Hosting Clockwork Web Framework With Amazon

I’ve blogged a lot about my admiration for Amazon’s web services stack. I think they understand the web as well as any company in the world. It’s always been my intention to investigate Amazon’s Electronic Compute Cloud (EC2) and since I needed hosting for my new Clockwork Web Framework, I decided to give it a try.

The reason I went with Amazon rather than a traditional hoster is that I have no idea what kind of interest there will be in the framework, and therefore cannot predict what the load on a web server will be. Amazon EC2 is designed for this kind of flexibility, and you pay per hour.

The Platform

I am running a small Windows Server 2003 32x server instance to begin with. It only has 1.7 gb of RAM. I can scale this up if I need to, or more likely I will run up another small instance and load balancing the two using Amazon’s Elastic Load Balancer technology.

On this, I am using IIS 6, .NET 3.5, SQL Server 2005 Express, and Powershell. Most of my files are kept on a permanent storage drive (more on this below) and served by IIS. In order to maximize the speed and lower the CPU burden on the server, I have decided to use another Amazon technology, CloudFront.

CloudFront Content Delivery Network

CloudFront is a Content Delivery Network (CDN), like Akamai or Limelight. I use it to serve my images and resource files. Basically Amazon has edge servers all over the world with a copy of my images and resource files, and when users request them from my website, CloudFront automatically sends them a copy from the nearest location to them, making for some very fast download times.

To make this work, you have to use Amazon Simple Storage System, or S3. This is a virtual file system. Basically you have “buckets” of files that are served up when requests come in from the CloudFront “distributions”.

I’ve optimized it a bit by having two distributions; one for images and one for resources. This means that a page which requires both things will load even faster since two parallel CDN distributions are processing the files at the same time.

You can create CloudFront distributions through code, or through Amazon’s web management portal.

  Since you can control the public URL of the distributions, you will notice if you view the properties of my website that my images are handled by the path “http://images.clockworkwf.com” and my resource files are handled by the path “http://resources.clockworkwf.com” . In other words, I have full control over what path I give them. Most people will never know these picture are being served from Amazon.

I notice the website loads really quickly, so the CloudFront makes a big difference.

EC2 Hosting Challenges

So that’s the high level architecture. There are a number of impacts when using Amazon as a hoster I’d like to talk about.

Server Goes Up, Server Goes Down

To begin with, you have to assume that at any moment your server will go down. If your server dies, it vanishes, and you have to “spin up” another one, using the web interface or code. It’s very easy to do from the web console, just click “Launch Instance” and you can pick any server ranging from Ubuntu Linux to Windows 2003 Server 64x Enterprise R2.

Although the server instances you can use have their own hard drive space on C: and D: drives, you have to treat that as transitory storage.

I’ve setup my system in such a way that I can use an Elastic Block Storage (EBS) hard drive volume, provided by Amazon.This is a more permanent drive space that you pay for, but can be attached to any server instance. Think of it as a SAN (that’s probably what it is).

So I’ve got my database and web files on this EBS block, which I then mount to any server instance I’m currently running.

On the server instance, I simply point IIS web server to the EBS block files, and away we go.

The EBS can be any size you like, and you pay per GB per month. Right now I’m using 10GB since my log files and database don’t take up much room. I can add more space later if I need to.

Here’s a screenshot of that EBS volume, in the Amazon web console.

Dynamic DNS Entries

Next problem: Since the server can go down at any moment, DNS is a problem. If my server dies and I spin another one up, it will be given its own IP address, which my DNS entry for www.clockworkwf.com wouldn’t know about. So there might be a long delay while DNS changes to the new IP address.

So, I’m using a Dynamic DNS service called Nettica. They have a management console where I can enter my various domain records and assign a short Time To Live (TTL), which means the DNS entries update frequently. So if my server dies, I can change the entry in Nettica to point to the new server’s IP address, and within a few seconds requests are going back to the right place.

Nettica even allows me to control all of this through C# code. Going forward I plan to write powershell server management scripts that can automatically spin up a new server on Amazon, determine the IP, and register that with Nettica.

Incidentally, Amazon EC2 allows you to buy what are called “Static IP Addresses”. Essentially you can “rent” a fixed IP address which can by dynamically allocated to a server instance. So, in the short run this makes life easier for me as I have rented one, used that for my Nettica domain name record, and can assign this fixed IP to any new server instance.

Next problem: Disaster Recovery.

Disaster Recovery is even more important in Amazon EC2 world than elsewhere, since again your instances could die at any moment….Not that they will, but the point is, they are “virtual” and Amazon isn’t making any promises (unless you buy a Service Level Agreement from them).

However, Amazon’s EC2 provides a level of DR by its very nature – you can spin up another machine in a small amount of time. Estimates for new Windows instances are about 20 minutes.

