
monitor additions to a file as they appear. This way you can keep log files 
and monitor them visually at the same time.

For an alternative with similar possibilities, lear about the "tee" 
utility. It operates in a pipeline by copying its input to its output (as 
"cat" would do with no arguments) but also writes a copy of all the data 
that passes through it to a file. I can append to the file, too.

Keep in mind that the terminal emulators have options that allow you to 
specify how many lines scroll-back to preserve.

Good luck.

Randall Schulz
Mountain View, CA USA


At 23:46 2002-08-25, neal wrote:
>In Windows, when you run Tomcat, a DOS command line window pops up and you
>see real-time messages from Tomcat.  If something isn't going right ... you
>see those messages.  Is there something analogous in Linux/Tomcat?  I'm
>trying to get the dumb thing running but I'm not seeing any debug info and
>the logs look relatively empty.
>
>Thanks.
>NEal


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Re: Tomcat Installation on linux

[Randall R Schulz]

Shakir,

Where did you get that command from?

Here's what you did: You truncated your "shutdown.sh" script. The ":" is 
the no-op command that is used when one wants to use side-effects (such as 
I/O redirection) without running a command. The ">" is similar to that of 
the DOS/CMD.exe/Command.com in Windows, it redirects output to the file 
whose name follows. So you ran the null command (which produces no output) 
and redirected it to the "shutdown.sh" script, thus truncating it. Had you 
used the append output redirection, ">>", all would be OK, since adding 0 
bytes to the end of "shutdown.sh" would not do any damage (it would only 
alter the last modification time of that file, which you could see with "ls 
-l shutdown.sh").

So you'll have to retrieve the "shutdown.sh" script from your Tomcat 
distribution.

Then to use it, just invoke it. Since it usually does not run indefinitely 
and does not produce a lot of output or usually any particularly 
interesting output, there's no need to redirect its output.


I recommend that people recently switching from Windows to Linux or another 
Unix-like system get some tutorial materials on these basics. There are 
some vague similarities with Windows, but a lot is different and groping 
around in the dark is not really advisable.

Good luck.

Randall Schulz
Mountain View, CA USA


At 04:21 2002-08-26, khozaima shakir wrote:
>Hi Jhair,
>yes, I am running tomcat from shell.
>About shoutdown, I shutdown tomcat by : > shutdown.sh
>Thanks
>Shakir


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Re: startup/shutdown Tomcat on Linux

[Randall R Schulz]

Neal,

Just use the ".sh" counterparts to the ".bat" files you used on Windows.

If you want Tomcat to start when the system comes up (or, to use some 
jargon, enters the proper "run level") you should find someone at your site 
who's familiar with Linux configuration. This can be handled manually, by 
editing startup and shutdown files in /etc/rc.d or, on many modern Linux 
systems, by using a GUI front-end to those configuration files. However, 
there are several variants on the underlying scheme and the tools that 
expose it, so it's not feasible to instruct you on the details from what 
you've told us (i.e., simply that you're using Linux).

Good luck.

Randall Schulz
Mountain View, CA USA


At 22:04 2002-08-25, neal wrote:
>How do you start and shutdown Tomcat on Linux?
>
>I'm (obvioulsy) a windows person.  I am attempting to get my app running on
>Linux.  From the /bin directory I attempted to call "shutdown.bat".  This
>didn't work so I restarted the server (shutdown -r now).  When the server
>came back, Tomcat was no longer responding.  Attempting to call the URLs
>pointing to Tomcat, I now get either (a) a DNS error or (b) a hung request
>that never comes back.
>
>I guess my ideal would be that Tomcat would auto-start upon reboot of the
>server.  Is this easy to setup? In the near-term though I just need to know
>how to start/restart/shutdown tomcat.
>
>Thanks in advance!
>
>Neal


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RE: Need help w. Tomcat Installation

[Randall R Schulz]

Steve,


At 14:04 2002-08-18, Jacob Hookom wrote:
>| -Original Message-
>| From: STEVE R BURRUS [mailto:[EMAIL PROTECTED]]
>| Sent: Sunday, August 18, 2002 3:55 PM
>| To: [EMAIL PROTECTED]
>| Subject: Need help w. Tomcat Installation
>|
>|   Hello all, this is steve burrus.I am an admitted Tomcat "newbie" user, 
>and I
>| find myself in need again of some advice from someone/somebody about 
>just how
>| the hell do you first install tomcat??! I am trying to install Tomcat 
>4.0.4, and I
>| get everything alright EXCEPT for getting an error msg. in DOS when I try to
>| start it up saying that the JAVA-HOME environment isn't properly set!!!
>
>Make sure you have j2sdk installed
>
>Right click on My Computer
>Go to Properties
>Click on Advanced Tab
>Click on Environment Variables at the bottom
>Under system variables, click New
>Variable Name: JAVA_HOME
>Variable Value: C:\j2sdk. Wherever your root sdk installation is

In your mail, Steve, you wrote "JAVA-HOME". Make sure you're using "JAVA_HOME".


>Note, if you already have a console window open, you will need to close
>it and open a new one to get the updated system variable (I don't know
>why, it just does).

In both Unix and Windows (at least NT, 2K and XP), each process carries 
it's own environment internally. A newly created process "inherits" its 
initial environment from the process that created it at the time it is 
crated. After that, changes in the system-wide or parent process's 
environment do not affect that of any already running process--only that 
process itself can change its environment.

Randall Schulz
Mountain View, CA USA


>| I know that I have
>| set it in the "System" applet correctly!! I am using Win XP. Oh, and one
>| more thing: Is there any new version of tomcat beyond v. 4.0.4?

Only development releases. This is made clear (and kept up-to-date) on the 
Tomcat home page .


>Of course... try looking at jakarta's home page, it reads at the top
>"15 August 2002 - Tomcat 4.1.9 Beta Released"


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