XaaS products, at your service

The number of XaaS offerings on the market is enough to make your head spin. You probably know what PaaS, SaaS and IaaS are, but how do DaaS and DRaaS fit in? It's time to get this straight.

Acronyms make it easier to talk -- and read -- about technology, but sometimes important details get lost in the shuffle. With so many "as a services" out there today, keeping track of all the names and differentiating the tech isn't easy.

Here's what you need to know to avoid a major SNAFU: If a term ends in "aaS," it's probably cloud-based. The first letter is what clues you in about what exactly is being hosted, from infrastructure and disaster recovery services to virtual desktops and applications. Collectively, they're "anything as a service" (XaaS).

All these XaaS offerings are available on a subscription basis. Whether that means a per-user or per-month fee depends on the vendor. They also all put you at the mercy of the cloud: Users need a solid Internet connection to reach whatever you're hosting, and downtime is always a possibility. And before you decide to put any data in the cloud, you should resolve or find a product to address any security concerns you have.

There are three main "as a services" from whence the others ostensibly came: IaaS, PaaS and SaaS. These are the important basic cloud computing categories to know for VDI administrators because they sometimes include or affect virtual desktops, and they have helped make DaaS and DRaaS a reality.

Infrastructure as a service

With infrastructure as a service (IaaS), a third-party provider hosts the hardware, software, servers, storage and other parts of infrastructure for customers. The provider also handles system maintenance, backup and resiliency planning. Administrative tasks are often automated, and IaaS providers can offer dynamic scaling, desktop virtualization and policy-based services. In addition to the subscription fee, providers may also charge based on the amount of virtual machine space that workers use. 

Pros: IaaS platforms are very easy to scale and adjust, so they're great for temporary or experimental workloads. And because someone else stands up and maintains the infrastructure, you don't have to.

Cons: The fact that the infrastructure is completely out of your hands is a double-edged sword. You may have trouble with systems management and monitoring. And you won't be able to set it and forget it -- it's important to keep any eye on the charges you're incurring and make sure you're not getting taken for a ride.

Market leaders: Amazon Web Services (AWS), Windows Azure, Google Compute Engine, Rackspace Open Cloud and IBM SmartCloud Enterprise.

Platform as a service

Platform as a service (PaaS) delivers applications over the Internet. A cloud provider hosts hardware and software tools for application development on its infrastructure and makes them available for customers to use.

Pros: Because the provider hosts the tools, you don't have to install them in-house. You just develop your application and then users access it through a Web browser. The PaaS provider supports all the hardware and software. Additionally, you can change or upgrade your application frequently, and various development teams can work together on the same project.

Cons: Once you develop an application on a certain PaaS provider's platform, you're locked into that vendor. If the application is or becomes mission-critical, and then you decide you want to switch vendors, that could be a painful process, and it could inhibit employees' productivity. Additionally, if your provider stops supporting a certain programming language, you might have to reprogram your application or switch vendors.

Market leaders: Salesforce.com's Force.com for customer relationship management, Appear IQ, Mendix, AWS Elastic Beanstalk, Google App Engine and Heroku for software development and management.

Software as a service

In the software as a service (SaaS) model, a vendor or cloud service provider hosts applications and customers access them over the Internet. Some people argue that hosting applications in the cloud is technically DaaS because the applications themselves run on operating systems. The difference is that with hosted apps, users don't see the desktop OS.

Pros: SaaS applications offer simplified administration and patching, they reduce compatibility issues and make collaboration easier. Some shops find that one benefit of using SaaS applications is that they can pare down their data centers, which means fewer servers and other infrastructure components to manage and maintain. Users can also have anywhere- and any device-access to their applications because they connect via the Internet and a Web browser.

Cons: To log into their SaaS applications, workers need usernames and passwords, which means identity management can become a problem, especially if you use Active Directory (AD) to give users single sign-on. Many companies don't want AD credentials to get outside their firewall, but AD also doesn't play nice with highly distributed applications. Plus, you have to keep track of and confirm that workers are using the licenses for your SaaS environment, rather than going rogue and using an unapproved SaaS application. Performance monitoring can be a headache as well; most monitoring tools use an agent, and you can't install the agent on a SaaS app.

Market leaders: Google Apps, Salesforce.com and Microsoft Office 365.

Desktop as a service

Desktop as a service (DaaS) is a cloud service where the back-end infrastructure of VDI is hosted by a cloud service provider. It has a multi-tenancy architecture. The DaaS provider takes care of the responsibilities of data storage, backup, security and upgrades, and user data is copied to and from the virtual desktops when they log on and off.

Pros: Users can access hosted desktops from any device, location or network. Customers usually manage their own images, apps and security, but the provider manages the infrastructure.  DaaS is a good alternative to VDI for small and midsize businesses that want to deliver virtual desktops to users, but can't afford the upfront and ongoing costs associated with doing VDI on-premises.

Cons: Licensing virtual desktops comes with headaches, but licensing them in the cloud is often even more complicated. Microsoft does not have a Service Provider License Agreement for Windows client OSes, so many organizations host Windows Server -based desktops in the cloud instead. This is a good way to get around the licensing concerns, but Server desktops can have application-compatibility problems.

Market leaders: Amazon WorkSpaces, VMware Horizon Air Desktops (formerly Horizon DaaS, formerly Desktone) and Microsoft Azure RemoteApp.

Bonus as a service: DRaaS

With disaster recovery as a service (DRaaS), a third party -- not necessarily a cloud provider -- replicates and hosts your physical or virtual servers to give you failover in case disaster strikes. Sometimes that provider will host your data in the cloud. It's especially useful for SMBs that don't have the infrastructure, technology or skilled personnel to implement a DR plan on-premises. Some companies look to DaaS providers for DR services, and vendors such as VMware offer DRaaS as part of their DaaS services. But logically, there are good reasons to stand DaaS up and use it for DR and to host desktops, rather than doing DaaS for one reason or the other.

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