A Money Tree From http://moneytree1000.yolasite.com/resources/money-tree.jpg

First a little background.. A while back I visited a Nursery that grew Advanced Trees in South Australia, after talking to the owner for a little while we got on the topic of website and how he was trying to increase his website exposure. I mentioned to him that I’d send him some tips. Below is those same tips. Now, before you go reading them, please note I don’t claim to be some Search Engine Optimization guru, but just another person with a blog. Many of the tips below are what have worked for me.

The tips relate to the website: http://www.engeltrees.com.au the nursery specialising in Advanced trees, in Australia. At the time of writing many of these tips had not been applied to that website. They may have since updated their website.

Prefix:

 Hi Paul,  I’ve only now found time to have a good look at your website and see what could be improved to help you achieve a better rank in Google.

You might want to grab a coffee, this is a rather long email …

Some tips I have are:

1. Setup a Google Analytics Account

http://www.google.com/analytics/

Google Analytics is a must for any website as it allows you to track where your visitors are coming from and what keywords they used to get to your site.
You’ll learn if they reached your site by searching or by a referral from another site. You’ll find what countries your site is being visited from and importantly, you’ll find out if changes you make are actually making an impact on your sites exposure.

You’ll be amazed what info you can get from this and it’s entirely free for most sites.

2. Look at how Google Sees your site.

Google’s robots don’t look at the images, they only see the text on your website. It’s a good idea to see how Google views your site.

The way I do this is I use the firefox web browser (http://getfirefox.net/) and install the web developer addon to it (https://addons.mozilla.org/en-US/firefox/addon/web-developer/).
This extension allows all images and CSS to be turned off. That then shows you what Google sees.. often it’s not very good.

3.  Improve your Search Engine Optimisations (SEO)

This item is a hard one as no one really know’s what makes a site rank higher in Google. It’s a bit of a black art.
Things that seem to work are:

* Be consistent with keywords

Come up with a set of keywords and make sure those same keywords are on every page, in the title of your site, if you can the domain name, meta description and url, etc

An example of where you could do this is make sure “Engels Advanced Trees” was in the title on every page. Ie your Specials page has a title of “Specials Price List”. You could change this to be “Specials Price List – Engels Advance Trees”. 

Another example is you could put a keyword in your url. Ie you could have a url: http://www.engelstrees.com.au/trees/advanced/bamboo/

A lot of SEO is getting Google to recognize the keywords.

So a question I have is what keywords represent your site? Are they keywords that represent both your business but are also high exposure keywords?

Google has tools to help tell you if they are high exposure keywords. I can’t provide a link as google don’t want people to link to it. But if you search for “google keyword tool” then you’ll find the site. Here you can put in keywords, or keyword phrases and see what the average search results for that keyword is – very useful. For instance you might think that bamboo is a high ranking keyword. But infact eucalyptus is a higher word (just a guess).

* Make sure the meta-description & meta-keywords are different on every page

Your site uses meta descriptions. These show up in Google as the excerpt when you do a search. For instance if I search “Engels Trees” the second result is:

Welcome to Engel Advanced Trees for Adelaide Bamboo, Advanced …

Adelaide Bamboo specialists Engel Trees Adelaide for Bamboo Adelaide Trees Shrubs Hedges and Garden design advice.

The “Adelaide Bamboo…” bit is your meta description. Google is less likely to show more than 1 page about your site if the description and keywords are the same on every page.

* Be prepared to pay for top spot

Google is all about making money. To do that you can pay to be top spot. Google has adwords (http://www.google.com/adwords)
which allows you to nominate keywords and place ads at the top. Depending on the keyword and the region you select depends on how much the keywords cost.

I note that as I search for Engels advanced trees the first link is actually a paid ad to Roneby advanced trees.

* Speed

Whilst I don’t think it’s as big factor as some might suggest. Load speed must have some type of impact. A quick test from (http://iwebtools.com/speed_test
gives:

Clearchain is my website located in the US, as in CNN.com. UniSA is in Adelaide so it might be a better comparison (the international link adds about 1.5 seconds to most requests). Still Engeltree does seem quite a bit slower.
If you want to speed this up, buy a cheap hosting service from someone like http://www.dreamhost.com  I note at the moment they have a 2 week free trial.. great to use as a speed comparison.

