Petter Reinholdtsen

Entries tagged "english".

The sorry state of multimedia browser plugins in Debian
2008-11-25 00:10

Recently I have spent some time evaluating the multimedia browser plugins available in Debian Lenny, to see which one we should use by default in Debian Edu. We need an embedded video playing plugin with control buttons to pause or stop the video, and capable of streaming all the multimedia content available on the web. The test results and notes are available on the Debian wiki. I was surprised how few of the plugins are able to fill this need. My personal video player favorite, VLC, has a really bad plugin which fail on a lot of the test pages. A lot of the MIME types I would expect to work with any free software player (like video/ogg), just do not work. And simple formats like the audio/x-mplegurl format (m3u playlists), just isn't supported by the totem and vlc plugins. I hope the situation will improve soon. No wonder sites use the proprietary Adobe flash to play video.

For Lenny, we seem to end up with the mplayer plugin. It seem to be the only one fitting our needs. :/

Tags: debian, debian edu, english, multimedia, web.
Devcamp brought us closer to the Lenny based Debian Edu release
2008-12-07 12:00

This weekend we had a small developer gathering for Debian Edu in Oslo. Most of Saturday was used for the general assemly for the member organization, but the rest of the weekend I used to tune the LTSP installation. LTSP now work out of the box on the 10-network. Acer Aspire One proved to be a very nice thin client, with both screen, mouse and keybard in a small box. Was working on getting the diskless workstation setup configured out of the box, but did not finish it before the weekend was up.

Did not find time to look at the 4 VGA cards in one box we got from the Brazilian group, so that will have to wait for the next development gathering. Would love to have the Debian Edu installer automatically detect and configure a multiseat setup when it find one of these cards.

Tags: debian, debian edu, english, ltsp.
Software video mixer on a USB stick
2008-12-28 15:40

The Norwegian Unix User Group is recording our montly presentation on video, and recently we have worked on improving the quality of the recordings by mixing the slides directly with the video stream. For this, we use the dvswitch package from the Debian video team. As this require quite one computer per video source, and NUUG do not have enough laptops available, we need to borrow laptops. And to avoid having to install extra software on these borrwed laptops, I have wrapped up all the programs needed on a bootable USB stick. The software required is dvswitch with assosiated source, sink and mixer applications and dvgrab. To allow this setup to work without any configuration, I've patched dvswitch to use avahi to connect the various parts together. And to allow us to use laptops without firewire plugs, I upgraded dvgrab to the one from Debian/unstable to get one that work with USB sources. We have not yet tested this setup in a production setup, but I hope it will work properly, and allow us to set up a video mixer in a very short time frame. We will need it for Go Open 2009.

The USB image is for a 1 GB memory stick, but can be used on any larger stick as well.

Tags: english, nuug, video.
When web browser developers make a video player...
2009-01-17 18:50

As part of the work we do in NUUG to publish video recordings of our monthly presentations, we provide a page with embedded video for easy access to the recording. Putting a good set of HTML tags together to get working embedded video in all browsers and across all operating systems is not easy. I hope this will become easier when the <video> tag is implemented in all browsers, but I am not sure. We provide the recordings in several formats, MPEG1, Ogg Theora, H.264 and Quicktime, and want the browser/media plugin to pick one it support and use it to play the recording, using whatever embed mechanism the browser understand. There is at least four different tags to use for this, the new HTML5 <video> tag, the <object> tag, the <embed> tag and the <applet> tag. All of these take a lot of options, and finding the best options is a major challenge.

I just tested the experimental Opera browser available from labs.opera.com, to see how it handled a <video> tag with a few video sources and no extra attributes. I was not very impressed. The browser start by fetching a picture from the video stream. Not sure if it is the first frame, but it is definitely very early in the recording. So far, so good. Next, instead of streaming the 76 MiB video file, it start to download all of it, but do not start to play the video. This mean I have to wait for several minutes for the downloading to finish. When the download is done, the playing of the video do not start! Waiting for the download, but I do not get to see the video? Some testing later, I discover that I have to add the controls="true" attribute to be able to get a play button to pres to start the video. Adding autoplay="true" did not help. I sure hope this is a misfeature of the test version of Opera, and that future implementations of the <video> tag will stream recordings by default, or at least start playing when the download is done.

The test page I used (since changed to add more attributes) is available from the nuug site. Will have to test it with the new Firefox too.

