Search results matching tags 'Best Practices' and 'design'

High Availability for IaaS, PaaS and SaaS in the Cloud

BuckWoody — Tue, 06 Nov 2012 15:15:28 GMT

Outages, natural disasters and unforeseen events have proved that even in a distributed architecture, you need to plan for High Availability (HA). In this entry I'll explain a few considerations for HA within Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). In a separate post I'll talk more about Disaster Recovery (DR), since each paradigm has a different way to handle that.

Planning for HA in IaaS

IaaS involves Virtual Machines - so in effect, an HA strategy here takes on many of the same characteristics as it would on-premises. The primary difference is that the vendor controls the hardware, so you need to verify what they do for things like local redundancy and so on from the hardware perspective.

As far as what you can control and plan for, the primary factors fall into three areas: multiple instances, geographical dispersion and task-switching.

In almost every cloud vendor I've studied, to ensure your application will be protected by any level of HA, you need to have at least two of the Instances (VM's) running. This makes sense, but you might assume that the vendor just takes care of that for you - they don't. If a single VM goes down (for whatever reason) then the access to it is lost. Depending on multiple factors, you might be able to recover the data, but you should assume that you can't. You should keep a sync to another location (perhaps the vendor's storage system in another geographic datacenter or to a local location) to ensure you can continue to serve your clients.

You'll also need to host the same VM's in another geographical location. Everything from a vendor outage to a network path problem could prevent your users from reaching the system, so you need to have multiple locations to handle this.

This means that you'll have to figure out how to manage state between the geo's. If the system goes down in the middle of a transaction, you need to figure out what part of the process the system was in, and then re-create or transfer that state to the second set of systems. If you didn't write the software yourself, this is non-trivial.

You'll also need a manual or automatic process to detect the failure and re-route the traffic to your secondary location. You could flip a DNS entry (if your application can tolerate that) or invoke another process to alias the first system to the second, such as load-balancing and so on. There are many options, but all of them involve coding the state into the application layer. If you've simply moved a state-ful application to VM's, you may not be able to easily implement an HA solution.

Planning for HA in PaaS

Implementing HA in PaaS is a bit simpler, since it's built on the concept of stateless applications deployment. Once again, you need at least two copies of each element in the solution (web roles, worker roles, etc.) to remain available in a single datacenter. Also, you need to deploy the application again in a separate geo, but the advantage here is that you could work out a "shared storage" model such that state is auto-balanced across the world. In fact, you don't have to maintain a "DR" site, the alternate location can be live and serving clients, and only take on extra load if the other site is not available. In Windows Azure, you can use the Traffic Manager service top route the requests as a type of auto balancer.

Even with these benefits, I recommend a second backup of storage in another geographic location. Storage is inexpensive; and that second copy can be used for not only HA but DR.

Planning for HA in SaaS

In Software-as-a-Service (such as Office 365, or Hadoop in Windows Azure) You have far less control over the HA solution, although you still maintain the responsibility to ensure you have it. Since each SaaS is different, check with the vendor on the solution for HA - and make sure you understand what they do and what you are responsible for. They may have no HA for that solution, or pin it to a particular geo, or perhaps they have a massive HA built in with automatic load balancing (which is often the case).

All of these options (with the exception of SaaS) involve higher costs for the design. Do not sacrifice reliability for cost - that will always cost you more in the end. Build in the redundancy and HA at the very outset of the project - if you try to tack it on later in the process the business will push back and potentially not implement HA.

References: http://www.bing.com/search?q=windows+azure+High+Availability (each type of implementation is different, so I'm routing you to a search on the topic - look for the "Patterns and Practices" results for the area in Azure you're interested in)

Book Review (Book 11) - Applied Architecture Patterns on the Microsoft Platform

BuckWoody — Tue, 15 May 2012 16:50:34 GMT

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, and the entire list is here. The book I chose for April 2012 was: Applied Architecture Patterns on the Microsoft Platform. I was traveling at the end of last month so I’m a bit late posting this review here.

Why I chose this book:

I actually know a few of the authors on this book, so when they told me about it I wanted to check it out. The premise of the book is exactly as it states in the title - to learn how to solve a problem using products from Microsoft.

What I learned:

I liked the book - a lot. They've arranged the content in a "Solution Decision Framework", that presents a few elements to help you identify a need and then propose alternate solutions to solve them, and then the rationale for the choice. But the payoff is that the authors then walk through the solution they implement and what they ran into doing it.

I really liked this approach. It's not a huge book, but one I've referred to again since I've read it. It's fairly comprehensive, and includes server-oriented products, not things like Microsoft Office or other client-side tools. In fact, I would LOVE to have a work like this for Open Source and other vendors as well - would make for a great library for a Systems Architect. This one is unashamedly aimed at the Microsoft products, and even if I didn't work here, I'd be fine with that. As I said, it would be interesting to see some books on other platforms like this, but I haven't run across something that presents other systems in quite this way.

