I’ve had a long standing problem. Every time I rebuild my main server (which contains my websites, my mail, my ldap directory, etc), I get myself wrapped around the axle with authentication. I particularly seem to get into trouble with authenticating access to phpMyAdmin. I use ldap for basic authentication in apache. This morning I figured out some obvious things (they are always obvious once you figure them out). I write this down so that the next time I make the same mistake, I’ll have someplace to look to trigger my memory. If it should happen that anyone else who suffers from the same density could get any help from this, so much the better.
All posts by dee
Leadville
Today I flew N8132Y to the Lake County Airport in Leadville, Colorado. This airport has the distinction of being the highest paved runway in North America, at 9927 feet. The folks at the airport tell me that it is the third highest in the world, after one in Nepal and another in Peru.
It is a beautiful flight on a nice day, although there is no escaping the fact that flying through the mountain valleys you are going to get bumped around a little. For me, this is part of the challenge of learning to fly in the mountains. I have never quite gotten used to turbulence, even mild turbulence. Most of my flying has been over the plains, and all in good weather. If it is turbulent out, mostly I don’t fly (although my private checkride was an exception). But if you go over the mountains at the lower altitudes of these small planes, there are going to be air currents. You just have to expect it, and learn to keep your heart from jumping into your throat. After all, the wings are not going to fall off.
The second thing which makes these flights different is the requirement that you constantly be thinking about where you will put the plane if you have to make an emergency landing. Naturally this is way less of an issue in a turbo-normalized twin like 32Y. If I lose an engine, I have another, and with the turbos I can maintain altitude with one engine, and find a place to put down safely. But I’m still thinking about it. How far am I from surrounding airports? Is there a reasonable straight road around?
Finally, there is the excitement of trying to take off in a fully fueled plane, in August, at 9934 feet! Right now with temp/dp at 19/-1 and 30.46 inches, density altitude is 12,100! The runway is 6400′ for just this reason. Fortunately, with N8132Y’s turbos this isn’t really that much of a challenge, but for a normally aspirated engine 6400′ would seem awfully damn short. I wouldn’t want to try taking off today in a fully loaded 172.
Vino, Vinagre, VNC
Another bit of lore that I don’t use often, manage to forget, and end up having to figure out again from time to time:
Vinagre is obsolete. This was the name of the previous built in remote viewing client in gnome (and therefore, for my purposes, in both Ubuntu and Fedora). It will operate as a VNC client (i.e. enable opening windows to VNC servers), but also an RDP client and will even pop up a terminal window for an SSH session. .
Remmina is the new remote viewing client, replacing Vinagre.
Vino is the name of the built in VNC server. This is launched when you invoke the “desktop sharing” preference and enable “allow other users to view your desktop”. Your gnome instance sprouts a vino server listening on 5900, giving (possibly password protected) access to the existing desktop to any vnc client that can reach port 5900. A remote user attached in this way is sharing the desktop with the user seated at the “console”. When either moves the mouse, both will see the cursor move on the the display.
Realvnc, Tightvnc, Tigervnc, Ultravnc are all different forks of the original VNC. Realvnc was the first, from the original devlopers. Tightvnc developed improvements in the encoding (tight encoding) if both ends are tightvnc. Tigervnc seems to be a Fedora fork of tightvnc. All will work with other, but some improvements only kick in if both ends share the improvement.
Xvnc in linux (as installed with the tigervnc package) is a little different animal. It is really a two-headed server, with an X server on one side and a vnc server on the other. The X server is an entirely separate virtual display than the console. There is no physical monitor anywhere, but applications can be started which open that X server and display upon it. On the other side, VNC clients are able to view and control the applications which are displaying on the X server. When the X server is launched, any X applications wanted can also be launched — including an entire gnome desktop environment (entirely independent of the gnome environment which might be running on the “console”, if there is one). Multiple users can have different desktop environments open, albeit using different network ports for each. VNC ports normally start at 5900, which vino attempts to use if it is enabled. So different remote users can use 5901, 5902, 5903… Continue reading Vino, Vinagre, VNC
Adding maps to my java flying apps
Just for fun I explored the Google Maps API and put maps into the flying apps. The google maps aren’t FAA charts or course, but on a multiple leg trip it is quite handy to be able to see the various stops laid out on a map. I also added maps to the page that shows the list of checkpoints. I think this is pretty handy in flight planning, as the alternative is to mark up a hardcopy chart.
Another nice new feature is airport lookup. This is a jquery enabled box on the pages that are asking for an airport ID. If you are planning to fly to some city but don’t know the ID of the airport there, you can just type in the name of the city. It is an autocomplete thing which does an ajax lookup in the airport database as you are typing, giving you a progressively narrower list of airports in cities that match what you have typed. Once you select an airport the ID is automatically put into the field.
