Page 566 - Cloud computing: From paradigm to operation

3 XaaS

8.2 DaaS platform-side functional requirements

The DaaS platform-side functional requirements include:
• Maintaining DaaS user status: It is required that the CSC be capable of reconnecting to virtual
desktop in the same virtual desktop state as left.
• Optimized adaptation for content type: It is recommended that the DaaS client be optimized for
the content type involved (e.g., each type of content is encoded with a codec that is tuned to best
support the content and the codec configuration can be automatically changed based on the
content type such as multimedia, images and text).
• Isolation between virtual desktop functions: It is required that the operation of the virtual desktop
functions of one CSC should not be negatively impacted by the use of virtual desktop functions by
other CSCs.

• Graphic processing acceleration support: In order to provide ability to DaaS clients to work with
graphic-intensive software packages (such as 3D computer-aided design or compression) running
on the server, it is recommended that the CSP provide the acceleration of graphic processing to
DaaS clients.
• Server-side rendering: In order to provide a consistent user experience to a wide range of DaaS
clients as well as to improve user experience, it is recommended that the local desktop be composed
and rendered on the host before the resulting image is encoded and sent to the DaaS client.
• Standard video codec support: For applicable video content, it is recommended to support standard
codecs, such as specified in [b-ITU-T H.264] or [b-ITU-T H.265].
• Progressive encoding support: For networks with limited bandwidth, in order to improve user
experience in case of a network bottleneck, it is recommended to use progressive encoding.
NOTE – Progressive encoding and rendering means that the image can be encoded and sent over several
stages, and the image quality becomes progressively clearer at each stage.

• CSC environment backup:
– It is recommended that the CSP backup and restore the allocated virtual machines with user
environment in order not to lose user data.

– It is recommended that the CSP should not degrade the service performance from the process
of backing up and restoring.
• Standard audio encoder support: It is recommended to support standard audio encoders.

8.3 DaaS client-side functional requirements
The DaaS client-side functional requirements include:
• Resource request: It is recommended that the CSC be capable of configuring the system resources
in its use (e.g., CPU, memory, storage and other devices) during service execution.
• Support of DaaS client peripherals: It is recommended that DaaS applications be able to use DaaS
client peripherals.
NOTE 1 – Examples of DaaS client peripherals include USB port, flash memory, global positioning system (GPS),
camera, etc.
• Video decoder support: For rendering video content on client, it is recommended to support
standard codecs, such as specified in [b-ITU-T H.264] or [b-ITU-T H.265] to decode encoded images.
• Standard audio decoder support: It is recommended to support standard audio decoders.

• Synchronization between DaaS client and DaaS platform: It is recommended that DaaS support
synchronization of DaaS user state when the connection is established and terminated.
NOTE 2 – DaaS user state include desktop background and layout, user interface preferences, current DaaS
user timezone, etc.

558