And that brings up an interesting point - This book is aimed at folks who create solutions within an organization. It's not aimed at Administrators, DBA's, Developers or the like, although I think all of those audiences could benefit from reading it. The solutions are made up, and not to a huge level of depth - nor should they be. It's a great exercise in thinking these kinds of things through in a structured way.

The information is a bit dated, especially for Windows and SQL Azure. While the general concepts hold, the cloud platform from Microsoft is evolving so quickly that any printed book finds it hard to keep up with the improvements.

I do have one quibble with the text - the chapters are a bit uneven. This is always a danger with multiple authors, but it shows up in a couple of chapters. I winced at one of the chapters that tried to take a more conversational, humorous style. This kind of academic work doesn't lend itself to that style.

I recommend you get the book - and use it. I hope they keep it updated - I'll be a frequent customer. :)

Preparation is key to a successful cloud deployment

BuckWoody — Tue, 01 May 2012 13:09:16 GMT

If you want to be wise, watch the actions and outcomes of others. Emulate the successful actions, and avoid the actions that cause failure. That’s true in life in general - and in technology projects in specific.

I’ve worked with several clients who have created or migrated an application to “the cloud” - meaning using Microsoft Windows Azure or another provider. Although the statement in the title of this post is trite, I cannot over-emphasize how accurate it is. In every case of those who had a great experience with a distributed computing environment (which is thankfully the vast majority of my projects),

What kind of preparation do you need to do? Here are some tips I’ve learned in the successful (and not-so-successful) deployments I’ve seen:

Follow standard recommendations for successful projects in general

You and your organization have probably done a few projects before - this one should have the same general attributes: a well-defined goal, a small, motivated team, a realistic timeline, and an adequate budget. I know, I know, you *never* seem to get those things - but if you don’t, you’ll fail. Simple as that.

Educate yourself

Computing technology started out on a single set of hardware for a single purpose - and realizing the limits of the hardware at hand, systems designers quickly realized that scale-out and virtualization was key. No, that’s not new - mainframes almost always worked on the concept of scale-out and virtual machines. But we switched in the 1980’s to single-user systems again, and we’ve been there ever since. By that I mean you install an OS on the things you work on. Now we move back to distributed system concepts, and there are some real differences. You’ll need to learn how those work, and do things a new way. Hey, we’re IT - we LOVE learning new things, right?

Get a partner if needed

There are a few of us white-haired Gandalf’s around that remember how to work in a distributed system, but if it’s new to you, that’s completely OK. You can save yourself a world of trouble by working with someone who’s done this before - a partner you hire, someone from Microsoft Consulting, whatever.

And don’t forget support - who will handle each issue, what is the escalation model, who are your contacts at Microsoft, and what is your “light’s out” strategy?

“A new broom sweeps clean”, the old adage goes, but the old brooms know where the dirt is.

Build a model

Take some time to do a Proof of Concept on your local system and using your Azure hours from your MSDN account if you have one. Going through this build - and being willing to throw it away and try it a different way - is invaluable.

Test your theories

Three statisticians are walking in a field. They see a rabbit - the first guy raises his gun, firing far in front of the rabbit. The second guy simultaneously raises his gun and fires far behind the rabbit. The third guy yells “We got him!”

Not every theory is correct - not every attempt is the right one. Build in your success tests while you’re building your model. Then check them - don’t leave this step out.

Rinse, lather, repeat

This is advice from a shampoo bottle - which I’ve never used (I don’t really have that much hair - especially now). But in a “Cloud” project, it’s important. It’s an evolving system, that gains new improvements at an amazing rate. As soon as you deploy and stabilize you need to start the process over again. If you created your system in a Services model, with contracts for the APIs and abstracted code, this is far easier.

It’s not hard to do a cloud project right. But it’s really simple to do it wrong. Follow these guidelines and you’ll learn from the successes - and mistakes - of others.

“I could use a little help here” or “I can do it myself, thank you” for Cloud Projects

BuckWoody — Tue, 03 Apr 2012 13:20:55 GMT

Windows Azure allows you to write code in languages within the .NET stack, you can use Java, C++, PHP, NodeJS and others. Code is code - other than keeping things stateless, using a Web or Worker Role in Azure is not all that different from working with an on-premises system.

However….

Working in a scalable, component-based stateless architecture that can use federated security is not all that common for many developers. Some are used to owning the server, scaling up, and state-full paradigms that have a single security domain. Making the transition whilst trying to create a new software application or even port a previous one can be daunting. Sure, we have absolutely tons of free training, kits, videos, online books and more to learn on your own, but some things like architecture can be pivotal as you move along.

