Answer My Query

This is a continuation of the books I challenged myself to read to help my career - one a month, for year. You can read my first book review here. The book I chose for October 2011 was: The Cloud of Unknowing, Anonymous: The role of faith in life. Once again, this is out of order, but the book came in from a hold at the library so I’ll do this one now.

Why I chose this Book:

This book is probably the most far afield for many of my readers – some folks don’t hold a faith, others have faiths that are different from mine. That’s fine – I think this is still an intriguing read.

However this is a religious work – if you’re not into that sort of thing, it’s completely OK. As I’ve mentioned early-on, a book list for your career can include many kinds of books. Faith is such a part of my life that I find it impossible to separate from my day-to-day efforts. To that end, a little about this book is in order.

The book was written in the 14th century by an unknown, anonymous author, probably a Carthusian monk in Europe. It’s a work involving the deep thoughts around the intersection of intellection over contemplation. Contemplation is what ancient Catholics called meditation, or focus. It’s a really deep work involving philosophical history, specifically in the Christian tradition. Even as old and philosophical as it is, many contemporary writers, singers (Like Leonard Cohen) and others have referenced it, used it words, or developed entire works around it.

What I learned:

So what did I learn? Actually quite a bit, specifically on the role in contemplation in life. As a technologist, I tend to stay incredibly busy and the temptation is always to be very scattered. But lack of focus is often the enemy of getting things done correctly. Focusing on what really matters and being in the moment is a powerful tool in professional life. It has taught me that now, more than ever, I need to decide what I will not give a lot

As I mentioned, this is a religious work – it has far more value to me there than in the pure business sense, although I find those two linked irrevocably. The way I treat others in both personal and business relationships is my character – which I strive to improve every day.

I highly recommend you read something that is internal like this in your career development. Money, success and fame are not all that there is – and those things are not separated from who you are as a person.

It’s not exactly news – it was announced in July in HTML5 Parsing in IE10 – but in case you missed it, Microsoft are removing support for conditional comments from IE10.

I don't expect this to be a big deal. Actually I’m not sure it will have any impact at all, at least not for me. It’s already a rare thing to need to do something special for IE9.

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Posted in Browsers.

Copyright © Roger Johansson

Moving your application to the cloud might not be easy as it sounds. The typical sample we always see in documentation or demos about an ASP.NET application created from the Visual Studio template and deploy it in Azure as a package is definitely very far from reality. There are multiple factors that can affect the response time and availability of your applications in the cloud but you can not easily see until you embark on a real project. Application distribution and deployment is one of those factors, and the one we are going to discuss in this post.

Windows Azure uses the idea of regions to manage the physical distribution of your applications and data. A region in a nutshell represents a Microsoft data center where you can deploy your application or part of it. Nowadays, you can find multiple regions spread across the globe in places such as North America, Europe and Asia.

There is another abstraction layer on top of regions called "Affinity Groups", which simply tells the Fabric controller to do its best to ensure groups of related services are deployed in close proximity whenever possible to ensure optimization for inter-app communication. For example, in a typical web application with a database,  you will want to deploy the web application as close as possible to the database server. 

Finally, another important concept you need to understand in this deployment model is the idea of “hosted service”. A hosted service basically represents an unit of deployment associated to a public DNS in the cloud. You deploy your applications in a hosted service, which is also tied to a region or affinity group. What Azure gives you is a public address for reaching that hosted service in the cloud, which is “[you app name].cloudapp.net” for applications hosted in the production environment and an auto generated guid for applications hosted in the staging environment. You can also think in a hosted service as a load balancer that forwards requests from that public address to one of the instances or VMs associated to it.

Let’s discuss the aspects you need to consider for selecting the right regions for deploying your application.

• Network latency: reducing the network latency is very important as it will impact directly on the response time for your applications. You will want to have your users as close as possible physically from your applications and data. For example, if you have some potential users in the US and Europe, you will want to deploy two exact replicas from your application and data in the US and Europe data centers. As you might guess, this is not as easy as it sounds and there are a lot of challenges you need to address, how you can effectively redirect the users to the right region, or how you can synchronize your data across regions are typical questions or concerns you have to tackle first.
• Availability: you will want to have your applications available all the time. Many things can happen, but you need to understand that a region or data center might become offline and your application should be prepared to handle that scenario. Your applications and data should be replicated across multiple regions to not be affected when things like this occur.   

