Larry Franks and Brian Swan on Open Source and Device Development in the Cloud
The June 7th update to Windows Azure introduced two new services (Windows Azure Websites and persistent VMs) that beg the question “When should I use a Windows Azure Website vs. a Web Role vs. a VM?” That’s exactly the question I’ll try to help you answer in this post. (I say “help you answer” because there is no simple, clear-cut answer in all cases. What I’ll try to do here is give you enough information to help you make an informed decision.)
Note: The information in this post has been turned into official documentation by the Windows Azure content team. For the most up to date information, see Windows Azure Web Sites, Cloud Services, and VMs: When to use which? on WindowsAzure.com.
The following table should give you some idea of what each option is ideal for:
Modern Web Apps Applications that consist of client-side markup and scripting and/or server-side scripting and a database. You can scale out or up as needed.
Also the web tier of multi-tier applications.
Multi-tier Applications Applications that are composed of multiple tiers, each of which can be scaled independently (i.e. asynchronous background processing, like order processing) using both Web and Worker Roles.
Note: Web Sites can also be used for the web tier.
Server Applications Existing applications that leverage SQL Server, MySQL, MongoDB, Sharepoint Server, etc.
Continuous Development Deploy directly from your source code repository using Git or Team Foundation Service.
Apps that require advanced administration Applications that require admin access, remote desktop access, or running code with elevated privileges.
Existing line-of-business apps Choose an image from the gallery or upload your own VHD.
Popular Open Source Apps Launch a site with a few clicks using apps like WordPress, Joomla!, and Drupal.
Apps that require advanced networking Applications that require network isolation with Windows Azure Connect or Windows Azure Virtual Network.
Windows or Linux Support for Windows Server and community/commercial versions of Linux. Connect VMs with Cloud Services to take advantage of PaaS services.
Actually, I think the use cases for VMs are wide open. You can use them for just about anything you could imagine using a VM for. The tougher distinction (and decision) is between Web Sites and Web Roles. The following table should give you some idea of what Windows Azure features are available in Web Sites and Web Roles:
Access to services like Caching, Service Bus, Storage, SQL Azure Database
Support for ASP.NET, classic ASP, Node.js, PHP
Shared content and configuration
Deploy code with GIT, FTP
Integrated MySQL-as-a-service support
Multiple deployment environments (production and staging)
Remote desktop access to servers
Ability to run programs with elevated permissions
Ability to define/execute start-up tasks
Ability to use unsupported frameworks or libraries
Support for Windows Azure Connect/ Windows Azure Network
* Web or Worker Roles can integrate MySQL-as-a-service through ClearDB's offerings, but not as part of the Management Portal workflow.
As I said earlier, it’s impossible to provide a definitive answer to the question of which option you should use (Web Sites, Web Roles, or VMs). It really does depend on your application. With that said, I hope the information in the tables above helps you decide what is right for your application. Of course, if you have any questions and/or feedback, let us know in the comments.
What about SSL certificates, and custom domain names? These are not availible in the Websites Preview at least.
@Thomas - Good question. Custom domain names are available in the Websites Preview in *reserved* mode (which is not the default, and not free: www.windowsazure.com/.../details). Support for SSL is currently not supported in either mode (shared or reserved), but this is a highly requested feature, so maybe we'll see support for it at some point.
Can we communicate to a worker role from a Windows Azure Website?
@shiju - Yes. You can access a worker role from *any* application, provided you have created an input endpoint for the worker role in the service definition (.csdef) file when deploying the role. The schema for the worer role .csdef file is here: msdn.microsoft.com/.../gg557552.aspx
Hope that helps.
"Ability to use unsupported frameworks or libraries"
What does it mean?
@Rami - Think of Web Sites as web hosting, where you don't have full access to or control over a VM. You can run code that is supported by the web host, but that's it. With Web Roles, you have full access to and control over the VM, so you can install anything you want and configure it as you like. An example here might be Ruby: it's not supported in Web Sites, but you can easily install RoR on a Web Role.
Does that answer your question?
THXS A LOT for your clarifications. Straight to the point ;)
Does PHP website really prevent people from using their own PHP library/framework? I had thought it was possible, just harder...
@Albert - No, Web Sites does not prevent you from using PHP frameworks. I think this post needs to be updated. Sorry for the confusion.
Hi Tony, there's no specific terms around doing this and no legal gotchas that I can find. I'm told by people in the know that this is expected/accepted/normal.
For Web Sites you say "YES" to "Access to services like Caching". Is access to caching possible with Web Sites?
Hi Peter, the caching Brian mentions above for web sites is the old-style Windows Azure Caching, now known as Shared Caching. This was caching as a service where you had an endpoint that the application used to communicate with the cache service, quotas, pricing for data stored, etc. Not to be confused with the new caching, which is a Windows Azure Cloud Service only thing that makes use of memory in your role instances. You can read more about shared caching at msdn.microsoft.com/.../hh914133.aspx.
We have some sites that we would like to move to Azure, but we are not really sure what all to choose with each. Is it possible to communicate outside of this post to explain our architecture and get your advise what to move forward with?
Hi John, please contact jroth at the Microsoft.com domain. He's been working on an article related to this blog post and can work with you on this.