In the test process, I discovered a missing feature. I was unable to find a way to get the URL of the playing video out of Opera, so I am not quite sure it picked the Ogg Theora version of the video. I sure hope it was using the announced Ogg Theora support. :)

Tags: english, multimedia, nuug, video, web.
Using bar codes at a computing center
2009-02-20 08:50

At work with the University of Oslo, we have several hundred computers in our computing center. This give us a challenge in tracking the location and cabling of the computers, when they are added, moved and removed. Some times the location register is not updated when a computer is inserted or moved and we then have to search the room for the "missing" computer.

In the last issue of Linux Journal, I came across a project libdmtx to write and read bar code blocks as defined in the The Data Matrix Standard. This is bar codes that can be read with a normal digital camera, for example that on a cell phone, and several such bar codes can be read by libdmtx from one picture. The bar code standard allow up to 2 KiB to be written in the tag. There is another project with a bar code writer written in postscript capable of creating such bar codes, but this was the first time I found a tool to read these bar codes.

It occurred to me that this could be used to tag and track the machines in our computing center. If both racks and computers are tagged this way, we can use a picture of the rack and all its computers to detect the rack location of any computer in that rack. If we do this regularly for the entire room, we will find all locations, and can detect movements and removals.

I decided to test if this would work in practice, and picked a random rack and tagged all the machines with their names. Next, I took pictures with my digital camera, and gave the dmtxread program these JPEG pictures to see how many tags it could read. This worked fairly well. If the pictures was well focused and not taken from the side, all tags in the image could be read. Because of limited space between the racks, I was unable to get a good picture of the entire rack, but could without problem read all tags from a picture covering about half the rack. I had to limit the search time used by dmtxread to 60000 ms to make sure it terminated in a reasonable time frame.

My conclusion is that this could work, and we should probably look at adjusting our computer tagging procedures to use bar codes for easier automatic tracking of computers.

Tags: english, nuug.
Checking server hardware support status for Dell, HP and IBM servers
2009-02-28 23:50

At work, we have a few hundred Linux servers, and with that amount of hardware it is important to keep track of when the hardware support contract expire for each server. We have a machine (and service) register, which until recently did not contain much useful besides the machine room location and contact information for the system owner for each machine. To make it easier for us to track support contract status, I've recently spent time on extending the machine register to include information about when the support contract expire, and to tag machines with expired contracts to make it easy to get a list of such machines. I extended a perl script already being used to import information about machines into the register, to also do some screen scraping off the sites of Dell, HP and IBM (our majority of machines are from these vendors), and automatically check the support status for the relevant machines. This make the support status information easily available and I hope it will make it easier for the computer owner to know when to get new hardware or renew the support contract. The result of this work documented that 27% of the machines in the registry is without a support contract, and made it very easy to find them. 27% might seem like a lot, but I see it more as the case of us using machines a bit longer than the 3 years a normal support contract last, to have test machines and a platform for less important services. After all, the machines without a contract are working fine at the moment and the lack of contract is only a problem if any of them break down. When that happen, we can either fix it using spare parts from other machines or move the service to another old machine.

I believe the code for screen scraping the Dell site was originally written by Trond Hasle Amundsen, and later adjusted by me and Morten Werner Forsbring. The HP scraping was written by me after reading a nice article in ;login: about how to use WWW::Mechanize, and the IBM scraping was written by me based on the Dell code. I know the HTML parsing could be done using nice libraries, but did not want to introduce more dependencies. This is the current incarnation:

use LWP::Simple;
use POSIX;
use WWW::Mechanize;
use Date::Parse;
[...]
sub get_support_info {
    my ($machine, $model, $serial, $productnumber) = @_;
    my $str;

    if ( $model =~ m/^Dell / ) {
        # fetch website from Dell support
        my $url = "http://support.euro.dell.com/support/topics/topic.aspx/emea/shared/support/my_systems_info/no/details?c=no&cs=nodhs1&l=no&s=dhs&ServiceTag=$serial";
        my $webpage = get($url);
        return undef unless ($webpage);

        my $daysleft = -1;
        my @lines = split(/\n/, $webpage);
        foreach my $line (@lines) {
            next unless ($line =~ m/Beskrivelse/);
            $line =~ s/<[^>]+?>/;/gm;
            $line =~ s/^.+?;(Beskrivelse;)/$1/;

            my @f = split(/\;/, $line);
            @f = @f[13 .. $#f];
            my $lastend = "";
            while ($f[3] eq "DELL") {
                my ($type, $startstr, $endstr, $days) = @f[0, 5, 7, 10];