So the question is, should you just strike out on your own for a Cloud project, or get Microsoft Consulting Services or another partner to work with you on your first one? I use a few decision points to help guide the projects I assist in.

Note: I’m a huge fan of having help that ends up giving you training and leaves you in charge. If you do engage with someone to help you, make sure you keep this clear and take more and more ownership yourself as the project progresses.

How much time do you have?

Usually the first thing I ask is about the timeline for the project. It doesn’t matter how skilled you are, if you have a short window to get things done it’s better to get help - especially if this is your first cloud project. Having someone that knows the platform well can save you amazing amounts of time. If you have longer, then start with the training in the link above and once you feel confident, jump in.

How complex is the project?

If there are a lot of moving parts, it’s best to engage a partner. The reason is that certain interactions - particularly things like Service Bus or Data Integration - can be quite different than what you may have encountered before.

How many people do you have?

I have a “pizza rule” about projects I’ve used in my career - if it takes over two pizzas to feed everyone on the project, it’s too big and will fail. That being said, one developer and a one-week deadline does not a good project make, usually. It’s best to have at least one architect (or someone in that role) guiding the project along, and at least two developers to work on a cloud project. That’s a generalization of course, since I’ve seen great software on Azure with one developer writing code all by herself, but for more complex projects, more (to a point) is better. The nice thing about bringing on a partner is that you don’t have to hire them full time - they help you and then they go away.

How critical is the project?

There’s no shame in using some help. If the platform is new, if the project is large and complex, and if it is critical to the business, you should engage a partner. That’s regardless of Cloud or anything else - get some help. You don’t want to hit your company’s bottom line in a negative way, but you have to innovate and get them a competitive advantage. Do your research, make sure the partner is qualified to help you, and get it done.

Don’t let these questions scare you off. There are lots of projects you can implement on Windows and SQL Azure with nothing other than the Software Development Kit (SDK) that you get for free with Windows Azure. And assistance comes in many forms - sometimes just phone support, a friend you can ask. Microsoft Consulting Services or any of our great partners. You can get help on just the architecture piece or have them show you how to write the code. They’ll get involved as little or as much as you like.

Cloud Computing Patterns: Using Data Transaction Commitment Models for Design

BuckWoody — Tue, 14 Feb 2012 20:45:47 GMT

There are multiple ways to store data in a cloud provider, specifically around Windows and SQL Azure. As part of a “Data First” architecture design, one decision vector – assuming you’ve already done a data classification of the elements you want to store – is to decide the transaction level you need for that datum. Once you’ve decided on what level of transactional commitment you need, you can make intelligent decisions about the storage engine, method of access and storage, speed and other requirements.

Although the list below is neither original nor exhaustive, these are the general considerations I use for a given data set. It’s important to note that in many on premises systems the engine choice at hand overrides these concerns. If you have a large Relational Database Management System (RDBMS) for instance, you might simply place all data there without further consideration. In a Platform as a Service (PaaS) like Windows and SQL Azure, however, selection of the proper engine for a particular dataset has implications ranging from cost to performance, and selecting the right engine is critical when you want to leverage the data across “Bid Data” analysis like Hadoop or other constructs.

Monolithic Consistent Transactional
The first selection is analogous to a local RDBMS system. The dataset is retrieved in a functionally single, monolithic transaction, i.e. kept together with ACID properties in mind. This is the most reliable type of data design for datasets that require a high degree of safety in the read/write pattern. As an example, a bank ATM transaction should be modeled in a monolithic way. If I make a transfer of funds from one account to another, I want the money to be subtracted from one account if and only if it is successfully added to the other. The bank, on the other hand, wants the money added to the second account if and only if it is subtracted from the first. This is a prime example of a monolithic (single atomic transaction), Consistent (if and only if) and Transactional (as a unit, with provision for roll-back and reporting if unsuccessful) data requirement.

The primary engine used for this type of data is often SQL Azure – an RDMBS in the same datacenters as Windows Azure. Placing both the calling application, whether that is a Data Access Layer-based code widget or a direct call from a Web or Worker Role, means that data is retrieved quickly and in a monolithic way. The costs for this method is based on overall database size. A consideration is how much data you can store this way. Database sizes have limits, although there are ways of overcoming size issues using technologies such as Sharding or SQL Azure Federations. There is also the consideration of performance. In an RDBMs that conforms to ACID properties, locking and other overhead for safety is at conflict with the highest possible read performance. But in some cases the ACID properties are worth the cost, as in the banking example.

You are not limited to SQL Azure in this model. Windows Azure Table storage, while similar to NoSQL offerings is different in that it is immediately consistent across all three replicated copies of data, offering a higher degree of safety. And while Table storage does not offer built-in support for transactions, there are ways to achieve certain transaction levels.

