Armin's personal Blog

Yesterday I got back my broken laptop from Acer's "Repair Center". They just exchanged the graphics card and updated the BIOS. It runs as smoothly as it did before, and the best thing is that they did not even touch the harddisk, so no data has been lost (of course I backupped the most important stuff, but this way I do not have to bother with replaying it). The next few hours it will do an "emerge -uDavN --world"...

I did not however expect the whole process to be that easy. I sent it in and got it back about a week later. Guess my next notebook will be an Acer again.

The current draft for the new obby protocol plans to use a peer-to-peer-like mechanism for transport via jabber, so every jabber participant talks to other jabber participants directly instead of tunnelung through the publisher. This should reduce bandwidth usage quite a lot but raises quite a few other questions regarding peer-to-peer: Could new users join the obby network via any peer instead of just the publisher? Could the session stay alive when the original publisher leaves? I met Phil yesterday and we discussed these questions, and we even came up with some results. But first of all, what are the problems?

As soon as every peer in the network is allowed to accept new peers, we have to handle the case that two peers join the same network via two different nodes at the same time.

• This affects ID generation. Currently, every user is assigned a unique user ID for the session. This is required because the protocol allows multiple users per connection (which is again required for the good old client/server model used by the TCP subsystem, but this option also allows another nice feature (republishing) I want to keep in mind for the future). An incoming request however is user-related rather than connection-related, so it must be clear which user generated it. It is still possible to produce unique IDs as soon as an ID is variable in length. When a peer has to generate a user ID, it just takes its own ID and appends something to it to generate a new one.

• We cannot catch name collision. Two users with the same names could join the same network via two different peers at the same time. However, this does not matter at all since we could just allow duplicate names in the session. If we want to distinguish between them UI-wise we could suffix one client-side, maybe sorted by the user ID to keep it the same on all peers (but which would lead to renamings if a new user with the same name joins and gets an ID which is sorted before the ID of the existing user).

• How to do user authentication? obby 0.4 allows each user to set a password which is stored on the server (respectively publisher) and recognizes users by name. So, if a user with the same name as a user which was in the session some time ago joins, the server looks whether a password has been set, and if the authentication was successful, the old user ID (with all text written by that user) is reassigned to the joining user. This is especially useful when the session has been serialized and should be continued later or when a user has lost the internet connection, perhaps by an automatically disconnection performed by the ISP (which is rather common at least in Germany, but that's another story).

  So, let's assume we want to implement a similar feature into the new obby. Since we just said that names could appear twice, we would need another criteria to recognize a user after disconnection. The user ID comes to mind. So each client could store a table assigning a session to the user ID he had. But since the user ID is known to all participants this feature could easily be misused, so some form of authentication would still be required. The only solution I see here is that you tell the peer through which you have joined (or perhaps others that you trust) a password and if you want to be recognized lateron, you have to join through one of these trusted peers. If all of them have left the session, well, bad luck. I you have some suggestions concerning this point feel free to add a comment or drop me a mail.

• We cannot just assign a vector time index to the new user because this could lead to conflicts as well. The solution would be an association between the user ID and the vector time component. This requires some more data to be stored in the state space and sent through the network.

As a last case, imagine the original publisher has left the session. In the flavour of a real peer-to-peer network the session would just go on as if nothing had happend. The only problem that could arise is that the publisher must not use the session ID that this session had for other sessions, because he cannot be sure that the old session with this ID might still be running somewhere. As sessions are identified by publisher and a session ID this could lead to conflicts. An easy approach would be to just generate a 32 bit random number as the session ID and assuming that we never generated this one before, but I do not like these approaches that only work in 99.999% of all cases and not in 100% (maybe just because I saw it too often that a mage in Wesnoth missed three times...). Having an ID counter somewhere in the user's home directory is not enough as well because another user might publish a session on the same port and with the same ID as another user on the same host (or just use the same jabber account). As above, I am open to any suggestions regarding this point.

Note however that these are just ideas and no final decisions and they only apply to the jabber communication level. All TCP communication is done as Server/Client as before because it is not guaranteed that all TCP participants can get direct connections to each others (think of NATs, different subnets and so on). This also means that Obby currently relies on all jabber users having direct connections (well, direct as in "I just need to send it to the jabber server and the other one will get it eventually").

About two years ago I gave a part of my webspace to a few people, mostly Clonkers, who did not have any and needed one. They got their own subdomain and FTP access. One of them hosted a phpBB based forum related to some browser game. The last activity therein was from early 2005, but the account still produced about 3GB of HTTP traffic each month and used 120 MB webspace, which is even more than I am currently using (if you do not count email). Today I finally had a look into the access log, and guess what:

ck@unununium ~ $ grep Googlebot access_log_2006-09-19 | wc -l
2763
ck@unununium ~ $ wc -l access_log_2006-09-19
2770 access_log_2006-09-19

The remaining seven entries were spammers that posted nonsense into said forum, but I am still wondering why the Googlebot performed (and, well, probably is still performing) 2700 requests a day to that site - the arbur.net main domain receives not even 10.

You might also wonder why I have so much webspace I am not using. In mid-2003, when I acquired it, only 200 MB have been provided (which I have exceeded in the meanwhile - mostly via email on the IMAP server) and since then, the tariff has been upgraded two times up to 1GB now and I do neither want to downgrade to a lower tariff because of PHP and IMAP being not provided, nor do I want to change the provider since I made really good experiences with the support.

