As anybody who has run a growing website or blog knows, response time is going to get worse with the more users you have visiting your site. The users come from all angles, RSS feeds, homepage visits, search engine visits, people sealing your static files that you host, and pretty much anything else that can be served over HTTP. The solution to this problem is to off load your static content on to a Content Delivery Network or CDN. CDN providers cost a lot of money though, so it is nothing for us mere mortals with one server can afford.

But thanks to Google anyone can now run their own CDN for free on Googles servers. Lucky for you and me Google has made the process really painless and you can even have the CDN under you own domain name. In my case static.coderjournal.com.

What Is A Content Delivery Network?

According to Wikipedia:

A content delivery network or content distribution network (CDN) is a system of computers networked together across the Internet that cooperate transparently to deliver content most often for the purpose of improving performance, scalability, and cost efficiency, to end users. The first web content based CDNs were Speedera, Sandpiper, Mirror Image and Skycache, followed by Akamai and Digital Island.

Basically it is a network of computers around the world that serves your content to the end user closest to one of those many servers around the world. This method of delivery cuts down on server overload, DNS hops, and delivery time.

When sites like Microsoft, Yahoo, Google, or Amazon delivery content they use Content Delivery Networks (CDN’s) to host most of their content, especially static files such as images, stylesheets, downloads and anything else you can think of. The reason they do this is to reduce load on their application servers, that serve dynamic content, such as PHP or ASP.NET pages.

What Is Google App Engine?

So you may ask what is Google App Engine:

Google App Engine lets you run your web applications on Google’s infrastructure. App Engine applications are easy to build, easy to maintain, and easy to scale as your traffic and data storage needs grow. With App Engine, there are no servers to maintain: You just upload your application, and it’s ready to serve your users.

You can serve your app using a free domain name on the appspot.com domain, or use Google Apps to serve it from your own domain. You can share your application with the world, or limit access to members of your organization.

App Engine costs nothing to get started. Sign up for a free account, and you can develop and publish your application for the world to see, at no charge and with no obligation. A free account can use up to 500MB of persistent storage and enough CPU and bandwidth for about 5 million page views a month.

Google has also announced a very very affordable price plan that any mere mortal can afford. They are not ready to start charging people yet, but here are the details:

• $0.10 – $0.12 per CPU core-hour
• $0.15 – $0.18 per GB-month of storage
• $0.11 – $0.13 per GB outgoing bandwidth
• $0.09 – $0.11 per GB incoming bandwidth

How do I setup my own CDN using Google App Engine?

To use Google App Engine you need to do a couple things that readies you computer to publish your static content to Google. Please take note that my setup is for Windows, but you can easily modify the process for any other OS.

Setup

1. You need to download and install Python on your computer. You may already have it if you are using a Unix environment (i.e. Linux or Mac OS X). If you need to download it or would just like to check to see if it is up to date, please visit http://www.python.org/download/ and download the correct version for you operating system.
2. Install Python to c:\Program Files\ (all my scripts that I have designed to make the publishing to Google are going to be using this path).
3. You will also need Google App Engine SDK which is available at http://code.google.com/appengine/downloads.html. Download the version that is for you OS. Note that the SDK will check for the Python install, so make sure you install it before the SDK.
4. Sign up for Google App Engine at http://appengine.google.com/, you will need a valid Google account. I suggest you sign up for a Google Apps account and use that as your Google account. Why I suggest this will become apparent later on.
5. Once you are done with the setup process you need to create an application. Click the “Create an Application” and give your application a name (called “application identifier”). This is a unique name for all Google App Engine applications. For example I set my application identifier to “coderjournal”. Click though to the next part of the application, if this is your first time registering an application you need to specify your cell phone number and confirm your account with a SMS code that Google sends you.

