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Installing Tomcat 6 on Debian Squeeze

Sebastian Thomschke — Sat, 13 Mar 2010 16:07:35 +0000

This post describes how to setup Tomcat 6 on Debian Squeeze. The configured Tomcat serves requests on port 80 without the need of an additional web server. This is especially good for virtual servers (VPS) providing limit memory. It also has multiple virtual hosts configured, each with it’s own webapp with context root / and optional support for PHP via the Quercus PHP implementation.

Installing Sun Java 6

Ensure the non-free section is enabled for the APT repository configuration in /etc/apt/sources.list, e.g. “deb http://ftp.de.debian.org/debian testing main contrib non-free”

apt-get update
apt-get install sun-java6-jdk
echo 'JAVA_HOME="/usr/lib/jvm/java-6-sun"' >> /etc/environment
echo 'JRE_HOME="/usr/lib/jvm/java-6-sun/jre"' >> /etc/environment

Installing Tomcat 6

apt-get install tomcat6 tomcat6-admin
/etc/init.d/tomcat6 stop

Creating standard Tomcat directory layout

mkdir /opt/tomcat
cd /opt/tomcat
ln -s /etc/tomcat6/ conf
ln -s /usr/share/tomcat6/bin/ bin
ln -s /usr/share/tomcat6/lib/ lib
ln -s /var/lib/tomcat6/webapps webapps
ln -s /var/log/tomcat6/ logs

Creating a Tomcat admin user

In /opt/tomcat/conf/tomcat-users.xml add an entry like:

Setting up virtual hosts

For each virtual host execute the following command. Replace “mydomain.com” with the desired virtual host name, but omit the “www.” part.

mkdir -p /opt/tomcat/webapps.mydomain.com/ROOT

In the tag of “/opt/tomcat/conf/server.xml” add one host entry for each virtual host.


    www.mydomain.com>/Alias>

The tag tells Tomcat to redirect from www.mydomain.com to mydomain.com.
The tag enables access logging in the standard logging format.

Using xinetd to configure port 80 for Tomcat

Binding a service on port 80 requires root permissions. Thus we use port forwarding to “bind” Tomcat to port 80. My VPS does not support the use of “iptables -j REDIRECT” therefore I am using xinetd as a web proxy.
Ensure that no other service is listening on port 80/443:

netstat -pan | grep ":80\|:443"

echo echo "
service www
{
        socket_type     = stream
        protocol        = tcp
        user            = root
        wait            = no
        bind            = 88.80.198.181
        port            = 80
        redirect        = localhost 8080
        disable         = no
        flags           = REUSE
        log_type        = FILE /var/log/wwwaccess.log
        log_on_success  -= PID HOST DURATION EXIT

        per_source      = UNLIMITED
        instances       = UNLIMITED
}

service https
{
        socket_type     = stream
        protocol        = tcp
        user            = root
        wait            = no
        bind            = 88.80.198.181
        port            = 443
        redirect        = localhost 8443
        disable         = no
        flags           = REUSE
        log_type        = FILE /var/log/httpsaccess.log
        log_on_success  -= PID HOST DURATION EXIT

        per_source      = UNLIMITED
        instances       = UNLIMITED
}
" > /etc/init.d/tomcat
/etc/init.d/xinetd restart

If you want to use a different service name, e.g. “tomcat” instead of “www” you must add this service to /var/services, e.g. “tomcat 80/tcp”
In /opt/tomcat/conf/server.xml modify the as follows:

This binds Tomcat to localhost. It also tells Tomcat that port 80 is the proxy port which is necessary for correct URL generation.
From now on the Tomcat admin applications are only accessible via localhost. You can use SSH port forwarding to still access the applications from your workstation’s web browser. E.g. if you are using PuTTY you can use this command line option “-L 8080:localhost:8080″ to forward the server’s local 8080 port to your workstation’s local 8080 port. On your workstation’s browser you then simply enter http://localhost:8080/manager/html and are connected to the server’s Tomcat admin application.

Enabling PHP support (optional)

Download Quercus.

mkdir -p /opt/downloads
wget -o /opt/downloads/quercus-4.0.3.war http://caucho.com/download/quercus-4.0.3.war

Install Quercus as a shared library.

unzip -j /opt/downloads/quercus-4.0.3.war \*.jar -d /opt/tomcat/lib

Enable PHP support for the virtual hosts by installing the quercus web.xml. For each virtual host execute:

unzip /opt/downloads/quercus-4.0.3.war *web.xml -d /opt/tomcat/webapps.mydomain.com/ROOT

Starting Tomcat

/etc/init.d/tomcat start

References

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Post tags: Java, PHP, port 80, port forwarding, quercus, tomcat, vhost, virtual servers, VPS, xinetd

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Leveraging PyDev’s auto completion for indirectly created objects

Sebastian Thomschke — Fri, 19 Feb 2010 23:29:00 +0000

This is just a quick tip how to enable auto completion in PyDev for indirectly created objects.

