AWS Auto Scaling Guide

The previous blog post spoke about a great tool called EZAutoScaling which offers a web-based interface for AWS Auto Scaling. Amazon currently makes AWS Auto Scaling available only as command line tools or APIs and EZAutoScaling offers an online tool to make managing Auto Scaling easier. There are other companies that offer a web-based interface for AWS Auto Scaling, but EZAutoScaling is definitely the cheapest ($1/month).

To follow up on that blog post, EZAutoScaling has put up a great guide for using the command line tools for setting up AWS Auto Scaling. The steps detail the pre-requisites, how to set up the command line tools (with many screenshots), and what commands to use in order to set up your auto scaled environment.

By posting this guide they are showing two things:

1. That setting up AWS Auto Scaling is not straight-forward - though it is not super hard either.
2. If you don’t feel like paying for EZAutoScaling then you can use the guide to set up and use the command line tools for free.

Here is an excerpt from the guide from the “Summary” section which summarizes all of the steps and commands:

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Auto Scaling Online Tool

This blog started out as a SaaS blog. After a while it moved into Android. I’m going to bring it back to its roots (sort of) with a post on IaaS (infrastructure as a service). I’ve been using Amazon AWS (Amazon Web Services) for about 2 years now. It has been fantastic. I’ve done research on other IaaS and PaaS providers (Microsoft, Rackspace, etc.) and I am extremely happy with the service, usability, and price that I get from Amazon.

One of Amazon’s cool services is called Auto Scaling. It allows you to automatically add/remove servers from an “Auto Scaling Group” as user load increases or decreases. The Auto Scaling group monitors itself (using a service called CloudWatch) and if an alert occurs then a server is automatically added or removed from the group. (Server are added to handle more user load; they are removed to save you money.)

And for the most part, setting this up is a huge pain in the butt… until now.

But before I describe why it’s a pain, here is an example of how Auto Scaling works:

- You have 1 server running in an Auto Scaling Group
- User load suddenly spikes and that server’s CPU usage is at 90%
- You are asleep, so you have no way of knowing this is happening and thus no way of quickly increasing the number of servers to improve performance for the user spike
- Fortunately, CloudWatch is set up to check if CPU usage is over 90% on that server and if it is it sends an alert/trigger…
- A new server is added to the Auto Scaling Group and added to a Load Balancer that is part of that Auto Scaling Group
- Now, automatically, 2 servers exist in your farm, load balanced, and user load can be handled literally without a hitch. CPU usage is down to 40% on each server and CloudWatch ends the alert.

I use EC2 servers exclusively for some of my projects and for me Auto Scaling is one of the main reasons for using Infrastructure as a Service with Amazon.

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Android Samsung Nexus S

I’ve been neglecting the blog for a while.. sorry RSS subscribers.

I bought the HTC Magic 2 years ago when it first came out in Canada. That’s why most of my blog posts about Android development are from 2 years ago :).

I decided it was time to get the latest and greatest Android phone in Canada: the NEXUS S. A friend currently working at Google on Android highly recommended the device. And the fact that the phone is unlocked, Rogers will not put its apps on it, and Google will push updates directly to the phone without Rogers mandating when, made it even easier to pay the $300. In Canada the phone currently sells for $99 on a brand new contract, but you know how North America works: if you already have a contract you are not as enticing to the carriers as a brand new client with no contract. So, I had to pay a few fees to get the phone for $300 instead of $100.

I won’t go into a full review of the phone. There are plenty of sites that review the phone and have been doing it since the beginning of the year. I will only review a couple of items that I was worried about and you might be too if you are looking at getting this phone (or just got it).

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The official release date for Windows Phone 7 is October 11th (in the US). Word around the internet is that it will be released in Canada around the end of October / beginning of November. LG, Samsung, HTC, and Dell have all developed handsets that will be available in Canada. One of the services we offer at my place of employment is mobile development and since we are a Microsoft Gold Partner, developing on Windows Phone 7 is our forte (actually it’s the only mobile development we do). I assume as this platform gets bigger more people will jump to learn how to program on it, so this is a quick-and-dirty list of resources that will help you to learn about programming on Windows Phone 7.