There’s also something called an Availability Zone. Essentially it means “Data Centre” – Amazon has several of these and so you can spread your servers around between US – East, US-West, Europe, and so on. So when that Dinosaur-killing comet hits North America, the Europe Availability Zone keeps chugging.

Right now I’m not really doing much with my database, so DR isn’t such an issue. I have some security since my files are on an EBS block. However, eventually I’ll setup a second server in another availability zone and load balance the two.

Another Challenge: Price

Amazon Web Services are flexible, and you are charged per hour, for only what you use. This is an amazing model but it doesn’t work so well for website hosting, because of course your servers are supposed to be online 24/7, 365 days a year.

It’s hard to tell for sure what the annual bill will be, but for my small server instance (remember, only 1.7 Gb of RAM) it will cost well over $1,000. That’s a lot more than shared space on a regular hosting provider. However I’m willing to pay this, for the flexibility I get, and also because I think Amazon web services are a strategic advantage and so the earlier I learn about them, the more business opportunities I might unlock.

One good thing is that Amazon has been aggressively dropping its prices as it improves its services. Additionally, they have started offering “Registered Servers” – basically a pre-pay option for 1-year, 2-year, and 3-year terms. Unfortunately these are only for Linux servers at the moment but hopefully they will add them for Windows and then I can save money year on year.

CloudHost Monitoring

Amazon offers a web-based monitoring option for its server instances. I’ve started using it (for an additional fee) but I’m not sold on its utility yet. I don’t think I’m using it to its full potential yet – it is supposed to help you manage server issues by monitoring thresholds.

Managing S3 Files Using Cloudberry Explorer

I needed an easy way to create and manage my buckets, CloudFront distributions, and S3 files. I found Cloudberry Explorer, and downloaded the free version of it. I was able to drag and drop 1600 files from my Software Development Kit to the S3 bucket where I’m serving the resources. Super!

There’s a pro version I might purchase which would allow me to set the gzip encryption and other properties on the files. This would help lower my bandwidth costs and speed up the transfer a bit.

Here’s a screenshot of Cloudberry in action:

I love how easy it is to setup and use Amazon’s web services stack. I think they have a great business model for the Cloud, and they’re the company to beat. I’m willing to rely on them for the launch of Clockwork Web framework and so far I haven’t been disappointed.

Introducing Clockwork Web Framework for .NET

In 2003, I read a book, “Making Space Happen”, by Paula Berinstein. It’s about the efforts of entrepreneurs to open up space to the public. It’s the kind of thing that gets my propeller-head spinning, and after reading it I resolved to create the best website on space travel on the internet.

So, I sat down in a park and within two hours I had covered several sheets of paper with scribbles and scrawls of what my website needed. I had notes on authentication, web components, search boxes, themes, dynamic images, language toggles, and all kinds of stuff.

Being a good little programmer, the more I designed, the more intricate the design became, and pretty soon I was knee-deep in code. Flash forward six years later, and I have yet to write a single page of that space website!

But I do have a web framework :)

What It Is

Clockwork makes it easy to build powerful .NET web sites. It’s completely free, open source (under the Apache 2 license) and you can use it in proprietary or open source projects, as you like.

Some of the ways it makes web development easy:

• Database-agnostic data access
• Dynamically displays content in different languages
• Leverages the .NET 3.5 framework, including the Provider Model, generics, LINQ, automatic properties, and more
• Integrates with popular web services such as those provided by UserVoice, LinkedIn, Google and Yahoo!
• Makes it really easy to use object-oriented programming standards like Dependency Injection / Inversion of Control, Repositories, and Specifications

Under the hood I use many popular components, including NHibernate for database access, Castle Windsor for Dependency Injection, and log4Net for logging.

Although today marks the official public release, the framework is currently at version 3.x because I’ve been using earlier versions of it in production websites since 2004.

I’ve built Clockwork using as many web standards as I can find, as many of the latest .NET elements as possible, software best practices, and a lot of love and stubbornness.

What It Will Become

Well, it’s obviously too early to say. But I am committed to continuing to develop it, I have a long list of things I plan to add, and I’m hopeful a community of .NET developers will adopt it and push it into areas I can’t even imagine today.

Please take a minute to visit the website and learn more about it. I hope you find it helpful.

Many thanks,

Nick

SharePoint: A Product and a Platform

SetFocus just published another of my articles for their Technical Articles section. This one is called “SharePoint: A Product and a Platform”, and discusses the implications of SharePoint as a software platform.

My conclusions are that the platform provides significant capabilities including a unified development environment, reduced maintenance, development, support, and training costs, and may increase the risk of vendor lock-in.

I’ve written for SetFocus before because I have a long association with them, dating back a decade. I had my Java certification training and first job placement through them. For the past year I’ve been developing and teaching parts of their SharePoint programming classes for the SharePoint Master’s Program (I’m instructing evening classes again starting this Saturday).

