CHAPTER 8 Quality Attributes and Sizing of the DXP Nonfunctional requirements, also known as quality attributes, decide the robustness and long-term success of the DXP. The quality attributes such as usability, reliability, scalability, availability, and performance help us to define, track, and measure the success metrics of the digital platform. Conforming to the service level agreements (SLAs) for these quality attributes ensures the long-term success of the program due to higher user satisfaction. This chapter explores various quality attributes needed for a digital solution. Infrastructure sizing is needed to handle user traffic and transactions for the digital application. We also explore various factors involved in infrastructure sizing and disaster recovery (DR) strategy of a DXP. As the cloud has become the de facto standard for the digital application, we will explore cloud deployment of digital applications. Key Quality Attributes of DXP The key quality attributes of DXP are explained in the following list. Each of these quality attributes has its own set of metrics and SLA to quantitatively measure the quality attribute. • Scalability: The ability of the DXP to scale to increased user traffic, data, and transaction volume without compromising the overall performance • Availability: The overall percentage of the time DXP is available and functioning normally over a specific time period (usually 1 year) © Shailesh Kumar Shivakumar, Sourabhh Sethii 2019 215 S. K. Shivakumar and S. Sethii, Building Digital Experience Platforms, https://doi.org/10.1007/978-1-4842-4303-9_8