                my $start = POSIX::strftime("%Y-%m-%d",
                                            localtime(str2time($startstr)));
                my $end = POSIX::strftime("%Y-%m-%d",
                                          localtime(str2time($endstr)));
                $str .= "$type $start -> $end ";
                @f = @f[14 .. $#f];
                $lastend = $end if ($end gt $lastend);
            }
            my $today = POSIX::strftime("%Y-%m-%d", localtime(time));
            tag_machine_unsupported($machine)
                if ($lastend lt $today);
        }
    } elsif ( $model =~ m/^HP / ) {
        my $mech = WWW::Mechanize->new();
        my $url =
            'http://www1.itrc.hp.com/service/ewarranty/warrantyInput.do';
        $mech->get($url);
        my $fields = {
            'BODServiceID' => 'NA',
            'RegisteredPurchaseDate' => '',
            'country' => 'NO',
            'productNumber' => $productnumber,
            'serialNumber1' => $serial,
        };
        $mech->submit_form( form_number => 2,
                            fields      => $fields );
        # Next step is screen scraping
        my $content = $mech->content();

        $content =~ s/<[^>]+?>/;/gm;
        $content =~ s/\s+/ /gm;
        $content =~ s/;\s*;/;;/gm;
        $content =~ s/;[\s;]+/;/gm;

        my $today = POSIX::strftime("%Y-%m-%d", localtime(time));

        while ($content =~ m/;Warranty Type;/) {
            my ($type, $status, $startstr, $stopstr) = $content =~
                m/;Warranty Type;([^;]+);.+?;Status;(\w+);Start Date;([^;]+);End Date;([^;]+);/;
            $content =~ s/^.+?;Warranty Type;//;
            my $start = POSIX::strftime("%Y-%m-%d",
                                        localtime(str2time($startstr)));
            my $end = POSIX::strftime("%Y-%m-%d",
                                      localtime(str2time($stopstr)));

            $str .= "$type ($status) $start -> $end ";

            tag_machine_unsupported($machine)
                if ($end lt $today);
        }
    } elsif ( $model =~ m/^IBM / ) {
        # This code ignore extended support contracts.
        my ($producttype) = $model =~ m/.*-\[(.{4}).+\]-/;
        if ($producttype && $serial) {
            my $content =
                get("http://www-947.ibm.com/systems/support/supportsite.wss/warranty?action=warranty&brandind=5000008&Submit=Submit&type=$producttype&serial=$serial");
            if ($content) {
                $content =~ s/<[^>]+?>/;/gm;
                $content =~ s/\s+/ /gm;
                $content =~ s/;\s*;/;;/gm;
                $content =~ s/;[\s;]+/;/gm;

                $content =~ s/^.+?;Warranty status;//;
                my ($status, $end) = $content =~ m/;Warranty status;([^;]+)\s*;Expiration date;(\S+) ;/;

                $str .= "($status) -> $end ";

                my $today = POSIX::strftime("%Y-%m-%d", localtime(time));
                tag_machine_unsupported($machine)
                    if ($end lt $today);
            }
        }
    }
    return $str;
}

Here are some examples on how to use the function, using fake serial numbers. The information passed in as arguments are fetched from dmidecode.

print get_support_info("hp.host", "HP ProLiant BL460c G1", "1234567890"
                       "447707-B21");
print get_support_info("dell.host", "Dell Inc. PowerEdge 2950", "1234567");
print get_support_info("ibm.host", "IBM eserver xSeries 345 -[867061X]-",
                       "1234567");

I would recommend this approach for tracking support contracts for everyone with more than a few computers to administer. :)

Update 2009-03-06: The IBM page do not include extended support contracts, so it is useless in that case. The original Dell code do not handle extended support contracts either, but has been updated to do so.

Tags: english, nuug.
Time for new LDAP schemas replacing RFC 2307?
2009-03-29 20:30

The state of standardized LDAP schemas on Linux is far from optimal. There is RFC 2307 documenting one way to store NIS maps in LDAP, and a modified version of this normally called RFC 2307bis, with some modifications to be compatible with Active Directory. The RFC specification handle the content of a lot of system databases, but do not handle DNS zones and DHCP configuration.

In Debian Edu/Skolelinux, we would like to store information about users, SMB clients/hosts, filegroups, netgroups (users and hosts), DHCP and DNS configuration, and LTSP configuration in LDAP. These objects have a lot in common, but with the current LDAP schemas it is not possible to have one object per entity. For example, one need to have at least three LDAP objects for a given computer, one with the SMB related stuff, one with DNS information and another with DHCP information. The schemas provided for DNS and DHCP are impossible to combine into one LDAP object. In addition, it is impossible to implement quick queries for netgroup membership, because of the way NIS triples are implemented. It just do not scale. I believe it is time for a few RFC specifications to cleam up this mess.

