Phil Chen

Apache Mod_Deflate and Flash SWF Files Don’t Like Each Other

Phil Chen — Wed, 05 Aug 2009 04:49:42 +0000

Recently I was working on a Flex project and upon completion and successful QA, I deployed it on a clients server for use. After embedding the SWF file and adding the data.xml that populated the flash application, I could not load the application in Firefox or IE. Several refreshes would load the application occasionally, however most of the time I just had a grey box.

So while troubleshooting using Firebug, I realized that the clients server I had deployed on was using Apache 2.2.11 with Mod_Deflate enabled, a method commonly used to compress up to 70% of data transfered over the wire to speed page loads. I then had a flash back on reading an article about issues with compression of SWF’s, and upon further investigation of the clients Apache configuration file I saw SWF was not excluded from compression via Mod_Deflate.

Mod_Deflate was compressing SWF files sending them with chunked transfer encoding to the browser. It appears the last part of the chunk was being missed by the browser. By refreshing the browser cache it sometimes filled in the missing chunk, and displayed the application.

So I added SWF to the list of files not to compress via Mod_Deflate and the application worked perfectly everytime.

Below is the section I added the SWF exclusion:

BEFORE:

<Location />
# Insert filter
SetOutputFilter DEFLATE
 
# Netscape 4.x has some problems...
BrowserMatch ^Mozilla/4 gzip-only-text/html
 
# Netscape 4.06-4.08 have some more problems
BrowserMatch ^Mozilla/4\.0[678] no-gzip
 
# MSIE masquerades as Netscape, but it is fine
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
 
# Don't compress images and other uncompressible content
SetEnvIfNoCase Request_URI \
 \.(?:gif|jpe?g|png|rar|zip|exe|flv|mov|wma|mp3|avi|mp?g)$ no-gzip dont-vary
 
# Make sure proxies don't deliver the wrong content
Header append Vary User-Agent env=!dont-vary
Location>

AFTER:

 
<Location />
# Insert filter
SetOutputFilter DEFLATE
 
# Netscape 4.x has some problems...
BrowserMatch ^Mozilla/4 gzip-only-text/html
 
# Netscape 4.06-4.08 have some more problems
BrowserMatch ^Mozilla/4\.0[678] no-gzip
 
# MSIE masquerades as Netscape, but it is fine
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
 
# Don't compress images and other uncompressible content
SetEnvIfNoCase Request_URI \
 \.(?:gif|jpe?g|png|rar|zip|exe|flv|mov|wma|mp3|avi|swf|mp?g)$ no-gzip dont-vary
 
# Make sure proxies don't deliver the wrong content
Header append Vary User-Agent env=!dont-vary
Location>

Mob Wars Trailer Contest

Phil Chen — Thu, 11 Jun 2009 04:08:42 +0000

Recently Michael Foster a friend of mine, decided to recruit a bunch of us to enter in the Mob Wars trailer contest. So after several weekends of filming in various residential streets, city streets, a warehouse, a strip club, with various handguns, shotguns, machine guns, and muscle car and motorcycle stunt work a master piece was born. I have a fight scene and got to stunt drive my mustang. Please rate the video on youtube and add a comment to help us win!

What is The Throughput For an Amazon EC2 Instance?

Phil Chen — Sat, 06 Jun 2009 00:02:01 +0000

Since bandwidth throughput when using Amazon Web Services Elastic Compute Cloud (EC2) is very important when routing traffic and services I decided to take some measurements and outline them here for your reference. I ran tests against both 32 Bit and 64 Bit instances, and found some interesting results. These tests were run several times over different days, and the figures are the averages I saw.