Monolithic Realtime
If consistency can be relaxed – meaning that a guaranteed read/write patter is not essential – then more options arise in Windows and SQL Azure. You can still use SQL Azure for this type of storage, with either automatic or programmatic hints allowing for “dirty reads”. Windows Azure Table storage is still consistent, but the selection of the method for querying the data such as separate copies of read and write data can be employed. Because of the relaxed transaction nature, higher speeds are possible by querying cached or separate datasets.

An example here is that same transaction from the bank, but a statement inquiry. Just after the money is deposited, the user wishes to query the current balance. The current balance – minus the transaction that just occurred – is retrieved and shown to the user, perhaps even combining the amount with the latest transaction, perhaps saved as a local cached object, with a caveat to the user.

Distributed Realtime
At some point, the data becomes too large to fit inside a single processing session, and parallelism is used. In this case, either separate databases in SQL Azure or Windows Azure Tables, local data storage on the Web or Worker Role, or a combination of all with Caches is the right approach for the data design.

The biggest implication in this type of system is speed – a higher degree of data separation is essential, and so the dataset selection must fit the pattern. It is unacceptable to force an ACID-properties type workload into this environment. Typical examples here are the actual data asset payload for streaming video or music, read-only documents and so on. This pattern is often separated from the meta-data, which is kept in more of a transactional model.

As an example, assume you log on to a website to watch a movie or listen to music. The provider needs to verify your identity and account balance, which are transactional data loads. After that process is complete, the workload shifts to a copy – perhaps one of several – of the asset to stream to your location.

In this case, Windows Azure Blob storage, along with the Content Delivery Network (CDN – a series of servers closer to the user) is employed along with the transactional realtime requirements for the metadata.

Distributed Eventual
At the furthest end of the data scale are large datasets that need deeper analysis, but not necessarily in realtime. Examples here are terrabytes of data requiring a Business Intelligence view, but with a tolerance of a few seconds to minutes or hours. In this case, Storage, Processing and Query methods, such as the Hadoop offering in Windows Azure, or perhaps the High Performance Computing (HPC) Windows Server in Windows Azure fit well. Here, the design of the data is often dictated by the source, and more emphasis is placed on the algorithms around processing and re-assembling the data.

There are, of course, other patterns. In many cases a single dataset may have needs in one or more of these categories – in fact, sitting at 30,000 feet typing this entry, I’m having that very design discussion with a gentleman sitting next to me. The key is to design data-first, and fit the technology to the requirement for each datum. Allow each function and engine to handle the data in the most efficient, effective way for cost, performance and utility.

Application Lifecycle Management Overview for Windows Azure

BuckWoody — Tue, 07 Feb 2012 14:58:39 GMT

Developing in Windows Azure is at once not that much different from what you’re familiar with in on-premises systems, and different in significant ways. Because of these differences, developers often ask about the specific process to develop and deploy a Windows Azure application - more formally called an Application Lifecycle Management, or ALM.

There are specific resources you can use to learn more about various parts of ALM - I’ve referenced those at the end of this post. But ALM has multiple definitions, from the governance of code injection, domain upgrade, testing, process flow and more. Many developers are interested in the finer-grained information, like how do I develop and deploy an application? What tools do I need, and how do I get the code running somewhere that I can test?

I’ll cover the very high-level process here, and refer you to specifics at the end of each section, so that you can take it all in at one viewing, and then bookmark for more detail when you need more information. I won’t be covering processes like Continuous Integration or Agile and other methodologies in this post - I’ll blog those later.

Initial Development

You start with writing code. You have three ways to do this. You can use Visual Studio (even the Express Edition Works), Eclipse, or by leveraging the REST API format. You can do this in a standalone (non-connected) environment like your laptop.

Using Visual Studio is one of the simplest methods to create an Azure application, allowing you to combine the Azure components you want to leverage (Storage, Compute, SQL Azure, the Service Bus, etc.) along with the on-premises code you have now or are creating. Once you’ve installed and patched Visual Studio, just download and install the Windows Azure Software Development Kit (SDK) and you’ll have not only all the API’s you need to talk to Azure, but a fully functioning local environment to run and test your code before you deploy it. You’ll also get a robust set of samples. You can download what you need for all of that (free) here: http://www.windowsazure.com/en-us/develop/downloads/ . There’s a step-by-step process here: http://msdn.microsoft.com/en-us/magazine/ee336122.aspx

You can also use Eclipse to develop for Windows Azure. You won’t get the full runtime environment in just that kit alone, but you can use this successfully on a Linux system. I have several folks using this method. The downloads and documentation for that is here: http://www.windowsazure4e.org/

