From BizApps Wiki, the free Business Applications encyclopedia
Jump to: navigation, search

XpressO (XO) is Workday's internal programming language created for development of their business applications and it abstracts application developers from having to worry about the underlying platform, allowing them to focus on building applications of varying complexities with configurable security and access layers. These developers expose their data models and functionality through web services and REST APIs so customers can integrate with and/or extend the Workday applications.[1]

XpressO in Workday architecture[edit]

At the heart of the architecture are the Object Management Services (OMS), a cluster of services that act as an in-memory database and host the business logic for all Workday applications. The OMS cluster is implemented in Java and runs as a servlet within Apache Tomcat. The OMS also provides the runtime for XpressOWorkday’s application programming language in which most of our business logic is implemented.[2]

XpressO in Metadata-Driven Development[edit]

Application developers design and implement Workday’s applications using XpressO, which runs in the Transaction Service. The Transaction Service responds to requests by providing both data and metadata. The UI Services use the metadata to select the appropriate layout for the client device. JavaScript-based widgets are used to display certain types of data and provide a rich user experience. This separation of concerns isolates XpressO developers from UI considerations. It also means that their JavaScript and UI service developers can focus on building the front-end components. This approach has enabled Workday to radically change its UI over the years while delivering a consistent user experience across all our applications without having to rewrite application logic.[2]


In Workday they are working hard on a successor to XO, called YP.[1]


  1. 1.0 1.1 "Sneak Peek into Workday's Technology Stack". Workday Technology. November 2017.
  2. 2.0 2.1 "Exploring Workday's Architecture". Workday Technology. March 2018.