*Remember Results May Vary

Methods of Transport:
SCP & CURL

Data File Size:
17 Megabytes

Data Center Bandwidth:
Gigabit (RoutesScience)

SCP Data:

32 Bit CentOS

Data Center –> EC2 32 = 10 megabit/s – 12 megabit/s

EC2 32 –> Data Center = 7.2 megabit/s

EC2 32 –> EC2 32 = 80 megabit/s – 96 megabit/s

64 Bit CentOS

Data Center –> EC2 = 12 megabit/s – 16 megabit/s

EC2 –> Data Center = 2.24 megabit/s – 3 megabit/s

EC2 –> EC2 = 240 megabit/s

CURL (GET NON SSL) Data:

32 Bit CentOS

Data Center (Server Running Apache) –GET–> EC2 = 3.7 megabit/s

EC2 (Running Apache) –GET–> Data Center = 5.7 megabit/s

EC2 (Running Apache) –GET–> EC2 32 = 80 megabit/s – 288 megabit/s

64 Bit CentOS

Data Center (Server Running Apache) –GET–> EC2 = 9.6 megabit/s

EC2 (Running Apache) –GET–> Data Center = 7.2 megabit/s

EC2 (Running Apache) –GET–> EC2 = 767 megabit/s

How to Save a Snapshot of your Amazon EC2 Instance

Phil Chen — Tue, 19 May 2009 23:53:29 +0000

This how to article will go over saving a snapshot of your Amazon Elastic Compute Cloud (EC2) Machine Image (AMI). This is very useful for taking an existing AMI and modifying it to customize your needs into a new separate AMI.

For my intents and purposes I have a base CentOS 5.3 AMI with only the bare essentials. I then use this snapshot method to create different class AMI’s for different server functions ie. (webserver, memcached server, etc)

First thing is first you are going to need to have an existing AMI created, you can read how to do so in my other blog article How to create an Amazon Elastic Compute Cloud EC2 Machine Image (AMI). Once you have this AMI created and you launch the instance the fun begins to modify it and then take a snapshot for a new AMI based on the original AMI.

So once you launch your instance off your base AMI, you simply connect to your Amazon EC2 instance and install all the software you need to serve your purpose as you would any other server. After you have completed all the software installs and customizations, you then can begin the snapshot process.

The first step is to create a directory and download the Amazon EC2 Tools

[root@ec2instance]$ mkdir /mnt/EC2TOOLS
[root@ec2instance]$ cd /mnt/EC2TOOLS
[root@ec2instance]$ wget http://www.philchen.com/wp-content/uploads/2009/05/ec2-ami-tools.zip
[root@ec2instance]$ unzip ec2-ami-tools.zip
[root@ec2instance]$ cd ec2-ami-tools-1.3-31780
[root@ec2instance]$ mv * ../
[root@ec2instance]$ cd ../
[root@ec2instance]$ rmdir ec2-ami-tools-1.3-31780/

Now scp over your AWS private and public certificate

/mnt/EC2TOOLS/pk-yourprivatekey.pem
/mnt/EC2TOOLS/cert-yourcertificate.pem

You want to setup your .bashrc to know where your tools are

[root@ec2instance]$ vi ~/.bashrc
export PATH=$PATH:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin
export EC2_HOME=/mnt/EC2TOOLS
 
[root@ec2instance]$ source ~/.bashrc

Now you will want to download the correct kernel modules:

If your creating a snapshot of a 32bit AMI and don’t have the proper xen kernel modules do the following:

[root@ec2instance]$ mkdir /mnt/MOD
[root@ec2instance]$ cd /mnt/MOD
[root@ec2instance]$ wget http://www.philchen.com/wp-content/uploads/2009/05/kernel-modules2616-xenu.tgz
[root@ec2instance]$ gunzip -c kernel-modules2616-xenu.tgz | tar -xvf -
[root@ec2instance]$ cd /mnt/MOD/lib/modules
[root@ec2instance]$ mv 2.6.16-xenU /lib/modules
[root@ec2instance]$ depmod -ae 2.6.16-xenU

If your creating a snapshot of a 64bit AMI and don’t have the proper xen kernel modules do the following:

