Desktop-as-a-service providers take different approaches to how they deliver cloud desktops, but they are usually...
either server-based or client-based.
At the heart of desktop as a service (DaaS) is a cloud infrastructure that includes the resources to host and deliver desktop services. The infrastructure includes a virtualization layer for managing the VMs that host the cloud desktops, which are then delivered to client devices via a display protocol, similar to an on-premises virtual desktop infrastructure.
DaaS delivery options
Cloud desktop delivery was traditionally limited to two basic approaches: server-based and client-based. Most server-based desktops are implemented through Windows Server Remote Desktop Services. In this model, Windows Server runs in a VM and is configured as a Remote Desktop Session Host (RDSH) that supports simultaneous desktop sessions where each session is associated with a single user. For this reason, the server-based model is sometimes referred to as session-based or RDHS-based.
Regardless of the name, the model makes it possible for multiple users to connect to a single VM that runs Windows Server, which helps streamline resource usage and management. From the user's perspective, cloud desktops appear to be a standard Windows client environment.
In the client-based model, each VM runs Windows 7, Windows 10 or a Linux distribution. The VM supports only one user at a time, similar to persistent VDI. The advantage is the VM's resources are dedicated to a single desktop and, therefore, do not suffer the resource contention that can occur with the server-based model. The client-based model also provides more flexibility when it comes to running applications and configuring the environment.
A client-based desktop can also include features that are not available to a server-based desktop, such as support for Cortana or Office 365 ProPlus. The client-based desktop also offers more consistency across an organization when managing both virtual and physical desktops. For example, IT can use a single base Windows image for both types of cloud desktops, apply service packs across all systems and support the same lifecycles.
The flip side to this is the client-based model tends to require more resources and can be more complex to implement and support. In addition, licensing can be trickier than with server-based desktops. Regardless of the differences between the two models, both deliver the full desktop experience and support persistent and nonpersistent desktops.