* Back links

When Google was first founded, they had the concept of rating a page based on how many sites linked to the page. Since then things have changed but it is still an important part of the search algorithm used. Hence the more sites you get linking to your website.. using the keywords you want. The better your site will rank. Google anayltics will help you see who links into your site. But if you have friends with websites relating to plants. Ask them if they could put a little blurb about your site and a link to the main page somewhere on their site.

You can also go to forums where questions are asked, answer questions and post your main page url. What ever you do, always post to the main page as this helps establish the main page as the one Google should rank higher. The main page links to the other pages of your site so they rank higher.

* Simplify your urls

If you look at your website can you guess what this url relates to?

http://www.engeltrees.com.au/index.php?option=com_content&view=article&id=52&Itemid=57

I can’t. Though I can tell you it’s your ‘Current Specials’ page (that’s what I clicked anyway)

What if the url was instead:

http://www.engletrees.com.au/advancedtrees/currentspecials/

Much easier to read.. much easier for Google to read. Also anything that links to the specials page uses the same link so google can follow your site structure.

* Keep your content changing

It’s a know fact that your site will rank higher if it’s changing. Old content on the internet is not good content so ranks lower.
You can easily do this by having some rotating articles on your main page. I can tell your site doesn’t get updated often as it still lists (C) 2010.

Another way to keep the content fresh is to keep a blog and show a section of that on the main page.
A blogs also a great way to get others linking to you. They leave comments or link to a blog post.

You might write an article about the best way of pruning trees for instance and get a lot of people referring to it.
As an example, my website (which is really something I work on when I can be bothered) brings in ~ $30 a month just by having adverts on it.
The most popular page http://www.clearchain.com/blog/posts/how-to-use-a-belkin-f5u409f5u409-cu-usb-to-pda-serial-converter-in-visawindows-7-64bit-mac-osx-10
brings in ~$10 a month by itself. Most of this is due to people linking to it. I note as of today it has been shared on facebook 14 times and two twitter tweets about it have occurred.

Ie, the people are building backlinks to the site by themselves just by having content that they find useful.

My mother keeps telling me how you have great tips on the radio.. why not post the same tips on a blog and at the end of the show/segment refer to your site with ‘and the tip in all it’s details area available on our website at engelstrees.com.au. I guarantee there will be people that visit just because the didn’t quite catch the entire tip… but make sure you setup analytics so you can see the before and after difference

Anyway, these are just some ways that you can help boost your company exposure via the web. But it should set you on the right track.

Hope these help you!

A Long time ago I was watching a story about data and one fact that rang in my mind was how much data was in transit at anyone point in time. A classic way to think about this is a transatlantic fibre cable. Even at the speed of light, the amount of data that is bouncing in that cable grows as the distance increases. It occurred to me you could actually use the in transit bandwidth as a filesystem.

There’s a number of reasons you might want to do this?

1. A really secure filesystem  – since you have to continually retransmit the data, you simply unplug your PC and the data disappears
2. A common storage system that multiple people can use
3. A Storage system that grows as the amount of diverse paths increases

Below are some notes I made on a recent international flight.. at the time I considered myself as the in transit filesystem!!

The filesystem to this day has not been implemented though the thought about finishing the design and building it still lingers in some parts of my brain.

—-

The In Transit Filesystem

Concept: A file system that exists in the propagation delay of a transit media

Examples: There exists many international fibre cables. These cables can
transmit large amounts of data in a relatively short amount of time. If a cable
is capable of 1Tb/s and there is a latency of 1ms to the other end of the cable
then there can be approximately 1Tb/0.001 bits of data in transit at any one
time. The aim of the intransit filesystem is to store data in this transmission
space. Constant retransmission of data maintains the live filesystem. If the
network goes down or the data is not retransmitted the filesystem goes down/is
lost.

Why: Reason behind the In Transit Filesystem

The In Transit filesystem does away with a physical storage medium attached
to any one machine. Instead the storage medium is simply propagation delay.
This sort of storage has a number of applications. These include security
related keys which exist with a limited time. Ie consider the concept of
email that decays. The keys to the email exist in the InTransit Filesystem
The email client ask for the keys and if available decodes the message. The
sender is the pingback for the filesystem hence the sender decides if they
retransmit the key or not. If they don’t the email is now undecodable (easily
anyway). The filesystem can also be used to establish common tables. Consider a
router that needs to build mac tables. Instead of sending a broadcast arp
request to find a ip for a machine, it can query the in transit filesystem, this
not only allows quicker recovery of the ip but also reduces traffic.