[root@ec2instance]$ mkdir /mnt/MOD
[root@ec2instance]$ cd /mnt/MOD
[root@ec2instance]$ wget http://www.philchen.com/wp-content/uploads/2009/05/kernel-modules-261633-xenu.tgz
[root@ec2instance]$ gunzip -c kernel-modules-261633-xenu.tgz | tar -xvf -
[root@ec2instance]$ cd /mnt/MOD/
[root@ec2instance]$ mv 2.6.16.33-xenU /lib/modules
[root@ec2instance]$ depmod -ae 2.6.16.33-xenU

Now you will want to create a location to store the image files

[root@ec2instance]$ mkdir /mnt/EC2IMAGE

At this step you are ready to create the EC2 image files and upload them to S3

[root@ec2instance]$ cd /mnt/EC2TOOLS
[root@ec2instance]$ bin/ec2-bundle-vol -d /mnt/EC2IMAGE --privatekey pk-yourprivatekey.pem --cert cert-yourcertificate.pem -u amazonaccountnumber -r i386 or x86_64 -p imagename
[root@ec2instance]$ bin/ec2-upload-bundle -b yours3bucketname -m /mnt/EC2IMAGE/whatever.manifest.xml -a accesskeyid -s secretaccesskey

Now on your local machine that you start instances from register the new AWS AMI

[phil@client]$ /Users/phil/EC2/bin/ec2-register yourbucketname/thenameofthenewami.manifest.xml

At this point you are done, and ready to fire up your new AMI instance whenever you like with your changes. Note the below directories have been excluded during the bundle process so your certs and secret info will be excluded, but also note anything you installed in these directories will not be kept though as well.

Excluding:
/sys
/proc
/dev/pts
/proc/sys/fs/binfmt_misc
/dev
/media
/mnt
/proc
/sys
/mnt

Happy snapshotting your AMI

Phil Chen — Mon, 18 May 2009 02:35:00 +0000

I have been doing a lot of work with Amazon Web Services Cloud Computing for VMIX Media Inc. so much recently we have started a relationship with Amazon. So far they have been very helpful and working with Amazon Web Services has been great! You can read about our relationship in the Amazon Solutions Catalog: VMIX Delivers SaaS Online Video and Digital Media Solution with AWS

How to Build a Skateboard to Satisfy a Midlife Crisis

Phil Chen — Mon, 18 May 2009 01:33:04 +0000

This article is a step buy step on building your own skateboard; the alternative is having your local skateboard shop do it for you. A long time ago back in my early youth, I worked at two skateboard / inline skate shops one in Lawndale CA, and the other in Hermosa Beach CA, from age 13-18. It was possibly the best work experience of my life. In any rate I decided 15 years later to relive old times and pick up parts to build a new board and go for a ride (yes midlife crisis here I come).

First thing I did was go to a local skateboard shop in Oceanside, CA K5 to be exact. Here I picked up the goods for my new skateboard, I was going for a semi budget board:

Gear:
1x Mystery Lopez Suicide King Deck 7.875 x 31.75
4x Bones REDS Precision Skate Bearings
4x Ricta Wheels Arto Saari 54mm Chrome Cores Gunmetal
2x Thunder Truck Company 149ers
4x Shorty’s 1″
1x Black Magic Grip Tape

Tools:
1x Phillips Tip Screwdriver
1x 3/8 open wrench
1x 7/16 socket or open wrench
1x Packing Knife

The first step was to put the Black Magic grip tape on the deck, since the tape was pre-cut I just had to align it on the board and stick it on.

The second step was to define the edges of the board and grip tape for cutting, I used the top edge of one of my trucks (the side that goes against the board) and scraped the edges all around the board.

The third step was to use a packing knife and cut the grip tape from the bottom with the blade facing up around the edge you defined with your truck. Be careful not to hurt yourself before you even get on the board!

The fourth step is to poke some holes with an allen wrench through your grip tape. You can use any other object that fits in that hole as well.