After I got my desktop working again by getting it to Phil who had another hard disk drive for me I had time and possibility to produce some code in the last few days (By the way, being there, it turned out that the hard disk was fully OK but the IDE cable was damaged. Luckily he also had one for me). After some obby and C4Scripter work I am proud to announce the release of the first public version of C4Scripter, 0.9.4. C4Scripter is an editor for the Clonk scripting language, C4Script, written in C++ using gtkmm, by Bernhard Bonigl (boni) and me, and is licensed under the GPL.

C4Scripter currently offers the following features:

• Line Numbers, Undo/Redo directly by using gtksourceview.
• Syntax highlighting of the C4Script syntax.
• Parameter tooltips that show the current parameter of the function the cursor is in (see screenshot).
• Automatically load C4Script function definitions from the document CHM file or online from clonk.de/docs.
• Recognize custom function definitions that are also used by the tooltip engine and allows to jump directly to a function.
• Runs on any platform GTK+ runs on.

Furthermore, the following features are planned:

• Rewrite in C. Apart from reducing code size this would remove gtkmm as a dependency. Normally, this would not be a problem, but most clonkers do not even get a GTK+ runtime installed properly... I did already start to write some classes in C that are already in use in 0.9.4 and saved already about 350k.
• As you can already see in the screenshot, the tab close buttons are clipped a bit too much... this one should be trivial to fix by just stealing code from gedit or gnome-terminal
• Move anything apart from main.cpp into a dynamically linked library to allow other projects to use C4Scripter's features - especially the Clonk IDE Niklas Gürtler (Prof. Clonk) is working on.
• Code auto completion: Press Ctrl+Space to pop up a window that shows auto completion suggestions (for example, if one writes "Create" and then presses Ctrl+Space, the list would show CreateObject, CreateContents, CreateConstruction and so on).
• Smart indentation: Automatically indent one level of indentation if the last line contains '{' when hitting Enter. The same should apply for decreasing indentation on '}'.
• Drag & Drop of documents into C4Scripter. Gobby already supports this, so this should also turn out pretty trivial to implement.
• Complete C4Script Syntax Check without having to run the Clonk Engine and, if possible, with slightly better error messages.
• gettext support: Most clonkers are still German and some of them seem not to know the English language good enough to be able to understand English software.

Tarballs are available here, a Windows binary will be available as soon as I get boni to make a new Windows build. It requires zlib, chmlib, GTK+, gtkmm and GtkSourceView to compile. You are encouraged to try out this release and report any bugs to boni_atbbgen.dot.net and/or armin_atarbur.dot.net.

Update: Windows binaries are here. Make sure you have GTK+ and gtkmm installed, at least version 2.8.0.

Exactly two months ago I was in Freiburg im Breisgau because of the Kreiswehrersatzamt (A kind of department that has to fulfill personal needs for the German armed forces, the Bundeswehr) wanting to check me for military use as part of the general conscription in Germany. They stated me as T2, meaning "partially useful" and they could draft me for military service at the beginning of october. However, I expected to become T5, meaning "not of any use" because of my glasses, somewhat broken back (I even had a medical attestation about this) and pretty bad grades in schoolar sport. But this was not the only reason why I was not satisfied with being T2: On the one hand I wanted to begin my study of physics in october, on the other hand most of my class mates have been rejected - even those with significantly better sport grades.

This is why I entered objection against the decision of the Kreiswehrersatzamt. After some exchange of letters they decided to recheck me today, so I went to Freiburg once again this morning. After several minutes of waiting here and there the doctor did a quick examination and finally called an orthopedist in Karlsruhe who decided to declare me T5 after having received some medical documents like the attestation mentioned above. So I came home just about an hour ago being happy that I have no longer to deal with those Armed Forces people and having removed the (hopefully) last obstacle for beginnig with my studies.

The problem is not even the general conscription as such, but the fact that they accept/reject people mostly arbitrarily satisfying their needs (well, at least it seems so to me). It just hurts that most of my friends could begin to study while I would have to do some military service (or civilian service) for nine months that gets me nowhere but is just another lost year. The other thing is that there is no corresponding obligation for women, but this argument has already been raised against the conscription several times. I hope that it is just a matter of time until they either drop the conscription at all or introduce obligatory civilian service for anyone except highly disabled people.

Yesterday, I came back from a journey to Ireland, and the first thing I realized (well, apart from a new bed for our cat) was that the hard disk drive of the desktop computer here seems now totally broken. The HD did already some strange things in the past like not being recognized at all, some read failures during boot (GRUB showing "ORUB loading stage N" multiple times, and no, this is not a typo) or producing files in the file system that could not even be read or deleted by root. But most of the time, one or more simple reboots fixed almost all. Now it just displays an error message I am not fully aware of (Something like "SYSTEM BOOT FAILURE") when writing this, and I don't want to reboot since I would lose all settings of this Knoppix session.

The laptop's graphics card (I assume) is also broken, but this happend already prior to the journey to Ireland. It shows red lines during boot and some other unwanted graphical effects in the linux console and the screen turns to black when starting X or Windows. Currently, I have booted from a Knoppix DVD on the desktop and use the notebook as a router to the home WLAN since neither Knoppix nor ndiswrapper support the local USB WLAN adapter.

I am now going to purchase a new hard drive for the desktop, save some important data from the laptop thereon and then send it to Acer. Since companies have to guarantee two years of warranty on electronic products in Germany (as far as I am informed) I hope to get it repaired without having to pay for it.