Objective: The aim of this brief is to asses the requirements needed to not only
build the In Transit Filesystem but also to make it resilent.

Problems & Solutions:

There is a number of issues when building a filesystem of this type. These are
listed below and discussed afterwards with possible solutions.

o Calculating the Filesystem Size
o Latency to packets/files in read/writing
o Dealing with packet drop
o Retransmission
o Error checking and redundancy
o transport medium

The problems discussed:

o Calculating filesystem size

With the storage medium live the filesystem size is not only hard to calculate
but may be continually changing. The aim is to be able to guarantee a minimum
file system size so data can be recovered.

A ongoing calculation supports this by calculating packet latency over time. A
simple average gives an upper limit to the available data space. Of course
adding another route gives the filesystem increased space. For advanced
filesystem calculations packet loss including RED and similar algorithms, window
sizing and other medium fallbacks must be considered. These algorithms are not
yet determined.

o Latency to packets/files in read/writing

The speed of the filesystem is limited to at most 2*the propagation delay of the
medium link. This delay can often be up to 10 seconds ( on large long haul links
with slow transmission speeds or congestion. This delay is unacceptable. To
increase speed local caching can be applied though really converts the
filesystem from an in transit system to an in-memory system. Delays can be also
reduced by secondary links and forward propagation, ie splitting up the blocks
so a file is transmitted in a fragmented with multiple packets containing the
same part of a file. Of cause this reduces the available size of the filesystem.

o Dealing with Packet Drop

Packet drop in the in Transit Filesystem is not just bad but devastating. The
packet without some sort of redundancy will cause filesystem corruptions. To deal
with this there has to be redundancy.

o Error checking and redundancy

Whilst initially the filesystem will be implemented with traditional algorithms
to support redundancy, ie md5, forward, backward crc’s, etc long term the use of
such files are not scalable. Data is growing at such a large rate. Much which
doesn’t need to be archived but is anyway. We take an approach that is used in
the zfs filesystem, that being block deduping. Ie files with a block of data that
is the same need only store that block once.

We also introduce a new concept that the current modern age of filesystems
doesn’t support. That being guaranteed reliability. Whilst the computer age has
brought us digital data, the laying to store that data relies on consistency at
the filesystem level. Ie A file is always 100% intact. If any bits of that file
are not intact bad things happen. This places lots of constraints on the
filesystem in regard to the management of data. Whilst I don’t believe
filesystems can’t have reliability, I believe that applications can perform some
redundancies of their own formats. They then ask the filesystem for a guarantee
of a level of consistency to a file. For example: Modern day application
requests the creation of a file with a guaranteed consistency of 100%.
Application X (which say stores a lossy image format) requests block x of file
to be 100% guaranteed (ie a file header) then places a 70% guarantee request on
all other blocks (image data). Hence if data is missing of the filesystem
begins to fill up the filesystem has the option of dropping packets to
accommodate expansion.

This page explains how to use a USB2.0 device in VirtualBox with a FreeBSD 8+ as a hostOS

Recently I got around to converting my last Linux box over to FreeBSD. The change over for almost everything was smooth except for one thing. A windows virtual machine. I have a number of applications which sadly are Windows only applications, one is accounting package.

One requirement of this package is the need to print. This worked under Linux so I think twice when I finally nuked the Linux partition. Sadly I soon found that my USB printer did not work under the VirtualBox VM under FreeBSD. 
It was crazy. I’d followed the guide about enabling USB support under FreeBSD with virtual box at  http://wiki.freebsd.org/VirtualBox and other USB devices worked fine. FreeBSD was able to see the device (usbconfig) showed it clearly. Even Virtual Box was able to see the device. The crazy thing was even Windows was able to see the device. However, no matter how much driver updating, plugging, replugging I did windows would show the printer existed but kept putting a yellow triangle next to it indicating it needed ‘Trouble Shooting’.  I was lost.

I left things this way for over a month. Until I had no choice but to print. Hence I had to fix the issue. 

I tried lots of things:

• Different USB Ports
• Hubs
• Resetting the printer
• Reinstalling the drivers
• Deleting the driver
• upgrading the driver

At one point I even noticed that the printer was being recognised by the FreeBSD ulpt driver and I thought that could be a problem so tried to disable that. Alas nothing.

