Floyd’s Thoughts…

Amazon EC2 really is amazing, and the Elastic Block storage is pretty darn good too, however I wish you could automate the snapshot process form the EC2 console.

It is however pretty easy to do yourself using a simple cron job.

Before you start make sure you have a JRE:

	sudo apt-get install sun-java6-jre

You will also need the EC2 API tools:

	wget http://s3.amazonaws.com/ec2-downloads/ec2-api-tools.zip
	unzip ec2-api-tools.zip

At this point you should make a metal note of where you unzipped the api tools to.

Now that you have the prerequisites you need the following simple script:

	#!/bin/bash
 
	export JAVA_HOME=/usr/lib/jvm/java-6-sun/jre/
	export EC2_HOME=/root/ec2-api-tools-1.3-42584
	export EC2_PRIVATE_KEY=/data/misc/pk-Umbongo.pem
	export EC2_CERT=/data/misc/cert-Umbongo.pem 
	export AWS_ACCESS_KEY_ID="Twinkle Twinkle Little star"
	export AWS_SECRET_ACCESS_KEY="If your happy and your know it, clap your hands"
 
 
	$EC2_HOME/bin/ec2-create-snapshot vol-999999

Obviously you need to specify your volume id where i have vol-999999

Once you have modified this file to be executable you are ready to test it.

	chmod +x snapshot.sh
 
	./snapshot.sh

Once your have ran it go to the EC2 Console and verify that the snapshot process has started.

And thats it, the first time you run this script the snapshot will take a while to complete but the next one will be much quicker as the snapshot process is incremental, so only the changes since the last snapshot will be read.

Oh, don’t forget to create a cron job for this (*/5 * * * * /path/snapshot/sh)

The IPhone 3.0 SDK includes support for detecting when a user “Shakes” the IPhone, this is intended to be a usability feature allowing app developers to implement Refresh or Read All functions on shake, wow those crazy guys at Apple really do know how to innovate!

It’s pretty easy to implement all you need to do is register your view controller as the first responder and listen for the motion event.

-(void) viewDidAppear:(BOOL)animated{
	[super viewDidAppear:animated];
	[self becomeFirstResponder];
}

Once your controller is the First Responder you can receive the motion event like so:

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
	if (motion == UIEventSubtypeMotionShake)
	{
		refresh;
	}
}

This will work beautifully but you will however notice that any views you present over this one will not respond to all touch events, for instance the keyboard will not show when you touch a text field, this is because you need to resign the First Responder before you present the view like so:

- (IBAction)showMyCustomView {    
	[self resignFirstResponder];	
	[self presentModalViewController:myCustomViewController animated:YES];
}

As you can see this is all pretty easy and the only gotcha is the First Responder stuff, which also is pretty trivial.

Enjoy and please people, Shake Responsibly!