I would like to have one LDAP object representing each computer in the network, and this object can then keep the SMB (ie host key), DHCP (mac address/name) and DNS (name/IP address) settings in one place. It need to be efficently stored to make sure it scale well.

I would also like to have a quick way to map from a user or computer and to the net group this user or computer is a member.

Active Directory have done a better job than unix heads like myself in this regard, and the unix side need to catch up. Time to start a new IETF work group?

Tags: debian, debian edu, english, nuug.
Returning from Skolelinux developer gathering
2009-03-29 21:00

I'm sitting on the train going home from this weekends Debian Edu/Skolelinux development gathering. I got a bit done tuning the desktop, and looked into the dynamic service location protocol implementation avahi. It look like it could be useful for us. Almost 30 people participated, and I believe it was a great environment to get to know the Skolelinux system. Walter Bender, involved in the development of the Sugar educational platform, presented his stuff and also helped me improve my OLPC installation. He also showed me that his Turtle Art application can be used in standalone mode, and we agreed that I would help getting it packaged for Debian. As a standalone application it would be great for Debian Edu. We also tried to get the video conferencing working with two OLPCs, but that proved to be too hard for us. The application seem to need more work before it is ready for me. I look forward to getting home and relax now. :)

Tags: debian, debian edu, english, nuug.
Standardize on protocols and formats, not vendors and applications
2009-03-30 11:50

Where I work at the University of Oslo, one decision stand out as a very good one to form a long lived computer infrastructure. It is the simple one, lost by many in todays computer industry: Standardize on open network protocols and open exchange/storage formats, not applications. Applications come and go, while protocols and files tend to stay, and thus one want to make it easy to change application and vendor, while avoiding conversion costs and locking users to a specific platform or application.

This approach make it possible to replace the client applications independently of the server applications. One can even allow users to use several different applications as long as they handle the selected protocol and format. In the normal case, only one client application is recommended and users only get help if they choose to use this application, but those that want to deviate from the easy path are not blocked from doing so.

It also allow us to replace the server side without forcing the users to replace their applications, and thus allow us to select the best server implementation at any moment, when scale and resouce requirements change.

I strongly recommend standardizing - on open network protocols and open formats, but I would never recommend standardizing on a single application that do not use open network protocol or open formats.

Tags: debian, english, nuug, standard.
Recording video from cron using VLC
2009-04-05 10:00

One think I have wanted to figure out for a along time is how to run vlc from cron to do recording of video streams on the net. The task is trivial with mplayer, but I do not really trust the security of mplayer (it crashes too often on strange input), and thus prefer vlc. I finally found a way to do it today. I spent an hour or so searching the web for recipes and reading the documentation. The hardest part was to get rid of the GUI window, but after finding the dummy interface, the command line finally presented itself:

URL=http://www.ping.uio.no/video/rms-oslo_2009.ogg
SAVEFILE=rms.ogg
DISPLAY= vlc -q $URL \
  --sout="#duplicate{dst=std{access=file,url='$SAVEFILE'},dst=nodisplay}" \
  --intf=dummy

The command stream the URL and store it in the SAVEFILE by duplicating the output stream to "nodisplay" and the file, using the dummy interface. The dummy interface and the nodisplay output make sure no X interface is needed.

The cron job then need to start this job with the appropriate URL and file name to save, sleep for the duration wanted, and then kill the vlc process with SIGTERM. Here is a complete script vlc-record to use from at or cron:

#!/bin/sh
set -e
URL="$1"
SAVEFILE="$2"
DURATION="$3"
DISPLAY= vlc -q "$URL" \
  --sout="#duplicate{dst=std{access=file,url='$SAVEFILE'},dst=nodisplay}" \
  --intf=dummy < /dev/null > /dev/null 2>&1 &
pid=$!
sleep $DURATION
kill $pid
wait $pid
Tags: english, nuug, video.
No patch is not better than a useless patch
2009-04-28 09:30

Julien Blache claim that no patch is better than a useless patch. I completely disagree, as a patch allow one to discuss a concrete and proposed solution, and also prove that the issue at hand is important enough for someone to spent time on fixing it. No patch do not provide any of these positive properties.