You can use REST API’s to hit Azure Assets and control them. Not my preferred method, but possible. There are REST API’s for various sections of Azure. You can find the main reference for that here: http://msdn.microsoft.com/en-us/library/windowsazure/ff800682.aspx

Note: We recently demonstrated using a Cloud-based Integrated Development Environment (IDE) for Node.js deployment to Windows Azure. More on that here: http://www.readwriteweb.com/cloud/2012/01/cloud9-ide-to-enable-nodejs-ap.php

Deploying to a Test Instance

After you write the code, you’ll need to test it somewhere. The Azure Emulator on your development laptop is for a single user on that laptop, and it also has some subtle differences from the production fabric as you might imagine. Normally you’ll set up a small subscription to run and test the application, just like you would have a set of test servers. Each subscription has its own management keys and certificates, so this assists in keeping the testing environment separate for billing and control.

More on that general information here: http://msdn.microsoft.com/en-us/library/ff803362.aspx

Deploying to Production

Once you have developed the code and tested it, you need to move it to a location where users can access it. In reality, there is no physical difference in the type of machines, fabric or any other component in “Production” Windows Azure accounts and the “Test” accounts, but you’ll most often pick smaller systems to deploy on in testing, and you’ll probably keep the URL in the plain format.

In the Production Windows Azure account, the team normally limits the access to the account for deployment to a separate set of developers. This ensures code flow and control. A DNS name is normally mapped to the longer, Microsoft-generated URL so that your users access the application or data the way you want them to.

More on setting up an account here: http://techinch.com/2010/06/14/setup-your-windows-azure-account/

Managing Code Change

With the application deployed, there are two broad tasks you need to consider. One is managing changes through the application, and the other involves management, monitoring and performance tuning for an application.

To make a code change, the standard ALM process is followed, just as above. You can use command-line tools to automate the process as you would with an on-premises system. A vide on that shows you how: http://www.microsoftpdc.com/2009/SVC25. Normally this is used with an “In-Place” upgrade into Production Account, since your testing is completed in a separate account. More on that process here: http://msdn.microsoft.com/en-us/library/windowsazure/ee517255.aspx

One difference is the “VIP Swap” process you can use for the final push to Production. In essence, this allows you to have two copies of the application running on the Production account, with a quick way to cut over and back when you’re ready. The process for that is detailed here: http://msdn.microsoft.com/en-us/library/windowsazure/ee517253.aspx

For monitoring, you have several options. You should enable the Windows Azure Diagnostics in your code - more on that here: http://archive.msdn.microsoft.com/WADiagnostics.

You can observe uptime and other information on the Windows Azure Service Dashboard, where you can also consume the uptime as an RSS feed: http://www.windowsazure.com/en-us/support/service-dashboard/

From there, you can also use System Center to monitor not only Windows Azure deployments but internal applications as well. The Management Pack and documentation for that is here: http://www.microsoft.com/download/en/details.aspx?id=11324.

There are also 3rd-party tools to manage Windows Azure. More on that here: http://www.bing.com/search?q=monitor+Windows+Azure&form=OSDSRC

Other References:

There is a lot more detail in this official reference: https://www.windowsazure.com/en-us/develop/net/fundamentals/deploying-applications/

Bryan Group explains the ramifications of the Secure Development Lifecycle (SDL) with lots of collateral you can review: http://blogs.msdn.com/b/bryang/archive/2011/04/26/applying-the-sdl-to-windows-azure.aspx

Rip and Replace or Extend and Embrace?

BuckWoody — Tue, 13 Sep 2011 11:20:05 GMT

As most of you know, I don’t like the term “cloud” very
much. It isn’t defined, which means it can be anything. I prefer “distributed
computing”, which is more technically accurate and describes what you’re doing
in more concrete terms.

So when you think about Windows and SQL Azure, you don’t
have to think about an entire product – you can use parts of the system
together or independently to accomplish what you need to do. You can use the
computing functions, storage, and more and more I see folks leverage the
Service Bus to enable current applications to expose things to the web.

And that brings up the point of this post. Once you decide
that a distributed architecture works to solve a problem, you’re faced with a
decision: should you completely re-write your architecture to take advantage of
the current systems or should you just fold in new code that makes the data or
function available to the web?

Of course, the answer is always “it depends” on the situation
– and it does. But unless you’re fixing a problem with current code, I usually
advocate a migration approach. That means at the very least retaining the
business logic (again, unless it’s not currently working) and as much of the
code as you can. In fact, if you follow this paradigm, you’re on your way to
making a Service Bus out of the functions you currently have. You can expose
the results of a system rather than opening the system up. Let’s take an
example.

