The Reference Architecture Model Industry 4.0 (RAMI4.0) proposes two models to guide the design of virtual representations of assets. A cubic model represents assets in the form of layers and allows them to be tracked over their lifetime and assigned to technical or organizational hierarchies. The I4.0 component model suggests how to organise virtual representations, i.e., asset properties (data and functions). A service hierarchy has also been proposed as the mechanism to gain access to asset properties. This paper presents an analysis of the RAMI4.0 service hierarchy, compared to traditional service oriented architecture, towards a methodology for the design of RAMI4.0 services. We envision a methodology based on object-oriented analysis and design principles. The rationale behind our approach is the similarity that holds between objects and assets as I4.0 components. Data and functions within objects are accessible through method invocations; data and functions of assets are accessible through service invocations. The paper outlines the use of this approach in defining RAMI4.0 services for a software system being designed to support decision making under events that disrupt manufacturing operations.