By default, PyDev has no problems in presenting you the possible object attributes and methods on a variable if that variable gets a new object instance assigned directly in the code.

For example, when you first type …

mybook = Book()

… and in the next line you enter …

mybook.

… PyDev will dutifully present you the statically declared features for the Book class in a popup.

If you however get that Book instance as the result of another method, e.g. …

mybook = bookstore.findBook("foobar")

… PyDev currently seems to be helpless.

Because of Python’s dynamic nature it is of course a bit harder for an IDE to figure out what kind of objects may a method. But PyDev could for example honor the @return / @rtype PyDoc annotations (which you can add to the findBook’s method declaration) but currently it just does not.

To still have autocompletion you have two options:

Temporarily instantiate a Book object in the code.
```
mybook = Book()
mybook = bookstore.findBook("foobar")
mybook. #--> now you have auto completion
```
This has the drawback, that if you forget to remove the first line before you finish coding an unneccessary Book instance will be created on every execution during runtime.

Use an assertion to ensure that the mybook variable contains an object of type Book

mybook = bookstore.findBook("foobar")
assert isinstance(mybook, Book)
mybook. #--> now you have auto completion

© sebthom for sebthom.de, 2010. | Permalink | One comment | Add to del.icio.us
Post tags: Jython, pydev, pydoc, python, rtype

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OVal 1.40 released

Sebastian Thomschke — Mon, 28 Sep 2009 20:42:38 +0000

I am happy to announce the immediate availability of Version 1.40 OVal the Object Validation Framework for Java. This release fixes some minor issues and provides the following two new features:

1. Enabling/disabling constraints based on the object state:
Using the newly introduced when attribute for constraints it is possible to specify under which circumstances the constraint will be considered during object validation. The when attribute holds a formula in one of the supported scripting languages. If the formula returns true, the constraint will be activated for the current validation cycle otherwise it is ignored. In the following example the alias attribute must have a value only when the name attribute is not set.

public class User {
   private String name;

   @NotNull(when = "groovy:_this.name == null")
   private String alias;

   // . . .
}

2. Fine grain control over how constraints are applied on arrays, maps, collections and their elements
The newly introduced attribute appliesTo allows you to specify if and how a constraint declared for a map, a collection or an array is applied to their elements as well or exclusively. See the following example how this works:

public class BusinessObject {

   // the ids field may be null, but if it is not null
   // none of it's items must be null
   @NotNull(appliesTo = { ConstraintTarget.VALUES })
   private String[] ids;

   // only the field itself must not be null,
   // the list can contain null values
   @NotNull(appliesTo = { ConstraintTarget.CONTAINER })
   private List items;

   // the field must not be null as well as all keys
   // and values of the map
   @NotNull(appliesTo = { ConstraintTarget.CONTAINER, ConstraintTarget.KEYS, ConstraintTarget.VALUES })
   private Map itemsByGroup;

   // . . .
}

Download
You can get the lates binaries and source files of OVal from here: http://sourceforge.net/projects/oval/files/

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Comparing version numbers in Jython / Python

Sebastian Thomschke — Fri, 13 Mar 2009 23:03:57 +0000

Here comes a function to compare version numbers of e.g. Maven artifacts in Jython / Python.

import re

def cmpver(vA, vB):
    """
    Compares two version number strings
    @param vA: first version string to compare
    @param vB: second version string to compare
    @author Sebastian Thomschke
    @return negative if vA < vB, zero if vA == vB, positive if vA > vB.

    Examples:
    >>> cmpver("0", "1")
    -1
    >>> cmpver("1", "0")
    1
    >>> cmpver("1", "1")
    0
    >>> cmpver("1.0", "1.0")
    0
    >>> cmpver("1.0", "1")
    0
    >>> cmpver("1", "1.0")
    0
    >>> cmpver("1.1.0", "1.0.1")
    1
    >>> cmpver("1.0.1", "1.1.1")
    -1
    >>> cmpver("0.3-SNAPSHOT", "0.3")
    -1
    >>> cmpver("0.3", "0.3-SNAPSHOT")
    1
    >>> cmpver("1.3b", "1.3c")
    -1
    >>> cmpver("1.14b", "1.3c")
    1
    """
    if vA == vB: return 0

    def num(s):
        if s.isdigit(): return int(s)
        return s

    seqA = map(num, re.findall('\d+|\w+', vA.replace('-SNAPSHOT', '')))
    seqB = map(num, re.findall('\d+|\w+', vB.replace('-SNAPSHOT', '')))