Assume for a moment that you have an order-taking system
on-premise. That system performs many functions, one of which might creating a
Purchase Order. Your system might be enclosed, meaning that it has an
application that talks to a middle-tier, and then from there to a database
system. A query is generated from a screen, and passed along to eventually
compute, store and return a Purchase Order Number, along with other
information. Imagine now that you wire up the code not only to return the PO
number to the client, but to make that number available on an endpoint –
actually really not that hard to do.

Now you can make that PO number available to the web using
Azure. You could restrict who can make that call to the system, or open it up
to a broader audience. Or instead of the PO Number, you could make a product
list available. And you can go further than that – EBay, for instance, uses the
OData protocol (which is very cool in and of itself) which you can query from
the web. You could compare your company’s product catalog to what is on EBay,
and list the items you have there if there are no competitors in that space.
And on and on it goes.

So the point is this – where you can, retain what works.
Fold in systems like Azure where they make sense. Extend and Embrace.

Plan for Diagnostics in Cloud Computing From the Git-Go

BuckWoody — Tue, 06 Sep 2011 13:11:22 GMT

“Git-Go” is something we say in the South that means “right at the start”. I’ve seen several applications for on-premise systems that don’t have much in the way of diagnostics - the developers rely on a debugger, the event logs on the server and client workstation, and most of all, the ability to watch the system from end-to-end.

This approach is a mistake for an on-premise system, and it’s definitely a problem for a distributed architecture. You simply do not own all of the components from end to end in a cloud environment, nor are you always able to attach a debugger or other remote monitoring tools to the various areas within the code path. So you need to make sure that from the very outset of your design that you build in diagnostics. My personal preference is to build a system such that a control file turns on deeper information gathering from the system, up to a minimal level.

When I do that, I set a high level of logging, a medium level, and a moderate level. I normally use the deepest level of information during the testing and acceptance phase of the deployment, then switch to moderate and then the least level of information gathering. Also in my design I often set an error condition to begin gathering the deeper information along with the exception, where possible.

There are decisions you need to make as to where to store the diagnostics (many operations in the cloud cost money), how often you collect them, and so on. You can get a quick overview on using the diagnostics that come with Windows Azure here: http://www.azuresupport.com/2010/03/getting-started-with-windows-azure-diagnostics-and-monitoring/ This is where you should start first. More detail on that: http://msdn.microsoft.com/en-us/library/gg433048.aspx

My friend Dave Pallman has a great tool he’s released for free: http://davidpallmann.blogspot.com/2009/03/azure-application-monitor-now-on.html

If the issue is in storage apps: http://social.msdn.microsoft.com/Forums/en-US/windowsazuredata/thread/d84ba34b-b0e0-4961-a167-bbe7618beb83

If you have System Center, this is the quickest and easiest way to implement the monitoring – really handy: http://pinpoint.microsoft.com/en-us/applications/windows-azure-application-monitoring-management-pack-release-candidate-12884907699

Windows Azure Security Review

BuckWoody — Tue, 02 Aug 2011 13:24:50 GMT

Current as of 08/01/2011 - Check the Resources listed below for more up-to-date information on this topic

Background:

Security for any computing platform involves three primary areas:

Principals (users or programmatic access to an asset or other program)
Securables (objects, data or programs that can be accessed)
Channels (methods of access by Principals to Securables)

On-premise systems normally use a central system to control security. In a Windows operating system-based environment, this is often accomplished with Active Directory or other systems that provide sign-on and user identity information. While other networking security paradigms have different terminology, all involve the three areas defined above.

In addition to the names and passwords for a user, Active Directory (like other security mechanisms) store other information about Principals - called Claims. These claims can include any custom fields the provider allows. In many networks, these fields are not used heavily, because applications that eventually need to secure the assets they control are not always deployed on the same platforms everywhere.

In a single environment, security is often quite simple. A Principal is created such as a user or group, and then the Principal is granted access to a Securable such as a a folder, database or other asset. Permissions or Rights (or both) combine to allow a particular Principal to read, write, delete or edit data, or to access or run a particular program.

Figure 1 - On-premise security environment example

The simplicity of this arrangement is due to a single, homogenous boundary. Even if more than one location is used, the Principals and Securables are grouped into a single logical boundary that is managed from one location.

This background serves as the starting point for the Federating Security topic below.

Windows Azure Security Boundaries

Windows Azure is a series of resources - servers, data and service buses, in addition to other features. Developers write code, and the deploy that to the Azure environment.

Figure 2 - Azure Components

The code or data can be deployed to use one or more of the services. In other words, the Web Role in Windows Azure might host a simple website, and no other component need be used.

Figure 3 - Simple Azure Web Role Application - only one feature used

Or, a complex mix of Web, Worker and Data Services, along with a Service Bus, RDBS and even on-site systems can be grouped into a much larger program.