Try the flight planner to see these new features.
Deploying Tomcat from Eclipse
I truly do not understand all I know about this, but I’ve been tripped up by this several times now.
After working on a java servlet in Eclipse on a home machine (which happens to be Windows in this case), when I’m ready to deploy I export a WAR file and upload it to Tarragon, the Fedora box that serves this site. I copy the WAR file into /usr/share/tomcat6/webapps, and tomcat redeploys it. Then I have to fix the context.xml to change the datasources from the test database to the real database. Naturally I do this in /usr/share/tomcat6/webapps/<app>/META-INF/context.xml. Then I fire it up, and it fails. Continue reading Deploying Tomcat from Eclipse
Flying the Rockies
In an earlier post I mentioned that my early flight education inculcated me with a healthy fear of flying in the mountains, and that I’m trying to build up my confidence. I’m “stretching” myself, pushing myself. Two weeks ago I flew to Steamboat Springs, a charming little town in Northern Colorado. Yesterday I flew to Glenwood Springs on the other side of the Rockies. In both cases this means flying through the mountains. Glenwood Springs is quite a challenging little airport, nestled down in a valley with mountains all around. To get down to pattern altitude (7000 feet) I was descending in a valley southeast where the airport was out of sight, and then flying around this little ridge to finally get into the pattern. The final comes over a little river which creates some little downdraft. And of course this is only a 3100 foot runway. Plenty of runway I suppose, unless you are as inexperienced as I am. I’m landing the twin at blue line, which is 120mph, so if I don’t get it down pretty quick I’ll run out of runway, and the other end of this runway is not very accommodating to running over. Experience pilots would laugh at me. Bush pilots put bigger planes down in much smaller runways. But I’m still pleased. I’m pushing myself, and I’m learning.
Standalone java apps vs JNDI datasources
This is another post as a memory jogger for me.
Whenever I switch back to java I have trouble remembering the evolving history of setting up mysql connections. Back in the dark ages, you used to do this with Class.forName. But by the time I started writing servlets initially, it was being done instead with DriverManager. Then along came DataSources which could be set up in JNDI. A much more elegant solurtion, as long as you have a container to offer the JNDI service. Most of the active java I have is servlets running in Tomcat, and these are happily set up to use DataSource objects, and the DataSources are all described in the context and picked off from there. Continue reading Standalone java apps vs JNDI datasources
Starting Services
There is no great insight in this post, it is only to help me remember how to start services in Fedora and Ubuntu as I have both. I used Fedora long enough to get used to the old chkconfig stuff, but now thats gone. Ubuntu never did that anyway. They are different, and I get confused about which new syntax to use on which system.
If somebody other than me ever reads this, be careful to check dates and versions before you believe anything I write. It will probably change. This is as of Fedora 16 and Ubuntu 12.04. Continue reading Starting Services
JQuery with Zend Framework
A couple of years ago I incorporated some jquery stuff, and some jquery-ui stuff into a website I had built on Zend Framework. At that time Zend Framework didn’t have its own support for jquery (or if it did, I didn’t know about it).
Now I’m working on a new site, and I find that there is now a jquery view helper to help do jquery stuff. It is located in the “extras” library. I also didn’t know about this library. When did this get added? Anyway, stumbling around on the net I discovered that there is now some jquery support in Zend Framework. Cool. So I set about learning how to use it.
I often find the documentation in the Programmers Reference in Zend Framework to be very cryptic and difficult. Probably this is because I am a very old programmer who learned the craft while dodging dinosaurs back in the stone age. I think people freshly learning to program today have a considerably different perspective (and probably vastly better). Sometimes I just have to go read the code. I had a devil of a time getting the jquery stuff to actually work. These notes maybe will help me the next time I have to do it. Continue reading JQuery with Zend Framework
XBMC Dvdplayer on Ubuntu 12.04
Since installing Ubuntu 12.04 shortly after it was released, XBMC has been unable to play .iso files. This has been the case for me, and for my friend who has a similar setup. I’ve found a way to overcome this.
By way of background, we both have a central shared MySQL database on an Ubuntu 12.04 instance, shared with multiple other XBMC instances running on different platforms. The XBMC instance I mostly watch happens to be Mac OS/X, and that has continued to work. In his case, the “living room” instance that he watches is the same Ubuntu box which houses the database. That XBMC instance is unable to play .iso files. My Ubuntu instance is also unable to play .iso files, though since I rarely watch on that instance it was not a big issue for me. He on the other hand was having to watch movies in another room on a Windows XBMC instance in order to be able to play the .iso files. We are both set up to share the files from the central repository with NFS. Over time we’ve experimented with different protocols, but mostly NFS and SMB, and at the moment we are set up with NFS. Continue reading XBMC Dvdplayer on Ubuntu 12.04