Tags: debian, english, nuug.
Two projects that have improved the quality of free software a lot
2009-05-02 15:00

There are two software projects that have had huge influence on the quality of free software, and I wanted to mention both in case someone do not yet know them.

The first one is valgrind, a tool to detect and expose errors in the memory handling of programs. It is easy to use, all one need to do is to run 'valgrind program', and it will report any problems on stdout. It is even better if the program include debug information. With debug information, it is able to report the source file name and line number where the problem occurs. It can report things like 'reading past memory block in file X line N, the memory block was allocated in file Y, line M', and 'using uninitialised value in control logic'. This tool has made it trivial to investigate reproducible crash bugs in programs, and have reduced the number of this kind of bugs in free software a lot.

The second one is Coverity which is a source code checker. It is able to process the source of a program and find problems in the logic without running the program. It started out as the Stanford Checker and became well known when it was used to find bugs in the Linux kernel. It is now a commercial tool and the company behind it is running a community service for the free software community, where a lot of free software projects get their source checked for free. Several thousand defects have been found and fixed so far. It can find errors like 'lock L taken in file X line N is never released if exiting in line M', or 'the code in file Y lines O to P can never be executed'. The projects included in the community service project have managed to get rid of a lot of reliability problems thanks to Coverity.

I believe tools like this, that are able to automatically find errors in the source, are vital to improve the quality of software and make sure we can get rid of the crashing and failing software we are surrounded by today.

Tags: debian, english.
Debian boots quicker and quicker
2009-06-24 21:40

I spent Monday and tuesday this week in London with a lot of the people involved in the boot system on Debian and Ubuntu, to see if we could find more ways to speed up the boot system. This was an Ubuntu funded developer gathering. It was quite productive. We also discussed the future of boot systems, and ways to handle the increasing number of boot issues introduced by the Linux kernel becoming more and more asynchronous and event base. The Ubuntu approach using udev and upstart might be a good way forward. Time will show.

Anyway, there are a few ways at the moment to speed up the boot process in Debian. All of these should be applied to get a quick boot:

These points are based on the Google summer of code work done by Carlos Villegas.

Support for makefile-style concurrency during boot was uploaded to unstable yesterday. When we tested it, we were able to cut 6 seconds from the boot sequence. It depend on very correct dependency declaration in all init.d scripts, so I expect us to find edge cases where the dependences in some scripts are slightly wrong when we start using this.

On our IRC channel for this effort, #pkg-sysvinit, a new idea was introduced by Raphael Geissert today, one that could affect the startup speed as well. Instead of starting some scripts concurrently from rcS.d/ and another set of scripts from rc2.d/, it would be possible to run a of them in the same process. A quick way to test this would be to enable insserv and run 'mv /etc/rc2.d/S* /etc/rcS.d/; insserv'. Will need to test if that work. :)

Tags: debian, english.
Taking over sysvinit development
2009-07-22 23:00

After several years of frustration with the lack of activity from the existing sysvinit upstream developer, I decided a few weeks ago to take over the package and become the new upstream. The number of patches to track for the Debian package was becoming a burden, and the lack of synchronization between the distribution made it hard to keep the package up to date.

On the new sysvinit team is the SuSe maintainer Dr. Werner Fink, and my Debian co-maintainer Kel Modderman. About 10 days ago, I made a new upstream tarball with version number 2.87dsf (for Debian, SuSe and Fedora), based on the patches currently in use in these distributions. We Debian maintainers plan to move to this tarball as the new upstream as soon as we find time to do the merge. Since the new tarball was created, we agreed with Werner at SuSe to make a new upstream project at Savannah, and continue development there. The project is registered and currently waiting for approval by the Savannah administrators, and as soon as it is approved, we will import the old versions from svn and continue working on the future release.

It is a bit ironic that this is done now, when some of the involved distributions are moving to upstart as a syvinit replacement.

Tags: debian, english, nuug.
Debian has switched to dependency based boot sequencing
2009-07-27 23:50

Since this evening, with the upload of sysvinit version 2.87dsf-2, and the upload of insserv version 1.12.0-10 yesterday, Debian unstable have been migrated to using dependency based boot sequencing. This conclude work me and others have been doing for the last three days. It feels great to see this finally part of the default Debian installation. Now we just need to weed out the last few problems that are bound to show up, to get everything ready for Squeeze.

The next step is migrating /sbin/init from sysvinit to upstart, and fixing the more fundamental problem of handing the event based non-predictable kernel in the early boot.

Tags: debian, english, nuug.

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