    # this is to ensure that 1.0 == 1.0.0 in cmp(..)
    lenA, lenB = len(seqA), len(seqB)
    for i in range(lenA, lenB): seqA += (0,)
    for i in range(lenB, lenA): seqB += (0,)

    rc = cmp(seqA, seqB)

    if rc == 0:
        if vA.endswith('-SNAPSHOT'): return -1
        if vB.endswith('-SNAPSHOT'): return 1
    return rc

Theoretically lines 43 – 49 could be written in a more compact way but using the short circuit evaluations (as below) lead to wrong results – at least in Jython 2.1:

    seqa = map(lambda s: s.isdigit() and int(s) or s, re.findall('\d+|\w+', vA.replace('-SNAPSHOT', '')))
    seqb = map(lambda s: s.isdigit() and int(s) or s, re.findall('\d+|\w+', vB.replace('-SNAPSHOT', '')))

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Running TomCat 6 in Debug Mode under Windows

Sebastian Thomschke — Wed, 11 Mar 2009 21:55:02 +0000

While tracing some problems in one of my grails applications I had the need to do step debugging on a remote Tomcat server. Eventually I came up with the following lines to launch TomCat in debug mode:

@echo off
set JPDA_TRANSPORT="dt_socket"
set JPDA_ADDRESS="8000"
set JPDA_SUSPEND="y"
catalina.bat jpda start

Simply create a debug.bat file in TomCat’s bin directory and add these lines.

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Lotus Notes’ [Send only] and [Send and File] buttons for Outlook 2003

Sebastian Thomschke — Thu, 19 Feb 2009 18:13:08 +0000

You can say what you want about Lotus Notes, if you have used it for a while and switched e.g. to Outlook, you’ll find yourself missing one or the other nifty Notes function.

Already two of my customers “forced” me to use MS Outlook 2003 and since this isn’t likely to change in the near future, I implemented two of these handy Notes functions for Outlook 2003:

The button [Send only] sends e-mails without storing a copy of it in the local mailbox.
The button [Send and File...] prompts you for the folder where to store the e-mail being send.

Installation:

Download the Visual Basic module in the favored language.
Note: There is a file embedded within this post, please visit this post to download the file.

Note: There is a file embedded within this post, please visit this post to download the file.
In Outlook open the Visual Basic editor.
Import the Visual Basic module.
Save the project.
Install the buttons in the toolbar.
When composing a new e-mail the additional buttons should appear in the toolbar.
When clicking “Send and File…” the folder dialog is displayed before the e-mail is send.

© sebthom for sebthom.de, 2009. | Permalink | 9 comments | Add to del.icio.us
Post tags: Outlook, Productivity, VBA, Visual Basic

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getpass for Jython

Sebastian Thomschke — Fri, 21 Nov 2008 00:02:15 +0000

In my current project I am developing some Jython based command line tools and had the need for masking passwords entered in the command shell. Python provides the getpass module for this purpose. Unfortunately this module has not been made available for Jython.

Here comes a module I wrote to provide this kind of functionality. It uses the mechanism described here http://java.sun.com/developer/technicalArticles/Security/pwordmask/ to mask characters entered at the command prompt. Additionally if Java 6 or higher is running Jython the module will instead use the new Console.readPassword() method. In case the module is running in an environment where the getpass module is available it will delegate to the corresponding methods of this module instead of using its own implementations.

# ext_getpass.py
# @author Sebastian Thomschke, http://sebthom.de/
import thread, sys, time, os

# exposed methods:
__all__ = ["getpass","getuser"]

def __doMasking(stream):
    __doMasking.stop = 0
    while not __doMasking.stop:
        stream.write("b*")
        stream.flush()
        time.sleep(0.01)

def generic_getpass(prompt="Password: ", stream=None):
    if not stream:
        stream = sys.stderr
    prompt = str(prompt)
    if prompt:
        stream.write(prompt)
        stream.flush()
    thread.start_new_thread(__doMasking, (stream,))
    password = raw_input()
    __doMasking.stop = 1
    return password

def generic_getuser():
    for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):
        usr = os.environ.get(name)
        if usr: return usr

def java6_getpass(prompt="Password: ", stream=None):
    if not stream:
        stream = sys.stderr
    prompt = str(prompt)
    if prompt:
        stream.write(prompt)
        stream.flush()

    from java.lang import System
    console = System.console()
    if console == None:
	    return generic_getpass(prompt, stream)
    else:
        return "".join(console.readPassword())

try:
    # trying to use Python's getpass implementation
    import getpass
    getpass = getpass.getpass
    getuser = getpass.getuser
except ImportError, e:
    getuser = generic_getuser

