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Safari Webinspektor

Vor fast 1.5 Jahren schrieb ich im Zusammenhang mit Daily Fratze on rails über den Safari Inspektor, der damals nur in den Nightlies verfügbar war: Damaliges Daily Fratze Preview.

Leider habe ich den Inspektor im aktuellen Safari 3 nie mehr gesehen, bis ich vor ein paar Tagen auf das SülzOMat Blog stieß. Einfach im Terminal folgenden Befehl absetzen:

defaults write com.apple.Safari WebKitDeveloperExtras -bool true

Safari neu starten und man hat über das Kontextmenü den neuen Punkt “Element-Informationen”, der den Inspektor startet, der dem beliebten Plugin “Firebug” für Firefox in kaum etwas mehr nachsteht.

Vielen Dank für diesen Beitrag!

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Oracle 11g: Default case-sensitive passwords

ORA-01017: invalid username/password; logon denied

Yiipiee… Although i created my schema with the usually scripts we use, i got a logon denied… Switching context from Oracle Forms 6 to Reports 6… (Please, don’t say anything about legacy apps).

I didn’t notify that passwords are now case-sensitive in a Oracle database (which is a good thing), because of two reasons: I created the user via SQL*Plus and there is a environment variable called “sqlcase” that converts, if set to upper or lower, all SQL code to the according case. Bummer! Even quoted literals are converted… Stupid shit, i think. But in my case, this thing was set to mixed, so i ended up with a lower case password as with 11g “sec_case_sensitive_logon” is set to true as default:

SQL> SHOW parameter sec_case_sensitive_logon
 
NAME                     TYPE    VALUE
------------------------ ------- -----
sec_case_sensitive_logon BOOLEAN TRUE

Now with forms things are different, again. Forms runtime don’t convert the lowercase password in the connect string so i could log in but it converts the password to uppercase if you switch contexts to Reports runtime which couldn’t connect and ended up with the ORA-01017. Weird stuff, as everything else worked as expected, although Forms and Reports 6 are ages old compared to 11g.

In the end, i changed to user to a an uppercase password, so the password passed from Forms to reports is the right one. I didn’t set sec_case_sensitive_logon to false, as i think, its way better to have standard password handling and to me, this means case-sensitive and nothing else.

I found some valuable information on this topic in the following blog: Mark A. Williams :: Blog, didn’t know about that sqlcase shit before.

For more information see:

• SEC_CASE_SENSITIVE_LOGON
• sqlcase
• Enabling or Disabling Password Case Sensitivity

Filed in English posts, Oracle | Comments (0) »

From Parallels Desktop to VirtualBox

For backup and testing purpose i keep a virtualized version of my webserver running under Parallels Desktop for Mac on my mac.

Recently Dell had some very convenient offers on their PowerEdge machines and i could barely resist to buy one, but finally, i managed to: cut the crap, i don’t want to have even more boxes standing around at home.

But i was thinking again: Whats better than one backup? Redundant backups 🙂

So i downloaded a copy of Parallels Workstation to install it on my PC at work. Equipt with a DVD and my image file from Parallels Desktop, i fired up the PC Version and after fiddling around with some pathes i can confirm that the Parallels Desktop 3.x vms are compatible with Parallels Workstation 2.x vms, at least a vm with a Debian OS inside.

But to me, performance was poor. My mac is a 2Ghz Core2Duo Mac Book with 3GB Ram, my Pc is a 2.66 Core2Duo Dell with 2GB Ram and Parallels Workstation was way slower on the PC than unter OS X. In addition: I didn’t want to spend another 50$ for Parallels (i already bought versions 2 and 3 for Mac, should be enough), so i thought about alternatives on my PC running Windows XP as host.

I already knew about QEMU which in contrast to Parallels and VMWare is a processor emulator and not a virtualization tool and therefore must be slower. I recommend the QEMU Manager for Windows Users, as this thingy already contains the kqemu virtualization extension.

Installation is dead simple and to my surprise, it was enough to convert my Parallels extending image with the Parallels Image Tool to a plain disk which i could use without further changes with QEMU.

Debian is very stable against the few “hardware” changes. The only problem i had that Debian wouldn’t find my eth0 device although the Realtek 8139too module was loaded. Solutions: The ethxxx devices are bound to the hardware (mac) address. I could look up the mac address in the Parallels configuration file, add this number in the QEMU config and voila, everything was up and running.

Somewhat complicated is bridged networking with QEMU. First you need the TAP-Win32 driver which is brought to you by the great OpenVPN project. The most simple way to install is through OpenVPN Gui for Windows.

After install add a new TAP device through the startmenu entry and then, the clou: There are some howtos which recommend enable bridged networking through the Internet Connection Sharing facilities of windows but it’s much simpler than that: Under network connections, select your default LAN Connection, the tap device, right click and choose bridge networks.

After that, change the network mode in your QEMU vm from user networking to tap networking and you’re ready to go.

Performance was quite good (at least at Parallels speed) but i guessed, there was room for more so i look for VMWare. Unfortunately, the QEMU image tool qemu-img.exe repeatedly crashed while converting my Parallels Image to the vmdk format so this was a dead end for me.

