Decentralized identities take a user-centric approach, which means that users are in control of their identity information. This allows users to share only selected information with specific service providers. One challenge associated with decentralized identities is managing the issuance and verification of digital identities within the software development process. There are standards and systems for decentralized identities, but an engineering approach is still missing. In this article, we focus on microservice-based applications. Several vendors offer decentralized identity systems that support the issuance and verification of digital credentials. During the development of an application, the concepts of decentralized identities need to be applied in a systematic way. The core contribution of this publication are the engineering processes for issuance and verification that address the requirements and architectural challenges associated with decentralized identities. During development, we consider how decentralized identities can be integrated into a microservice architecture in a loosely coupled manner. We illustrate the applicability by demonstrating how the engineering concepts of decentralized identities can be applied within a proof of concept, the DrivingLicensePoC. This PoC consists of two microservice-based applications, one for the issuance of a digital driving license and one for the verification of this digital driving license in the context of a car rental. In addition, we address the interoperability aspects of DI integration that need to be addressed.