Windows Azure for PHP developers
Introduction
Since a couple of years the term "cloud" has moved from simple buzz-word to real business opportunities that make a difference within the market. The technology behind "cloud" is not new as we've grown accustomed to server clusters, distributed datacenters and separation of responsibilities, but the "cloud" offers everyone the opportunity to scale and not just the companies who have a huge cash reserve to purchase another rack with servers.
The strange thing is that cloud is being provided by companies you wouldn't expect to serve it. Best known are Amazon.com and Rackspace.com that offers a complete set of services you can use to run applications in the cloud, they provide the infrastructure and you have to set up and maintain your platform and infrastructure. Microsoft also jumped on this cloud hype offering a platform in the cloud. And this is exactly the reason it caught my attention and got me interested. I'm a developer and I don't want to fiddle with setting up and maintaining an operating system, basically since I don't have the time for it.
Windows Azure
I got in touch with Microsoft's
Windows Azure
back in 2008 through our local Microsoft Evengalist Katrien De Graeve, who
told me Windows
Azure is like running a Windows 2008 Server with IIS in the
cloud. Along with Maarten
Balliauw Microsoft
was working out more tools and features to support PHP (amongst other open source
technologies) on their new cloud platform.
I was completely sold when Josh Holmes came to
Brussels in 2009 and told us more about what Windows Azure has
to offer and how perfectly it is to build applications consuming
these cloud services, without having to deal with setting up and
maintaining the platform the run on. And so, I started playing
with it and discovering about what Windows Azure is
all about, what kind of services they offer and how I as a PHP developer could make good use
out of it. In 2010 PHPBenelux
and Microsoft joind
efforts to promote Windows
Azure by organizing a PHPonAzure contest to
develop an application that would run and make use of Windows Azure's
services.
Developing for cloud
When developing PHP
applications, you mostly develop for a single server setup or
maybe one server running your PHP
code and one server for the database. This is the easiest way to
set up an environment as you don't need to worry about anything
except to connect to the correct database.
When developing for the cloud, more things should be considered
before you get started. Some things that you take for granted
require some additional thoughts when designing the architecture
of your application. Fortunately for you, there are only a few
things to take into account before you can deploy your latest
killer app in the cloud provided by Windows Azure.
Operating System
On a bare metal server or even a virtual server, you know you
need to set up your own operating system (or have your hosting
service provider or sysadmin do this for you). This means you need
to take responsibilty in keeping your OS up-to-date with security
fixes and all kinds of software upgrades.
Windows Azure is
a platform on it's own, comparable to a fully set up Windows 2008
Server complete with IIS 7. Microsoft takes care of updating and
securing their instances you use without compromizing your
application.
Data Storage
When creating a normal website session data, logs, caches and file uploads are often stored on the local filesystem. With a cloud solution, you need to consider that multiple instances of your web application might be up and running and don't share each others filesytem. To facilitate filesystem storage, cloud services offer so called "file buckets" or storage endpoints. Windows Azure offers 5 types of storage:
- Blob storage: simple binary storage for video, images, audio
and other types of files
- Table storage: a structured storage for large amounts of data,
behaving like a NoSQL storage
- Queue: a messaging queue to transfer messages between
applications and services
- Windows Azure Drive: a mounted shared disk partition formatted as NTFS VHD
- SQL Azure: a true relational database based on Microsoft SQL Server technology
One storage location I need to mention a little separate is
Windows Azure Cache, a memory storage. It's a caching layer
comparable to Memcached or WinCache,
residing completely in memory.
File uploads are easy as you only need to worry where they end up and how you make sure files cannot overwrite existing files, unless specified to do so. Using one of the 5 storage solutions provided by Windows Azure is not difficult using PHP, it only requires correct settings for transferring the uploaded file to the chosen storage. PHP's move_uploaded_file() method can be used in most cases. In other cases, use the Windows Azure SDK for PHP as it offers a rich abstraction layer for the different storage options of Windows Azure.
Sessions in PHP can easily be
stored in a database, a storage endpoint or on a memory layer by
modifying the session_set_save_handler().
Windows Azure can
store session data on the blob storage, table storage, the Windows
Azure Drive, in SQL Azure or on it's Cache layer. I prefer to use
either the SQL Azure or the Cache, as they both perform really
fast, even for session data.
When using logs within your application, you also need to be
aware that your log files should reside somwehere central. Best is
to either log against Table storage or SQL Azure as it's a fast
way to keep track of changes and easily accessible. But, storing
logs on the blob storage is perfectly good as well, only know it
might grow your storage space too much.
Caching is something best handled by Windows Azure Cache, the
memory storage I mentioned earlier. It's fast, very easy to
maintain and super easy to scale in or out.
Data itself can be stored in SQL Azure or on Table Storage. SQL
Azure is a full featured relational database, comparable to
Microsoft SQL Server. It offers all the features you can expect
from a relational database, including stored procedures,
transactions and separation of responsibilities. Table Storage is
a simple key/value storage table, that behaves more like a NoSQL
storage and thus capable of storing documents and constructs in an
organized way.
Other considerations
Cloud applications should be designed to scale horizontally. This
means when your application requires more resources to cope with
the usage, more instances of the application will run together
behaving as a single application.
Cloud is also "pay as you go". If you use a little, you pay a
little. If you use a lot, you pay also a lot but less then when
you need to scale with traditional hardware. The following graphs
by Josh Holmes
explains it best.
Now it doesn't matter if you're a big company or just a start-up.
You can launch your product slowly and grow as your usage and
budget grows. A perfect match.
Next
Now that I've introduced you to what Windows Azure has
to offer PHP developers, or any
other technology developer for that matter, I show you how I have
a simple Zend Framwork application build on a traditional LAMP
stack deployed to Windows
Azure. So stay tuned for more.
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