1. http://developer.windowsphone.com/
   If you are a developer, the first thing you need to do is visit the developer’s home page. You can download tools from here, read about the SDK, look at sample code, and get questions answered in the forums.
2. http://silverlight.codeplex.com/releases
   You must download the Silverlight Toolkit for Windows Phone 7. It has alot of great Silverlight controls that will make your app much cooler. For example, the version of the SDK and Silverlight that you get from the first link does not have a calendar control. The Toolkit from this link has a DatePicker and a TimePicker control that you can just plop on your page and use.
3. http://channel9.msdn.com/Learn/Courses/WP7TrainingKit
   The best place I have found for guides, best practices, code samples, etc was Channel9. This is the home page.
4. http://channel9.msdn.com/Learn/Courses/WP7TrainingKit/WP7Silverlight
   I particularly like the home page for Silverlight on WP7. There are a ton of tutorials here, the ones I found most useful are listed below.
5. http://channel9.msdn.com/Learn/Courses/WP7TrainingKit/WP7Silverlight/WindowsPhoneNavigationAndControlsLab
   How to handle navigation, going back and forth between pages, the best practices for setting up your pages.
6. http://channel9.msdn.com/Learn/Courses/WP7TrainingKit/WP7Silverlight/ApplicationLifetimeWP7Lab
   Very important read on the application life cycle of a WP7 app.
7. http://channel9.msdn.com/Learn/Courses/WP7TrainingKit/WP7Silverlight/LaunchersAndChoosersWP7Lab
   Working with launchers and choosers. Launchers and choosers are parts ofthe API that allow you interact with the Windows Phone 7 first-partyapps, such as the email client, calendar/agenda, contact list, messaging app, etc.
8. http://channel9.msdn.com/Learn/Courses/WP7TrainingKit/WP7Silverlight/UsingPivotAndPanoramaControls
   This tutorial shows you how to make your apps have the cool Windows Phone 7 feel with the sliding between screens (called pivot and panorama controls).
9. http://www.silverlight.net/learn/videos/all/windows-phone-application-bar/
   Great tutorial video on how to set up the application bar at the bottom of your app. The video also shows the different customizations that you can do to the application bar.
10. http://channel9.msdn.com/Blogs/SlickThought/Simplify-Page-Transitions-in-Windows-Phone-7-Silverlight-Applications
    Getting the cool fade-in, fade-out page transitions to work. This effect is done by using the TransitioningContentControl that comes with the Silverlight toolkit (an extra install from link #2). Note: this tutorial was done on the April release of the Windows Phone 7 SDK, the latest SDK is slightly different.
11. Read the rest of this entry »

I just found this article from reddit…
Samsung may drop Windows Mobile for Android

Apparently Samsung is going to stop using Windows Mobile on its cellphones and will concentrate on Android!! I have been a supporter of Android since its inception and stories like these bring tears of joy to my eyes.

Oh, and there’s something about Samsung rolling out their own open source OS called “Bada”. Good for them.

In my previous post I linked to a terrific website (Working with XML on Android) which describes how you can read and parse XML documents in Android. The code supplied by that website used polymorphism to show 4 different methods for parsing the XML data. I vowed to simplify that and share the new source code.

To download the AndroidXmlSimple project click here. You will be taken to another page where you can click to download to the ZIP file.

Below are some instructions on setting yourself up with this source code and customizing it for your own XML data.

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One of the most powerful aspects of any mobile application for a 3G phone is that it can connect to the Internet. By connecting to the Internet the application can offer much more value to the user since it becomes an interface for a web-based component, e.g. using Twitter’s API to create a Twitter application so that you can get your Twitter updates without having to open the mobile browser. The most common way of interfacing with a web-based component is by using web services in XML format.

While trying to developer my own app which reads a web service from my own server, I ran into a lot of difficulties in implementing the client that consumes the web service. Android does not have libraries for XPath handling of XML documents, so it makes deciphering XML data a little bit more difficult. From what I’ve read online the Android team is currently working on including such libraries in future versions.

After some digging around I found an amazing link that shows different methods for consuming an XML file in Android and parsing through it without the use of XPaths. The link is this: Working with XML on Android. To start off, this link is an absolute must-read. Everything that I am going to write in my post here relates to this link. The code offered on that webpage uses polymorphism to show you 4 different methods of working with XML data. It provides a fully-functional Android application and all the source code for it. The source code can be found here: AndroidXML.zip.

My post today will concentrate on how to customize the code from the application in the above link, in order to read and parse your own XML data. If you are a Java pro, you might not need this post. My Java is a little rusty, so I needed some time to figure out exactly what I had to change and where in order to get this to work with my own web service XML. Now that I’ve figured it out, I thought I’d share it. In my next post I will give the simplified version of this code – where there is no polymorphism, and thus there are only the minimum number of classes needed to implement this XML-reading solution. I can’t offer this simplified code right now – because I haven’t coded it yet :).

So until I post the simplified source code for working with XML data in Android, here are some tips on getting through the larger polymorphism-based source code and customizing it for your own XML data:

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