Figure 4 - Complex Windows and SQL Azure Application With Multiple Interactions

For a more basic introduction to Windows and SQL Azure, see this link: http://channel9.msdn.com/Events/TechEd/Europe/2010/COS322

Windows Azure, like any web-based property, has three general layers of security:

Physical Access
Operating Environment (Including the Operating System itself)
Data and Programmatic Security

Each of these layers have additional layers within themselves, and this forms the basis of a secure experience for the end user or program. Some of these layers are the responsibility of Microsoft; others are the responsibility of the architect and developer; others are a joint or shared responsibility of both Microsoft and the client.

Layer One: Physical Access

The first layer of security within a web property such as Windows or SQL Azure is a secure facility. the following data points are important to understand for the worldwide facilities that host Windows and SQL Azure:

Microsoft Global Foundation Services (GFS) is responsible for the physical security of the datacenters located worldwide for Windows and SQL Azure. Information on Microsoft datacenters can be found here: http://www.globalfoundationservices.com/
The address and exact locations facilities are not commonly documented for security reasons.
Microsoft runs it’s own data centers and does not contract this function out.
The GFS controlled facilities hold an ISO/IEC 27001:2005 certification, and are audited to SAS level II.
Standard secure operations protocols are in place, including least-privilege access.

Layer Two: Operating Environment

Windows Azure and SQL Azure do not currently hold certifications. Microsoft does not comment on the security certifications being pursued for Windows or SQL Azure. That being said, the Windows Azure environment is based on a modified Windows 2008 R2 Enterprise environment, developed using the Trustworthy Computing Initiative (TCI).

The system controlling the host machines and their guest environments that ultimately hold the Web and Worker Roles within Windows Azure is called the Fabric - not to be confused with the Application Fabric feature. The Fabric is not accessible by client code - it controls the inner workings of Windows Azure, including Load-balancing, system restarts, maintenance and monitoring.

Within the host machines that house the Web and Worker Roles, special networking constructs broker all conversations between Virtual Machines. Virtual Machines - even ones configured to communicate with each other - move through this network. Direct-machine to machine communication is not allowed, protecting one application from another or one data construct from another.

Figure 5 - Windows Azure Fabric

Windows and SQL Azure support only TCP-based communications. Ports commonly used are:

80 - Default public port used for Web Roles - can be enabled/disabled per configuration
443 - Default secure port used for Web roles - can be enabled/disabled per configuration
9350-9353 - These ports are used by the Windows Azure AppFabric service bus bindings. Refer to http://msdn.microsoft.com/en-us/library/ee732535.aspx for more details
1433 - SQL Azure
3389 - This port is used for RDP access to VM-based roles, only if enabled

Layer Three: Data and Programmatic Security

All internal access through use of keys only. Without the proper key, code or data will not transfer. Storage Accounts have individual keys, so in this manner different security layers may be applied not only programmatically but at the account layer.

Figure 6 - Windows Azure communications between components

Calls to Windows Azure are made using standard SOAP, XML or REST-based protocols. The communications channel can be encrypted between the client and Windows Azure or allow it to remain unencrypted based on security needs.

SQL Azure uses the standard SQL Server Tabular Data Stream (TDS) protocol, but only allows encrypted communications.

Data is unencrypted within Windows Azure Blob or Table Storage - but is only accessible via the key for a storage account. Data can be encrypted client-side and stored in Windows Azure in an encrypted fashion. Microsoft does not inspect internal data for validity or encryption enforcement. The key is that the data is client-side encrypted and decrypted.

Figure 7 - Example data at rest encryption scenario

Alternatively, a hybrid solution can store sensitive data locally and non-sensitive data in Azure Storage. The data can be coalesced at the client level such that the data is never transferred over any channel not owned or controlled by the organization.

Federating Security:

In the case of a single security boundary for Windows Azure, multiple security options are available. Users can be anonymously authorized, such as in the case of a public website for advertisement or informational purposes.

Another option is to create an Internet Information Services (IIS) Internal Security Store. This is not a best-practice (although still possible) approach since the Fabric services within Windows Azure may recycle an instance and the session may sever between a given role and a client. Architecting stateless applications is a preferred approach.

Using Claims-Based Authentication is a better solution. In this approach, the Principal is authenticated through a trusted party, such as Active Directory, OpenID, OpenAuthentication, or LiveID. Many web-properties use these methods, such as Microsoft, Google, Yahoo and Facebook to name a few. After authenticating with one of these services, the client is issued Claims using the WS-Federation (WS-Fed) or Security Assertion Markup Language (SAML) that are passed to Windows Azure. At no time does Windows Azure store, transfer or interrogate the Principal’s security token. Claims can be anything from a group or role membership to location or any other settable attribute. Assets are then secured allowing only the Claim, without regard to the user’s location or access method. In this fashion a single security paradigm covers the Securables, with the Principals being controlled in any number of other mechanisms. This allows single-sign-on and/or federated security access from multiple providers.