It wasn’t until I noticed that USB2.0 was deselected in Virtualbox that it all made sense. I clicked the tick box and got a dialog complaining that USB2.0 could not be enabled due to a missing extension pack. A look at Virtual box’s website indicated there was one for all platforms.. it didn’t work on FreeBSD. A quick google search revealed it’s got native binaries that don’t work under FreeBSD.

Hence I was again at a loss. Then it occurred to me, could I force the printer to negotiate at usb1 or usb1.1 speeds? A lot of google searching revealed nothing, I looked at using usbconfig, usbdevs all proved pointless until I found this post.

My printer was definitely running USB2, usbconfig confirmed it:

ugen4.3: <Samsung CLP-500 Series SAMSUNG ELECTRONICS CO., LTD> at usbus4, cfg=255 md=HOST spd=HIGH (480Mbps) pwr=ON

It’s from the writer of the Virtualbox FreeBSD usb driver (and also the FreeBSD usb maintainer as well). Turns out that USB2/2.0 devices may not work without the Virtualbox Extension pack hence the following sysctl needs to be run in order to convert USB2 devices to 1.1

sysctl hw.usb.ehci.no_hs=1

This converted my printer to a USB1.1 device (or a FULL speed device ) after replugging and windows was all happy!
You can confirm the device change using the command usbconfig 

ugen2.4: <Samsung CLP-500 Series SAMSUNG ELECTRONICS CO., LTD> at usbus2, cfg=0 md=HOST spd=FULL (12Mbps) pwr=ON

So if you find yourself using FreeBSD and have a device that doesn’t seem to work correctly, give the above a shot and see if it solves your issue too!

Briggs & Stratton 8hp Engine Internals Complete

This article details a method I used to fix a large hole in the crankcase of a 8hp Briggs & Stratton Vertical Engine.

First a little background:

When we first bought our property we quickly realised we would need either a tractor or a ride on lawn mower. Whilst I would have loved a tractor, cost meant we went for a ride on lawn mower. However this ride on mower was unique. It was a 1977 Rover Ranger mower. Go Kart style steering, Briggs and Stratton engine, all steel construction, etc.  Built solid as a rock but it was in need of some work. After about 6 months restoring the mower it was ready for testing – restoring the mower not the engine that is.

With the mower restored I added some oil, fuel/gas and gave the engine pull cord a tug, then another tug, and another…eventually I got the engine going. The mower worked great! Cut through thick grass, drove hard, ran smooth -though fast until… I hit a brick. Hidden in the long grass was a house brick and after hitting it at full speed something had to give. Normally this would be the mower blades. However, unknowingly at the time, the previous owner thought it was a good idea to weld the blades fixed. The engine did not like this and after spluttering a little decided the connecting rod (conrod) was the piece of metal that had to break. Sadly as it broke it put approximately a 5cm/1.5″ hole in the crank case wall. Not surprizingly the mower then stopped.

I was devastated. Months of work were now down the drain. A hole in the crankcase surely was unrepairable – especially since I’d never opened up an engine before. Consequently the mower was wheeled into the shed and left for a week. That week was a slow week. However, it also gave me time to think about the motor with a clear head. In particular: Why is a hole in a crank case unrepairable? After eventually pulling the engine apart I came to the conclusion I would try and repair the hole.

The hole was in the side wall, the conrod had created a few additional cracks as it flew through the crankcase side wall, but in general the engine looked repairable. Luckily when the conrod went, the various small pieces of broken conrod didn’t destroy any of the valve stems, oil slinger, etc. The main damage was the side wall.

Initially I thought “I’ll just weld something over it”. That was a nice theory but I very quickly discovered that the crank case was made from cast aluminium. One touch with the Arc welder and it would turn to molten metal! (Aluminum melting point is quite low in comparison with steel – about 700 degrees C vs 2300 degrees C). Hence my options were either TIG weld the case or find some other method of repairing it.

Sadly I’m not rich enough to own a TIG welder and none of my friends had one either. Hence I was left with finding some other method of welding aluminium. After searching Google I found out about a product called Durafix. Durafix is a type of welding rod, or more accurately a solder rod that can be used on aluminium. A little more searching revealled there was a number of products on the market that do a similar products. These can be found by searching for the names Alumaloy, Aladdin, HTS2000. They all do the same thing. So I started looking around for some of these welding rods. Sadly they were not cheap. Hence before I bought them I thought I’d check both prices of new engines as well if the rest of the engine I had was still any good.