Although the Parallels image worked fine with QEMU and later on also in our Oracle VM Server as a hw virtualized XEN machine, i was not content and i looked out for VirtualBox which is available under a GPL license without USB support which i don’t need, but is able to use Intel VT-x and AMD-V technology.

I needed to convert the Parallels image from a raw disk format to innoteks vdi format, following the steps explained here.

All the tools mentioned there are also available under a Windows installation of QEMU and Virtualbox. Commands as follow:

qemu-img.exe convert foobar.hdd foobar.bin
VBoxManage.exe convertdd foobar.bin foobar.vdi

For bridged networking unter VirtualBox the same applies as to QEMU without the need for OpenVPN, you can add a TAP device right from within VirtualBox . If you already have the bridged described above, you can add the VirtualBox interface with a right click to that bridge. Also, to have Debian not change the eth number, add the same mac address in the network tap of VirtualBox.

All this said and done, booting the system was blazing fast and also the backup of my Daily Fratze project which is pulled via rsync from my server, runs extremly smooth and i have absolutely no hassle setting up Ruby on Rails, RMagick and MySQL under the Windows “Operating System” but can use Debian or any other distro with a sane environment.

After fiddling around with both VMWare and VirtualBox, i’d prefer VirtualBox over VMWare Server (which is also available for free {i.e. for giving VMWare your personal data}). VirtualBox has less overhead then VMWare Server, is simple to configure and as i said, amazingly fast.

When the OS X version leaves beta, i’ll switch from Parallels on my Mac to VirtualBox, at least for my server live backup, so i can make it redundant with the one some kilometres away (call me paranoid if you like) at my workplaces PC.

Filed in Virtualization | Comments (17) »

Why opinionated software sucks… Not!

The best software has a vision. The best software takes sides.

Make Opinionated Software

There’s been a lot of discussion around David Heinemeier Hanssons principle of “opinionated software”. Some people say that “to David, a piece of opinionated software is written in such a way that makes it easy to do things one way and ugly and difficult to do things another way”.

Maybe this approach “with a carrot and a stick” seams odd and old-fashioned, but i think its actually working and because of that, many people don’t like it.

Imagine, you’re using a product you like, you value its creator and especially his opinion and then, something you wanna do, doesn’t work because of obvious arbitrary restriction, you will be pissed for sure.

Certainly not all decisions made with a strong opinion are good, but i think, many of them made boldly had a reason to be done in a definite way and not another, often arising from the same reason you valued the creator of them before.

I’m writing this because i was really pissed when Rails 2.0 came out. It may be sound picky, but in Agile Web Development with Rails” DHH stated: “This fom of attribute accessor looks at the coluumn’s value. It is interpreted as false only if it is the number zero; one of the strings “0”, “f”, “false” or “” (the empty string); a nil; or the constant false. Otherwise it is interpreted as true.”, which means: A convenient method to add a question mark to attribute accessors to query them if they are true or false.

This due to the fact that there is an SQL standard that defines a datatype BOOLEAN but most of the RDBMS do implement them in their own way, most of the time as tinyint constrained to 0 and 1 (Oracle favours “y” and “n” for whatever reason) and so on.

I myself went with “t” or “f” as i can easily memorize it (true and false, obviously, sure, we can argue if i shouldn’t know about 0 being false and all other being true, i do know but the less i need to think about the obvious the more i can concentrate on actually doing something).

So with Rails 2.0 stuff breaks: DHH and the Rails team went with the MySQL approach: 0 and 1 only, 0 is false, 1 is true. This is fine as for example MySQL defines constants like TRUE and FALSE, that although being 1 and 0, conforms to the standard.

As i saw pieces of app failing with the new release (important parts like things being public or not, blocked users and so on), i was angry… “The bad guys destroy my toy” boohoo and i filed this ticket.

After thinking about (and actually changing my enums(‘t’,’f’) to the pseudotype boolean), i think it’s the right decision. As the model existed before i started working with Rails, i didn’t use migrations to generate tables, which is pity as with this decision, i would get the right datatypes in all supported databases. But even though, i like things being conform to a standard most vendors seem to listen to.

Without the Railsteam willingly breaking compatibility and being opinionated, i would have sweared less on the one side but i would have missed the opportunity to do some justified rewriting.

For me it’s ok to be opinionated and a little bit rockstar like, if you got the right reasons. I myself tend to be opinionated enough on my own work but i can defend my decisions most of the time.

It’s not always nice to be corrected and the corrector maybe doesn’t seem like a teamplayer, but i can life with the concept of the “Benevolent Dictator” when the product does the things its expected to do good and isn’t a “creative” mess.

Just in case you haven’t seen the great movie Borat or are totally unaware to irony, i don’t think that software with an opinion and attitude suck.

Filed in Rails | Comments (0) »

Copy and paste within cmd (command interpreter under Windows)

Under Windows 2k and XP exists no keyboard shortcut in cmd.exe to copy and past text. You need not only use your mouse but hit the proximity icon in the top left and choose edit|mark, edit|copy and so on.

cmd has a special mode named QuickEdit which can be enabled via the following command

REG.EXE add HKCU\Console /v QuickEdit /t REG_DWORD /d 1 /

all new cmd windows will now be in QuickEdit mode. Text can be selected with the left mouse button, copied via right mouse button and pasted via right mouse button.

Found on a msdn blog. Thanks!

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