Publish To Your CDN

1. Download my publishing files, hosted on my CDN, at http://static.coderjournal.com/downloads/coderjournal-cdn.zip
2. Create a directory on your computer specifically for you CDN files. My directory is c:\websites\static.coderjournal.com. Fill this directory with all your static files you want hosted on your CDN. Fill it full of all your css, downloads, flash, images, javascripts, videos, and anything else you want hosted.
3. Unzip the files I provided to you in step 1 into the directory you created in step 2.
4. Next we need to edit the YAML configuration file. Open the app.yaml file in your favorite text editor and change application: coderjournal to application: {your application identifier}.
5. Next go down and edit your static directories, in mine I have css, downloads, flash, images, and js. You can create your own by just modifying the ones I put in the file.
6. If you installed the Google App Engine SDK in the default directory and Python in c:\Program Files\ then skip to step 7. The next part is also required if you are using the x64 version of Windows, because Google App Engine SDK installs in c:\Program Files (x86)\. So change the paths in publish-cdn-coderjournal.bat to your actual paths.
7. Now double click on publish-cdn-coderjournal.bat and a command window will display. Fill in your Google account and password that you used to sign up for the Google App Engine account. And you content will start to publish.
8. You now have you own private CDN that can be accessed at http://application-identifier.appspot.com.

Using Your Own Domain (Optional)

1. If you created your own Google App as suggested up in Setup step 4, you can create your own custom domain for your CDN. If you didn’t, don’t worry just create one, and follow the steps below.
2. Go to the dashboard of your Google Apps and click “Add more services”.
3. Under other services you will see Google App Engine and a place to enter your application identifier. Enter you application identifier and click “Add It Now”.
4. It will take you to the next page where you enter in the domain you want for your CDN, I suggest something simple like static.yoursite.com.
5. Then you just need to follow the steps for adding a CNAME to your DNS and you are ready to go with you custom domain.

How do I use my own CDN?

Well this is the cool part! You just use the absolute path to your files. For example if you wanted to host the image to your right you would just use the following in your HTML:

Potential Gotcha: I forgot to mention that currently the files hosted statically are case-sensitive. I have reported this issue to Google, hopefully they will correct it soon. http://code.google.com/p/googleappengine/issues/detail?id=466

<img src="http://static.coderjournal.com/images/ideapipe-logo.png" />

It is really that simple. Now comes the cool part that I need your help with, and proof that this is really a true CDN. I would like to see how many different IP Addresses my CDN points to. So far I was able to find the following IP addresses:

• 72.14.207.121
• 64.233.179.121
• 66.249.91.121

That point to:

static.coderjournal.com

To see what IP Address you get on your local machine just pull up the command prompt and type:

ping static.coderjournal.com

Please report your findings in the comments below. I am sure everybody would love to see how big Google’s CDN really is.

Just recently I started experimenting with the ASP.NET MVC Framework and the Facebook Development Platform, it has been a very bumpy road, but I have ironed out some major issues that I would like to share with you today. I will start with a little history of what I am trying to do. For about a month and a half I have had one of my IdeaPipe interns, Dimitry, experimenting with creating a FBML (Facebook Meta Language) Application with MVC. MVC is an ideal platform for FBML because with MVC you have total control over your markup which is needed to have a lean FBML application. I am not going to go in to the differences of developing an FBML vs IFrame Facebook Application, because that information is easily found with a Google Search. What I am going to talk about is the hurdles I overcame and the custom software I had to develop to get MVC working smoothly with Facebook.

In my last post on the subject I was using the Facebook Developer Toolkit, however because of various implementation problems that were at the foundation of the software when working with MVC, I moved to Facebook.NET which is a object based model for implementing the Facebook Session instead of an inheritance model. What you will need in order to get started is:

• Facebook Developers
• Facebook Developers Wiki
• Facebook.NET Source Code (the source code is important because we need to modify one external interface from internal to public)

One of the problems I ran into was creating a Facebook Session from my Action Method. To remedy this issue I created a FacebookAttribute that is an ActionFilterAttribute and a FacebookWebSession based off of the work done on Facebook.NET.

FacebookAttribute

The FacebookAttribute is added to your Action Methods and will look like the following:

[Facebook(ApplicationName = "IdeaPipe")]
public ActionResult SomeAction(FacebookService facebookService, FacebookSession facebookSession, int myOtherVariables)
{ ... }

As you can see the FacebookAttribute just attaches to the Action Method and you just have to specify your ApplicationName that you want to instantiate. The FacebookAttribute also passes in a FacebookService and FacebookSession object for use in your method. The other keys get set in your Web.Config as any standard Facebook.NET application would.

