SemanticXmlDiff failed on Unicode

I am using CPAN module SemanticXmlDiff to compare two set of XML files. It complains about not being able to handle "wide character". After looking at the source code, it turns out the problem is the MD5 function used inside the module. The MD5 hash is used to spead up the comparson of text node in the XML file. However, MD5 only supports computing hash of ASCII characters, thus it will fail on wide characters which has multiple bytes.

The solution? According to the Digest::Digest module, the text should be encoded before it is passed to MD5 function. To apply this, I change the following line from

$doc->{"$test_context"}->{TextChecksum} = md5_base64("$text");

to

 $doc->{"$test_context"}->{TextChecksum} = md5_base64(encode_utf8("$text"));

Now it works!

Configure Catalyst 5.61 with Apache2 on Windows

I reconfigured my Catalyst app using mod_perl today. It was configured using CGI before as I was making a lot of changes and would like to page to always reflect the last change. The original configuration is:

<VirtualHost *:80>
 ServerAdmin my@server.com
 DocumentRoot c:/site/myapp/root
 ServerName myserver2
 ErrorLog c:/site/myapp/myapp-error.log
 CustomLog c:/site/myapp/myapp-access.log common
 ScriptAliasMatch ^/(.+) c:/site/myapp/script/myapp_cgi.pl/$1
 Alias /static c:/site/myapp/root/static
 <Location "/static">
  SetHandler none
 </Location>
</VirtualHost>

It works but the performance is horrorable. The new configuration is:

<VirtualHost *:80>
 ServerAdmin my@server.com
 DocumentRoot c:/site/myapp/root
 ServerName myserver2
 ErrorLog c:/site/myapp/myapp-error.log
 CustomLog c:/site/myapp/myapp-access.log common
 PerlOptions +Parent
 PerlSwitches -IC:/site/myapp/lib
 <Location />
  SetHandler modperl
  PerlHandler myapp
  </Location>
 <LocationMatch "/static">
  SetHandler none
 </LocationMatch>
</VirtualHost>

Use DBD: :Oracle 1.16 to access Oracle 9.2 database

I try to connect to an Oracle 9.2 database using following code:

 my $dbh = DBI->connect($config->{dburl}, $config->{dbuser}, $config->{dbpass});

It failed with error:

DBI connect('host=host;sid=dbsid','user',...) failed: ORA-12705: invalid or unknown NLS parameter value specified (DBD ERROR: OCISessionBegin) at ..

I have to explicitly set the ENV variable NLS_LANG to make it work. The new code looks like:

$ENV{NLS_LANG}="AMERICAN_AMERICA.UTF8";
my $dbh = DBI->connect($config->{dburl}, $config->{dbuser}, $config->{dbpass});

and it works.

The initial thought is that the default NLS_LANG from DBD::Oracle has to match the server configuration which is "AMERICAN_AMERICA.UTF8". But the follwoing code works as well:

$ENV{NLS_LANG}="AMERICAN_AMERICA.US7ASCII";
my $dbh = DBI->connect($config->{dburl}, $config->{dbuser}, $config->{dbpass});

So maybe the DBD:Oracle is sending some invalid NLS_LANG string though I havn't figured out what it is.

The SimpleDateFormat class is NOT threadsafe

In researching a defect in my project, I find SimpleDateFormat class is not thread safe. The "bug" is reported back in JDK 1.2 and JavaDoc is added in JDK 1.5. I just don't see it. :(

Perl object is just a blessed hash

To work on a small testing utility, I have to pick up perl again. Fortunately my memory still served me well until I got into this problem. How to trun a hash into object. After a little reading of my Learning Perl book. I figured out how it works. Once you understand perl object is just a blessed hash, then the solution is clear.

============================

package MyTest;

use strict;

my %hash = (color=>"red", shape=>"round");
my $hashref = \%hash;

sub not_typical_new {
 my ($proto, $arg) = @_;
 my $class = ref($proto) || $proto;
 my $self = $arg;
 bless ($self, $class);
 return $self;
}

my $obj = mytest->not_typical_new($hashref);
print $obj->{color}, "\n";

Added a nice JSCalendar to the blogger

I added a nice JSCalendar to my blog. The instructions from ecmanaut helped. The first part is relatively easy. But the seconf part is difficult to follow. I ended up have to dig into the source code to find out how it works. After a hour or so, I finally figured out the basic functions. The challenge is because I used a customized template so that many CSS tags used by the scripts are not included. I have to change the template to include al l those CSS tags just to make the calendar work. I still cannot get the title hint to work as it requires more template change which I am not willing to spend more time. So I stopped here. But it is good enough for me now.

The del.icio.us tag script does not get along with Google's tools bar

I added the del.icio.us greasemonkey script so that I can create the bookmark after the post. However, it stopped working today. After a search on google, I learned that the script, for some reason, does not work with Google's toolbar extension. After remove the Google's toolbar, it works just fine. :(

Added the freshtag to the blog

I added the freshtag to my blog today. It allows me to use del.icio.us tag to categorize my blog.