PHP is now officially supported as a language for developing applications that can run on Windows Azure. This makes a lot of sense from Microsoft’s viewpoint as the number of PHP developers that use Windows environments for PHP is not insignificant. Microsoft have now made it possible to run PHP applications on Microsoft Azure servers and also take advantage of the Azure storage services (Table and Blob Storage).
Microsoft PHP SDK, PHPAzure, provides a set of PHP classes to use Azure services for storing data and files up to 50GB of size. PHP applications are not compiled into .Net, PHP runs on Azure using FastCGI. You need to create a standard project structure, which requires the PHP FastCGI binaries, and later submit it to the Azure servers for deployment.
There are restrictions in using PHP on Azure, with the main one being that file manipulation has to be done using AzureBlobs i.e. you cannot use write to regular PHP files. It is also not possible to execute regular SQL queries to access data in Azure Tables, you have to use the PHP Azure SDK classes to compose and execute queries.
There are also benefits, namely that Azure is built to handle extreme volumes providing greater security and availability. PHP applications can also easily share information other .NET applications and vice-versa which could lead for some interesting integrations and applications.
Using PHP on Windows Azure is free at the moment for the Community Technology Preview edition and it is expected normal Azure pricing will eventually apply.
Those interested in PHP and .Net may also be interested in Phalanger, which is a PHP compiler for .NET that makes creates .NET assemblies from PHP code, enabling it to be used with other applications.
In supporting PHP Microsoft are showing their hand in the way they are targeting the market (and PHP has a large market and online application presence) and developers. For example in providing support for PHP they have got one over on Google App Engine, where PHP is not natively supported. It is possible to use PHP to Java compilers to run PHP applications in Google App Engine, but this is more of a hack.