New engines turned out to be much more expensive than I thought and I sadly I soon found the piston didn’t run smooth.

Piston with scoring marks from sanding to fit cylinder

One of the side effects of the conrod giving way is the rod arm in the piston had slightly deformed the piston. Hence it wasn’t correctly round any more. At this point I realised I needed a parts list. Going to Briggs and Stratton’s website I punched in the engine numbers and guess what – the parts list was still available. So after ringing around locally and checking Ebay I discovered a new piston wasn’t cheap. Especially since I didn’t know if I could repair the engine. I left the entire project for a few more weeks whilst I thought about what to do.

I eventually decided that if I could get the piston running smoothly I’d get the welding rods and try and repair the crank case. After all a set of aluminium welding rods could always come in handy. The problem was how to fix the piston. Everything I read said it had to be machined round, or replaced. I thought to myself, this is just a lawn mower, not a Ferrari V12. So I did the next best thing. I put the piston in the vice and crimped it until it was reasonably round. This got most of the shape back but it did still catch a little. (A note for anyone attempting a repair, I found the piston would only correctly work when put in from the bottom of the cylinder, it wouldn’t fit from the top).

To fix the small catch that it had left I sanded the side wall of the piston. I figured since it’s only the side wall the worst that would happen is a little movement (later I found out this is called piston slap and can be harmless or can destroy the rings depending on the amount of movement).

With the piston now running smooth I bought aluminium soldering rods off Ebay (It was cheaper to buy them in the US and get them shipped to Australia than buy them in Australia). After a few weeks they arrived and I replicated a couple of youtube videos I’d seen that welded coke can together. This was pretty easy stuff to work with – so I thought. Turns out small things are easy! The biggest issue was I was working with a large crank case.

After cleaning up the crankcase as best as I could with degreaser, some elbow grease, water and a stainless steel brush (as it

doesn’t cause the aluminium to oxidise) I began to heat the case. I’d borrowed a propane blow torch for the job and also had my electric heat gun. Initially I used the heat gun to get the entire crank case to a temperature where it was hot to touch (Electricity wasn’t a consumable like the propane tank).  I then used the propane torch in the cracked areas on the welding rods. It took ages!! Heating, heating, and more heating. Eventually the crank case got hot enough.

(At this point a little side note. The best way to use the welding rods is to heat the surface you want to repair. The rods are designed to melt below the melting point of aluminium. If you heat the rods they just turn in to little solder blobs but never cling to the surface your trying to weld. If you heat the surface your trying to weld then touch the rod to it, the solder melts and clings to the surface).

Finished Weld

With the surface now hot enough (hot enough to smoke the plastic grips in my vice), I began welding…er soldering. It was at this point I realised fixing this would be a little tricker than expected. You see the rods are more of a solder than a welding compound. My aim was to weld a piece of scrap aluminum I’d picked up at a local steel recycler over the hole on the outside of the crank case, then seal the inside with more weld. Being a solder this was a difficult task. The outside weld went perfect. The inside on the otherhand was not so successful. Turns out because the rods are a solder, touching the inside of the piece of aluminium covering the hole, ended up shifting the outside (as the piece was sitting on a layer of molton solder). Quite a few attempts later I had finished the repair.

Sealing the inside of the crankcase with liquid gasket

After 2 hours cool down time (the case took that long). I then did a water test for leaks. Drip………….Drip…….. Drip……… sadly the weld was not water tight. Due to time constraints and limited propane, sadly I could not reweld the case. Instead I applied liquid gasket to the inside of the weld, let it set the retried the water test – I was now water tight – success!

So with the case welded, it was a matter of putting the engine back together. (See the shots below for step by step instructions). By this time I had already bought a new after market conrod which fitted perfectly and despite quite a few mistakes where I had to take bits apart to put other bits in I eventually got the engine back together.

With the engine together, I added oil, petrol a new spark plug and crossed my fingers. I tugged on the pull cord….then again… and again… finally, the engine coughed to life. After quite a bit of spluttering whilst I adjusted the carby, it was running really nice. Time to put some load on it  – This time I had removed the fatal welds on the mower blades, if I hit anything THEY were going to give first.