The simplest mechanism for building this environment is the Access Control Services (ACS) feature found in the Windows Azure Application Fabric component. It is a federated authorization management service that simplifies user access authorization across organizations and ID providers and performs claims transformation to map identities with access levels.

ACS can:

Create and manage scopes such as URLs
Create and manage claim types
Create and manage signing and encryption keys
Create and manage rules within an application scope
Chain claims rules
Manage permissions on scopes or perform delegation

Figure 8 - Federated Security Example

Full information on the Access Control Service is available at this link: http://social.technet.microsoft.com/wiki/contents/articles/windows-identity-foundation-wif-and-azure-appfabric-access-control-service-acs-survival-guide.aspx?wa=wsignin1.0

Since the Web and Worker Roles within Windows Azure are designed to be stateless, Microsoft created a Certification Store within the Management area to hold Certificates that can be called from within code. An example of using the Certification Store is here: http://blogs.msdn.com/b/jnak/archive/2010/01/29/installing-certificates-in-windows-azure-vms.aspx

Additional Resources:

Official, authoritative security resource list: http://msdn.microsoft.com/en-us/library/ff934690.aspx
Technical Overview of the Security Features in the Windows Azure Platform: http://www.microsoft.com/online/legal/?langid=en-us&docid=11.
Windows Azure Security Overview: http://www.globalfoundationservices.com/security/documents/WindowsAzureSecurityOverview1_0Aug2010.pdf
Windows Azure Privacy: http://www.microsoft.com/online/legal/?langid=en-us&docid=11
Securing Microsoft Cloud Infrastructure: http://www.globalfoundationservices.com/security/documents/SecuringtheMSCloudMay09.pdf.
A list of other security resources is here: http://blogs.msdn.com/b/buckwoody/archive/2010/12/07/windows-azure-learning-plan-security.aspx

Image Attribution: David Pallmann: http://davidpallmann.blogspot.com/2011/07/windows-azure-design-patterns-part-1.html

Cloud Computing and the Importance of Code Diagrams

BuckWoody — Tue, 03 May 2011 13:59:20 GMT

Most mature development shops use various code diagrams to give a symbolic representation of high-level and database code structures. Standards such as Business Process Model Notation (BPMN), Entity Relationship Diagrams (ERD) and the Unified Modeling Language (UML) are a few I use all the time.

In the Distributed Computing (Cloud Computing) paradigm, these three diagrams (or their equivalent) become essential. In the past, I’ve been able to rely on a single architecture where my code will run. I understand the servers, the networking and the path the code takes between the client and the components within that architecture.

With Distributed Computing (DC), the architecture changes. In fact, the reason I use the term “Distributed Computing” instead of “Cloud Computing” most often (except in the title of this post, as you can see) is that I feel it’s more technically accurate about how we write code. I don’t view DC coding as an “all or nothing” exercise – I view it as just another option to solve a computing problem. A “hybrid” approach, where I mix in the strengths of a cloud provider is often a great way to leverage the best cost, performance and other advantages of each part of your solution. It can also help keep data secure, provide options for High Availability and Disaster Recovery, and more.

To gain these advantages, we have to think more about the components of the application rather than a monolithic stack of components in a single architecture. And that brings us to the title of this post…

For us to correctly identify code components, database objects, security paths and other elements, we have to be able to conceptualize them. And that’s where those diagrams come into play. Starting with some sort of business or organizational need, we can use BPMN or UML Actor diagrams to explain what the program needs to do. That helps segregate the security and location requirements. For instance, if the BPMN shows a data access to Private Information, we can evaluate the need for an on-premise system that is federated to a DC provider. If the business users need global access, we can decide whether to set up a VPN to allow access to an on-premise system or whether a login component can be used on the web.

After determining the flow of the program, move on to the data the system will store. In the case of Windows and SQL Azure, there are several options for storing data. In the past, I’ve often selected a single storage type, such as an RDBMS, and stored program data there. Now we can store in multiple formats, in multiple locations and more. The ERD is pivotal, because it defines data types, which can help decisions around where things go. Another important aspect to the data decision which is not covered in an ERD (but perhaps should be) is the estimated size and growth of a datum, since that can also drive the decision on where to put a data component.

From there, the UML document helps me understand where each computing element can live. There are strengths for each type of computing, and using the UML diagram I can place each code component in the best environment for speed, security and other considerations.

So in the new Distributed Computing world, these graphical documents do much more than just help design the application – they can help define the architecture as well.