Microsoft already offers a set of tools or technologies you can use to address these two aspects, so let’s discuss some of them in detail in the next paragraphs.

Windows Azure Traffic Manager

While this technology is still a CTP and not available for all public in general, it will provide several methods for distributing internet traffic among two or more hosted services in different Windows Azure datacenters. It is in essence a distributed DNS service that knows which Windows Azure Services are sitting behind the traffic manager URL and distributes requests based on different policies  or modes you can configure. It will initially support three modes, “Failover”, “Performance” and “Round-Robin”.

In the “Failover” mode,  all the traffic is redirected to a single hosted service, unless it fails. If the redirection fails because the hosted service is not longer available,  it then directs the traffic to the hosted service configured as failover. For example, you can configure the South Central US region as a backup for the North Central US region and vice versa. If any of those regions go offline, the other one will take its place.

In the “Performance” mode, all traffic is mapped to the hosted service “closest” to the client requesting it.  For example, this will direct users from the US to one of the US datacenters and European users will probably end up in one of the European datacenters.

Finally, in the “Round-robin” mode, the traffic is distributed in a round robin fashion across several hosted services configured in the policy.

As you can see, this tool only tackles the two aspects mentioned before from the point of view of traffic redirection. However, you also need to make sure the data is also consistently available in all the regions, and that’s something this tool won’t solve. For example, if the users are redirected from North US to Central US, you need to make sure the data they get access look the same.

Content Delivery Network (CDN)

You can imagine the Windows Azure Content Delivery Network as a huge http cache spread across the globe for content such as images, files, scripts, or static html to name a few. You can either configure CDN for a blob storage account or an http endpoint in your application (and endpoint with an url ending in “cdn”, for example xxx.cloudapp.net/cdn). All that content will be cached in the nodes that are part of the network using standard Http caching. The CDN will serve later the cached copy closest to the user requesting it, improving in this way the response time.

There are today more than 18 locations or nodes globally (United States, Europe, Asia, Australia and South America) and this number keeps growing.

SQL Azure Data Sync

While the Azure Table Service already provides some built-in support for crash recovery based on the idea of partitions that are replicated across different nodes (in different sub regions, for example North US and Central US), a SQL Azure database is not prepared for that scenario.  If you also use something like the Traffic Manager to redirect users to the closest data center, you probably would want to have all the databases in the different regions in sync between them making all this process transparent to the user.

If you want to support that scenario, the SQL Azure Data Sync is the tool that will help you in this matter. In a nutshell, SQL Azure Data Sync is a cloud-based data synchronization service built on the Microsoft Sync Framework technologies. It provides bi-directional data synchronization and data management capabilities allowing data to be easily shared across SQL Azure databases within multiple data centers.

There are a few things you will have to configure in this tool

• The databases you want to keep in sync, and also the tables and columns in those databases
• The schedule or frequency for doing the synchronization.
• How you want to resolve any conflict that might occur during the synchronization.

As you can see, the combination of this tool with the traffic manager will help you to keep applications and data in sync between different region for the most common scenarios.

If you’ve ever seen any of my presentations lately, I’ve been using these lovely Star Wars-inspired pictures to emphasize a point or just for plainly visually improving my slides. Today I’d like to tell you a little more about the pictures and the person behind them.

A few months ago, a close friend of mine made me aware of Kristina Alexanderson‘s wonderful Star Wars-based photo collection CClone 365-2011. What she does is taking Star Wars figures and putting them in everyday contexts, creating wonderful, touching and beautiful situations!

Kristina is also a big fan and partaker of Creative Commons and sharing, and works with helping students becoming more aware of Internet and its possibilities in the project Webbstjärnan, and anyone with such good values deserves the attention!

Now, feast your eyes!