The mower worked a treat, ran smoothly – after a few adjustments (the safety wire on the flywheel was rubbing against the flywheel cover making a awful noise) and kept running well.. so I thought.

It wasn’t until about 15 minutes into mowing I noticed the excess smoke coming from the mower. There was a little smoke as it accellerated but the amount of smoke had certainly increased quite noticable. Not wanting to destroy the Briggy any more I stopped the mower to inspect what was happening. Sure enough there was a small leak of oil through the weld.

You see Briggs & Stratton engines are designed to run with a negative pressure in the crank case. This helps suck the oil back down when the piston drop and prevents excessive oil burning. Without this negative pressure the oil get up to the combustion chamber and burns – also makes a nice black coated spark plug.

That’s what was happening here. The leak in the crank case weld was letting air in, stopping the back pressure and causing oil to burn. As a quick fix I wedged some metal putty over the hole, topped up the oil and tried again.

It still smoked and leaked. Though dramatically less than the first time. A little more putty and practically no leaks.

So now 5 months down track with the mower use pretty much ever weekend (A lot of grass grew whilst I was repairing it). The repaired B&S 8hp is still going strong. By using some premium unleaded (98 octane) it’s got a lot more punch, and getting the right spark plug gap (0.3″/.72mm)  it works very well.

When summer comes and I can’t mow due to the temperature (due to bush fire regulations). I intend to rip the engine apart again and reweld-solder the cover plate I put over the hole, and not give up until it’s water tight.

I’ve also learnt a lot in the process of doing this. All about engines, how to get them running, keep them running etc. A tip I want to try with the welding is to use a dremel and carve a V groove before welding. Especially over the cracks that are hairline but widen as the engine heats up this should fill them better. (This tip was from a site asking about welding a motorbike crank case with JBWeld – though I can’t find the link again). I also think I’ll purchase a rebuild kit and replace the rings to help eliminate smoke due to a worn piston/rings. The engine runs well enough to justify this. The rebuild kit also has a complete gasket set which will help.

So if suddenly you find yourself with hole in your crank case, a broken conrod and a warped piston,  but otherwise the engine looks fine, don’t believe everyone that the engine is scrap metal. You just might be able to fix it yourself!

Putting a 8hp Briggs and Stratton Engine Back Together

If you have friends or family who are often offering to lend you a hand with various tasks, then it can be a great idea to take them up on the offer when you are moving house. Be clear about what needs doing, and give anyone who volunteers specific tasks to carry out, in order to make the most of the help which you have. Often, it is the most menial tasks which can prove to be the most time-consuming when moving house, so it can be extremely useful if you have a group of willing helpers. Just make sure you’re willing to return the favour in the future!

Make a list of what you are likely to move shortly after your move, and make sure they are easily accessible. It is a good idea for each house member to pack a small holdall for a few days, so that they will not require immediate access to the rest of their belongings. In addition to clothes and toiletries, you may also want to make sure you are able to set up your computer shortly after your move – not just so that you can relax with a game of partypoker, but to help you get in contact with anyone you might need to speak to regarding any problems which you may have encountered while moving. You may also want to get appliances such as your fridge up and running as soon as possible, so that you will be able to store basic food provisions.

Lastly, remember to label EVERYTHING. Keep track of your belongings as best as possible, so that you can easily check if anything has gone missing. Don’t let important documents get lost in the move, and protect anything which is breakable. If you follow these basic guidelines, you can help to make move day as straightforward as possible.

Whilst working on an application that makes use of a 1394a/firewire camera I found a strange bug/feature with libdc1394. The problem was dc1394 was being used to the mode of the camera to 800×600 resolution. However, when querying the frame size after dequeuing the frame, the size was only 640×480. Ie: See the below snippits:

..
dc1394error_t result = dc1394_video_set_mode( this->camera, DC1394_VIDEO_MODE_800x600_RGB8);
if( result != DC1394_SUCCESS )
exit(0);
 
....
dc1394video_frame_t *frame=NULL;
dc1394error_t result;
 
// capture one frame
result = dc1394_capture_dequeue( this->camera, DC1394_CAPTURE_POLICY_WAIT, &frame );
if( result != DC1394_SUCCESS )
exit(0);
 
// Allocate image memory if required
if( this->lastFrame.image == NULL ){
memcpy(this->lastFrame,frame, sizeof(dc1394video_frame_t));
this->lastFrame.image = (uint8_t *)malloc(frame->total_bytes * sizeof(uint8_t));
 
..