    # trying to use Java 6's Console.readPassword() implementation
    try:
        from java.io import Console
        getpass = java6_getpass
    except ImportError, e:
        # use the generic getpass implementation
        getpass = generic_getpass

Here is an usage example:

import ext_getpass as getpass

pw = getpass.getpass("Please enter your password:")
print "The entered password was: " + pw

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Sun JDK5/6 compilers broken when linking overloaded methods with variable arguments

Sebastian Thomschke — Thu, 15 May 2008 23:23:44 +0000

We are currently switching the build system of OVal from custom Ant scripts to Maven 2. During that process we accidentally compiled the project using the Java compiler of the Sun JDK 5 instead of the AspectJ compiler. Surprisingly javac did not complain about the missing aspect class files. Instead it already aborted while compiling an ordinary Java class which only referenced other non-AspectJ related classes. This is the original error message:

[INFO] [compiler:compile]
[INFO] Compiling 180 source files to C:\projects\oval\src\trunk\target\classes
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Compilation failure
C:\projects\oval\src\trunk\src\main\java\net\sf\oval\Validator.java:[373,58]
addMethodParameterChecks(java.lang.reflect.Method,int,java.lang.Object)
has private access in net.sf.oval.internal.ClassChecks

There exist multiple methods named addMethodParameterChecks in the class ClassChecks with different signatures. The problem is that javac tries to link against the wrong method when compiling the class calling one of the methods.

(...)
Read the rest of Sun JDK5/6 compilers broken when linking overloaded methods with variable arguments (284 words)

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OVal 1.0 released!

Sebastian Thomschke — Sun, 22 Jul 2007 12:10:22 +0000

OVal is a pragmatic and extensible validation framework for any kind of Java objects (not only JavaBeans). Constraints can be configured with annotations, POJOs or XML. Custom constraints can be expressed in pure Java or by using scripting languages such as JavaScript, Groovy, BeanShell, OGNL or MVEL. Besides simple object validation OVal implements Programming by Contract features by utilizing AspectJ based aspects.

Visit the project page at http://sourceforge.net/projects/oval/

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MyPad v1.1.6 – a PHP Editor

Sebastian Thomschke — Mon, 26 Jul 2004 19:26:49 +0000

MyPad is a very compact PHP Editor. I developed this editor because I could not find a suitable PHP Editor with a Single Document Interface.
The Editor I was searching for should look and behave like Notepad, but should be able to colorize PHP source code.
Such a small Editor can be perfectly used in conjunction with a norton commander like filemanager.

(...)
Read the rest of MyPad v1.1.6 – a PHP Editor (123 words)

© sebthom for sebthom.de, 2004. | Permalink | No comment | Add to del.icio.us
Post tags: bug, My Freeware, PHP, Visual Basic

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Visual Basic – Multiple Undos Class v2.04

Sebastian Thomschke — Sun, 09 Mar 2003 19:06:05 +0000

I tried a lot of differnet multi undo solutions, but every had at least one draw back. So I had to write my on solution and I think my one is quite smart.

If you want to use it, you don’t have to clutter your code by pasting in lots of undo-related subs, functions and variables. Everything comes within two small class files.

(...)
Read the rest of Visual Basic – Multiple Undos Class v2.04 (116 words)

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Visual Basic – High Precision Timer v1.20

Sebastian Thomschke — Mon, 05 Aug 2002 19:12:41 +0000

This code is a VB implementation of the high precision multimedia timer which can be found in the winmm.dll.

I wrote this code because of the same reason I developed the multiple undo class: I wanted to have a smart solution that can be easily added to different VB projects, that doesn’t clutter the code, that doesn’t let depend my project on another custom OCX or DLL file and that is object oriented as much as possible.
(...)
Read the rest of Visual Basic – High Precision Timer v1.20 (171 words)

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Excel – VBA Timer Example v1.00

Sebastian Thomschke — Sat, 06 Apr 2002 18:52:07 +0000

A friend of mine asked me about how to let excel periodically update some worksheets.
So the first thing I did was searching the web for a solution in Visual Basic for Applications. But the only one I found was to use a 3rd party ActiveX timer control which you have to place onto a userform. Then I found the VBA command “Application.onTime” and had an idea.

Here is my solution only utilizing the VBA onTime command. No need for ActiveX control or any other 3rd party module.

(...)
Read the rest of Excel – VBA Timer Example v1.00 (2 words)

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