You can read more at http://www.setfocus.com/TechnicalArticles/Articles/sharepointproductandplatform.aspx. I hope you enjoy it and welcome your feedback!

P.S. The article is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License which means you can modify it and share it around!

Data Splunking

I’ve had my head down for the last couple of months, churning out code for that elusive framework I keep hinting at :) Right now I’m staying in a trailer with no tv, internet, or cell phone coverage and I’ve never been more productive (says I).

Still, I thought I would pop up briefly to mention a cool IT tool that can provide you with a centralized, browser-based repository to search on all the millions of log files, event viewers, and databases that are inevitably scattered around any company’s data centres.

It’s called splunk. Its name is clever – users get to spelunk into their data silos and see what’s there. It’s a simple, single package install that runs on most desktop machines and servers. There’s a free version if you use less than 500 megs of indexed data, and enterprises can pay to index larger corpuses. I’m running that on my Vista 64 bit box and it indexes and searches like a little champ.

In my case I’ve been using it on my framework log files to help analyze bugs and performance bottlenecks. Here’s a screenshot of a search on the keyword “nhibernate” (NHibernate is an Object Relational Mapping software):

As you can see, it quickly pops up all the logged events where NHibernate was called from my classes.

To get this to work, all I had to do was add an “Input” for splunk to index – in this case the full path to my log file folder.

As you would expect, it does lots of reporting. It has broken down my log files into various columns. Examples of these columns are: custom C# properties I search on; the standard log file “stuff” such as the source name, date created, file size; even the sql commands that NHibernate generates for me. I can filter these columns for even more detailed breakdowns. In the next screenshot I am reporting on Entity ID values I use to track my framework objects.

I like splunk because it’s a one-stop shop for me to analyze all my various bits of IT Operations information. There’s a slick AJAX web user interface, and so far performance seems fine for me on my little dev laptop. I find it solid, intuitive, and I don’t have to expend much effort to install, manage, or learn it.

There’s also a way to extend splunk using its custom Application Programming Interface. I plan to investigate that when I have some free time but have not had a look yet.

I think any IT company should give splunk a test run.

WCF WTF

Today I was working on a WCF application integration layer for my framework. For some bizarre reason, no matter how many times I updated the service contract and rebuilt my client service references, I never got the latest version.

Specifically, I was trying to call the following method:

public void CreatePages(IList<WebPageDTO> pagesToCreate)

The WebPageDTO was declared (temporarily) in the WCF project. I put DataContract and DataMember on it, the project built fine, and I could even add a reference to it from a client application. However, I could never update the reference from my clients, and when trying to view the service directly I would get this error:

The type '[namespace].[servicename]', provided as the Service attribute value in the ServiceHost directive could not be found.

Finally, I had to modify the method signature to RETURN WebPageDTO – which I didn’t want to do. However, that fixed the service reference and now I can update it. Now I have switched the method stub back to return a custom ServiceResponse object, and that also works.

Bit of a head scratcher. I don’t fully understand why this is happening. Anyone know?

Above the Clouds: A Berkeley View of Cloud Computing

The Electrical Engineering and Computer Sciences department at the University of California at Berkeley just put out a research paper on Cloud Computing as they see it.

The paper is an in-depth exploration of what some consider to be just another buzzword, Cloud Computing. Since nobody has agreed on what exactly it means, the implication is that it's just a marketing term.

I remember when web services started to appear, around 2000/2001 if I recall correctly. The descriptions and possibilities seemed great, but nobody really knew what to do with them or why. So there came a time when nobody talked about web services anymore and it looked like that particular bubble had burst.

In fact, behind the scenes, a host of companies and individuals were figuring web services out, building their own, and releasing them. A couple of years after the term started popping up, web services arrived for real and now we have mashups and SaaS and Software + Services and some really well-traveled XML fragments zipping around the globe.

The same thing seems to be going on with Cloud Computing. We're in the early days, and still hearing the "Moon on a stick" promises that Cloud Computing is a silver bullet for everything.

This white paper is one of the first I've seen that really quantifies the (potential) cost savings of Cloud Computing.

Some gems:

• Explanations on Cloud Computing and how it differs from previous attempts;
• Classes of Utility Computing on page 10, comparing Google AppEngine, Amazon Web Services, and Microsoft's beta Azure platform;
• Cloud Computing economic models, on page 12;
• A discussion of the Top 10 challenges- and potential solutions to them - on page 16;
• The observation that FedExing your data is a good way to cut down on your bandwidth costs and delays.

This is very impressive work. The full paper is here:

http://www.eecs.berkeley.edu/Pubs/TechRpts/2009/EECS-2009-28.pdf

Poll: Open Source .NET Web Frameworks