At this point total_bytes was 921600 which works out to be 640x480x3 (RGB);

I was stumped. I asked for one mode and got another back. All with no errors what so ever from libdc1394.

After over an hour of debugging, google searching and more,  I eventually found the reason.  The comment that ended up in the code explains the cause:

// Shutdown any isotransports that are setup for the camera.
// It turns out that libDC1394 will quite happily let you set modes,
// framerates, etc but if there is an iso stream running none of them
// will actually take affect. Hence you can set a 800x600 res and get
// back 640x480 video frame - really nice libdc1394. It could at least
// indicate there was a active stream when setting the mode!
// Anyway to deal with this we force the camera to stop capturing
// before we change the settings, if the camera was capturing prior to
// setConfiguration being called, we restart the capture

So the solution is to make sure the iso transmission stream has been shutdown. this can be achieved using:

dc1394_video_set_transmission( this->camera, DC1394_OFF );
dc1394_capture_stop( this->camera );

An easy fix but certainly an annoying setup. I’ve not tested it but I’m guessing many of the other functions:

• dc1394_video_set_framerate
• dc1394_video_set_iso_speed
• dc1394_feature_set_mode
• dc1394_video_set_one_shot

are also affected.

Recently I was working on a piece of code that updated a texture with a camera frame. The application was using the fixed function (non shaders) pipeline of OpenGL. Whilst I didn’t notice it at first, I soon found that the camera image was very delayed. For example the camera was capturing at 30 frames per second, but the screen update rate was only 6 frames per second.

After commenting out vast amounts of code, disabling functions the reason behind the slow frame rates was traced to the OpenGL call: glTexSubImage2D. The exact call that was being made was:

glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0,  mWidth, mHeight,  GL_RGB, GL_UNSIGNED_BYTE, image->getData());

Everything to this call looked normal. I tried a simple test program that used glTextSubImage2D and surprizingly it ran fast! So at this point I was a little confused. How could two very similar programs produce different results.
I kept searching. I tried Google searches found various comments but none of them seemed to work.

Eventually I looked at the Texture class I had been using and began commenting lines out of that. It was only when I found and commented out the line:

glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE );

Things improved. This makes perfect sense as well. Generating a mipmap each frame is expensive. A quick fix and the application was running smoothly!

Rich Short Crust Pastry

A little while ago I was making a quiche and found I had no shortcrust pastry left. Rather than ducking out to the local shop and buying some I decided to make some. Searching through the recipie books I had I found a the following recipie (per Breville Inspirations book)

Recipie:

• 180g butter chopped
• 2 & 1/4 cups plain flour
• 1 & 1/2 teaspoons baking powder
• 1/4 teaspoon salt
• 2 tablespoons lemon juice
• 1 egg yolk, lightly beaten
• Extra Flour for kneading

Steps to make the pastry

1. Using a beater, cream butter until soft.
2. Add flour, baking power and salt. Gradually add lemon juice and egg youlk to form a slightly crumbled dough.
3. Tourn dough onto a lightly flour dusted board and knead lightly to form a smooth ball.
4. Wrap dough in plastic wrap and refrigerate for 20 minutes before using

Things to remember

After making this recipie there would be a few things I’d change for next time. The pastry is Very rich and hence I’d add the entire egg rather than just the yolk. Also the comment about refrigerating for 20mins depends on how cold the pastry is before it goes in the refrigerator. Don’t do what I did and refrigerate it all day until you make the quiche that night – the pastry will be rock hard and need microwaving before you can even make an indent in it!

Also remember to blind bake this pastry. (That is bake it for about 20minutes on 200 degrees Celcius) before filling it. If you don’t do this it might not be cooked before your filling is!

[Thu Jan 20 14:15:16 2011] [error] Oops, no RSA or DSA server certificate found for 'www.somedomain.com:0'?!

Whilst somedomain.com isn’t the official domain name reported (I can’t reveal the client), this error was being printed for every SSL host except the default SSL host. Ironically the default SSL host was simply a redirect to one of the others. A quick check and indeed the problem lied with the SSL hosts – we removed every ssl host and the webserver would start fine – obviously without any ssl.

