Above The Cloud

When I was searching for an appropriate definition of ‘Multitenancy’ to quote, I found that people and organisations had differing opinions of what it really means. Even the Wikipedia article claims that different organisations are ‘using it as source of competitive differentiation’.

This could be true, but perhaps the term is just evolving. In a few short years the cloud landscape (ok lets call it the ‘sky’) has changed quite a lot with numerous vendors entering into this growing, competitive market. The original terminology has been abstracted and reapplied to new forms of virtualization.

If you scroll back through the calendar a few years I think there would have been a general consensus of what the term means. Gianpaolo from Microsoft once stated that in ‘a pure multi-tenant architecture a single instance of the hosted application is capable of servicing all customers (tenants)’. The key idea is that an application is deemed multi-tenant if it can service multiple clients in a unique fashion from a single instance of the application.

A good example that comes to mind is DotNetNuke. It is a CMS system that supports multiple unique portals. Each portal can be stand-alone and secured separately from one another, while still leveraging a single code base and database. It is the configuration that allows the separation.

A more SaaS example is salesforce.com where you can perform customer relationship management from the cloud. Every salesforce client is secured away from other clients, each instance presumably sandboxed from another.

So why would the term ‘multitenancy’ change over time?

Lets think about what the term means in a literal sense: multiple tenants. In other words, there can be many residents at a multitenant location, just like a rental house tenanted by multiple people. So what if instead of a house we had a server? Every server can have multiple applications installed – file services, DNS, Active Directory, DHCP services, etc. To me, that sounds like a server has multiple tenants.

What about virtualization? Multiple virtual machines running on a single host? Sounds like multiple tenants to me. In fact when you think about it in such simple terms, then anything could be multitenant. My head has billions of hairs – its multitenant. My street has many houses – its multitenant. The Azure Fabric has many servers – its multitenant. Each server has multiple virtual machines – they are all multitenant.

In summary, when Microsoft or any other company refer to something in their technology stack as ‘multitenant’ then there’s a fairly strong chance that it really is. In my opinion, the Wikipedia article on multitenancy needs some revision.

Just a quick post to point out two interesting (but unrelated) cloud links I stumbled upon today.

The first is the Cloud Computing Manifesto which exists to facilitate the discussion between the major vendors to come up with a set of key principles to be adhered to by all providers. The site also describes a Cloud Computing Bill of Rights and has been constructed in direct response to this post by Steve Martin regarding a secret cloud manifesto written without input from his employer, Microsoft. After a cursory inspection, it seems very lightweight to me; hopefully they will pad it out soon because the effort has merit.

The other interesting thing I discovered today was the Cloud Computing Podcast. I had toyed with the idea of creating such a podcast myself; luckily I committed absolutely no resources to doing so! I’ve listened to a couple now and the premise of the podcast seems to be around reacting to cloud specific industry events and articles. It’s not overly long, each episode around 15 minutes. But they are very regular, averaging around two a week. Also, there’s a long backlist to listen to since its been going since October last year! There’s definitely not enough Azure coverage, but hey, not everyone’s perfect. I’m definitely adding this one to my RSS feeds.

Welcome to my new blog, ‘Above The Cloud’ where I will be exploring “the cloud” as it relates to the development community, with a particular focus (but not limited to) the new Azure Services offering by Microsoft.

At PDC08 Microsoft announced www.azure.com and in their own words:

The Azure Services platform provides a wide range of internet services that can be consumed from both on-premises environments or the internet.

Currently the Azure Services Platform is available on an invitation basis only, however you can apply for an invitation token via the Microsoft Connect program which is their community connection point and a place where you can register for all sorts of trials, alphas, etc. I suggest you sign up to Connect today, have a browse of any previews you might be interested in and apply.

What happens next is that eventually (could be a day, could be a month) Microsoft would widen their invitation base on a particular product, and you will receive an email with an invitation token. Once you receive your Azure token, you can connect to the Azure Services Platform.

Please note that there are a number of different services you can apply for in the Azure space. The 3 primary ones are:

• Azure Services Platform
• Microsoft .Net Services
• Microsoft Sql Services

The first focuses on high availability of web sites and services through load balancing and dynamic allocation of resources. At the click of a button you can take your website from a 3 node cluster to 4. The second is the platform for developing .Net applications in the Azure space. There is an SDK available from here that lets you simulate “the cloud” on your desktop. Finally, Microsoft Sql Services is the cloud-based database offering that will let you store data in the cloud.

All 3 services are available for you to play with now! And this blog will be dedicated to helping you explore all these services, the SDK’s and much more. So go check out www.azure.com now and signup so you can join me as we uncover the mysteries of the cloud.