<facebook>
    <application name="IdeaPipe" apiKey="1234" secret="5678" type="GlobalApplication" />
</facebook>

The magic behind this attribute is pretty simple.

public override void OnActionExecuting(ActionExecutingContext filterContext)
{
	FacebookApplicationSettings settings = FacebookSection.GetApplication(ApplicationName);

	ApplicationKey = ApplicationKey ?? settings.ApiKey;
	Secret = Secret ?? settings.Secret;

	FacebookWebSession session = new FacebookWebSession(ApplicationKey, Secret);
	session.Initialize(HttpContext.Current);

	FacebookService service = new FacebookService(session);

	if (filterContext.ActionParameters.ContainsKey(ActionParameterFacebookSession))
		filterContext.ActionParameters[ActionParameterFacebookSession] = session;

	if (filterContext.ActionParameters.ContainsKey(ActionParameterFacebookService))
		filterContext.ActionParameters[ActionParameterFacebookService] = service;
}

Download: FacebookAttribute.cs

FacebookWebSession

The FacebookWebSession was developed out of necessity because the only other FacebookSession objects in Facebook.NET are strongly tied to a WebForms Control that couldn’t be created as easily as I did in the FacebookAttribute. I am going to fore go the source code since much of this is a copy, paste, and rearrange from the Facebook.NET source. Plus much of it is just boring if-then-else statements that go on for awhile and just do a technical setup from the query string fields.

Download: FacebookWebSession.cs

FacebookSection

This is the file that I had to change the one method from internal to public so that I could get the information contained in the Web.Config configuration for my application. Note this file will not be necessary in the future if my changes get accepted in to the Facebook.NET source tree.

This file replaces the WebConfigurationFacebookSection.cs of the Facebook.NET source.

Download: FacebookSection.cs
Download: Facebook.NET Binaries For MVC

So that is all that you should need in order to start working with Facebook Applications in MVC. Note that it is still a good idea to include the FacebookApplication control on your pages because it is still needed. The primary goal of the source code above was to allow the use the the FacebookSession in the Action methods. If you have any questions please post them below.

Scaling ASP.NET Application just got easier with a new technology that Microsoft has just released that they have dubbed codename “Velocity”. This product is still in the early stages of development, but it is meant as a direct competitor against memcached. If you are not familiar with memcached, here is how it is described in Wikipedia:

memcached (pronunciation: mem-cache-dee) is a general-purpose distributed memory caching system that was originally developed by Danga Interactive for LiveJournal, but is now used by many other sites. It is often used to speed up dynamic database-driven websites by caching data and objects in memory to reduce the number of times the database must be read. Memcached is distributed under a permissive free software license.

So basically it allows you to create a distributed memory cache across your server farm, that allows any computer in the server farm to access the data in the cache. So there is no more issues with storing session data on server farms, or worrying about setting up common SQL stores of temporary data. This is also very practical for reducing database stress on Web 2.0 sites, many of the top Web 2.0 sites use this to reduce reads on the database.   The biggest user of memcached to date is Facebook.  This diagram below gives a basic idea of how distributed caching works.

There have been many Open Source projects for getting memcached working on C#, and most have been pretty successful, but because memcached was designed for the UNIX environment, porting memcached to a Windows Service has always lagged behind the actual releases of the required libraries to get memcached working. Enter Velocity, as the Velocity team describes:

Velocity is intended to provide distributed caching (in memory) for all .NET applications – from enterprise scale to web-scale. We believe that there are many applications that need a distributed caching mechanism, and that there is, therefore, a need for distributed caching as a core part of the .NET platform. We expect to have more integrated support for this functionality with other parts of the .NET platform in our upcoming releases.

There is also a pretty nice Velocity writeup on MSDN that goes in depth about how Velocity works as well as providing some basic code examples on how to get data into and out of your Velocity Cache. The current set of features looks pretty nice, and I can’t wait for Velocity to become more stable so I can introduce it in to the IdeaPipe mix.

Here is a breif overview of the Current Features:

1. Support for different cache types, partitioned and local
2. Support for different client types, simple and routing
3. Load Balancing & Dynamic Scaling
4. ASP.Net Integration, currently there is only a Session Provider
5. Key and Tag based Access

And Beyond

1. Availability – support for Failover when machines go down
2. Replicated Cache – another cache type
3. Embedded Topology – run the cache embedded within you application instead of as a cache service
4. Notifications – Get notified when a object in the cache is updated
5. Consistency Models – Support for both weak and strong consistency when doing reads/writes
6. Native client access to the cache service (E.g – PHP, C++ etc)
7. Manageability & Administration