My colleague and I were  perplexed. He’d tried a quite few things to fix this all without luck. A so call Server Admin told him it was due to not using ip based virtual hosts for ssl, he claimed you can’t use Name Base Virtual hosts with SSL. No doubt this was obtained from a quick google search for the error. The problems is you can run NamedBasedVirtual hosts with SSL on port 443 provided you have a wildcard SSL certificate. A wild is required for NamedBaseVirtual hosts as the SSL connection is established first before the headers are sent. A wildcard will allow any subdomain to use the SSL connection then apache will see the host header and respond with the appropriate vhost. If on only have a single certificate this does not work and you’ll need a separate IP per certificate.

Anyway, we began trying to debug the issue. First we checked the certificate files were at the specified locations – they were. Next we checked the certificates were actually valid. You can use the openssl command below to do this:

openssl x509 -noout -text -in YOURCERTIFICATE.crt

The certificate, key, and certificate authority (CA) were all valid and in date.
Next we tried putting each Vhost in to the config one by one to see if one host had errors over another. Turns out it didn’t matter what order each host was in the config file or which ssl hosts were included, they all had issues – except for the default ssl vhost.

At this point we were a little lost. So we decided to go back to basics and work out what the error really meant. We search to see what apache module the error came from. A simple grep later we’d narrowed down the error to mod_ssl. A search of the mod_ssl source code found the following instance of the message:

# grep Oops *
ssl_engine_init.c:                         "Init: Oops, you want to request client "
ssl_engine_init.c:                "Oops, no RSA or DSA server certificate found "
ssl_engine_init.c:                "Oops, no RSA or DSA server private key found?!");
ssl_engine_io.c:                    (argp != NULL ? "(BIO dump follows)" : "(Oops, no memory buffer?)"));

Looking in ssl_engine_init.c we found the error came from the following function

static void ssl_init_server_certs(server_rec *s,
                                  apr_pool_t *p,
                                  apr_pool_t *ptemp,
                                  modssl_ctx_t *mctx)
{
    const char *rsa_id, *dsa_id;
    const char *vhost_id = mctx->sc->vhost_id;
    int i;
    int have_rsa, have_dsa;
 
    rsa_id = ssl_asn1_table_keyfmt(ptemp, vhost_id, SSL_AIDX_RSA);
    dsa_id = ssl_asn1_table_keyfmt(ptemp, vhost_id, SSL_AIDX_DSA);
 
    <em>have_rsa</em> = ssl_server_import_cert(s, mctx, rsa_id, SSL_AIDX_RSA);
    <em>have_dsa</em> = ssl_server_import_cert(s, mctx, dsa_id, SSL_AIDX_DSA);
 
    if (!(have_rsa || have_dsa)) {
        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
                <strong>"Oops, no RSA or DSA server certificate found "
                "for</strong> '%s:%d'?!", s-&gt;server_hostname, s-&gt;port);
        ssl_die();
    }
 
    for (i = 0; i &lt; SSL_AIDX_MAX; i++) {         ssl_check_public_cert(s, ptemp, mctx-&gt;pks-&gt;certs[i], i);
    }
 
    have_rsa = ssl_server_import_key(s, mctx, rsa_id, SSL_AIDX_RSA);
    have_dsa = ssl_server_import_key(s, mctx, dsa_id, SSL_AIDX_DSA);
 
    if (!(have_rsa || have_dsa)) {
        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
                "Oops, no RSA or DSA server private key found?!");
        ssl_die();
    }
}

Hence  the error was caused by the certificates not being able to be imported. Once again we checked paths to make sure the certificates/keys were correct. Alas they were. So we began to wonder why the certificates couldn’t be found. We’d specified the correct files, confirmed they were correct. It occurred to me that perhaps the openSSL context had not been setup correctly. But why not? I took a look at the default SSL vhost which did work and noticed a single line that were not in any of the other ssl vhosts.

SSLEngine on

The comment above this line read:

#   SSL Engine Switch:
#   Enable/Disable SSL for this virtual host.

I added “SSLEngine On” to the other ssl vhosts and it worked! So it turns out you can have an vhost setup on port 443 without SSL hence for each vhost you want SSL working in you must add the above line. My colleague was extremely thankful – why it happened in the  first place, we still don’t know. We suspect previously the option may have been enabled globally. However the fix allows apache to run again and works after a clean shutdown and startup.