Users count on digital identities to make everyday's tasks, therefore digital identities become valuable assets. Within networked and interconnected information systems arena, where digital identity related risks arise, effective digital identity management is required in order to secure and protect them. We provide from the literature and discuss taxonomy of digital identity management based on definition-focus. While, user-supremacy processes guarantee user control over attributes and privacy but they should be integrated and aligned to common networked information systems' security policies and business strategy. We argument that digital identity management should change from being vertical or functional into inter-information systems and horizontal integrated business processes with service orientations. We point out that SoaML-based methodology would help to decompose and reduce digital identity management requirements into a set of collaborative services.