The fifth step is to put your Shorty truck screws in the deck.

The sixth step is to mount your trucks onto the board with your Shorty screws and nuts, I used a Phillips tip screw driver and a 3/8 wrench to do so.

The seventh step is to put on your wheels, I had the skateboard shop press the bearings into the wheels at the store since I don’t own a bearing press. I made sure to have a washer at both sides of the wheel (included with the trucks), and used a 7/16 socket wrench to tighten the wheels on. Make sure not to over tighten your wheels they should move free, you will have to find the sweet spot.

The last step is to go out and have fun on your new board! For me its midlife crisis time, skate or die!

How long does it take to launch an Amazon EC2 instance?

Phil Chen — Wed, 22 Apr 2009 05:08:20 +0000

As part of a project to offset usage spikes by auto spinning up EC2 instances on the fly for added computing power during high traffic periods, I needed to answer the question how fast could I really spin up an EC2 instance. So after running several tests against small and large EC2 instances running a base CentOS 5.3 AMI this is what I found:

Small Instance 1.7 GB of memory, 1 EC2 Compute Unit (1 virtual core with 1 EC2 Compute Unit), 160 GB of instance storage, 32-bit platform with a base install of CentOS 5.3 AMI

Amount of time from launch of instance to availability:
Between 5 and 6 minutes us-east-1c

Large Instance 7.5 GB of memory, 4 EC2 Compute Units (2 virtual cores with 2 EC2 Compute Units each), 850 GB of instance storage, 64-bit platform with a base install of CentOS 5.3 AMI

Amount of time from launch of instance to availability:
Between 11 and 18 minutes us-east-1c

Both were started via command line using Amazons tools.

Given my research instances are not so instant, so in order to accommodate for the delay calculating your usage patterns is key to avoid the gap. Having a reserve set of instances running as a buffer to carry you over the delay of launching new instances during peak load times is a must. By knowing your usage patterns you can at least make an educated decision as to how many instances you will need in the buffer. Also a system of seeing load acceleration against running capacity will be important for auto launching instances as necessary given your determined algorithm.

Phil Chen — Wed, 22 Apr 2009 03:53:08 +0000

I had a dream last night that I needed to fix the US Air Forces Stratum 1 server which had a bum Stratum 0 card in order for all their Stratum 2 servers to sync over NTP correctly. Apparently in my dream the world would come to an end, if I couldn’t fix the issue! Somewhere along the lines of things launching that shouldn’t as a result of the time glitch. Why can’t I have normal dreams of having super powers like the ability to fly instead?

Phil Chen — Sun, 19 Apr 2009 03:39:28 +0000

It’s that time of year when I try to raise some $ for a good cause the National Multiple Sclerosis Society! You can help donate at http://www.mswalk.com/phil

On April 26 at LEGOLAND, I will be joining thousands of walkers at Walk MS 2009,
benefiting the Pacific South Coast Chapter of the National Multiple Sclerosis Society.

What is The Throughput For Pushing Files to Amazon S3?

Phil Chen — Mon, 06 Apr 2009 11:59:46 +0000

So recently I wanted to test how fast it would take to push a large amount of data into the Amazon S3 Cloud Computing Service. I already had an idea of the throughput, but wanted to make sure with a large amount of data over time my assumption was correct.

SPECIFICATIONS:

Amount of Data: 165.85895 gigabytes
Average File Size of Data: 4.5 megabytes
ISP Connection Speed: 45 megabit connection
Method: Single Threaded Process

RESULTS:

Amount: 165.85895 gigabytes
Time to completion: 19.06775 hours
Throughput: 22.31 megabit/second average

CONCLUSION:

I have consistently seen on average 22 megabit/s speeds for pushing files onto S3. Occasionally I have seen the fastest speeds at around 35 megabit/s. This test helps bolster that, looks like Amazon rate limits it to this range.